Neuroimaging Insights: Kava's (Piper methysticum) Effect on Dorsal Anterior Cingulate Cortex GABA in Generalized Anxiety Disorder

Generalised Anxiety Disorder (GAD) is a prevalent, chronic mental health disorder. The measurement of regional brain gamma-aminobutyric acid (GABA) offers insight into its role in anxiety and is a potential biomarker for treatment response. Research literature suggests Piper methysticum (Kava) is efficacious as an anxiety treatment, but no study has assessed its effects on central GABA levels. This study investigated dorsal anterior cingulate (dACC) GABA levels in 37 adult participants with GAD. GABA was measured using proton magnetic resonance spectroscopy (1H-MRS) at baseline and following an eight-week administration of Kava (standardised to 120 mg kavalactones twice daily) (n = 20) or placebo (n = 17). This study was part of the Kava for the Treatment of GAD (KGAD; ClinicalTrials.gov: NCT02219880), a 16-week intervention study. Compared with the placebo group, the Kava group had a significant reduction in dACC GABA (p = 0.049) at eight weeks. Baseline anxiety scores on the HAM-A were positively correlated with GABA levels but were not significantly related to treatment. Central GABA reductions following Kava treatment may signal an inhibitory effect, which, if considered efficacious, suggests that GABA levels are modulated by Kava, independent of reported anxiety symptoms. dACC GABA patterns suggest a functional role of higher levels in clinical anxiety but warrants further research for symptom benefit. Findings suggest that dACC GABA levels previously un-examined in GAD could serve as a biomarker for diagnosis and treatment response.

Characterization of Different Forms of Kava (Piper methysticum) Products by UPLC-MS/MS

There are several forms of kava (Piper methysticum) products available for human consumption, and many factors are known to influence their chemical compositions and therefore their pharmacological properties. Because of the increased popularity of kava intake, a rigorous characterization of their content diversity is prerequisite, particularly due to its known potential to cause hepatotoxicity. To understand the composition diversity of kavalactones and flavokavains in commercial kava products, we developed a UPLC-MS/MS-based analytical method for the quantification of six kavalactones (kavain, dihydrokavain, methysticin, dihydromethysticin, yangonin and desmethoxyyangonin) and two flavokavains (flavokavains A and B) and analyzed their contents in 28 different kava products in the form of capsules, tinctures, traditional aqueous suspensions and dried powders. Our results demonstrated a great variation in terms of the total and relative abundance of the analyzed kavalactones and flavokavains among the analyzed kava preparations. More importantly, the kavalactone abundance in the product label could differ up to 90% from our experimental measurements. Therefore, more rigorous and comprehensive quality control of kava products is required with respect to the content of individual kavalactones and flavokavains. Accurate content information is essential to understand the pharmacological properties and safety of different kava products.

Clinical pharmacokinetics of kavalactones after oral dosing of standardized kava extract in healthy volunteers

ETHNOPHARMACOLOGICAL RELEVANCE

Piper methysticum G. Forst. (Piperaceae), commonly known as kava, has been used as a traditional beverage for centuries for its relaxing properties. Kavalactones are considered to be the major constituents responsible for kava's beneficial effects. Despite the extensive use of kava, clinical pharmacokinetic data is not available in the literature; therefore, the findings of this study will be critical for the dosage calculations for future clinical evaluation of kava.

AIM OF THE STUDY

The aim of the current study is to examine the clinical pharmacokinetics of six major kavalactones following oral dosing of flavokavain A/B-free standardized kava extract capsules in healthy volunteers using two dosage regimens.

MATERIALS AND METHODS

A sensitive, reliable, and specific ultra-high pressure liquid chromatography-mass spectrometry (UPLC-MS/MS) method was developed and validated for the simultaneous quantification of six major kavalactones (kavain, dihydrokavain, methysticin, dihydromethysticin, yangonin, and desmethoxyyangonin) and two flavokavains (A and B) in human plasma. Pharmacokinetic profiles were assessed in ten healthy volunteers after oral doses of standardized kava product, and plasma samples were analyzed for six kavalactones and two flavokavains using the validated UPLC-MS/MS method. Concentration-time data was subjected to pharmacokinetic analysis.

RESULTS

The systemic exposure of the kavalactones was found to be in the following order: dihydrokavain > dihydromethysticin > kavain > methysticin > yangonin. Desmethoxyyangonin was quantifiable only at a couple of time points, while flavokavain A and flavokavain B were not present in any of the plasma samples. Fast absorption of five kavalactones was observed with time to reach the maximum plasma concentration of 1-3 h. A dose proportionality in pharmacokinetics was established from 75 to 225 mg of kavalactone doses. In the multiple-dose study, a significant reduction in the extent of absorption of kavalactones with food was observed.

CONCLUSION

Single and multiple-dose clinical pharmacokinetic studies for kava were performed in healthy volunteers, and higher exposure to the kavalactones was observed after single-dosing (225 mg), while a longer duration of exposure was observed after three times a day (3 x 75 mg) dosing.

Biopharmaceutical evaluation of kavain in Piper methysticum G. Forst dried extract: Equilibrium solubility and intestinal permeability in Caco-2 cell model

ETHNOPHARMACOLOGICAL RELEVANCE

Piper methysticum G. Forst, popularly known as kava, is a traditional medicinal plant native from South Pacific islands and widely used to treat anxiety, depression and stress. The psychoactive properties are related to the kavalactones, mainly kavain.

AIM OF THE STUDY

To evaluate the biopharmaceutical properties of synthetic kavain and when present in kava dried extracts by means of equilibrium solubility and intestinal permeability studies in the Caco-2 cell model.

MATERIALS AND METHODS

The equilibrium solubility of kavain was performed using a shake flask incubator at 37 °C in different media at physiological pH range (1.2-6.8). The intestinal permeability of kavain evaluated in Caco-2 cells in the presence and absence of the P-glycoprotein inhibitor verapamil. Kavain concentrations were determined by reversed phase high performance liquid chromatography (HPLC).

RESULTS

HPLC methods were developed and fully validated for kavain quantitation. Kavain demonstrated low solubility and the pH of the aqueous media did not affect its solubility. Kavain was found to be highly permeable and efflux of kavain mediated by P-glycoprotein was not significant during intestinal permeation.

CONCLUSION

The results of biopharmaceutical studies provided useful information for predicting availability of kavain from the gastrointestinal tract and this compound was ranked as BCS Class II, exhibiting dissolution rate-limited absorption.

Investigating volatiles as the secondary metabolome of Piper methysticum from root powder and water extracts using comprehensive two-dimensional gas chromatography

ETHNOPHARMACOLOGICAL RELEVANCE

Kava (Piper methysticum G. Forst) is a plant grown in the Pacific that is used in traditional medicines. The roots are macerated and powdered for consumption as a beverage in social settings as well as in ceremonies. Other types of preparations can also be used as traditional medicines. There has been an increase in demand for kava as there is continued traditional use and as it is becoming utilized more both socially and medicinally outside of Oceania. Currently, most research of this plant has focused on bioactive kavalactones and flavokawains, and there are few studies focusing on the other compounds that kava contains, such as volatile and semivolatile components.

AIM OF THE STUDY

This study investigated the kava volatile organic compound (VOC) profile from nine different commercially available samples of dried, powdered kava root sourced across the Pacific region.

MATERIALS AND METHODS

The headspace above the kava samples was analyzed, both from the root powder as originally purchased and by performing a scaled-down extraction into water mimicking traditional preparation of the beverage. The headspace of each sample was extracted using solid-phase microextraction arrow (SPME Arrow), followed by analysis using comprehensive two-dimensional gas chromatography - quadrupole mass spectrometry/flame ionization detection (GC×GC-qMS/FID). The superior peak capacity of GC×GC was invaluable in effectively separating the complex mixture of compounds found in all samples, which enabled improved monitoring of minor differences between batches.

RESULTS

Dry root powder samples contained high levels of β-caryophyllene while water extracted samples showed high levels of camphene. Many alcohols, aldehydes, ketones, terpenes, terpenoids, and aromatics were also characterized from both types of samples. All water extracted samples from the different brands followed similar trends in terms of compounds being detected or not. Additional major compounds found in water extracts included benzaldehyde, hexanal, methoxyphenyloxime, camphor, limonene, 1-hexanol, endoborneol, and copaene. While some samples could be differentiated based on brand, samples did not group by purported geographic origin.

CONCLUSIONS

This study provides foundational data about a different subset of compounds within kava than previous research has studied, and also informs the community of the compounds that transfer into the consumed beverage during the traditional means of preparing kava.

Flavokawain C exhibits anti-tumor effects on in vivo HCT 116 xenograft and identification of its apoptosis-linked serum biomarkers via proteomic analysis

Chalcones and their derivatives belong to the flavonoid family. They have been extensively studied for their anticancer properties and some have been approved for clinical use. In this study, the in vivo anti-tumor activity of flavokawain C (FKC), a naturally occurring chalcone found in Kava (Piper methysticum Forst) was evaluated in HCT 116 cells (colon carcinoma). We also attempted to identify potential biomarkers and/or molecular targets in serum with applicability in predicting treatment outcome. The anti-tumor effects and toxicity of FKC were assessed using the xenograft nude mice model. Cisplatin was used as positive control. The anti-proliferative and apoptotic activities were then evaluated in tumor tissues treated with FKC. Furthermore, two-dimensional electrophoresis (2-DE) followed by protein identification using MALDI-TOF/TOF-MS/MS was performed to compare the serum proteome profiles between healthy nude mice and nude mice bearing HCT 116 tumor treated with vehicle solution and FKC, respectively. Our results showed that FKC treatment significantly inhibited HCT 116 tumor growth. In vivo toxicity studies showed that administration of FKC did not cause damage to major organs and had no significant effect on body weight. FKC was found to induce apoptosis in tumor, and this was associated with increased expression of cleaved caspase-3 and decreased expression of Ki67 in tumor tissues. Our proteomic analysis identified five proteins that changed in abundance - Ig mu chain C region (secreted form), GRP78, hemopexin, kininogen-1 and apolipoprotein E. Overall, our findings demonstrated the potential of FKC as an anti-cancer agent for the treatment of colon carcinoma.

Kava decreases the stereotyped behavior induced by amphetamine in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Kava extract (Piper methysticum) is a phytotherapic mainly used for the treatment of anxiety. Although the reported effects of Kava drinking improving psychotic symptoms of patients when it was introduced to relieve anxiety in aboriginal communities, its effects on models of psychosis-like symptoms are not investigated.

AIM OF THE STUDY

To investigate the effects of Kava extract on behavioral changes induced by amphetamine (AMPH) and its possible relation with alterations in monoamine oxidase (MAO) activity.

MATERIALS AND METHODS

Mice received vehicle or Kava extract by gavage and, 2 h after vehicle or AMPH intraperitoneally. Twenty-five minutes after AMPH administration, behavioral (elevated plus maze, open field, stereotyped behavior, social interaction and Y maze) and biochemical tests (MAO-A and MAO-B activity in cortex, hippocampus and striatum) were sequentially evaluated.

RESULTS

Kava extract exhibited anxiolytic effects in plus maze test, increased the locomotor activity of mice in open field test and decreased MAO-A (in cortex) and MAO-B (in hippocampus) activity of mice. Kava extract prevented the effects of AMPH on stereotyped behavior and, the association between Kava/AMPH increased the number of entries into arms in Y maze test as well as MAO-B activity in striatum. However, Kava extract did not prevent hyperlocomotion induced by AMPH in open field test. The social interaction was not modified by Kava extract and/or AMPH.

CONCLUSION

The results showed that Kava extract decreased the stereotyped behavior induced by AMPH at the same dose that promotes anxiolytic effects, which could be useful to minimize the psychotic symptoms in patients.

Kava as a Clinical Nutrient: Promises and Challenges

Kava beverages are typically prepared from the root of Piper methysticum. They have been consumed among Pacific Islanders for centuries. Kava extract preparations were once used as herbal drugs to treat anxiety in Europe. Kava is also marketed as a dietary supplement in the U.S. and is gaining popularity as a recreational drink in Western countries. Recent studies suggest that kava and its key phytochemicals have anti-inflammatory and anticancer effects, in addition to the well-documented neurological benefits. While its beneficial effects are widely recognized, rare hepatotoxicity had been associated with use of certain kava preparations, but there are no validations nor consistent mechanisms. Major challenges lie in the diversity of kava products and the lack of standardization, which has produced an unmet need for quality initiatives. This review aims to provide the scientific community and consumers, as well as regulatory agencies, with a broad overview on kava use and its related research. We first provide a historical background for its different uses and then discuss the current state of the research, including its chemical composition, possible mechanisms of action, and its therapeutic potential in treating inflammatory and neurological conditions, as well as cancer. We then discuss the challenges associated with kava use and research, focusing on the need for the detailed characterization of kava components and associated risks such as its reported hepatotoxicity. Lastly, given its growing popularity in clinical and recreational use, we emphasize the urgent need for quality control and quality assurance of kava products, pharmacokinetics, absorption, distribution, metabolism, excretion, and foundational pharmacology. These are essential in order to inform research into the molecular targets, cellular mechanisms, and creative use of early stage human clinical trials for designer kava modalities to inform and guide the design and execution of future randomized placebo controlled trials to maximize kava's clinical efficacy and to minimize its risks.

Kava and its Kavalactones Inhibit Norepinephrine-induced Intracellular Calcium Influx in Lung Cancer Cells

Kava, the extract of the roots of Piper methysticum, has been traditionally consumed in the South Pacific islands for its natural relaxing property. Epidemiological data suggests that kava consumption may reduce human cancer risk, and in vitro and in vivo models suggest chemopreventive potential against carcinogen-induced tumorigenesis. Therefore, knowledge about its molecular mechanisms and responsible ingredient(s) for these beneficial properties will better guide kava's use for the management of these disorders. Psychological stress typically results in increased production of stress hormones, such as norepinephrine (NE), which activate adrenergic receptors (ARs). Psychological stress has also been associated with increased cancer incidence and poor clinical outcomes in cancer patients. Mechanistically, binding of NE to ARs induces intracellular calcium influx, which activates downstream signaling pathways involved in both stress and cancer development. In this study, we characterized the effect of kava and its components, 3 fractions and 6 major kavalactones, on NE-induced intracellular calcium influx in H1299, a human non-small cell lung carcinoma cell line. Results show that kava extract effectively inhibits NE-mediated intracellular calcium influx in H1299 cells, potentially through antagonizing β-AR signaling. This inhibitory activity is recapitulated by the major kavalactones in kava. Among the 6 major kavalactones, DHK demonstrated the best potency. Taken together, our study suggests a novel mechanism through which kava and its ingredients potentially offer the anxiolytic and cancer-preventive activity.

Rapid detection and validated quantification of psychoactive compounds in complex plant matrices by direct analysis in real time-high resolution mass spectrometry - Application to "Kava" psychoactive pepper products

RATIONALE

Classified by the UNODC as a top 20 plant of concern, Piper methysticum (also known as Kava) is being increasingly abused recreationally for its mind-altering effects. It is of significant forensic relevance to establish methods to rapidly identifyand quantify psychoactive compounds, especially those yet to be scheduled ascontrolled substances and which have exhibited various noteworthy health concerns.

METHODS

Direct analysis in real time high-resolution mass spectrometry (DART-HRMS) demonstrated the ability to detect a range of kavalactones in Pipermethysticum derived products and plant material with no sample preparation. Inaddition, a validated method using calibration curves developed with a deuteratedinternal standard was used for the quantification of the psychoactive moleculeyangonin in various products.

RESULTS

DART-HRMS detected the protonated masses of six major kavalactonesand three flavokavains in 18 commercial Kava products. A method consistent withFDA validation guidelines was established for the quantification of yangonin in thevarious complex matrices. Implementation of this method, with an LLOQ of 5 mg/mL, enabled successful quantification of yangonin in 16 Kava products.Concentrations for solid products ranged from 2.71 to 8.99 mg/g, while that forliquid products ranged from 1.03 to 4.59 mg/mL.

CONCLUSIONS

Rapid identification and quantification of psychoactive smallmolecules in plant material can be accomplished using a validated DART-HRMSprotocol. This work illustrates an approach to qualitative and quantitative analysesof a wide variety of complex matrices derived from plants, and demonstrates thatthe commercially available products analyzed are P. methysticum derived and docontain psychoactive yangonin at quantifiable levels.

Monoamine Oxidase Inhibition by Kavalactones from Kava (Piper Methysticum)

Monoamine oxidases (MAOs) are key metabolic enzymes for neurotransmitter and dietary amines and are targets for the treatment of neuropsychiatric and neurodegenerative disorders. This study examined the MAO inhibition potential of kavain and other kavalactones from the roots of kava (Piper methysticum), a plant that has been used for its anxiolytic properties. (±)-Kavain was found to be a good potency in vitro inhibitor of human MAO-B with an IC₅₀ of 5.34 µM. (±)-Kavain is a weaker MAO-A inhibitor with an IC₅₀ of 19.0 µM. Under the same experimental conditions, the reference MAO inhibitor, curcumin, displays IC₅₀ values of 5.01 µM and 2.55 µM for the inhibition of MAO-A and MAO-B, respectively. It was further established that (±)-kavain interacts reversibly and competitively with MAO-A and MAO-B with enzyme-inhibitor dissociation constants (K_i) of 7.72 and 5.10 µM, respectively. Curcumin in turn, displays a K_i value of 3.08 µM for the inhibition of MAO-A. Based on these findings, other kavalactones (dihydrokavain, methysticin, dihydromethysticin, yangonin, and desmethoxyyangonin) were also evaluated as MAO inhibitors in this study. Yangonin proved to be the most potent MAO inhibitor with IC₅₀ values of 1.29 and 0.085 µM for MAO-A and MAO-B, respectively. It may be concluded that some of the central effects (e.g., anxiolytic) of kava may be mediated by MAO inhibition.

Identification of a Kavain Analog with Efficient Anti-inflammatory Effects

Kavain, a compound derived from Piper methysticum, has demonstrated anti-inflammatory properties. To optimize its drug properties, identification and development of new kavain-derived compounds was undertaken. A focused library of analogs was synthesized and their effects on Porphyromonas gingivalis (P. gingivalis) elicited inflammation were evaluated in vitro and in vivo. The library contained cyclohexenones (5,5-dimethyl substituted cyclohexenones) substituted with a benzoate derivative at the 3-position of the cyclohexanone. The most promising analog identifed was a methylated derivative of kavain, Kava-205Me (5,5-dimethyl-3-oxocyclohex-1-en-1-yl 4-methylbenzoate.) In an in vitro assay of anti-inflammatory effects, murine macrophages (BMM) and THP-1 cells were infected with P. gingivalis (MOI = 20:1) and a panel of cytokines were measured. Both cell types treated with Kava-205Me (10 to 200 μg/ml) showed significantly and dose-dependently reduced TNF-α secretion induced by P. gingivalis. In BMM, Kava-205Me also reduced secretion of other cytokines involved in the early phase of inflammation, including IL-12, eotaxin, RANTES, IL-10 and interferon-γ (p < 0.05). In vivo, in an acute model of P. gingivalis-induced calvarial destruction, administration of Kava-205Me significantly improved the rate of healing associated with reduced soft tissue inflammation and osteoclast activation. In an infective arthritis murine model induced by injection of collagen-antibody (ArthriomAb) + P. gingivalis, administration of Kava-205Me was able to reduce efficiently paw swelling and joint destruction. These results highlight the strong anti-inflammatory properties of Kava-205Me and strengthen the interest of testing such compounds in the management of P. gingivalis elicited inflammation, especially in the management of periodontitis.

Chemical and in vitro toxicity analysis of a supercritical fluid extract of Kava kava (Piper methysticum)

ETHNOPHARMACOLOGICAL RELEVANCE

Kava and kava extracts have shown great potential as a way to minimize anxiety-associated symptoms and to help alleviate pain. Hepatoxicity has been associated with the consumption of kava products. The chemical compounds, kavalactones (KL) and flavokavains (FK) have been implicated in kava's psychotropic and possible hepatotoxic properties.

AIM OF THE STUDY

To investigate the kavalactone and flavokavain content and in vitro toxicity of KAVOA™, a supercritical carbon dioxide extraction (SFE) of kava.

MATERIALS AND METHODS

Kavalactone and flavokavain content of SFE kava and noble kava root were determined following extraction in acetone, cell culture media, and water using ultra high-performance liquid chromatography (UHPLC). Using water extractions of the kava products, the cell viability and toxicity on the human hepatocellular carcinoma cell line (HepG2) were determined using luminescent and fluorescent assays, respectively. The half maximal inhibitory concentration (IC₅₀) of the SFE kava and noble kava root, extracted in cell culture media, were determined utilizing a luminescent cell viability assay.

RESULTS

Quantification of the KAVOA™, a SFE extract of kava and kava root showed similar profiles of kavalactone and flavokavain content. Water extracted SFE and root kava did not show a negative impact on cell viability and toxicity when compared to the vehicle control treated cells. IC₅₀ values were determined for the SFE kava and kava root extracted in cell culture media in respect to cell viability, 78.63 and 47.65 µg/mL, respectively.

CONCLUSIONS

KAVOA™, a supercritical carbon dioxide extract of kava displays a similar kavalactone profile to a noble variety of kava. In relation to total kavalactone content, KAVOA™ also has a lower content of the cytotoxic compound FKB. Aqueous extractions of KAVOA™ and noble kava root had no significant negative impact on cell viability and toxicity on HepG2 cells when compared to vehicle controlled treated cells. Results indicate KAVOA™ demonstrates a similar in vitro safety profile to that of noble kava root when experiments are normalized to kavalactone content.

A UHPLC-UV Method Development and Validation for Determining Kavalactones and Flavokavains in Piper methysticum (Kava)

An ultra-high-performance liquid chromatographic (UHPLC) separation was developed for six kava pyrones (methysticin, dihydromethysticin (DHM), kavain, dihydrokavain (DHK), desmethoxyyangonin (DMY), and yangonin), two unidentified components, and three Flavokavains (Flavokavain A, B, and C) in Piper methysticum (kava). The six major kavalactones and three flavokavains are completely separated (Rs > 1.5) within 15 min using a HSS T3 column and a mobile phase at 60 °C. All the peaks in the LC chromatogram of kava extract or standard solutions were structurally confirmed by LC-UV-MS/MS. The degradations of yangonin and flavokavains were observed among the method development. The degradation products were identified as cis-isomerization by MS/MS spectra. The isomerization was prevented or limited by sample preparation in a non-alcoholic solvent or with no water. The method uses the six kava pyrones and three flavokavains as external standards. The quantitative calibration curves are linear, covering a range of 0.5⁻75 μg/mL for the six kava pyrones and 0.05⁻7.5 μg/mL for the three flavokavains. The quantitation limits for methysticin, DHM, kavain, DHK, DMY, and yangonin are approximately 0.454, 0.480, 0.277, 0.686, 0.189, and 0.422 μg/mL. The limit of quantification (LOQs) of the three flavokavains are about 0.270, 0.062, and 0.303 μg/mL for flavokavain C (FKC), flavokavain A (FKA), and flavokavain B (FKB). The average recoveries at three different levels are 99.0⁻102.3% for kavalactones (KLs) and 98.1⁻102.9% for flavokavains (FKs). This study demonstrates that the method of analysis offers convenience and adequate sensitivity for determining methysticin, DHM, kavain, DHK, yangonin, DMY, FKA, FKB, and FKC in kava raw materials (root and CO₂ extract) and finished products (dry-filled capsule and tablet).

Single-Lab Validation for Determination of Kavalactones and Flavokavains in Piper methysticum (Kava)

Piper methysticum (Kava) is a plant whose roots are used in the preparation of traditional beverages with spiritual, medicinal, and social importance for the Pacific Islanders. Kava is also sold as a herbal supplement or recreational beverage consumed for its mild inebriating effect in Europe and North America. With an ongoing interest in the safety and quality of kava products, it is necessary to develop a validated method for determination of kava chemical composition to ensure confidence in quality assessment. Thus, an high-performance liquid chromatography with ultraviolet detection (HPLC-UV) method was developed, optimized, and validated for determining six major kavalactones and three flavokavains in kava raw materials and finished products based on AOAC single-laboratory validation guidelines. This is the first fully validated analytical method for measuring kavalactones and flavokavains in a single run. The separation of the analytes was achieved in 10 min with an Agilent Poroshell C18 column using gradient separation. The sample was extracted with methanol first and then acetone. The signals were detected at 240 nm and 355 nm. The limit of quantification was under 1.2 µg/mL (0.3 mg/g) for kavalactones and under 0.35 µg/mL (0.01 mg/g) for flavokavains. The Horwitz ratio values described ranged from 0.3 to 1.82. The spike recovery experiments showed an accuracy between 92 and 105% for all analytes. The results of the study demonstrate that the method is fit for the purpose of determining methysticin, dihydromethysticin, kavain, dihydrokavain, yangonin, desmethoxyyangonin, flavokavain A, flavokavain B, and flavokavain C in kava raw material and finished products (dry-filled capsule, liquid phytocaps, and tincture).

Three new kavalactone dimers from Piper methysticum (kava)

Three new dimeric kavalactones, designated as diyangonins A-C (1-3), along with two known analogs were isolated from the roots of Piper methysticum. Their structures were elucidated by means of extensive analysis of their 1D, 2D NMR, and mass spectroscopic data. All these dimers possess a skeleton featuring a cyclobutane ring connecting two kavalactone units in head-to-tail or head-to-head mode. Compounds 1-5 were evaluated for their cytotoxic activities against human tumor cell lines.

Isolation and Purification of Potent Growth Inhibitors from Piper methysticum Root

Piper methysticum (kava) root is known to possess promising weed suppressing activity. The present study was conducted to search for potent plant growth inhibitors from the root of this medicinal pepper plant. The ethyl acetate (EtOAc) extract exhibited the strongest reduction on growth of Raphanus sativus (radish) (IC₅₀ shoot and root growth = 172.00 and 51.31 µg/mL respectively) among solvent extracts. From this active extract, nine potent growth inhibitors involved in the inhibitory activities of P. methysticum root were isolated, purified and characterized by column chromatography (CC), gas chromatography-mass spectrometry (GC-MS), electrospray ionization-mass spectrometry (ESI-MS) and nuclear magnetic resonance (NMR). The six fractions purified by CC included two flavanones: 5-hydroxy-4′,7-dimethoxyflavanone (C1) and 5,7-dihydroxy-4′-methoxy-6,8-dimethylflavanone (matteucinol, C2) and six kavalactones: 5,6-dehydro-kavain (C3), a mixture of kavain and yagonin (C4), yagonin (C5) and dihydro-5,6-dehydrokavain, 7,8-dihydrokavain, dihydromethysticin and methysticin (C6). The amounts of 5-hydroxy-4′,7-dimethoxyflavanone, matteucinol, 5,6-dehydrokavain and yangonin were 0.76, 2.50, 2.75 and 2.09 mg/g dry weight (DW), respectively. The two flavanones C1 and C2 exhibited the strongest inhibition on shoot elongation (IC₅₀ = 120.22 and 248.03 µg/mL, respectively), whilst the two kavalactone mixtures C4 and C6 showed the highest suppression on root growth of R. sativus (IC₅₀ = 7.70 and 15.67 µg/mL, respectively). This study was the first to report the purification and inhibitory activities of the two flavanones 5-hydroxy-4′,7-dimethoxyflavanone and matteucinol in P. methysticum root. The isolated constituents from P. methysticum root including the flavanones C1 and C2 and the mixtures C4 and C6 may possess distinct modes of action on plant growth. Findings of this study highlighted that the combinations of hexane-ethyl acetate by 9:1 and 8:2 ratios successfully purified flavanones and kavalactones in P. methysticum root.

A stable isotope dilution tandem mass spectrometry method of major kavalactones and its applications

Kava is regaining its popularity with detailed characterizations warranted. We developed an ultraperformance liquid chromatography high-resolution tandem mass spectrometry (UPLC-MS/MS) method for major kavalactones (kavain, dihydrokavain, methysticin, dihydromethysticin and desmethoxyyangonin) with excellent selectivity and specificity. The method has been validated for different matrices following the Food and Drug Administration guidance of analytical procedures and methods validation. The scope of this method has been demonstrated by quantifying these kavalactones in two kava products, characterizing their tissue distribution and pharmacokinetics in mice, and detecting their presence in human urines and plasmas upon kava intake. As expected, the abundances of these kavalactones differed significantly in kava products. All of them exhibited a large volume of distribution with extensive tissue affinity and adequate mean residence time (MRT) in mice. This method also successfully quantified these kavalactones in human body fluids upon kava consumption at the recommended human dose. This UPLC-MS/MS method therefore can be used to characterize kava products and its pharmacokinetics in animals and in humans.

Natural Products from Single Plants as Sleep Aids: A Systematic Review

Insufficient sleep, insomnia, and sleep-related problems are important health issues, as their overall prevalence accounts for about 30% of the general population. The aim of this study was to systematically review previous studies investigating the effects of orally administered single plant-derived extracts on sleep-related outcomes in humans. Data sources were PubMed, Google Scholar, and Cochrane Library. The data search was conducted in two steps: step 1, names of plants which have been studied as sleep aids in humans were searched and retrieved; and step 2, each ingredient listed in step 1 was then added into the search term. Only original articles or reviews were applicable to the scope of this review. Studies on human subjects, with or without sleep-related disorders, were included. Sleep-related disorders refer to not only insomnia or sleep behavior disorders but also diseases with sleep-related symptoms. Studies were considered eligible for this review when the plant extracts were administered orally. Outcome measures relevant to sleep quality, duration, or other sleep-related problems were included. Twenty-one plants were listed in the first step of the search as potential candidates for natural sleep aids. Seventy-nine articles using these single plant-derived natural products were included in the final review. Although valerian was most frequently studied, conflicting results were reported, possibly due to the various outcome measures of each study. Other plants were not as rigorously tested in human studies. There was limited evidence with inconclusive results regarding the effects of single plant-derived natural products on sleep, warranting further studies.

Kava-241 reduced periodontal destruction in a collagen antibody primed Porphyromonas gingivalis model of periodontitis

AIM

The aim of this study was to evaluate the effect of Kava-241, an optimized Piper methysticum Kava compound, on periodontal destruction in a collagen antibody primed oral gavage model of periodontitis.

METHODS

Experimental periodontitis was induced by oral gavage of Porphyromonas gingivalis (P. gingivalis) + type II collagen antibody (AB) in mice during 15 days. Mice were treated with Kava-241 concomitantly or prior to P. gingivalis gavage and compared to untreated mice. Comprehensive histomorphometric analyses were performed.

RESULTS

Oral gavage with P. gingivalis induced mild epithelial down-growth and alveolar bone loss, while oral gavage with additional AB priming had greater tissular destruction in comparison with gavage alone (p < .05). Kava-241 treatment significantly (p < .05) reduced epithelial down-growth (72%) and alveolar bone loss (36%) in P. gingivalis+AB group. This Kava-241 effect was associated to a reduction in inflammatory cell counts within soft tissues and an increase in fibroblasts (p < .05).

CONCLUSION

Priming with type II collagen antibody with oral gavage is a fast and reproducible model of periodontal destruction adequate for the evaluation of novel therapeutics. The effect of Kava-241 shows promise in the prevention and treatment of inflammation and alveolar bone loss associated with periodontitis. Further experiments are required to determine molecular pathways targeted by this therapeutic agent.

Quantitative Determination of Lactones in Piper methysticum (Kava-Kava) by Supercritical Fluid Chromatography

A fast and validated supercritical fluid chromatography method for the quantitative determination of major lactones in Piper methysticum, a plant used against nervous anxiety, stress, and restlessness, was developed. The baseline separation of dihydrokavain, demethoxyyangonin, kavain, yangonin, dihydromethysticin, and methysticin was possible in less than 4 min on an Aquity UPC² BEH 1.7 µm column, in combination with a mobile phase comprising CO₂ and methanol with diethylamine. The column temperature had a great impact on the results because only at 70 °C could kavain and yangonin be fully resolved. With correlation coefficients above 0.998, recovery rates between 95.9 and 104.1 % as well as limit of detection values below 1.5 ng on-column, the procedure fulfilled all validation requirements and was well suited for the quantitative analysis of commercial products containing P. methysticum root powder and/or extract. All of them contained the target analytes, however, the absolute content of lactones was quite variable. Accordingly, depending on the product, the total daily intake of lactones varied from 56 to 312 mg. Concerning speed, selectivity, and environmental friendly operation, this supercritical fluid chromatography approach surpasses all previously reported ones.

Utilizing Ayurvedic literature for the identification of novel phytochemical inhibitors of botulinum neurotoxin A

ETHNOPHARMACOLOGICAL RELEVANCE

Ayurveda, an ancient holistic system of health care practiced on the Indian subcontinent, utilizes a number of multi-plant formulations and is considered by many as a potential source for novel treatments, as well as the identification of new drugs. Our aim is to identify novel phytochemicals for the inhibition of bacterial exotoxin, botulinum neurotoxin A (BoNT/A) based on Ayurvedic literature. BoNT/A is released by Clostridium species, which when ingested, inhibits the release of acetylcholine by concentrating at the neuromuscular junction and causes flaccid paralysis, resulting in a condition termed as botulism, and may also lead to death due to respiratory arrest.

METHODS

Fifteen plants were selected from the book 'Diagnosis and treatment of diseases in Ayurveda' by Vaidya Bhagwan Dash and Lalitesh Kashyap, based on their frequency of use in the formulations used for the treatment of six diseases with neuromuscular symptoms similar to botulism. Phytochemicals from these plants were screened using in silico, and in vitro methods. Structures of 570 reported phytochemicals from 14 plants were docked inside six reported BoNT/A light chain crystal structures using ensemble docking module in Maestro (Schrödinger, LLE).

RESULTS

From the docking scores and structural diversity, nine compounds including acoric acid 1, three flavonoids, three coumarins derivatives, one kava lactone were selected and screened using an in vitro HPLC-based protease assay. The bioassay results showed that several compounds possess BoNT/A LC inhibition of 50-60% when compared to positive controls NSC 84094 and CB7967495 (80-95%).

CONCLUSION

Further testing of the active compounds identified from Ayurvedic literature and structure-activity studies of acoric acid 1 using more sensitive bioassays is under way. The identification of acoric acid 1, a novel scaffold against BoNT/A, exemplifies the utility of Ayurvedic literature for the discovery of novel drug leads.

Traditional preparations of kava (Piper methysticum) inhibit the growth of human colon cancer cells in vitro

BACKGROUND

Epidemiological studies indicate there is low incidence of colon cancer in the South Pacific islands, including Fiji, West Samoa, and Vanuatu. Cancer incidence has been shown to be inversely associated with kava (Piper methysticum G. Forst.) ingestion. Hypothesis/Purpose: Kava prepared traditionally will inhibit the growth of human cancer cells. This investigation entails preparation and analysis of kava extracts and study of the growth inhibitory activity of the extracts, alone and combined with hibiscus.

STUDY DESIGN

We will prepare kava as in Micronesia - as a water extract, high in particulate content, alone or combined with sea hibiscus (Hibiscus tiliaceus L.) - and examine the components and growth inhibitory activity.

METHODS

We obtained ground kava prepared in the traditional way from lateral roots and sea hibiscus mucilage and sap from different sources in Micronesia, and prepared water extracts (unfiltered, as well as filtered, since in traditional use the kava beverage contains a high particulate content) and partitions. We used the MTT assay to determine the growth inhibitory activity of the preparations on colon and breast cancer cells and nonmalignant intestinal epithelial cells. LC-MS analysis was used to examine the components of the kava and sea hibiscus extracts and partitions.

RESULTS

Traditional preparations of kava inhibit the growth of breast and colon cancer cells. Among the kava preparations, the order of decreasing activity was Fiji(2), Fiji(1), Hawaii; the unfiltered preparations from Fiji were more active than the filtered. Phytochemical analysis indicated that filtering reduced most kavalactone and chalcone content. For example, for Fiji(2), the ratio of dihydromethysticin in filtered/unfiltered kava was 0.01. Thus, for the extracts from Fiji, growth inhibitory activity correlates with the content of these compounds. Unfiltered and filtered kava from Fiji(1) were more active on malignant than nonmalignant intestinal epithelial cells. Since kava is prepared in Micronesia by squeezing the extract through sea hibiscus bark, we assayed the growth inhibitory activity of combinations of kava and sea hibiscus sap and found that sea hibiscus enhanced the growth inhibitory effect of kava.

CONCLUSION

Our results show that traditional kava, alone or combined with sea hibiscus, displays activity against human cancer cells and indicate it will be worthwhile to develop and further analyze these preparations to prevent and treat colon and other cancers. Our findings suggest it is important to examine the activity of plants in the form that people consume them.

Flavokawains A and B from kava (Piper methysticum) activate heat shock and antioxidant responses and protect against hydrogen peroxide-induced cell death in HepG2 hepatocytes

Context Flavokawains are secondary metabolites from the kava plant (Piper methysticum Forst. f., Piperaceae) that have anticancer properties and demonstrated oral efficacy in murine cancer models. However, flavokawains also have suspected roles in rare cases of kava-induced hepatotoxicity. Objective To compare the toxicity flavokawains A and B (FKA, FKB) and monitor the resulting transcriptional responses and cellular adaptation in the human hepatocyte cell line, HepG2. Materials and methods HepG2 were treated with 2-100 μM FKA or FKB for 24-48 h. Cellular viability was measured with calcein-AM and changes in signalling and gene expression were monitored by luciferase reporter assay, real-time PCR and Western blot of both total and nuclear protein extracts. To test for subsequent resistance to oxidative stress, cells were pretreated with 50 μM FKA, 10 μM FKB or 10 μM sulphoraphane (SFN) for 24 h, followed by 0.4-2.8 mM H2O2 for 48 h, and then viability was assessed. Results FKA (≤100 μM) was not toxic to HepG2, whereas FKB caused significant cell death (IC50=23.2 ± 0.8 μM). Both flavokawains activated Nrf2, increasing HMOX1 and GCLC expression and enhancing total glutathione levels over 2-fold (p < 0.05). FKA and FKB also activated HSF1, increasing HSPA1A and DNAJA4 expression. Also, flavokawain pretreatment mitigated cell death after a subsequent challenge with H2O2, with FKA being more effective than FKB, and similar to SFN. Conclusions Flavokawains promote an adaptive cellular response that protects hepatocytes against oxidative stress. We propose that FKA has potential as a chemopreventative or chemotherapeutic agent.

Kavain, the Major Constituent of the Anxiolytic Kava Extract, Potentiates GABAA Receptors: Functional Characteristics and Molecular Mechanism

Extracts of the pepper plant kava (Piper methysticum) are effective in alleviating anxiety in clinical trials. Despite the long-standing therapeutic interest in kava, the molecular target(s) of the pharmacologically active constituents, kavalactones have not been established. γ-Aminobutyric acid type A receptors (GABA_ARs) are assumed to be the in vivo molecular target of kavalactones based on data from binding assays, but evidence in support of a direct interaction between kavalactones and GABA_ARs is scarce and equivocal. In this study, we characterised the functional properties of the major anxiolytic kavalactone, kavain at human recombinant α1β2, β2γ2L, αxβ2γ2L (x = 1, 2, 3 and 5), α1βxγ2L (x = 1, 2 and 3) and α4β2δ GABA_ARs expressed in Xenopus oocytes using the two-electrode voltage clamp technique. We found that kavain positively modulated all receptors regardless of the subunit composition, but the degree of enhancement was greater at α4β2δ than at α1β2γ2L GABA_ARs. The modulatory effect of kavain was unaffected by flumazenil, indicating that kavain did not enhance GABA_ARs via the classical benzodiazepine binding site. The β3N265M point mutation which has been previously shown to profoundly decrease anaesthetic sensitivity, also diminished kavain-mediated potentiation. To our knowledge, this study is the first report of the functional characteristics of a single kavalactone at distinct GABA_AR subtypes, and presents the first experimental evidence in support of a direct interaction between a kavalactone and GABA_ARs.

Driving following Kava Use and Road Traffic Injuries: A Population-Based Case-Control Study in Fiji (TRIP 14)

Objective

To investigate the association between kava use and the risk of four-wheeled motor vehicle crashes in Fiji. Kava is a traditional beverage commonly consumed in many Pacific Island Countries. Herbal anxiolytics containing smaller doses of kava are more widely available.

Methods

Data for this population-based case-control study were collected from drivers of ‘case’ vehicles involved in serious injury-involved crashes (where at least one road user was killed or admitted to hospital for 12 hours or more) and ‘control’ vehicles representative of ‘driving time’ in the study base. Structured interviewer administered questionnaires collected self-reported participant data on demographic characteristics and a range of risk factors including kava use and potential confounders. Unconditional logistic regression models estimated odds ratios relating to the association between kava use and injury-involved crash risk.

Findings

Overall, 23% and 4% of drivers of case and control vehicles, respectively, reported consuming kava in the 12 hours prior to the crash or road survey. After controlling for assessed confounders, driving following kava use was associated with a four-fold increase in the odds of crash involvement (Odds ratio: 4.70; 95% CI: 1.90–11.63). The related population attributable risk was 18.37% (95% CI: 13.77–22.72). Acknowledging limited statistical power, we did not find a significant interaction in this association with concurrent alcohol use.

Conclusion

In this study conducted in a setting where recreational kava consumption is common, driving following the use of kava was associated with a significant excess of serious-injury involved road crashes. The precautionary principle would suggest road safety strategies should explicitly recommend avoiding driving following kava use, particularly in communities where recreational use is common.

German Kava Ban Lifted by Court: The Alleged Hepatotoxicity of Kava (Piper methysticum) as a Case of Ill-Defined Herbal Drug Identity, Lacking Quality Control, and Misguided Regulatory Politics

Kava, the rhizome and roots of Piper methysticum, are one of the most important social pillars of Melanesian societies. They have been used for more than 1000 years in social gatherings for the preparation of beverages with relaxing effects. During the colonial period, extract preparations found their way into Western medicinal systems, with experience especially concerning the treatment of situational anxiety dating back more than 100 years. It therefore came as a surprise when the safety of kava was suddenly questioned based on the observation of a series of case reports of liver toxicity in 1999 and 2000. These case reports ultimately led to a ban of kava products in Europe - a ban that has been contested because of the poor evidence of risks related to kava. Only recently, two German administrative courts decided that the decision of the regulatory authority to ban kava as a measure to ensure consumer safety was inappropriate and even associated with an increased risk due to the higher risk inherent to the therapeutic alternatives. This ruling can be considered as final for at least the German market, as no further appeal has been pursued by the regulatory authorities. However, in order to prevent further misunderstandings, especially in other markets, the current situation calls for a comprehensive presentation of the cardinal facts and misconceptions concerning kava and related drug quality issues.

Kava for the treatment of generalised anxiety disorder (K-GAD): study protocol for a randomised controlled trial

BACKGROUND

Generalised anxiety disorder (GAD) is a chronic and pervasive condition that generates high levels of psychological stress, and it is difficult to treat in the long term. Current pharmacotherapeutic options for GAD are in some cases only modestly effective, and may elicit undesirable side effects. Through targeted actions on the gamma-aminobutyric acid (GABA) pathway, the South Pacific medicinal plant kava (Piper methysticum) is a non-addictive, non-hypnotic anxiolytic with the potential to treat GAD. The evidence for the efficacy of kava for treating anxiety has been affirmed through clinical trials and meta-analyses. Recent research has also served to lessen safety concerns regarding the use of kava due to hepatotoxic risk, which is reflected in a recent German court overturning the previous kava ban in that country (which may in turn influence a reinstatement by the European Union). The aim of current research is to assess the efficacy of an 'aqueous noble cultivar rootstock extract' of kava in GAD in a larger longer term study. In addition, we plan to investigate the pharmacogenomic influence of GABA transporters on response, effects of kava on gene expression, and for the first time, the neurobiological correlates of treatment response via functional and metabolic imaging.

METHODS/DESIGN

This clinical trial is funded by the Australian National Health and Medical Research Council (APP1063383) and co-funded by MediHerb (Integria Healthcare (Australia) Pty. Ltd). The study is a phase III, multi-site, two-arm, 18-week, randomised, double-blind, placebo-controlled study using an aqueous extract of noble kava cultivar (standardised to 240 mg of kavalactones per day) versus matching placebo in 210 currently anxious participants with diagnosed GAD who are non-medicated. The study takes place at two sites: the Centre for Human Psychopharmacology (Swinburne University of Technology), Hawthorn, Melbourne, Australia; and the Academic Discipline of Psychiatry (The University of Queensland) based at the Royal Brisbane and Women's Hospital, Herston, Brisbane, Australia. Written informed consent will be obtained from each participant prior to commencement in the study. The primary outcome is the Structured Interview Guide for the Hamilton Anxiety Rating Scale (SIGH-A). The secondary outcomes involve a range of scales that assess affective disorder symptoms and quality of life outcomes, in addition to the study of mediating biomarkers of response (assessed via genomics and neuroimaging).

DISCUSSION

If this study demonstrates positive findings in support of the superiority of kava over placebo in the treatment of GAD, and also is shown to be safe, then this plant-medicine can be considered a 'first-line' therapy for GAD. Genomic and neuroimaging data may reveal clinical response patterns and provide more evidence of the neurobiological activity of the plant extract.

TRIAL REGISTRATION INFORMATION

ClinicalTrials.gov: NCT02219880 Date: 13 August 2014:.

Biotransformation of Flavokawains A, B, and C, Chalcones from Kava (Piper methysticum), by Human Liver Microsomes

The in vitro metabolism of flavokawains A, B, and C (FKA, FKB, FKC), methoxylated chalcones from Piper methysticum, was examined using human liver microsomes. Phase I metabolism and phase II metabolism (glucuronidation) as well as combined phase I+II metabolism were studied. For identification and structure elucidation of microsomal metabolites, LC-HRESIMS and NMR techniques were applied. Major phase I metabolites were generated by demethylation in position C-4 or C-4' and hydroxylation predominantly in position C-4, yielding FKC as phase I metabolite of FKA and FKB, helichrysetin as metabolite of FKA and FKC, and cardamonin as metabolite of FKC. To an even greater extent, flavokawains were metabolized in the presence of uridine diphosphate (UDP) glucuronic acid by microsomal UDP-glucuronosyl transferases. For all flavokawains, monoglucuronides (FKA-2'-O-glucuronide, FKB-2'-O-glucuronide, FKC-2'-O-glucuronide, FKC-4-O-glucuronide) were found as major phase II metabolites. The dominance of generated glucuronides suggests a role of conjugated chalcones as potential active compounds in vivo.

In vitro Toxicity and in vivo Immunomodulatory Effects of Flavokawain A and Flavokawain B in Balb/C Mice

Flavokawains are chalcones that can be found in the root extracts of the kava-kava (Piper methysticum) plant. Flavokawain A and flavokawain B are known to possess potential anti-inflammation and anti-cancer activities. Nevertheless, the effects of both these compounds on the normal function of the host have not been studied. There is a need to find agents that can enhance the functionality of the immune system without disturbing the homeostatic balance. This study aimed to determine the toxicity and immunomodulatory effects of flavokawain A and flavokawain B on Balb/c mice. Several assays were conducted, the MTT viability assay, cytokine detection (IL-2 and TNF-α), immunophenotyping of important immune markers, serum biochemical analysis and detection of nitric oxide levels. Based on our results, flavokawain A and B did not cause mortality and all mice were observed normal after the treatment period. Both flavokawains stimulated splenocyte proliferation, the secretion of IL-2 and TNF-α and raised the population of T cell subsets without significantly altering the level of several serum biochemical parameters. Overall, flavokawain A and B could serve as potential immune-modulator drugs without causing any toxicity, however further in vivo evidence is needed.

Dihydromethysticin from kava blocks tobacco carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone-induced lung tumorigenesis and differentially reduces DNA damage in A/J mice

We have previously shown that kava and its flavokavain-free Fraction B completely blocked 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced lung tumorigenesis in A/J mice with a preferential reduction in NNK-induced O (6)-methylguanine (O (6)-mG). In this study, we first identified natural (+)-dihydromethysticin (DHM) as a lead compound through evaluating the in vivo efficacy of five major compounds in Fraction B on reducing O (6)-mG in lung tissues. (+)-DHM demonstrated outstanding chemopreventive activity against NNK-induced lung tumorigenesis in A/J mice with 97% reduction of adenoma multiplicity at a dose of 0.05mg/g of diet (50 ppm). Synthetic (±)-DHM was equally effective as the natural (+)-DHM in these bioassays while a structurally similar analog, (+)-dihydrokavain (DHK), was completely inactive, revealing a sharp in vivo structure-activity relationship. Analyses of an expanded panel of NNK-induced DNA adducts revealed that DHM reduced a subset of DNA adducts in lung tissues derived from 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL, the active metabolite of NNK). Preliminary 17-week safety studies of DHM in A/J mice at a dose of 0.5mg/g of diet (at least 10× its minimum effective dose) revealed no adverse effects, suggesting that DHM is likely free of kava's hepatotoxic risk. These results demonstrate the outstanding efficacy and promising safety margin of DHM in preventing NNK-induced lung tumorigenesis in A/J mice, with a unique mechanism of action and high target specificity.

Kava blocks 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone-induced lung tumorigenesis in association with reducing O6-methylguanine DNA adduct in A/J mice

We previously reported the chemopreventive potential of kava against 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)- and benzo(a)pyrene (BaP)-induced lung tumorigenesis in A/J mice during the initiation and postinitiation stages. In this study, we investigated the tumorigenesis-stage specificity of kava, the potential active compounds, and the underlying mechanisms in NNK-induced lung tumorigenesis in A/J mice. In the first experiment, NNK-treated mice were given diets containing kava at a dose of 5 mg/g of diet during different periods. Kava treatments covering the initiation stage reduced the multiplicity of lung adenomas by approximately 99%. A minimum effective dose is yet to be defined because kava at two lower dosages (2.5 and 1.25 mg/g of diet) were equally effective as 5 mg/g of diet in completely inhibiting lung adenoma formation. Daily gavage of kava (one before, during, and after NNK treatment) completely blocked lung adenoma formation as well. Kavalactone-enriched fraction B fully recapitulated kava's chemopreventive efficacy, whereas kavalactone-free fractions A and C were much less effective. Mechanistically, kava and fraction B reduced NNK-induced DNA damage in lung tissues with a unique and preferential reduction in O(6)-methylguanine (O(6)-mG), the highly tumorigenic DNA damage by NNK, correlating and predictive of efficacy on blocking lung adenoma formation. Taken together, these results demonstrate the outstanding efficacy of kava in preventing NNK-induced lung tumorigenesis in A/J mice with high selectivity for the initiation stage in association with the reduction of O(6)-mG adduct in DNA. They also establish the knowledge basis for the identification of the active compound(s) in kava.

A plant kavalactone desmethoxyyangonin prevents inflammation and fulminant hepatitis in mice

Alpinia pricei Hayata is a Formosan plant which has been popularly used as nutraceutical or folk medicine for inflammation and various disorders. An active compound of the plant rhizomes, desmethoxyyangonin (DMY), was identified in this study for its novel effect against endotoxin lipopolysaccharide (LPS)-stimulated inflammation in murine macrophages and LPS/D-galactosamine (LPS/D-GalN)-induced fulminant hepatitis in mice. DMY was observed to significantly inhibit proliferation and activation of T cells ex vivo and the activity of several pro-inflammatory mediators in vitro. DMY also protected LPS/D-GalN−induced acute hepatic damages in mice through inhibiting aminotransferases activities and infiltrations of inflammatory macrophages, neutrophils and pathogenic T cells into the liver tissues. In addition, pretreatment with DMY significantly improved the survival rate of LPS/D-GalN−treated mice to 90% (9/10), compared to LPS/D-GalN−treated group (40%, 4/10). UPLC/MS platform-based comparative metabolomics approach was used to explore the serum metabolic profile in fulminant hepatic failure (FHF) mice with or without the DMY pretreatment. The results showed that LPS/D-GalN−induced hepatic damage is likely through perturbing amino acid metabolism, which leads to decreased pyruvate formation via catalysis of aminotransferases, and DMY treatment can prevent to a certain degree of these alterations in metabolic network in mouse caused by LPS/D-GalN. Mechanistic investigation demonstrated that DMY protects LPS or LPS/D-GalN−induced damages in cell or liver tissues mainly through de-regulating IKK/NFκB and Jak2/STAT3 signaling pathways. This report provides evidence-based knowledge to support the rationale for the use of A. pricei root extract in anti-inflammation and also its new function as hepatoprotetive agent against fulminant hepatitis.

Proposal for a kava quality standardization code

Rare cases of hepatotoxicity emerged with the use of kava drugs and dietary supplements prepared from rhizomes and roots of the South Pacific plant kava (Piper methysticum). Their psychoactive, anxiolytic, relaxing, and recreational ingredients are the kavalactones kavain, dihydrokavain, methysticin, dihydromethysticin, yangonin, and desmethoxyyangonin, but there is little evidence that these kavalactones or the non-kavalactones pipermethystine and flavokavain B are the culprits of the adverse hepatic reactions. It rather appears that poor quality of the kava material was responsible for the liver toxicity. Analysis of existing kava quality standardizations with focus on chemical, agricultural, manufacturing, nutritional, regulatory, and legislation backgrounds showed major shortcomings that could easily explain quality problems. We therefore suggest a uniform, internationally accepted device for kava quality standardizations that are in the interest of the consumers because of safety reasons and will meet the expectations of kava farmers, pharmaceutical manufacturers, regulators of agencies, and legislators. The initial step resides in the establishment of Pan-Pacific kava quality legislation as an important part of the proposed Kava Quality Standardization Code. In conclusion, a sophisticated approach to establish kava quality standardizations is needed for safe human use of kava as relaxing traditional beverages, the anxiolytic drugs, and recreational dietary supplements.

Kava extract, an herbal alternative for anxiety relief, potentiates acetaminophen-induced cytotoxicity in rat hepatic cells

The widely used over-the-counter analgesic acetaminophen (APAP) is the leading cause of acute liver failure in the United States and due to this high incidence, a recent FDA Advisory Board recommended lowering the maximum dose of APAP. Kava herbal dietary supplements have been implicated in several human liver failure cases leading to the ban of kava-containing products in several Western countries. In the US, the FDA has issued warnings about the potential adverse effects of kava, but kava dietary supplements are still available to consumers. In this study, we tested the potential of kava extract to potentiate APAP-induced hepatocyte cytotoxicity. In rat primary hepatocytes, co-treatment with kava and APAP caused 100% loss of cell viability, while the treatment of kava or APAP alone caused ∼50% and ∼30% loss of cell viability, respectively. APAP-induced glutathione (GSH) depletion was also potentiated by kava. Co-exposure to kava decreased cellular ATP concentrations, increased the formation of reactive oxygen species, and caused mitochondrial damage as indicated by a decrease in mitochondrial membrane potential. In addition, similar findings were obtained from a cultured rat liver cell line, clone-9. These observations indicate that kava potentiates APAP-induced cytotoxicity by increasing the magnitude of GSH depletion, resulting in oxidative stress and mitochondrial dysfunction, ultimately leading to cell death. These results highlight the potential for drug-dietary supplement interactions even with widely used over-the-counter drugs.

Re-introduction of kava (Piper methysticum) to the EU: is there a way forward?

Kava (Piper methysticum) is an effective anxiolytic that has been withdrawn from various consumer markets in European countries due to concerns over its hepatotoxicity. It is plausible that the reported hepatotoxicity may be due in part to plant substitution, or an incorrect cultivar, or plant parts being used (such as leaves or bark); thus both the plant chemotype and the plant part used may be critical factors. If re-institution of kava in the EU is to occur, more evidence is required to determine its safety and efficacy. Furthermore, according to current evidence, the study of traditional water soluble rhizome extracts using a noble cultivar of kava may be advised. The Kava Anxiety-Lowering Medication (KALM) project is due to start in late 2010 to address these considerations. The KALM project uses an aqueous rhizome extract of a noble cultivar of kava in participants with generalised anxiety and Generalised Anxiety Disorder (GAD). The project comprises of 1) an acute RCT, kava (180 mg of kavalactones) versus oxazepam and placebo in 20 anxious people, testing effects on cognition, mood, anxiety, and driving; 2) an 8-week RCT comparing kava (120 mg kavalactones) versus placebo in 100 patients with GAD. To assess differences between dosages, non-responders at 3 weeks will be titrated to 240 mg of kavalactones. The project will also assess the effects of kava on liver function tests and its side effects profile. A novel component of the project is the pharmacogenomic exploration of phenotypical responses (GABA system and cytochrome P450 markers). The results of the study may be of benefit to sufferers of anxiety and the future economy of the Pacific islands, potentially providing an important step in the way forward with kava.

Identification of methysticin as a potent and non-toxic NF-kappaB inhibitor from kava, potentially responsible for kava's chemopreventive activity

Nuclear factor-kappaB (NF-kappaB) is a transcription factor that plays an essential role in cancer development. The results of our recent chemopreventive study demonstrate that kava, a beverage in the South Pacific Islands, suppresses NF-kappaB activation in lung adenoma tissues, potentially a mechanism responsible for kava's chemopreventive activity. Methysticin is identified as a potent NF-kappaB inhibitor in kava with minimum toxicity. Other kava constituents, including four kavalactones of similar structures to methysticin, demonstrate minimum activities in inhibiting NF-kappaB.

Identification and characterization of kava-derived compounds mediating TNF-alpha suppression

There is a substantial unmet need for new classes of drugs that block TNF-alpha-mediated inflammation, and particularly for small molecule agents that can be taken orally. We have screened a library of natural products against an assay measuring TNF-alpha secretion in lipopolysaccharide-stimulated THP-1 cells, seeking compounds capable of interfering with the TNF-alpha-inducing transcription factor lipopolysaccharide-induced TNF-alpha factor. Among the active compounds were several produced by the kava plant (Piper mysticum), extracts of which have previously been linked to a range of therapeutic effects. When tested in vivo, a representative of these compounds, kavain, was found to render mice immune to lethal doses of lipopolysaccharide. Kavain displays promising pharmaceutical properties, including good solubility and high cell permeability, but pharmacokinetic experiments in mice showed relatively rapid clearance. A small set of kavain analogs was synthesized, resulting in compounds of similar or greater potency in vitro compared with kavain. Interestingly, a ring-opened analog of kavain inhibited TNF-alpha secretion in the cell-based assay and suppressed lipopolysaccharide-induced TNF-alpha factor expression in the same cells, whereas the other compounds inhibited TNF-alpha secretion without affecting lipopolysaccharide-induced TNF-alpha factor levels, indicating a potential divergence in mechanism of action.

Kava hepatotoxicity: comparison of aqueous, ethanolic, acetonic kava extracts and kava-herbs mixtures

ETHNOPHARMACOLOGICAL RELEVANCE

Ethanolic and acetonic kava extracts have previously been causally related to rare hepatotoxicity observed in patients from Germany and Switzerland, but causality assessment was not performed in cases of patients having taken the traditional aqueous kava extracts of South Pacific islands or kava-herbs mixtures.

AIM OF THE STUDY

To study the possible hepatotoxicity of aqueous kava extracts of the South Pacific Islands.

MATERIALS AND METHODS

Causality of hepatotoxicity by aqueous kava extracts and kava-herbs mixtures was assessed, using the updated score of the quantitative CIOMS (Council for the International Organizations of Medical Sciences).

RESULTS

Causality was established in five patients from New Caledonia, Australia, the United States and Germany for aqueous kava extracts and kava-herbs mixtures. A comparison with 9 patients from Germany and Switzerland with established causality of hepatotoxicity by ethanolic and acetonic kava extracts reveals that the clinical picture in all 14 patients is similar, independently whether aqueous, ethanolic and acetonic kava extracts or kava-herbs mixtures were used.

CONCLUSIONS

Kava hepatotoxicity occurs also with traditional aqueous kava extracts of the South Pacific islands and thereby independently from ethanol or acetone as chemical solvents, suggesting that the toxicity is linked to the kava plant itself with a possibly low quality of the used kava cultivar or kava plant part rather than to chemical solvents.

The social, cultural and medicinal use of kava for twelve Tongan born men living in Auckland, New Zealand

Kava consumption is a very popular practise amongst Pacific people especially amongst the Tongan communities. The purpose of this paper is to identify some of the key cultural, social and medicinal elements of kava use amongst Tongan men. Twelve face to face interviews in this study were undertaken. The paper argues that kava drinking is strongly linked to many of the ceremonial, social and cultural obligations that are deeply embedded within the Tongan culture. The positive uses of kava include medicinal purposes, male bonding, alternative to alcohol consumption, reaffirming and establishing relationships amongst other Tongan men, The men also stated negative uses of kava such as it made them lazy, tired so they were not able to go to work, a lack of sexual activities by being too tired have sex with their partners, and very expensive to buy in New Zealand.

AIM

The aim of this paper is to discuss and examine the social, cultural and medicinal kava use amongst twelve Tongan born men living in Auckland, New Zealand.

METHODS

The study used qualitative methods, specifically individual interviews were conducted in Tongan or English. Participants were recruited through community networks in Auckland. A number of Tongan churches, Tongan medical clinics such as Langimailie, and kava clubs were approached to recruit participants. The open ended interview schedule covered themes such as access, quantity, frequency, and problems associated with kava use. The interviews were conducted by a Tongan researcher either in English or Tongan. All interviews were translated and transcribed into English. A thematic analysis based on multiple readings of the transcripts was used The analysis identified commonalities and differences. The study was granted ethical approval by the University of Auckland Human Subjects Ethics Committee in December 2004. Interviews were conducted at the beginning of 2005. Interviews were undertaken in a place where the participants felt comfortable. Interview times were arranged at a time convenient for the participants. All participants were given information sheets prior to interviews, and participants were asked to sign consent forms before the interviews commenced. These forms were provided in Tongan and English versions. Most of the interviews ranged between one to three hours. Interviews were audiotaped, and confidentiality was maintained throughout the research.

PARTICIPANTS

Twelve men were interviewed. All participants were Tongan men born and raised in Tonga. The ages of men ranged between 30 and 75 years. Most of the men had been residing in New Zealand for over 30 years, although some men had only been in New Zealand between 2-18 years. Most of the men were employed and a few had retired from work. Most of these men also belonged to a church. All of the men who participated were married.

Herbal drug treatment

Herbal drug treatment has been known for centuries as a part of traditional medicine. Nowadays, it is still considered a useful and natural way to treat several medical conditions, including mental disturbances. The most frequently treated mental conditions include mood disorders (mainly depression), anxiety disorders, somatoform disorders, age-related cognitive decline, and sometimes psychotic disorders. Some herbal formulations, such as St. John's wort, have been analyzed in clinical trials to estimate their real value. The use of other herbal medicines, such as Kava-kava, valerian, and Ginkgo biloba is discussed.

Quantification of kavalactones and determination of kava (Piper methysticum) chemotypes using near-infrared reflectance spectroscopy for quality control in vanuatu

Kava ( Piper methysticum Forst f., Piperaceae) has anxiolytic properties and the ability to promote a state of relaxation without the loss of mental alertness. The rapid growth of the nutraceutical market between 1998 and 2000 has been stopped by a ban in Europe and Australia because of some suspicion of liver toxicity. It is now important to develop a fast, cheap, and reliable quality test to control kava exports. The aim of this study is to develop a calibration of the near-infrared reflectance spectroscopy (NIRS) using partial least-squares (PLS) regression. Two hundred thirty-six samples of kava roots, stumps, and basal stems were collected from the Vanuatu Agricultural Research and Technical Centre germplasm collection and from four villages. These samples, representing 45 different varieties, were analyzed using NIRS to record their absorption spectra between 400 and 2500 nm. A set of 101 selected samples was analyzed for their kavalactone content using HPLC. The results were used for PLS calibration of the NIRS. The NIRS prediction of the kavalactone content and the dry matter were in agreement with the HPLC results. There were good correlations between these two series of results, and coefficients ( R (2)) were all close to 1. The measurements were reproducible and had repeatability on par with the HPLC method. The NIRS system has been calibrated for the six major kavalactone content measurements, and it is suggested that this method could be used for quality control in Vanuatu.

Selection of bioavailability markers for herbal extracts based on in silico descriptors and their correlation to in vitro permeability

Bioavailability data for herbal supplements in humans is not readily available or is difficult to obtain, because of the complexity of the composition and the diversity of the constituents. Potency of an herbal extract is due to the synergistic interactions between several constituents. Thus, the use of in silico methods is an attractive alternative to predict the qualitative intestinal permeability of the active constituents for the selection of appropriate bioavailability markers. Molecular descriptors such as CLogP, minimal cross-sectional area and polar surface area of 37 active components from selected herbal extracts such as milk thistle, kava, ginkgo, ginseng, valerian, black cohosh and garlic were estimated. In vitro permeability of the compounds was determined by SimBioDAS an in vitro epithelial cell permeability assay. Based on the in silico descriptors and their relationship with the in vitro permeability, the qualitative intestinal permeability of the active compounds was predicted. Bioavailability and bioequivalence markers were predicted for kava, Ginkgo biloba and milk thistle. Choosing a compound which has the least intestinal permeability as a marker is the most conservative approach toward ensuring the bioavailability of the entire extract.

Lipid peroxidation and cyclooxygenase enzyme inhibitory activities of acidic aqueous extracts of some dietary supplements

The botanical supplement market is growing at a fast pace with more and more people resorting to them for maintaining good health. Echinacea, garlic, ginkgo, ginseng, Siberian ginseng, grape seed extract, kava kava, saw palmetto and St John's wort are some of the popular supplements used for a variety of health benefits. These supplements are associated with various product claims, which suggest that they possess cyclooxygenase (COX) enzyme and lipid s inhibitory activities. COX enzymes are found to be at elevated levels in inflamed and cancerous cells. To test some of the product claims, selected supplements were analysed for their ability to inhibit COX-1 and -2 enzymes and lipid peroxidation in vitro. The supplements were extracted with acidified water (pH 2) at 37 degrees C to simulate the gastric environment. The supplements tested demonstrated varying degrees of COX enzyme inhibition (5-85% for COX-1 and 13-28% for COX-2). Interestingly, extracts of garlic (Meijer), ginkgo (Solaray), ginseng (Nature's Way), Siberian ginseng (GNC, Nutrilite, Solaray, Natrol), kava kava (GNC, Sundown, Solaray) and St John's wort (Nutrilite) selectively inhibited COX-2 enzyme. These supplements also inhibited lipid peroxidation in vitro (5-99%). The results indicated that the consumption of these botanical supplements studied possess health benefits.

Validation of high-performance thin-layer chromatographic methods for the identification of botanicals in a cGMP environment

Current Good Manufacturing Practices (cGMP) for botanicals stipulates the use of appropriate methods for identification of raw materials. Due to natural variability, chemical analysis of plant material is a great challenge and requires special approaches. This paper presents a comprehensive proposal to the process of validating qualitative high-performance thin-layer chromatographic (HPTLC) methods, proving that such methods are suitable for the purpose. The steps of the validation process are discussed and illustrated with examples taken from a project aiming at validation of methods for identification of green tea leaf, ginseng root, eleuthero root, echinacea root, black cohosh rhizome, licorice root, kava root, milk thistle aerial parts, feverfew aerial parts, and ginger root. The appendix of the paper, which includes complete documentation and method write-up for those plants, is available on the J. AOAC Int. Website (http://www.atypon-link.com/AOAC/loi/jaoi).

Is the alkaloid pipermethystine connected with the claimed liver toxicity of Kava products?

The pyridone alkaloid pipermethystine has been considered to be responsible for alleged hepatoxicity of Kava products. Investigation of a series of retain samples of finished products from the German market and self-produced extracts from root and stem material of Piper methysticum clearly showed that pipermethystine (1) is absent from all root and retain samples and extracts, with a limit of quantification of 45 ppm. As a positive control, leaves of P. methysticum showed an amount of 0.2% of 1. Thus, if there is any hepatotoxicity, compound 1 should not be the responsible constituent in the case reports with ethanolic extracts produced in Germany.

Toxicity of kava kava

Kava is a traditional beverage of various Pacific Basin countries. Kava has been introduced into the mainstream U.S. market principally as an anti-anxiety preparation. The effects of the long-term consumption of kava have not been documented adequately. Preliminary studies suggest possible serious organ system effects. The potential carcinogenicity of kava and its principal constituents are unknown. As such, kava extract was nominated for the chronic tumorigenicity bioassay conducted by the National Toxicology Program (NTP). At present toxicological evaluation of kava extract is being conducted by the NTP. The present review focuses on the recent findings on kava toxicity and the mechanisms by which kava induces hepatotoxicity.

Hepatocellular toxicity of kava leaf and root extracts

Kava extracts are used widely for different purposes and were thought to be safe. Recently, several cases of hepatotoxicity have been published. To explore possible mechanisms of kava hepatotoxicity, we prepared and analyzed three different kava extracts (a methanolic and an acetonic root and a methanolic leaf extract), and investigated their toxicity on HepG2 cells and isolated rat liver mitochondria. All three extracts showed cytotoxicity starting at a concentration of 50 microg/ml (lactate dehydrogenase leakage) or 1 microg/ml (MTT test). The mitochondrial membrane potential was decreased (root extracts starting at 50 microg/ml) and the respiratory chain inhibited and uncoupled (root extracts) or only uncoupled (leaf extract) at 150 microg/ml, and mitochondrial beta-oxidation was inhibited by all extracts starting at 100 microg/ml. The ratio oxidized to reduced glutathione was increased in HepG2 cells, whereas the cellular ATP content was maintained. Induction of apoptosis was demonstrated by all extracts at a concentration of 150 microg/ml. These results indicate that the kava extracts are toxic to mitochondria, leading to inhibition of the respiratory chain, increased ROS production, a decrease in the mitochondrial membrane potential and eventually to apoptosis of exposed cells. In predisposed patients, mitochondrial toxicity of kava extract may explain hepatic adverse reactions of this drug.