Antioxidant activity of guaiazulene and protection against paracetamol hepatotoxicity in rats

Guaiazulene and related compounds: A review of current perspective on biomedical applications

BACKGROUND

Thousands of people worldwide pass away yearly due to neurological disorders, cardiovascular illnesses, cancer, metabolic disorders, and microbial infections. Additionally, a sizable population has also been impacted by hepatotoxicity, ulcers, gastroesophageal reflux disease, and breast fissure. These ailments are likewise steadily increasing along with the increase in life expectancy. Finding innovative therapies to cure and consequently lessen the impact of these ailments is, therefore, a global concern.

METHODS AND MATERIALS

All provided literature on Guaiazulene (GA) and its related compounds were searched using various electronic databases such as PubMed, Google Scholar, Web of Science, Elsevier, Springer, ACS, CNKI, and books via the keywords Guaiazulene, Matricaria chamomilla, GA-related compounds, and Guaiazulene analogous.

RESULTS

The FDA has approved the bicyclic sesquiterpene GA, commonly referred to as azulon or 1,4-dimethyl-7-isopropylazulene, as a component in cosmetic colorants. The pleiotropic health advantages of GA and related substances, especially their antioxidant and anti-inflammatory effects, attracted a lot of research. Numerous studies have found that GA can help to manage various conditions, including bacterial infections, tumors, immunomodulation, expectorants, diuretics, diaphoresis, ulcers, dermatitis, proliferation, and gastritis. These conditions all involve lipid peroxidation and inflammatory response. In this review, we have covered the biomedical applications of GA. Moreover, we also emphasize the therapeutic potential of guaiazulene derivatives in pre-clinical and clinical settings, along with their underlying mechanism(s).

CONCLUSION

GA and its related compounds exhibit therapeutic potential in several diseases. Still, it is necessary to investigate their potential in animal models for various other ailments and establish their safety profile. They might be a good candidate to advance to clinical trials.

Azulene-Containing Squaraines for Photoacoustic Imaging and Photothermal Therapy

Photoacoustic imaging (PAI) guided photothermal therapy (PTT) can realize real-time diagnosis and in situ treatment of cancer at the same time. Absorption in the near-infrared (NIR) region with large molar extinction coefficient (ε) and high value of photothermal conversion efficiency (PCE) are key prerequisites for photothermal agents (PTAs) to realize dual PAI and PTT treatments. Squaraines have stable quinoid structures with strong planarity and rigidity, in favor of the NIR absorption and high ε values. On the other hand, azulene derivatives mostly have very faint fluorescence emission, which is beneficial for photothermal transformation. Herein, two azulene-containing squaraines Az-SQ-1 and Az-SQ-2 are synthesized as high-performance PTAs. In comparison with Az-SQ-1, Az-SQ-2 possesses larger ε_max of 3 × 10⁵ M^-1 cm^-1 at 780 nm in organic solution and higher PCE of 53.2% in the form of nanoparticles under 808 nm laser irradiation. Accordingly, Az-SQ-2 NPs present stronger photoacoustic signals (about 15.1-times the background signal) and more efficient suppression of tumor growth. Our research indicates that the introduction of azulene unit to traditional NIR dyes is a simple but effective approach to obtain outstanding PTAs in the aspect of phototheranostics.

Tumor-Specificity, Neurotoxicity, and Possible Involvement of the Nuclear Receptor Response Pathway of 4,6,8-Trimethyl Azulene Amide Derivatives

Background: Very few papers covering the anticancer activity of azulenes have been reported, as compared with those of antibacterial and anti-inflammatory activity. This led us to investigate the antitumor potential of fifteen 4,6,8-trimethyl azulene amide derivatives against oral malignant cells. Methods: 4,6,8-Trimethyl azulene amide derivatives were newly synthesized. Anticancer activity was evaluated by tumor-specificity against four human oral squamous cell carcinoma (OSCC) cell lines over three normal oral cells. Neurotoxicity was evaluated by cytotoxicity against three neuronal cell lines over normal oral cells. Apoptosis induction was evaluated by Western blot and cell cycle analyses. Results: Among fifteen derivatives, compounds 7, 9, and 15 showed the highest anticancer activity, and relatively lower neurotoxicity than doxorubicin, 5-fluorouracil (5-FU), and melphalan. They induced the accumulation of a comparable amount of a subG₁ population, but slightly lower extent of caspase activation, as compared with actinomycin D, used as an apoptosis inducer. The quantitative structure–activity relationship analysis suggests the significant correlation of tumor-specificity with a 3D shape of molecules, and possible involvement of inflammation and hormone receptor response pathways. Conclusions: Compounds 7 and 15 can be potential candidates of a lead compound for developing novel anticancer drugs.

Synthesis of C3-functionalized indole derivatives via Brønsted acid-catalyzed regioselective arylation of 2-indolylmethanols with guaiazulene

The first Brønsted acid catalyzed method for the construction of guaiazulenyl C3-functionalized indole derivatives was established. The reactions proceeded smoothly at ambient temperature by used (±)-10-camphorsulfonic acid (CSA) as catalyst,...

Guaiazulene Triggers ROS-Induced Apoptosis and Protective Autophagy in Non-small Cell Lung Cancer

Non-small cell lung cancer (NSCLC) is one of the most frequent cancers worldwide, yet effective treatment remains a clinical challenge. Guaiazulene (GYZ), a cosmetic color additive, has previously been characterized as a potential antitumor agent due to observed anticancer effects. However, the efficacy of GYZ in the treatment of NSCLC and the involved molecular mechanisms remain largely unknown. Here, we indicated a role for GYZ in the suppression of NSCLC both in vitro and in vivo via triggering reactive oxygen species (ROS)-induced apoptosis. Concomitantly, GYZ induced complete autophagic flux in NSCLC cells via inhibiting the Akt/mTOR signaling pathway, which displayed cytoprotective effect against GYZ-induced growth suppression. Accompanied with autophagy inhibition obviously enhanced the effects of GYZ. Notably, GYZ acts synergistically with paclitaxel in the suppression of NSCLC in vitro. Together, our results for the first time reported that GYZ suppressed the proliferation of NSCLC and suggested a potential strategy for inhibiting NSCLC growth by combinational use of GYZ and autophagy inhibitors.

Anti-inflammatory effect of photodynamic therapy using guaiazulene and red lasers on peripheral blood mononuclear cells

INTRODUCTION

Photodynamic therapy improves oral mucositis treatment. The reactive oxygen species (ROS) generated from this reaction could contribute to an anti-inflammatory effect by suppressing inflammatory cells.

OBJECTIVE

To evaluate the anti-inflammatory effect of photodynamic therapy using guaiazulene and a red laser in peripheral blood mononuclear cells (PBMCs).

METHODS

Guaiazulene solutions (1, 2, 5, 25, 35, and 100 μM in 99.8 % methanol) were irradiated with red laser light (625 nm, 146.2 mW/cm²) in continuous mode at 0, 4, and 8 J/cm² in black 96-well plates. ROS were measured using spin trapping technique with electron spin resonance (ESR) spectroscopy and fluorescence. The two highest concentrations were tested using cell viability (PrestoBlue®) and anti-inflammation (RANTES and PGE₂ ELISA) assay kits. Kruskal-Wallis and Dunn Bonferroni tests were used for statistical analyses with significant differences at p-value < 0.05.

RESULTS

Guaiazulene solutions between 2 and 5 μM exposed to red laser light at 4-8 J/cm² generated significantly more singlet oxygen compared to the no guaiazulene group (p < 0.01) and reduced RANTES and PGE₂ levels in TNF-α-inflamed peripheral blood mononuclear cells without affecting cell viability.

CONCLUSION

Photodynamic activation of guaiazulene generated singlet oxygen and suppressed inflammatory markers in PBMCs.

Sesquiterpenes in grapes and wines: Occurrence, biosynthesis, functionality, and influence of winemaking processes

Grapes are an important global horticultural product, and are mainly used for winemaking. Typically, grapes and wines are rich in various phytochemicals, including phenolics, terpenes, pyrazines, and benzenoids, with different compounds responsible for different nutritional and sensory properties. Among these compounds, sesquiterpenes, a subcategory of the terpenes, are attracting increasing interest as they affect aroma and have potential health benefits. The characteristics of sesquiterpenes in grapes and wines in terms of classification, biosynthesis pathway, and active functions have not been extensively reviewed. This paper summarizes 97 different sesquiterpenes reported in grapes and wines and reviews their biosynthesis pathways and relevant bio-regulation mechanisms. This review further discusses the functionalities of these sesquiterpenes including their aroma contribution to grapes and wines and potential health benefits, as well as how winemaking processes affect sesquiterpene concentrations.

E-Synthesis: A Bayesian Framework for Causal Assessment in Pharmacosurveillance

Background: Evidence suggesting adverse drug reactions often emerges unsystematically and unpredictably in form of anecdotal reports, case series and survey data. Safety trials and observational studies also provide crucial information regarding the (un-)safety of drugs. Hence, integrating multiple types of pharmacovigilance evidence is key to minimising the risks of harm.

Methods: In previous work, we began the development of a Bayesian framework for aggregating multiple types of evidence to assess the probability of a putative causal link between drugs and side effects. This framework arose out of a philosophical analysis of the Bradford Hill Guidelines. In this article, we expand the Bayesian framework and add “evidential modulators,” which bear on the assessment of the reliability of incoming study results. The overall framework for evidence synthesis, “E-Synthesis”, is then applied to a case study.

Results: Theoretically and computationally, E-Synthesis exploits coherence of partly or fully independent evidence converging towards the hypothesis of interest (or of conflicting evidence with respect to it), in order to update its posterior probability. With respect to other frameworks for evidence synthesis, our Bayesian model has the unique feature of grounding its inferential machinery on a consolidated theory of hypothesis confirmation (Bayesian epistemology), and in allowing any data from heterogeneous sources (cell-data, clinical trials, epidemiological studies), and methods (e.g., frequentist hypothesis testing, Bayesian adaptive trials, etc.) to be quantitatively integrated into the same inferential framework.

Conclusions: E-Synthesis is highly flexible concerning the allowed input, while at the same time relying on a consistent computational system, that is philosophically and statistically grounded. Furthermore, by introducing evidential modulators, and thereby breaking up the different dimensions of evidence (strength, relevance, reliability), E-Synthesis allows them to be explicitly tracked in updating causal hypotheses.

Xenobiotic Metabolising Enzymes: Impact on Pathologic Conditions, Drug Interactions and Drug Design

Background:

The biotransformation of xenobiotics is a homeostatic defensive response of the body against bioactive invaders. Xenobiotic metabolizing enzymes, important for the metabolism, elimination and detoxification of exogenous agents, are found in most tissues and organs and are distinguished into phase I and phase II enzymes, as well as phase III transporters. The cytochrome P450 superfamily of enzymes plays a major role in the biotransformation of most xenobiotics as well as in the metabolism of important endogenous substrates such as steroids and fatty acids. The activity and the potential toxicity of numerous drugs are strongly influenced by their biotransformation, mainly accomplished by the cytochrome P450 enzymes, one of the most versatile enzyme systems.

Objective:

In this review, considering the importance of drug metabolising enzymes in health and disease, some of our previous research results are presented, which, combined with newer findings, may assist in the elucidation of xenobiotic metabolism and in the development of more efficient drugs.

Conclusion:

Study of drug metabolism is of major importance for the development of drugs and provides insight into the control of human health. This review is an effort towards this direction and may find useful applications in related medical interventions or help in the development of more efficient drugs.

Trimethylphosphate as a Methylating Agent for Cross Coupling: A Slow-Release Mechanism for the Methylation of Arylboronic Esters

A methyl group on an arene, despite its small size, can have a profound influence on biologically active molecules. Typical methods to form a methylarene involve strong nucleophiles or strong and often toxic electrophiles. We report a strategy for a new, highly efficient, copper and iodide co-catalyzed methylation of aryl- and heteroarylboronic esters with the mild, nontoxic reagent trimethylphosphate, which has not been used previously in coupling reactions. We show that it reacts in all cases tested in yields that are higher than those of analogous copper-catalyzed reactions of MeOTs or MeI. The combination of C-H borylation and this methylation with trimethylphosphate provides a new approach to the functionalization of inert C-H bonds and is illustrated by late-stage methylation of four medicinally active compounds. In addition, reaction on a 200 mmol scale demonstrates reliability of this method. Mechanistic studies show that the reaction occurs by a slow release of methyl iodide by reaction of PO(OMe)₃ with iodide catalyst, rather than the typical direct oxidative addition to a metal center. The low concentration of the reactive electrophile enables selective reaction with an arylcopper intermediate, rather than nucleophilic groups on the arylboronate, and binding of tert-butoxide to the boronate inhibits reaction of the electrophile with the tert-butoxide activator to form methyl ether.

In Vitro Anti-tumor Activity of Azulene Amide Derivatives

BACKGROUND/AIM

There exist few research articles regarding the anticancer activity of azulene-related compounds. We investigated here the relative cytotoxicity of 10 azulene amide derivatives against cancer and normal cells.

MATERIALS AND METHODS

Cytotoxicity against four human oral squamous cell carcinoma (OSCC) cell lines and three human oral normal cells (gingival fibroblasts, periodontal ligament fibroblasts and pulp cells) was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetra-zolium bromide method. Antitumor activity was evaluated by tumor-specificity (TS) (ratio of mean 50% cytotoxic concentration (CC₅₀) against normal cells to that against OSCC cell lines) and potency-selectivity expression (PSE) (ratio of TS to CC₅₀ against tumor cells). Apoptosis-inducing activity was evaluated by cleavage of poly ADP-ribose polymerase and caspase-3 with western blot analysis.

RESULTS

N-Propylguaiazulenecarboxamide [1] showed the highest TS and PSE values, compared to that of doxorubicin, and induced apoptosis in two OSCC cell lines. QSAR analysis demonstrated that their tumor-specificity of azulene amide derivatives was correlated with hydrophobicity and molecular shape.

CONCLUSION

Compound [1] can be considered as a lead compound for manufacturing new anticancer drug candidates.

Rapid identification and global characterization of multiple constituents from the essential oil of Cortex Dictamni based on GC-MS

The root of Dictamnus dasycarpus Turcz., also known as Cortex Dictamni, is a Chinese herbal medicine that has been commonly used in the treatment of inflammation, microbial infection, cancer, and other diseases in China for thousands of years. Recently, the essential oil of Cortex Dictamni has been widely studied, and a large number of volatile constituents have been discovered. However, the research of the essential oil of Cortex Dictamni in vivo remains unknown, especially the constituents absorbed into blood after oral administration. Hence, a sensitive and rapid method using gas chromatography with mass spectrometry combined with MassHunter software and the National Institute of Standards and Technology 2014 database was used to investigate the absorbed components in rat serum after oral administration of the essential oil of Cortex Dictamni. With the established method, a total of 36 compounds were screened and identified in the essential oil of Cortex Dictamni based on the mass spectrometry data and compound database. Among them, eight compounds, elemol, thymol methyl ether, β-eudesmol, β-cyclocostunolid, guaiazulene, trans-4-hydroxystilbene, ethyl oleate, and monoelaidin, were tentatively characterized in rat serum. This work demonstrated that the established method proved to be a powerful technique for rapid, simple, reliable, and automated identification of bioactive components of herbal medicine.

Management of afatinib-induced stomatitis

Severe stomatitis may lead to the need to interrupt or discontinue cancer therapy and, thus, may affect control of the primary disease. Stomatitis may also increase the risk of local and systemic infection and significantly affects the quality of life and the cost of care. The present study was conducted to evaluate the efficacy of two traditional herbal medicines in controlling treatment-induced stomatitis in a small cohort of lung cancer patients treated with afatinib. All patients who were treated with afatinib for epidermal growth factor receptor (EGFR) mutated nonsmallcell lung cancer (NSCLC) between January, 2015 and March, 2016, were included in this study. During the study period, a total of 14 NSCLC patients were treated with afatinib, an EGFR-tyrosine kinase inhibitor (TKI). Two patients already had stomatitis at the time of initiation of afatinib therapy; among the remaining 12 NSCLC patients, 2 (16.7%) developed stomatitis. All the lesions in the 4 patients who developed stomatitis were completely alleviated after 2 weeks of therapy with Aznol mouthwash, a chamomile extract with anti-inflammatory effects, and Hangeshashinto, a traditional herbal (Kampo) medicine. Afatinib therapy was re-initiated, but none of the patients developed stomatitis thereafter. To the best of our knowledge, this is the first report evaluating oral care and management of stomatitis. This type of care and treatment may reduce the incidence of complications associated with EGFR-TKI therapy.

Guaiazulene biochemical activity and cytotoxic and genotoxic effects on rat neuron and N2a neuroblastom cells

AIM

Neuroblastoma (NB)cells are often used in cancer researches such as glioblastoma cells since they have the potential of high mitotic activity, nuclear pleomorphism, and tumor necrosis. Guaiazulene (GYZ 1,4-dimethyl-7-isopropylazulene)is present in several essential oils of medicinal and aromatic plants. Many studies have reported the cytotoxic effect of GYZ; however, there are no studies that compare such effects between cancer cell lines and normal human cells after treatment with GYZ.

MATERIALS AND METHODS

In this study, we aimed to describe in vitro antiproliferative and/or cytotoxic properties (by 3-[4,5 dimetylthiazol -2-yl]-2,5 diphenlytetrazolium bromide [MTT] test), oxidative effects (by total antioxidant capacity [TAC] and total oxidative stress [TOS] analysis)and genotoxic damage potentials (by single cell gel electrophoresis)of GYZ.

RESULT

The results indicated that GYZ have anti-proliferative activity suppressing the proliferation of neuron and N2a-NB cells at high doses. In addition, GYZ treatments at higher doses led to decreases of TAC levels and increases of TOS levels in neuron and N2a-NB cells. On the other hand, the mean values of the total scores of cells showing DNA damage were not found different from the control values.

CONCLUSION

From this study, it is observed that GYZ has in vitro cytotoxic activity against neuron and N2a-NB cells.

Assessment of the antioxidant and antiproliferative effects of sesquiterpenic compounds in in vitro Caco-2 cell models

In this study, the antiradical and antiproliferative effects of the sesquiterpenic compounds trans, trans-farnesol, cis-nerolidol, α-humulene and guaiazulene, commonly found in plants and plant-derived foods and beverages, were evaluated. Chemical (DPPH and hydroxyl radicals) and biological (Caco-2 cells) models were used. Guaiazulene (IC50=0.73mM) showed higher scavenger capacity against DPPH, while trans, trans-farnesol (IC50=1.81mM) and cis-nerolidol (IC50=1.48mM) were more active towards hydroxyl radicals. All compounds, with the exception of α-humulene, were able to protect Caco-2 cells from oxidative stress induced by tert-butyl hydroperoxide. As antiproliferative agents, guaiazulene and cis-nerolidol were more effective than trans, trans-farnesol and α-humulene. The results obtained for the sesquiterpenic compounds by these in vitro assays opens a perspective for their promising use as antioxidants and antiproliferative agents. However, in vivo tests should be carried out in the future to confirm their safety and effectiveness.

Hepatoprotection of sesquiterpenoids: a quantitative structure-activity relationship (QSAR) approach

The relative hepatoprotection effect of fifteen sesquiterpenoids, commonly found in plants and plant-derived foods and beverages was assessed. Endogenous lipid peroxidation (assay A) and induced lipid peroxidation (assay B) were evaluated in liver homogenates from Wistar rats by the thiobarbituric acid reactive species test. Sesquiterpenoids with different chemical structures were tested: trans,trans-farnesol, cis-nerolidol, (-)-α-bisabolol, trans-β-farnesene, germacrene D, α-humulene, β-caryophyllene, isocaryophyllene, (+)-valencene, guaiazulene, (-)-α-cedrene, (+)-aromadendrene, (-)-α-neoclovene, (-)-α-copaene, and (+)-cyclosativene. Ascorbic acid was used as a positive antioxidant control. With the exception of α-humulene, all the sesquiterpenoids under study (1mM) were effective in reducing the malonaldehyde levels in both endogenous and induced lipid peroxidation up to 35% and 70%, respectively. The 3D-QSAR models developed, relating the hepatoprotection activity with molecular properties, showed good fit (Radj(2) 0.819 and 0.972 for the assays A and B, respectively) with good prediction power (Q(2)>0.950 and SDEP<2%, for both models A and B). A network of effects associated with structural and chemical features of sesquiterpenoids such as shape, branching, symmetry, and presence of electronegative fragments, can modulate the hepatoprotective activity observed for these compounds.

Synthesis and biological evaluation of C-glucosides with azulene rings as selective SGLT2 inhibitors for the treatment of type 2 diabetes mellitus: discovery of YM543

Here, a series of C-glucosides with azulene rings in the aglycon moiety was synthesized and the inhibitory activities toward hSGLT1 and hSGLT2 were evaluated. Starting from the azulene derivative 7 which had relatively good SGLT2 inhibitory activity, compound 8a which has a 3-[(azulen-2-yl)methyl]phenyl group was identified as a lead compound for further optimization. Introduction of a phenolic hydroxyl group onto the central benzene ring afforded a potent and selective SGLT2 inhibitor 8e, which reduced blood glucose levels in a dose-dependent manner in rodent diabetic models. A mono choline salt of 8e (YM543) was selected as a clinical candidate for use in treating type 2 diabetes mellitus.

Phototoxicity of herbal plants and herbal products

Plants are used by humans in daily life in many different ways, including as food, herbal medicines, and cosmetics. Unfortunately, many natural plants and their chemical constituents are photocytotoxic and photogenotoxic, and these phototoxic phytochemicals are widely present in many different plant families. To date, information concerning the phototoxicity and photogenotoxicity of many plants and their chemical constituents is limited. In this review, we discuss phototoxic plants and their major phototoxic constituents; routes of human exposure; phototoxicity of these plants and their constituents; general mechanisms of phototoxicity of plants and phototoxic components; and several representative phototoxic plants and their photoactive chemical constituents.

Guaiazulene: a new treatment option for recalcitrant diaper dermatitis in NICU patients

AIM

Based on a maternal observation, we aimed to evaluate the treatment effectiveness of guaiazulene (GA) containing local pomade in the high-risk neonates with recalcitrant diaper dermatitis (RDD).

METHODS

We included 30 NICU patients of RDD, with level II-III aged between 22 and 67 days. Study group patients (n = 20) were treated with GA containing local pomade (0.05 g/100 g). Control group consisted of patients who had extended antifungal treatment. A visual scale was used to assess the response to treatment at the end of a week. Scoring was done at the beginning of the treatment, on the first, third and seventh days.

RESULTS

Statistically significant differences in visual scores were determined between the two groups at the initial and following days of the treatment. In study group, improvements at the first and third days of the treatment were better than those of control group. Additionally, complete recovery rate in study group was better than that in controls.

CONCLUSION

Having beneficial but no adverse effects, GA containing local pomade provided rapid recovery in risky neonates with RDD, who required rapid improvement.

Role of Grape Seed Extract on Methotrexate Induced Oxidative Stress in Rat Liver

The efficacy of methotrexate (MTX), a widely used cytotoxic chemotherapeutic agent, is often limited by its severe hepatotoxicity. Regarding the mechanisms of these adverse effects, several hypotheses have been put forward, among which oxidative stress is noticeable. The present study was undertaken to determine whether grape seed extract (GSE), a new natural free radical scavenger, could ameliorate the MTX-induced oxidative injury in the rat liver. The animals were divided into 3 groups. Each group consisted of 12 animals. MTX-GSE group: rats were given GSE (100mg/kg body weight) orally for 15 days, and a single dose of MTX (20mg/kg, intraperitoneally) was added on the 10th day. MTX group: these received placebo distilled water (orally) instead of GSE for 15 days and the same MTX protocol applied to this group on the 10th day. Control group: rats were given distilled water (orally) through 15 days and physiological saline (intraperitoneally) instead of MTX was administered on the 10th day in a similar manner. On the 16th day, liver tissue samples were obtained under deep anaesthesia. The level of malondialdehyde (MDA), an end product of lipid peroxidation, and the activities of süperoxide dismutase (SOD) and catalase (CAT), two important endogenous antioxidants, were evaluated in the tissue homogenates. MTX administration increased the MDA level and decreased the SOD and CAT activities in the liver homogenates ( p < 0.001), while these alterations were significantly reversed by GSE treatment ( p < 0.001). MTX led to significantly reduced whole blood count parameters ( p < 0.05). When GSE was supplemented, no significant changes in blood count parameters were noted. It appears that GSE protects the rat liver and inhibits methotrexate-induced oxidative stress. These data indicate that GSE may be of therapeutic benefit when used with MTX.

Cytotoxic activity of guaiazulene on gingival fibroblasts and the influence of light exposure on guaiazulene-induced cell death

Guaiazulene (GA) is widely used as a natural ingredient in many health care products and solutions. Although it has been reported to have interesting biological effects, GA and azulene derivatives have been proven to be cytotoxic against normal human cells and human tumor cells; moreover, guaiazulene has shown photomutagenic properties on bacterial strains. Therefore, we evaluated and compared the cytotoxicity of GA at different concentrations on human gingival fibroblast (HGF) cell cultures under normal conditions and under UV irradiation (UV-A dose: 6.4 J/cm(2)). The compound tested was found to significantly reduce cell viability (dose-dependent trend, IC(50) 72.1 μM), decrease protein procollagen α1 type I synthesis, a marker for HGF protein, and COL1A1 mRNA expression. The cytotoxic effects were accompanied by activation of an intrinsic apoptotic pathway, studied using transmission electron microscopy (TEM) and caspase-3 activation. The light exposure of the cell culture treated decreased GA-induced cell death (IC(50) 128.9 μM), suggesting a photoprotective effect due to the photodegradation of the toxic agent, guaiazulene. Furthermore, the products of the photodegradation reaction of GA proved not to be toxic against HGFs.

Study on the photostability of guaiazulene by high-performance liquid chromatography/mass spectrometry and gas chromatography/mass spectrometry

The photostability of guaiazulene (1,4-dimethyl-7-isopropylazulene; GA), a natural azulenic compound used in cosmetic and health-care products, as well as in pharmaceutical preparations, was investigated in solution (methanol, ethanol, acetonitrile), by different techniques: gas chromatography/mass spectrometry (GC/MS) and high-performance liquid chromatography combined with atmospheric pressure chemical ionization mass spectrometry and UV detection (LC/APCI-MS and HPLC/UV). A solar simulator (xenon-arc lamp) was used as UV-A radiation source. The study involved: monitoring compound decomposition, identifying products of photodegradation (PPs), assessing the role of oxygen and evaluating the kinetics of the process. Minor PPs are volatile compounds and were characterized by GC/MS, while oligomeric polyoxygenated compounds, tentatively characterized on the basis of MS and MS/MS spectra, were found to be the main photoproducts. The photodegradation was found to be enhanced by the presence of oxygen; nevertheless, determination of the singlet oxygen quantum yield for GA gave a lower value than that for the reference standard Rose Bengal. The obtained results and the developed stability-indicating methods (GC/MS and LC/MS) are of interest for stability studies and/or quality control purposes of GA as raw material or cosmetic products.

Design and study of some novel ibuprofen derivatives with potential nootropic and neuroprotective properties

Six novel ibuprofen derivatives and related structures, incorporating a proline moiety and designed for neurodegenerative disorders, are studied. They possess anti-inflammatory properties and three of them inhibited lipoxygenase. One compound was found to inhibit cyclooxygenase (COX)-2 production in spleenocytes from arthritic rats. The HS-containing compounds are potent antioxidants and one of them protected against glutathione loss after cerebral ischemia/reperfusion. They demonstrated lipid-lowering ability and seem to acquire low gastrointestinal toxicity. Acetylcholinesterase inhibitory activity, found in two of these compounds, may be an asset to their actions.

New analogues of butylated hydroxytoluene as anti-inflammatory and antioxidant agents

Amine or amide derivatives bearing the 2,6-di-tert-butyl phenol moiety are synthesised. Almost all are antioxidants, reduce acute inflammation and inhibit COX-1 and lipoxygenase activity. The most potent anti-inflammatory, COX-1 inhibitor and antioxidant agent, with low toxicity, is 2,6-di-tert-butyl-4-thiomorpholin-4-ylmethyl-phenol.

Attenuation of tamoxifen-induced hepatotoxicity by taurine in mice

BACKGROUND

One of the most attractive approaches to disease prevention involves the use of natural antioxidants to protect tissue against toxic injury. We investigated the modulatory effects of exogenously administered taurine on the toxicity of the anticancer drug tamoxifen with special reference to protection against disruption of drug metabolizing and antioxidant enzymes in Swiss albino mice.

METHODS

Male Swiss albino mice were divided into 4 groups. The extent of lipid peroxidation was evaluated in terms of thiobarbituric acid reactive substances formed. The following assays were performed in the hepatic tissue (a) antioxidant enzymes such as superoxide dismutase and catalase, (b) cytochrome P450 content, (c) glutathione-metabolizing enzymes such as glutathione peroxidase, glutathione reductase, glutathione-S-transferase and glucose 6-phosphate dehydrogenase, and (d) low molecular weight antioxidants (reduced glutathione, ascorbic acid) and protein carbonyl content.

RESULTS

Tamoxifen induced lipid peroxidation, protein carbonyl content and inhibited the enzymes of antioxidant defense system. It was also observed that the activities of antioxidant enzymes and glutathione-metabolizing enzymes were considerably stabilized in mice pretreated with taurine.

CONCLUSION

Taurine protects the integrity of the hepatic tissue by stabilizing the reactive oxygen species mediated lipid peroxidation and protein carbonyl formation. Additionally taurine may prove to be efficacious as an antioxidant in tamoxifen-induced hepatotoxicity.

Nitric oxide releasing derivatives of tolfenamic acid with anti-inflammatory activity and safe gastrointestinal profile

Tolfenamic acid esters with nitrooxyalcohols are synthesized. They are anti-inflammatory agents reducing carrageenan rat paw edema, with low gastrointestinal and general toxicity. In vitro, they are nitric oxide donors, inhibitors of lipoxygenase and cyclooxygenases. A two to three carbon chain between carboxylic and nitric ester groups seems optimal for activity.

Antinociceptive effect of leaf essential oil from Croton sonderianus in mice

The leaf essential oil from Croton sonderianus (EOCS) was evaluated for antinociceptive activity in mice using chemical and thermal models of nociception. Given orally, the essential oil at doses of 50, 100 and 200 mg/kg produced significant inhibitions on chemical nociception induced by intraperitoneal acetic acid and subplantar formalin or capsaicin injections. However, it evidenced no efficacy against thermal nociception in hot-plate test. More prominent inhibition of acetic acid-induced writhing and capsaicin-induced hind-paw licking responses was observed at 100 and 200 mg/kg of EOCS. At similar doses, the paw licking behavior in formalin test was more potently suppressed during the late phase (20-25 min, inflammatory) than in early phase (0-5 min, neurogenic). The EOCS-induced antinociception in both capsaicin and formalin tests was insensitive to naloxone (1 mg/kg, s.c.), but was significantly antagonized by glibenclamide (2 mg/kg, i.p.). In mice, the essential oil (100 and 200 mg/kg) neither significantly enhanced the pentobarbital-sleeping time nor impaired the motor performance in rota-rod test, indicating that the observed antinociception is unlikely due to sedation or motor abnormality. These results suggest that EOCS produces antinociception possibly involving glibenclamide-sensitive KATP+ channels, which merit further studies on its efficacy in more specific models of hyperalgesia and neuropathic pain.

Gargling with Sodium Azulene Sulfonate Reduces the Postoperative Sore Throat After Intubation of the Trachea

Postoperative sore throat (POST) is a complication that remains to be resolved in patients undergoing endotracheal intubation. In this study, we investigated whether preoperative gargling with sodium 1,4-dimethyl-7-isopropylazulene-3-sulfonate monohydrate (sodium azulene sulfonate, Azunol) reduces POST after endotracheal intubation. Forty patients scheduled for elective surgery under general anesthesia were randomized into Azunol and control groups. In the Azunol group, patients gargled with 4 mg Azunol diluted with 100 mL tap water (40 microg/mL). In the control group, patients gargled with 100 mL of tap water. After emergence from general anesthesia, the patients with POST were counted and POST was evaluated using a verbal analog pain scale. There were no significant differences between the two groups by age, height, body weight, gender distribution, or duration of anesthesia and surgery. In the control group, 13 patients (65%) complained of POST, which remained 24 h later in nine patients (45%). In the Azunol group, five patients (25%) also complained of POST, which completely disappeared by 24 h later. The incidence of POST and verbal analog pain scale scores in the Azunol group decreased significantly compared with the control group. We demonstrated that gargling with Azunol effectively attenuated POST with no adverse reactions.

Effect of sodium azulene sulfonate on capsaicin-induced pharyngitis in rats

Abstract: Sodium azulene sulfonate is a water‐soluble derivative of azulene which is an antiinflammatory component of chamomile of the family of Asteraceae. Sodium azulene sulfonate is clinically used as a therapeutic agent in the treatment of pharyngitis as well as other inflammatory diseases such as tonsillitis, stomatitis and conjunctivitis. There has been no documentation on the effect of sodium azulene sulfonate on pharyngitis in laboratory models, probably because of no availability of such models. We recently established a pharyngitis model using capsaicin application on pharyngeal mucosa in rats. The present study investigated the antipharyngitis activity of sodium azulene sulfonate comparing with those of ruthenium red (vanilloid receptor antagonist, 8.5 and 85 mg/ml), ascorbic acid (antioxidative compound, 100 μg/ml), povidone iodine (gargle as disinfectant, oxidative compound, 5 and 20 mg/ml) and diclofenac sodium (cyclooxygenase inhibitor, 0.1 and 1 mg/ml). As an antipharyngeal effect, the capsaicin‐induced plasma exudation in the pharyngeal mucosa of the rat was evaluated. The capsaicin‐induced plasma exudation in the pharyngeal mucosa was inhibited by sodium azulene sulfonate (100 and 200 μg/ml) as well as ruthenium red and ascorbic acid, but not by povidone iodine and dicrofenac sodium; povidone iodine rather promoted the plasma exudation. In conclusion, the antipharyngitis effect of sodium azulene sulfonate was demonstrated for the first time in a laboratory model. Although the mechanism by which sodium azulene sulfonate inhibited the capsaicin‐induced pharyngitis is not yet unraveled, antioxidative effect, but not inhibitory effect on cyclooxygenase pathway, might be involved.

Modulation of the antioxidant activity of HO* scavengers by albumin binding: a 19F-NMR study

The interaction between different HO(z.rad;) radical scavengers in a three-component antioxidant system has been investigated by means of 19F-NMR spectroscopy. This system is composed of bovine serum albumin (BSA), trolox, and N-(4-hydroxyphenyl)-trifluoroacetamide (CF(3)PAF). The antioxidant capacity of BSA and trolox has been assessed by measuring the amount of trifluoroacetamide (TFAM) arising from the radical mediated decomposition of CF(3)PAF. When assayed separately, both trolox and BSA behaved as antioxidants, as they were effective to protect CF(3)PAF from HO* radical-mediated decomposition. By contrast, trolox enhanced the production of TFAM in the presence of BSA, thus behaving as a pro-oxidant. Urate, carnosine, glucose, and propylgallate showed antioxidant properties both with or without BSA. CF(3)PAF and trolox were found to bind to BSA with association constants in the order of 5 x 10(3)M(-1) and to compete for the same binding sites. These results have been discussed in terms of BSA-catalysed cross-reactions between trolox-derived secondary radicals and CF(3)PAF.

Protective effects of melatonin, vitamin E and N-acetylcysteine against acetaminophen toxicity in mice: a comparative study

Acetaminophen (AA) is a commonly used analgesic and antipyretic drug; however, when used in high doses, it causes fulminant hepatic necrosis and nephrotoxic effects in both humans and experimental animals. It has been reported that the toxic effects of AA are the result of oxidative reactions that take place during its metabolism. In this study we investigated if melatonin, vitamin E or N-acetylcysteine (NAC) are protective against AA toxicity in mice. The doses of the antioxidants used were as follows: melatonin (10 mg/kg), vitamin E (30 mg/kg) and NAC (150 mg/kg). Blood urea nitrogen (BUN), serum creatinine, alanine aminotransferase (ALT), aspartate aminotransferase (AST) levels in blood, and glutathione (GSH), malondialdehyde (MDA), oxidized protein levels and myeloperoxidase (MPO) activity in liver and kidney tissues were measured. BUN and serum creatinine, ALT and AST levels which were increased significantly following AA treatment decreased significantly after pretreatment with either vitamin E, melatonin or NAC; however, they were not reduced to control levels. ALT and AST levels were significantly higher at 4 hr compared with the 24 hr levels after AA administration. However, BUN and creatinine levels were significantly elevated only at 24 hr. GSH levels were reduced while MDA, MPO and oxidized protein levels were increased significantly following AA administration. These changes were reversed by pretreatment with either melatonin, vitamin E or NAC. Liver toxicity was higher at 4 hr, whereas nephrotoxicity appeared to be more severe 24 hr after treatment with AA. Vitamin E was the least efficient agent in reversing AA toxicity while melatonin, considering it was given as at lower dose than either vitamin E or NAC, was the most effective. This may be the result of the higher efficacy of melatonin in scavenging various free radicals and also because of its ability in stimulating the antioxidant enzymes.

HPLC analysis of vitamin E isoforms in human epidermis: correlation with minimal erythema dose and free radical scavenging activity

The content and composition of different vitamin E isoforms was analyzed in normal human skin. Interestingly the epidermis contained 1% alpha-tocotrienol, 3% gamma-tocotrienol, 87% alpha-tocopherol, and 9% gamma-tocopherol. Although the levels of tocotrienol in human epidermis appear to be considerably lower than reported in the hairless mouse, the presence of significant amounts of tocotrienol levels leads to speculation about the physiological function of tocotrienols in skin. Besides antioxidant activity and photoprotection, tocotrienols may have skin barrier and growth-modulating properties. A good correlation was found for epidermal alpha-tocopherol (r = 0.7909, p <.0003), gamma-tocopherol (r = 0.556, p <.025), and the total vitamin E content (r = 0.831, p <.0001) with the free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging in epidermis, as assessed by electron paramagnetic resonance (EPR) spectroscopy. In human epidermis, alpha-tocopherol is quantitatively the most important vitamin E isoform present and comprises the bulk of first line free radical defense in the lipid compartment. Epidermal tocotrienol levels were not correlated with DPPH scavenging activity. The minimal erythema dose (MED), an individual measure for sun sensitivity and a crude indicator for skin cancer susceptibility, did not correlate with the epidermal content of the vitamin E isoforms. Hence it is concluded that vitamin E alone is not a determinant of individual photosensitivity in humans.

Effect of a novel NSAID derivative with antioxidant moiety on oxidative damage caused by liver and cerebral ischaemia-reperfusion in rats

Tissue ischaemia-reperfusion evokes toxic and harmful biochemical processes such as oxidative stress and inflammation. The aim of this study is to investigate the indices of tissue damage in rat liver and brain after ischaemia-reperfusion injury of these organs, and to study prospective cytoprotection of molecules such as the novel anti-inflammatory N-(2-thiolethyl)-2-(2-[N'-(2,6-dichlorophenyl)amino] phenyl)acetamide (compound 1) and alpha-tocopherol. Two experimental models were studied: firstly, 30 min liver ischaemia via hepatoduodenal ligament clamping followed by 60 min reperfusion; and secondly, 45 min cerebral ischaemia via bilateral common carotid artery occlusion followed by 90 min reperfusion. Compound 1 and alpha-tocopherol were administered intraperitoneally before induction of ischaemia. We hereby report that compound 1, a molecule that combines potent in-vitro antioxidant and in-vivo anti-inflammatory activity with low gastrointestinal toxicity, offered protection in-vivo against liver or brain ischaemia-reperfusion-induced damage. Both compound 1 and alpha-tocopherol prevented changes in lipid peroxidation in the rat liver and brain tissue and in tumour necrosis factor (TNF-alpha) levels in brain. Also compound 1 attenuated glutathione depletion, evoked by ischaemia-reperfusion, in the rat brain but not in the liver. These results could be explained on the basis of the antioxidant/anti-inflammatory properties of compound 1 and suggest its beneficial effect and potential therapeutic use in post-ischaemic injury.

Synthesis of new azulene derivatives and study of their effect on lipid peroxidation and lipoxygenase activity

The relationship between free radicals and acute or chronic inflammation has been well established. We have previously reported the significant antioxidant activity of the natural azulene derivatives chamazulene and guaiazulene. Furthermore, some synthetic azulene analogues have been found to possess anti-inflammatory activity. In this investigation we report the synthesis of five 3-alkyl or 3-(hydroxy)alkylazulene-1-carboxylic acids and esters, from tropolone, via the corresponding furanone. The synthesised compounds were tested for their effect on the peroxidation of rat hepatic microsomal membrane lipids, applying the 2-thiobarbituric acid test. Their anti-inflammatory activity was evaluated in vitro by the offered inhibition of soybean lipoxygenase. All the tested molecules were found to inhibit lipid peroxidation by 100% at 1 mM. They were also found to considerably inhibit lipoxygenase activity. The above results are discussed in relation to the structure and physicochemical properties of the examined azulene derivatives.

A review of HNS-32: a novel azulene-1-carboxamidine derivative with multiple cardiovascular protective actions

HNS-32 [N(1),N(1)-dimethyl-N(2)-(2-pyridylmethyl)-5-isopropyl-3,8-dimethylazulene-1- carboxamidine] (CAS Registry Number: 186086-10-2) is a newly synthesized azulene derivative. Computer simulation showed that its three dimensional structure is similar to that of the class Ib antiarrhythmic drugs, e.g., lidocaine or mexiletine. HNS-32 potently suppressed ventricular arrhythmias induced by ischemia due to coronary ligation and/or ischemia-reperfusion in dogs and rats. In the isolated dog and guinea pig cardiac tissues, HNS-32 had negative inotropic and chronotropic actions, prolonged atrial-His and His-ventricular conduction time and increased coronary blood flow. In the isolated guinea pig ventricular papillary muscle, HNS-32 decreased maximal rate of action potential upstroke (Vmax) and shortened action potential duration (APD). These findings suggest that HNS-32 inhibits inward Na+ and Ca2+ channel currents. In the isolated pig coronary and rabbit conduit arteries, HNS-32 inhibited both Ca2+ channel-dependent and -independent contractions induced by a wide variety of chemical stimuli. HNS-32 is a potent inhibitor of protein kinase C (PKC)-mediated constriction of cerebral arteries. It is likely to block both, Na+ and Ca2+ channels expressed in cardiac and vascular smooth muscles. These multiple ion channel blocking effects are largely responsible for the antiarrhythmic and vasorelaxant actions of HNS-32. This drug may represent a novel approach to the treatment of arrhythmias.

Antioxidant potential of natural and synthesised polyprenylated hydroquinones

The metabolites 2-octaprenyl-1,4-hydroquinone (1) and 2-(24-hydroxy)-octaprenyl-1,4-hydroquinone (2), isolated from the sponge Ircinia spinosula, along with a series of synthetic derivatives, were evaluated for their antioxidant capacity, in order to establish a potential relationship between structural characteristics and antioxidant activity. The antioxidant potential of both natural and synthesised compounds was evaluated in vitro by their ability: (1) to interact with the stable free 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) and (2) to inhibit the peroxidation, induced by the Fe(++)/ascorbate system, of heat inactivated hepatic microsomal membrane lipids. Metabolite 1 presented a strong interaction with DPPH and had a moderate effect on lipid peroxidation, while metabolite 2 interacted extensively with DPPH and exhibited a significant effect against lipid peroxidation. All derivatives retaining the free 1,4-hydroquinone system maintained fully or partly the free radical scavenging capacity.

EC-SOD gene therapy reduces paracetamol-induced liver damage in mice

BACKGROUND

Paracetamol overdose causes acute liver damage which leads to severe centrilobular hepatic necrosis. The hepatotoxic effect is caused by reactive metabolites and oxidative stress. Since extracellular superoxide dismutase (EC-SOD) protects tissues against the harmful effects of superoxide anion, the hypothesis that systemic adenovirus-mediated EC-SOD gene transfer could reduce liver damage was tested.

METHODS

Mice were given paracetamol (600 mg/kg) enterally 2 days after adenovirus-mediated gene transfer of EC-SOD (2 x 10(9) pfu). Five days after gene transfer, plasma and tissue samples were collected for clinical chemistry analyses and tissue pathology evaluation.

RESULTS

EC-SOD was expressed in a dose-dependent manner with the highest enzyme activity occurring 3 days after the gene transfer. Clinical chemistry and tissue pathology analyses showed that adenoviral EC-SOD gene transfer significantly attenuated release of liver enzymes and inhibited necrosis and apoptosis caused by paracetamol overdose.

CONCLUSION

The results indicate the involvement of superoxide anion in paracetamol-mediated liver damage and suggest a possible protective role for EC-SOD gene transfer in paracetamol-induced liver damage.

Mutagenicity and antioxidant assessment of Stachitarpheta jamaicensis (L.) Vahl

Stachitarpheta jamaicensis (L.) Vahl. is a member of the Verbenaceae commonly used in Cuba, mainly as vermifugue and against diarrhoea. The mutagenic potential of a hydroalcohol extract of its aerial parts was assessed in vitro using the Salmonella/microsome assay and in vivo in the mouse bone marrow micronucleus test. No positive response was observed in a battery of four Salmonella typhimurium strains employed: TA 1535, TA 1537, TA 98 and TA 100, when exposed to concentrations up to 5 mg/plate, with and without mammalian metabolic activation. In the same way, no increase in the micronucleus frequency in mitotic erythropoietic tissue was observed when animals were administered the extract orally in doses of 500, 1000 and 2000 mg/kg. The extract inhibited lipid peroxidation in the rat liver microsomal fraction (IC(50) = 3.6 microg/mL) but it does not seem to be an effective.OH radical scavenger (IC(50) = 76.7 microg/mL). Noteworthy, it increased in a dose dependent way the level of revertant colonies in E. coli IC 203, a strain sensitive to oxidative mutagenesis, when assayed together with hydrogen peroxide and ferrous sulphate, which suggests a pro-oxidant action.

Screening of Brazilian plant extracts for antioxidant activity by the use of DPPH free radical method

Brazilian plant extracts belonging to 16 species of 5 different families (71 extracts) were tested against the stable DPPH (2,2-diphenyl-1-picryl-hydrazyl-hydrate) free-radical. The ability to scavenge DPPH radical was measured in these experiments by the discoloration of the solution. Ginkgo biloba and rutin, commonly used as antioxidants for medical purposes, were used as standards. Based on our results, we can say that as a general rule the ethanol extracts of plants belonging to the Verbenaceae family showed lower EC(50) values than the other plant extracts. Among the partitions, the more polar ones (ethyl acetate and n-butanol) are those that generally have higher antioxidant activity (AA).