Kaurane diterpenes from Isodon japonicus inhibit nitric oxide and prostaglandin E2 production and NF-kappaB activation in LPS-stimulated macrophage RAW264.7 cells

Kamebakaurin Suppresses Antigen-Induced Mast Cell Activation by Inhibition of FcεRI Signaling Pathway

INTRODUCTION

Kamebakaurin is an active constituent of both Rabdosia japonica and Rabdosia excisa, which are utilized in Chinese traditional medicine for improving symptoms in patients with allergies. We investigated the molecular mechanisms of the anti-allergic effects of kamebakaurin using BMMCs.

METHODS

The degranulation ratio, histamine release, and the interleukin (IL)-4, leukotriene B4 (LTB4), and cysteinyl leukotriene productions on antigen-triggered BMMC were investigated. Additionally, the effects of kamebakaurin on signal transduction proteins were examined by Western blot and binding to the Syk and Lyn kinase domain was calculated. The effects of kamebakaurin on antigen-induced hyperpermeability were investigated using mouse model.

RESULTS

At 10 μm, kamebakaurin partially inhibited degranulation, histamine release, and IL-4 production. At 30 μm, kamebakaurin partially reduced LTB4 and cysteinyl leukotriene productions and suppressed degranulation, histamine release, and IL-4 production. Phosphorylation of both Syk Y519/520 and its downstream protein, Gab2, was reduced by kamebakaurin, and complete inhibition was observed with 30 μm kamebakaurin. In contrast, phosphorylation of Erk was only partially inhibited, even in the presence of 30 μm kamebakaurin. Syk Y519/520 is known to be auto-phosphorylated via intramolecular ATP present in its own ATP-binding site, and this auto-phosphorylation triggers degranulation, histamine release, and IL-4 production. Docking simulation study indicated kamebakaurin blocked ATP binding to the ATP-binding site in Syk. Therefore, inhibition of Syk auto-phosphorylation by kamebakaurin binding to the Syk ATP-binding site appeared to cause a reduction of histamine release and IL-4 production. Kamebakaurin inhibited antigen-induced vascular hyperpermeability in a dose-dependent fashion but did not reduce histamine-induced vascular hyperpermeability.

CONCLUSION

Kamebakaurin ameliorates allergic symptoms via inhibition of Syk phosphorylation; thus, kamebakaurin could be a lead compound for the new anti-allergic drug.

Ethnobotanical, Phytochemical, and Pharmacological Properties of the Subfamily Nepetoideae (Lamiaceae) in Inflammatory Diseases

Nepetoideae is the most diverse subfamily of Lamiaceae, and some species are well known for their culinary and medicinal uses. In recent years, there has been growing interest in the therapeutic properties of the species of this group regarding inflammatory illnesses. This study aims to collect information on traditional uses through ethnobotanical, pharmacological, and phytochemical information of the subfamily Nepetoideae related to inflammatory diseases. UNAM electronic resources were used to obtain the information. The analysis of the most relevant literature was compiled and organised in tables. From this, about 106 species of the subfamily are traditionally recognised to alleviate chronic pain associated with inflammation. Pharmacological studies have been carried out in vitro and in vivo on approximately 308 species belonging to the genera Salvia, Ocimum, Thymus, Mentha, Origanum, Lavandula, and Melissa. Phytochemical and pharmacological evaluations have been performed and mostly prepared as essential oil or high polarity extracts, whose secondary metabolites are mainly of a phenolic nature. Other interesting and explored metabolites are diterpenes from the abietane, clerodane, and kaurane type; however, they have only been described in some species of the genera Salvia and Isodon. This review reveals that the Nepetoideae subfamily is an important source for therapeutics of the inflammatory process.

Diastereoselective Synthesis of trans-anti-Hydrophenanthrenes via Ti-mediated Radical Cyclization and Total Synthesis of Kamebanin

Ent-kaurenes consist of an ABC-ring based on a trans-anti-hydrophenanthrene skeleton and a D ring with an exomethylene. Highly oxygen-functionalized ent-kauren-15-ones have promising antiinflammatory pharmacological activity. In this study, we developed a novel diastereoselective synthesis of trans-anti-hydrophenanthrenes via a Ti-mediated reductive radical cyclization. We also demonstrated the applicability of this method by developing the first total synthesis of (±)-kamebanin (longest linear sequence; 17 steps, overall yield; 6.5 %). Furthermore, this synthesis provided a formal semi-pinacol rearrangement for the construction of the quaternary carbon at C8 and a novel Thorpe-Ziegler-type reaction for the construction of the D-ring.

Anti-inflammatory kaurane diterpenoids of Erythroxylum bezerrae

Five unusual kaurane diterpenes, designated as bezerraditerpenes A-E (1-5), along with six known ones (6-11), were isolated from the hexane extract of the stems of Erythroxylum bezerrae. Their structures were elucidated based on the interpretation of the NMR spectroscopy, mass spectrometry, and X-ray diffraction analysis. The anti-inflammatory potential of the diterpenes 1-11 was screened through cellular viability and lipopolysaccharide (LPS)-induced nitric oxide (NO) production on murine macrophage-like cells RAW 264.7. Diterpene 6 (cauren-6β-ol) showed potent cytotoxicity and increased ability to inhibit NO production. Diterpenes 1 (bezerraditerpene A), 2 (bezerraditerpene B), and 8 (ent-kaur-16-ene-3β,15β-diol) exhibited the same significant anti-inflammatory activity with NO CI₅₀ inhibition (3.21-3.76 μM) without cytotoxicity, in addition to decreasing the levels of pro-inflammatory cytokines TNF-α and IL-6 in LPS-induced RAW264.7 cells.

Therapeutic Potential of Linearol in Combination with Radiotherapy for the Treatment of Glioblastoma In Vitro

Glioblastoma is one of the most malignant and lethal forms of primary brain tumors in adults. Linearol, a kaurane diterpene isolated from different medicinal plants, including those of the genus Sideritis, has been found to possess significant anti-oxidant, anti-inflammatory and anti-microbial properties. In this study, we aimed to determine whether linearol could exhibit anti-glioma effects when given alone or in combination with radiotherapy in two human glioma cell lines, U87 and T98. Cell viability was examined with the Trypan Blue Exclusion assay, cell cycle distribution was tested with flow cytometry, and the synergistic effects of the combination treatment were analyzed with CompuSyn software. Linearol significantly suppressed cell proliferation and blocked cell cycle at the S phase. Furthermore, pretreatment of T98 cells with increasing linearol concentrations before exposure to 2 Gy irradiation decreased cell viability to a higher extent than linearol or radiation treatment alone, whereas in the U87 cells, an antagonistic relationship was observed between radiation and linearol. Moreover, linearol inhibited cell migration in both tested cell lines. Our results demonstrate for the first time that linearol is a promising anti-glioma agent and further studies are needed to fully understand the underlying mechanism of this effect.

Natural Terpenoids as Neuroinflammatory Inhibitors in LPS-stimulated BV-2 Microglia

Neuroinflammation is a typical feature of many neurodegenerative diseases, including Alzheimer's disease and Parkinson's disease. Microglia, the resident immune cells of the brain, readily become activated in response to an infection or an injury. Uncontrolled and overactivated microglia can release pro-inflammatory and cytotoxic factors and are the major culprits in neuroinflammation. Hence, research on novel neuroinflammatory inhibitors is of paramount importance for the treatment of neurodegenerative diseases. Bacterial lipopolysaccharide, widely used in the studies of brain inflammation, initiates several major cellular activities that critically contribute to the pathogenesis of neuroinflammation. This review will highlight the progress on terpenoids, an important and structurally diverse group of natural compounds, as neuroinflammatory inhibitors in lipopolysaccharidestimulated BV-2 microglial cells over the last 20 years.

Bioactivity, bioavailability, and gut microbiota transformations of dietary phenolic compounds: implications for COVID-19

The outbreak of mysterious pneumonia at the end of 2019 is associated with widespread research interest worldwide. The coronavirus disease-19 (COVID-19) targets multiple organs through inflammatory, immune, and redox mechanisms, and no effective drug for its prophylaxis or treatment has been identified until now. The use of dietary bioactive compounds, such as phenolic compounds (PC), has emerged as a putative nutritional or therapeutic adjunct approach for COVID-19. In the present study, scientific data on the mechanisms underlying the bioactivity of PC and their usefulness in COVID-19 mitigation are reviewed. In addition, antioxidant, antiviral, anti-inflammatory, and immunomodulatory effects of dietary PC are studied. Moreover, the implications of digestion on the putative benefits of dietary PC against COVID-19 are presented by addressing the bioavailability and biotransformation of PC by the gut microbiota. Lastly, safety issues and possible drug interactions of PC and their implications in COVID-19 therapeutics are discussed.

Natural products: A lead for drug discovery and development

Natural products are used since ancient times in folklore for the treatment of various ailments. Plant-derived products have been recognized for many years as a source of therapeutic agents and structural diversity. A literature survey has been carried out to determine the utility of natural molecules and their modified analogs or derivatives as pharmacological active entities. This review presents a study on the importance of natural products in terms of drug discovery and development. It describes how the natural components can be utilized after small modifications in new perspectives. Various new modifications in structure offer a unique opportunity to establish a new molecular entity with better pharmacological potential. It was concluded that in this current era, new attempts are taken to utilize the compounds derived from natural sources as novel drug candidates, with a focus to find and discover new effective molecules that were referred to as "new entities of natural product drug discovery."

Ent-kaurane-type diterpenoids from Isodonis Herba activate human hair follicle dermal papilla cells proliferation via the Akt/GSK-3β/β-catenin transduction pathway

A methanol extract from Isodonis Herba demonstrated significant proliferative effect on human hair follicle dermal papilla cells (HFDPC, % of control: 150.0 ± 2.0% at 20 µg/mL, p < 0.01). From the extract, 14 ent-kaurane-type diterpenoids (1-14), two abietane-type diterpenoids (15 and 16) and four triterpenoids (17-20) were isolated. Among the isolates, enmein (1, 160.9 ± 3.0% at 20 µM, p < 0.01), isodocarpin (2, 169.3 ± 4.9% at 5 µM, p < 0.01), nodosin (4, 160.5 ± 12.4% at 20 µM, p < 0.01), and oridonin (8, 165.4 ± 10.6% at 10 µM, p < 0.01) showed the proliferative effects. The principal component enmein (1) activated the expression of vascular endothelial growth factor (VEGF) mRNA, upregulated the production of VEGF and increased levels of phospho-Akt, phospho-GSK-3β, and β-catenin accumulation in HFDPC, which could be the mechanism of these activate proliferation activity.

Fruticuline A, a chemically-defined diterpene, exerts antineoplastic effects in vitro and in vivo by multiple mechanisms

Natural products have been recognized as important bioactive compounds on the basis of their wide biological properties. Here we investigated the antitumor effect and molecular mechanisms of the diterpene Fruticuline A (fruti) from Salvia lachnostachys, in human cancer cell lineages and Solid Ehrlich Carcinoma in mice. Fruti reduced MCF-7 and HepG2 proliferation by the reduction of Cyclin D1 levels and decreased NF-κB gene levels in both cell types. Furthermore, fruti also induced apoptosis in HepG2 cells, reduced Bcl-2 gene expression and induced necroptosis by increasing Ripk in MCF-7 cells. In mice, fruti prevented tumor development and reduced Cyclin D1, Bcl-2 and Rela gene levels, and reduced the p-NF-κB/NF-κB ratio in tumor tissue. Furthermore, fruti induced necrosis and apoptosis, increased N-acetyl-β-D-glucosaminidase and TNF-α levels and reduced IL-10 and Vegf levels in tumor tissue. Collectively, fruti exerts antitumor effects through the inhibition of the NF-κB pathway, reducing Cyclin D1 and Bcl-2 levels. In vitro the apoptosis and necroptosis pathways are involved in the cellular death, whereas in vivo, cells undergo necrosis by increased tumor inflammation and reduction of angiogenesis. Thus, fruticuline A acts in tumor cells by multiple mechanisms and represents a promising molecule for drug development in cancer treatment.

1-O-Acetylgeopyxin A, a derivative of a fungal metabolite, blocks tetrodotoxin-sensitive voltage-gated sodium, calcium channels and neuronal excitability which correlates with inhibition of neuropathic pain

Chronic pain can be the result of an underlying disease or condition, medical treatment, inflammation, or injury. The number of persons experiencing this type of pain is substantial, affecting upwards of 50 million adults in the United States. Pharmacotherapy of most of the severe chronic pain patients includes drugs such as gabapentinoids, re-uptake blockers and opioids. Unfortunately, gabapentinoids are not effective in up to two-thirds of this population and although opioids can be initially effective, their long-term use is associated with multiple side effects. Therefore, there is a great need to develop novel non-opioid alternative therapies to relieve chronic pain. For this purpose, we screened a small library of natural products and their derivatives in the search for pharmacological inhibitors of voltage-gated calcium and sodium channels, which are outstanding molecular targets due to their important roles in nociceptive pathways. We discovered that the acetylated derivative of the ent-kaurane diterpenoid, geopyxin A, 1-O-acetylgeopyxin A, blocks voltage-gated calcium and tetrodotoxin-sensitive voltage-gated sodium channels but not tetrodotoxin-resistant sodium channels in dorsal root ganglion (DRG) neurons. Consistent with inhibition of voltage-gated sodium and calcium channels, 1-O-acetylgeopyxin A reduced reduce action potential firing frequency and increased firing threshold (rheobase) in DRG neurons. Finally, we identified the potential of 1-O-acetylgeopyxin A to reverse mechanical allodynia in a preclinical rat model of HIV-induced sensory neuropathy. Dual targeting of both sodium and calcium channels may permit block of nociceptor excitability and of release of pro-nociceptive transmitters. Future studies will harness the core structure of geopyxins for the generation of antinociceptive drugs.

16-Kauren-2-beta-18,19-triol inhibits melanosome transport in melanocytes by down-regulation of melanophilin expression

BACKGROUND

Rab27a, Mlph, and MyoVa form a tripartite complex and relate to melanosome distribution. Melanophilin (Mlph) acts as a linker protein between Rab27a and MyoVa. The biological activity and function of 16-kauren on the expression of Mlph has not yet been studied.

OBJECTIVE

We examined the effect of 16-kauren on melanosome transport and skin pigmentation.

METHODS

Murine Melan-a melanocytes and SP-1 keratinocytes were used for in vitro analysis. Western blot analysis, quantitative real-time polymerase chain reaction, luciferase assay and immunohistochemical staining in 3D pigmented human skin model were performed.

RESULTS

We found that 16-kauren inhibits melanosome transport in Melan-a melanocytes without affecting melanin synthesis. Treatment with 16-kauren reduced melanophilin (Mlph), a key protein in melanosome transport, in Melan-a melanocytes, at both the protein and mRNA levels while it did not affect the expression of Rab27a and MyoVa, the other two key proteins for melanosome transport. Notably, the expression of melanogenic proteins, including tyrosinase, trp1, trp2, and MITF, was not affected by 16-kauren. However, 16-kauren attenuated melanosome distribution in co-culture of Melan-a melanocytes and SP-1 keratinocytes as well as in Melan-a monolayer culture. In further confirmation of the depigmenting effects of 16-kauren on Melanoderm™, a 3D pigmented human skin model, treatment with 16-kauren for 12 days increased the brightness of the tissue as determined by lightness value and reduced the distribution of melanosomes as shown in histological examination.

CONCLUSION

These results demonstrated that 16-kauren is a selective modulator of a melangenic target, Mlph expression, and can be employed as a new depigmenting strategy.

Elucidation of the Molecular-Mechanisms and In Vivo Evaluation of the Anti-inflammatory Effect of Alginate-Derived Seleno-polymannuronate

Alginate-derived polymannuronate (PM) is a type of polysaccharide found in edible brown seaweeds. Seleno-polymannuronate (Se-PM) was prepared from PM via synthesis using sulfation- and selenation-replacement reactions. The anti-inflammatory activity of Se-PM and its corresponding molecular mechanisms were investigated. In lipopolysaccharide (LPS)-activated murine macrophage RAW264.7 cells, Se-PM significantly attenuated the production of nitric oxide (NO), prostaglandin E₂ (PGE₂), and reactive oxygen species (ROS); the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2); and the secretion of proinflammatory cytokines. Moreover, Se-PM remarkably suppressed the LPS-induced activation of the nuclear-factor (NF)-κB and mitogen-activated-protein-kinase (MAPK) signaling pathways in RAW264.7 cells. Furthermore, Se-PM also decreased the production of proinflammatory mediators in LPS-triggered primary murine macrophages. Additionally, Se-PM inhibited the inflammatory response in the air-pouch inflammation model. These results might contribute to the overall understanding of the potential health benefits of Se-PM for food and drug applications.

Marantodes pumilum (Blume) Kuntze Inhibited Secretion of Lipopolysaccharide- and Monosodium Urate Crystal-stimulated Cytokines and Plasma Prostaglandin E2

Background

Marantodes pumilum is traditionally used for dysentery, gonorrhea, and sickness in the bones. Previous studies revealed its antibacterial and xanthine oxidase inhibitory activities.

Objective

To evaluate the inhibitory effects of three M. pumilum varieties on the secretion of lipopolysaccharide (LPS)- and monosodium urate crystal (MSU)-induced cytokines and plasma prostaglandin E₂ (PGE₂) in vitro.

Materials and Methods

The leaves and roots of M. pumilum var. alata (MPA), M. pumilum var. pumila (MPP), and M. pumilum var. lanceolata (MPL) were successively extracted with dichloromethane (DCM), methanol, and water. Human peripheral blood mononuclear cells and ELISA technique were used for the cytokine assay, whereas human plasma and radioimmunoassay technique were used in the PGE₂ assay. Flavonoids content was determined using a reversed-phase high-performance liquid chromatography.

Results

DCM extract of MPL roots showed the highest inhibition of LPS-stimulated cytokine secretion with IC₅₀ values of 29.87, 7.62, 5.84, 25.33, and 5.40 μg/mL for interleukin (IL)-1α, IL-1β, IL-6, IL-8, and tumor necrosis factor (TNF)-α, respectively; while that of plasma PGE₂ secretion was given by DCM extract of MPP roots (IC₅₀ 31.10 μg/mL). Similarly, the DCM extract of MPL roots demonstrated the highest inhibition against MSU-stimulated IL-1α, IL-1β, IL-6, IL-8, TNF-α, and PGE₂ secretion with IC₅₀ values of 11.2, 8.92, 12.29, 49.51, 9.60, and 31.58 μg/mL, respectively. Apigenin in DCM extracts of MPL (0.051 mg/g) and MPP (0.064 mg/g) roots could be responsible for the strong inhibitory activity against IL-1β, IL-6, TNF-α, and PGE₂.

Conclusion

The results suggested that DCM extracts of MPL and MPP roots are potential anti-inflammatory agents by inhibiting the secretion of LPS- and MSU-stimulated pro-inflammatory cytokines and PGE₂.

SUMMARY

Amongst 18 tested extracts, DCM extracts of MPL and MPP roots remarkably inhibited LPS- and MSU-stimulated pro-inflammatory cytokines and PGE₂ secretionPhytochemical analysis was performed for the active extracts using RP-HPLC systemThe presence of flavonoids particularly apigenin could be responsible for the anti-inflammatory activity. Abbreviations used: BSA: Bovine serum albumin, COX-2: Cyclooxygenase-2, CPM: Count per minute, DAMP: Danger-associated molecular pattern, DCM: Dichloromethane, DMSO: Dimethyl sulfoxide, ELISA: Enzyme-linked immunosorbent assay, FBS: Fetal bovine serum, H₂O: Water, HEPES: 4-(2-Hydroxyethyl)piperazine-1-ethanesulfonic acid, HMC-1: Human mast cell-1, HMGB1: High-mobility group box 1, ICAM: Intercellular adhesion molecule, IFN: Interferon, IgG: Immunoglobulin G, IKK: IkB kinase, IL: Interleukin, iNOS: Inducible nitric oxide synthase, LPS: Lipopolysaccharide, MeOH: Methanol, MPA: Marantodes pumilum var. alata, MPL: Marantodes pumilum var. lanceolata, MPP: Marantodes pumilum var. pumila, MSU: Monosodium urate, MTT: Methylthiazole tetrazolium, NF-κB: Nuclear factor-kappa B, NLR: NOD-like receptor, NLRP3: NLR family pyrin domain containing protein 3, NO: Nitric oxide, NOD: Nucleotide-binding oligomerization domain, NSAID: Nonsteroidal anti-inflammatory drug, PAMP: Pathogen-associated molecular pattern, PBMC: Peripheral blood mononuclear cell, PBS: Phosphate buffered saline, PGE₂: Prostaglandin E_2, PMACI: Phorbol-12-myristate 13-acetate and calcium ionosphere A23187, PRR: Pathogen recognition receptor, PTFE: Polytetrafluoroethylene, RIA: Radioimmunoassay, RIG: Retinoic acid-inducible gene I, RLR: RIG I-like receptor, RP-HPLC: Reversed-phase high-performance liquid chromatography, RPMI-1640: Roswell Park Memorial Institute-1640, TLR: Toll-like receptor, TNF: Tumor necrosis factor, VCAM: Vascular cell adhesion molecule.

Melanogenesis Inhibitory Activity of Diterpenoid and Triterpenoid Constituents from the Aerial Part of Isodon trichocarpus

A methanol extract from the aerial part of Isodon trichocarpus (Labiatae) demonstrated inhibitory effects on melanogenesis in theophylline-stimulated murine B16 melanoma 4A5 cells (IC50 = 1.6 μg/mL). From the extract, nine diterpenoids (1–9) and four triterpenoids (10–13) were isolated. Among the isolates, enmein (1, IC50 = 0.22 μM), isodocarpin (2, 0.19 μM), nodosin (4, 0.46 μM), and oridonin (6, 0.90 μM) showed an inhibitory effect without notable cytotoxicity at the effective concentrations. These diterpenoids (1, 2, 4, and 6) inhibited the expression of tyrosinase, tyrosine-related protein (TRP)-1, and TRP-2 mRNA, which could be the mechanism of melanogenesis inhibitory activity.

3β-Angeloyloxy-8β,10β-dihydroxyeremophila-7(11)-en-12,8α-lactone Inhibits Lipopolysaccharide-Induced Nitric Oxide Production in RAW264.7 Cells

Farfugium japonicum (L.) KITAM, named "Lian-Peng-Cao" in China, has been traditionally used in Chinese folk medicine to treat sore throat, cold and cough due to its anti-inflammatory properties. In this study, the anti-inflammatory action of 3β-angeloyloxy-8β,10β-dihydroxyeremophila-7(11)-en-12,8α-lactone (FJ1) isolated from Farfugium japonicum and its molecular mechanism in RAW264.7 cells were investigated. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay showed that FJ1 with or without 3 µg/mL lipopolysaccharide (LPS) had no significant cytotoxicity in RAW264.7 cells. The production of nitric oxide (NO) was identified with a Griess reagent kit. The mRNA expression of inducible nitric oxide synthase (iNOS) and cytokines, including tumor necrosis factor α (TNF-α) and cyclooxygenase-2 (COX-2), was measured by real-time polymerase chain reaction (PCR). Reactive oxygen species (ROS) production was detected by flow cytometry analysis. Western blot was used to examine the protein expression of nuclear factor-kappa B (NF-κB)/p65, inhibitor of kappa B (IκB)-α, phosphorylated IκB-α (p-IκB-α), mitogen-activated protein kinase (MAPK) molecules, iNOS, and TNF-α. We discovered that FJ1 possesses anti-inflammatory effects that inhibit the release of LPS-stimulated pro-inflammatory cytokines, including NO and ROS. The molecular mechanism of FJ1-mediated anti-inflammation is associated with decreasing phosphorylation of MAPK molecules, including extracellular signal-related kinase 1/2 (ERK1/2), p38 MAPK, and c-Jun NH2-terminal kinase (JNK), FJ1 also reverses IκB degradation and attenuates the mRNA and protein expression of NF-κB-related downstream inducible enzymes and cytokines, such as iNOS, TNF-α in RAW264.7 cells. The results suggest that FJ1 has anti-inflammatory properties, which indicates that F. japonicum can be utilized to treat inflammatory diseases. The potential mechanism is associated with the NF-κB and MAPK activation pathways in LPS-stimulated macrophages.

Kaurane diterpenes as mitochondrial alterations preventive agents under experimental oxidative stress conditions

CONTEXT

Foliol, linearol, and sidol are the most common diterpenes found in Sideritis L. spp. (Lamiaceae) with a wide range of demonstrated properties including anti-inflammatory, antioxidant, and anti-apoptotic effects.

OBJECTIVE

For the first time, the present work was studied for the potential protective role of these kaurane-type diterpenes on mitochondrial oxidative stress induced by H2O2 in the human astrocytoma U373-MG cell line and in the rat adrenal pheochromocytoma PC12 cell line.

MATERIALS AND METHODS

Mitochondrial protection was assayed at 5 and 10 µM concentrations for 24 h (for kaurane diterpenes) and H2O2 as oxidative stress inducer (0.1 mM for PC12 cells and 1 mM for U373-MG, for 30 min). ATP concentration was determined by high-performance liquid chromatography (HPLC), and changes in mitochondrial membrane potential, caspase-3 activity as well as in cytosolic and mitochondrial calcium levels were assessed by fluorometric techniques, by using specific fluorescent probes.

RESULTS

Pretreatments for 24 h with linearol and sidol, prior to H2O2 exposure, acted as mitochondrial alterations preventive agents by increasing membrane potential (over 40-60% in PC12 cells and over 10-20% in U373-MG), restoring both cytosolic and mitochondrial calcium homeostasis (linearol at 10 µM caused a 3.5-fold decrease in cytosolic calcium concentration in PC12 cells), decreasing caspase-3 activity (over 1.25-1.5-fold for linearol and sidol) and avoiding ATP depletion (linearol increased over 20% ATP level in both cell types).

CONCLUSION

Our results suggest that linearol and sidol could provide protective activity by targeting mitochondria in response to the deleterious changes induced by H2O2.

Identification of Magnolia officinalis L. Bark Extract as the Most Potent Anti-Inflammatory of Four Plant Extracts

This study was designed to compare the anti-inflammatory potential of a Magnolia officinalis L. bark extract solely or in combination with extracts prepared from either Polygonum aviculare L., Sambucus nigra L., or Isodon japonicus L. in bacterial lipopolysaccharide (LPS) stimulated human gingival fibroblasts (HGF-1) and human U-937 monocytes, as cell models of periodontal disease. HGF-1 and U-937 cells were incubated with LPS from either Porphyromonas gingivalis or Escherichia coli together with the four plant extracts alone or in combination. Secretion of anti-inflammatory cytokines from HGF-1 and U-937 cells was measured by means of a multiplexed bead assay system. Magnolia officinalis L. bark extract, at concentrations of 1 μg/mL and 10 μg/mL, reduced interleukin 6 (IL-6) and interleukin-8 (IL-8) secretion from HGF-1 cells to 72.5 ± 28.6% and reduced matrix metalloproteinase 2 (MMP-2) and matrix metalloproteinase 9 (MMP-9) secretion from U-937 cells to 8.87 ± 7.97% compared to LPS-treated cells (100%). The other three extracts also reduced secretion of these inflammatory markers but were not as effective. Combination of 9 μg/mL Magnolia officinalis L. extract with 1 μg/mL of each of the other extracts maintained the anti-inflammatory effect of Magnolia officinalis L. extract. Combination of 5 μg/mL Magnolia officinalis L. extract with 5 μg/mL Isodon japonicus L. extract also maintained the anti-inflammatory potential of the Magnolia officinalis L. extract, whereas increasing concentrations of any of the other plant extracts in the combination experiments reduced the Magnolia officinalis L. extract efficacy in U-937 cells.

Inflexinol reduces severity of acute pancreatitis by inhibiting nuclear factor-κB activation in cerulein-induced pancreatitis

OBJECTIVES

To examine the effect of inflexinol on the development of acute pancreatitis (AP) and to investigate the mechanisms responsible for the protective effect against AP.

METHODS

Acute pancreatitis was induced in mice by intraperitoneal injection of cerulein. Inflexinol was administered intraperitoneally 4 times every 6 hours from 1 hour before the first cerulein injection. Serum amylase activity and histology of the pancreas were measured. Determination of pancreatic nuclear factor-κB (NF-κB) p65 expression was conducted by Western blotting and immunohistochemistry to investigate the mechanisms responsible for the inflexinol effects.

RESULTS

Serum amylase activity in the cerulein group was significantly higher than that in the control group (P < 0.05). Pancreatic histology revealed marked inflammatory changes in the cerulein group such as interstitial edema, vacuolization, necrosis, and infiltration of inflammatory cells; and Western blotting and immunohistochemistry showed marked NF-κB p65 expression. Treatment with inflexinol significantly attenuated the inflammatory changes in pancreatic histology at 24, 48, and 72 hours (P < 0.05). Pancreatic NF-κB p65 expression decreased significantly after inflexinol treatment (P < 0.05).

CONCLUSION

Inflexinol reduced the severity of cerulein-induced AP by inhibiting NF-κB activation.

Critical role of the death receptor pathway in the antitumoral effects induced by hispanolone derivatives

Labdane diterpenoids have a broad spectrum of biological activities including antibacterial, antiviral and anti-inflammatory properties. However, little is known about their possible role in the apoptotic cell death machinery. Here, we report that hispanolone derivatives, a group of labdane diterpenoids, induce apoptosis in different tumor cell lines by activating caspase-8 with subsequent participation of mitochondrial signaling. Activation of caspase-8 by hispanolone derivatives was followed by a decrease in mitochondrial membrane potential, the release of apoptotic factors from mitochondria to the cytosol, and activation of caspases-9 and 3. Hispanolone derivatives also led to a time-dependent cleavage of Bid. Inhibition of caspase-8 abrogated these processes, suggesting that the death receptor pathway has a critical role in the apoptotic events induced by hispanolone derivatives. In addition, silencing death receptors with small interfering RNA s or pretreating cells with neutralizing antibodies to Fas ligand, tumor necrosis factor receptor 1 (TNF-R1), and TNF-α receptor 2 (TRAIL) inhibited diterpenoid-induced apoptosis, revealing it to be dependent on these death receptors. Interestingly, hispanolone derivatives had no effect on non-tumor cells. Consistently, in vivo bioluminescence imaging corroborates this antineoplasic effect, as hispanolone derivatives significantly decrease cancer growth in tumor xenograft assays. These data demostrate the antitumoral effects of hispanolone derivatives and provide relevant preclinical validation for the use of these compounds as potent therapeutic agents in cancer treatment.

Antispasmodic effects of a new kaurene diterpene isolated from Croton argyrophylloides on rat airway smooth muscle

OBJECTIVES

The effects of rel-(1S,4aS,7S,8aS)-7-(1-vinyl)-tetradecahydro-1,4a-dimethylphenanthrene-7,8a-carbolactone-1-carboxylic acid (TCCA), a new ent-kaurene diterpene isolated from Croton argyrophylloides, on rat tracheal preparations were investigated.

METHODS

Tracheae were removed and cut into two-cartilage segments that were mounted in organ baths containing Tyrode's solution.

RESULTS

TCCA reduced the contractions induced by electrical field stimulation, relaxed K(+)-induced contractions, and inhibited both phasic and tonic components of the K(+)- and ACh-induced contractions. TCCA reduced the serotonin-induced contraction, abolished that evoked by K(+) in the presence of epinephrine, and also reduced the ACh-induced contractions under Ca(2+)-free conditions. TCCA blocked contractions that depend on divalent cation inflow through voltage-operated Ca(2+) channels (VOCCs) and receptor-operated Ca(2+) channels (ROCCs), but had greater potency to block VOCC- than ROCC-dependent contractions or contractions induced by ACh in Ca(2+)-free conditions. TCCA relaxed the phorbol 12,13 dibutyrate (1 µm) induced contraction, but with slight potency.

CONCLUSIONS

TCCA induces an antispasmodic effect through several mechanisms including blockade of either VOCCs (with greater potency) or ROCCs, blockade of IP(3)-induced Ca(2+) release from sarcoplasmic reticulum (with intermediate potency) and reduction of the sensitivity of contractile proteins to Ca(2+).

Geopyxins A-E, ent-kaurane diterpenoids from endolichenic fungal strains Geopyxis aff. majalis and Geopyxis sp. AZ0066: structure-activity relationships of geopyxins and their analogues

Four new ent-kaurane diterpenoids, geopyxins A-D (1-4), were isolated from Geopyxis aff. majalis, a fungus occurring in the lichen Pseudevernia intensa, whereas Geopyxis sp. AZ0066 inhabiting the same host afforded two new ent-kaurane diterpenoids, geopyxins E and F (5 and 6), together with 1 and 3. The structures of 1-6 were established on the basis of their spectroscopic data, while the absolute configurations were assigned using modified Mosher's ester method. Methylation of 1-3, 5, and 6 gave their corresponding methyl esters 7-11. On acetylation, 1 and 7 yielded their corresponding monoacetates 12 and 14 and diacetates 13 and 15. All compounds were evaluated for their cytotoxic and heat-shock induction activities. Compounds 2, 7-10, 12, 14, and 15 showed cytotoxic activity in the low micromolar range against all five cancer cell lines tested, but only compounds 7-9, 14, and 15 were found to activate the heat-shock response at similar concentrations. From a preliminary structure-activity perspective, the electrophilic α,β-unsaturated ketone carbonyl motif present in all compounds except 6 and 11 was found to be necessary but not sufficient for both cytotoxicity and heat-shock activation.

Direct Rel/NF-κB inhibitors: structural basis for mechanism of action

The Rel/NF-κB transcription factors have emerged as novel therapeutic targets for a variety of human diseases and pathological conditions, including inflammation, autoimmune diseases, cancer, ischemic injury, osteoporosis, transplant rejection and neurodegeneration. Several US FDA-approved drugs may, in part, attribute their therapeutic effects to the inhibition of the Rel/NF-κB pathway. Strategies for blocking the Rel/NF-κB signaling pathway have inspired the pharmaceutical industry to develop inhibitors for I-κB kinase, however, this article focuses instead on identifying natural compounds that directly target and inhibit DNA binding and transcription activity of Rel/NF-κB. These include compounds containing a quinone core, an α,β unsaturated carbonyl and a benzene diamine. By investigating the mechanisms of action of existing natural inhibitors, novel strategies and synthetic approaches can be devised that will facilitate the development of novel and selective Rel/NF-κB inhibitors with better safety profiles.

Anti-neuroinflammatory activity of Kamebakaurin from Isodon japonicus via inhibition of c-Jun NH₂-terminal kinase and p38 mitogen-activated protein kinase pathway in activated microglial cells

Compelling evidence supports the notion that the majority of neurodegenerative diseases are associated with microglia-mediated neuroinflammation. Therefore, quelling of microglial activation may lead to neuronal cell survival. The present study investigated the effects of Kamebakaurin (KMBK), a kaurane diterpene isolated from Isodon japonicus HARA (Labiatae), on the production of pro-inflammatory mediators in lipopolysaccharide (LPS)-stimulated cytotoxicity in rat primary microglial cultures and the BV-2 cell line. KMBK significantly inhibited the LPS-induced production of nitric oxide (NO) in a concentration-dependent fashion in activated microglial cells. The mRNA and protein levels of inducible nitric oxide synthase (iNOS) and cyclooxycenase-2 (COX-2) were also decreased dose-dependently. Furthermore KMBK inhibited the JNK and p38 mitogen-activated protein kinases (MAPKs) in LPS-stimulated BV-2 microglial cells. Considering the results obtained, the present study authenticated the potential benefits of KMBK as a therapeutic target in ameliorating microglia-mediated neuroinflammatory diseases.

Modulation of expression of IL-8 gene in bronchial epithelial cells by 5-methoxypsoralen

Persistent recruitment of neutrophils in the bronchi of cystic fibrosis patients contributes to airway tissue damage, suggesting the importance of intervening on the expression of the neutrophil chemokine IL-8. Extracts from plants have been investigated to select components able to reduce IL-8 expression in bronchial epithelial cells challenged with Pseudomonas aeruginosa. Extracts and purified components have been added to cells 24 h before pro-inflammatory challenge with P. aeruginosa and IL-8 transcription was quantified in the IB3-1 CF cells in vitro. P. aeruginosa-dependent IL-8 mRNA induction was increased by Argemone mexicana and Vernonia anthelmintica whereas no significant modification of transcription was observed with Aphanamixis polystachya, Lagerstroemia speciosa and Hemidesmus indicus. Finally, inhibition of IL-8 was observed with Polyalthia longifolia (IC50=200 microg/ml) and Aegle marmelos (IC50=20 microg/ml). Compounds from A. marmelos were isolated and identified by GC-MS. No significant effect was observed with butyl-p-tolyl sulphate, whereas the inhibition obtained with 6-methyl-4-chromanone concentration was accompanied by an anti-proliferative effect. On the contrary, 5-methoxypsoralen resulted in IL-8 inhibition at 10 microM concentration, without effects on cell proliferation. In synthesis, 5-methoxypsoralen can be taken into consideration to investigate mechanisms of neutrophil chemotactic signalling and for its potential application in modulating the excessive CF lung inflammation.

Inhibition of NF-kappaB activation and iNOS induction by ent-kaurane diterpenoids in LPS-stimulated RAW264.7 murine macrophages

Xerophilusin A (1), xerophilusin B (2), longikaurin B (3), and xerophilusin F (4) from Isodon xerophylus inhibit LPS-induced NO production in RAW 264.7 macrophages, with IC(50) values of 0.60, 0.23, 0.44, and 0.67 muM, respectively, and they all inhibited mRNA production in these same cells. They decreased the luciferase activity in RAW 264.7 cells transiently transfected with the NF-kappaB-dependent luciferase reporter, with IC(50) values of 1.8, 0.7, 1.2, and 1.6 muM, respectively. Compounds 1-3 reduced NF-kappaB activation, with compound 4 showing no effect, but p65 translocation from the cytoplasm to the nucleus and the LPS-induced degradation of IkappaB were inhibited by all four test compounds. These findings indicate that ent-kauranes are potential anti-inflammatory agents, with a specific mechanism in which both the inhibition of NF-kappaB translocation and the consequent decrease of pro-inflammatory mediators are implicated.

Bioactive triterpenoids from Callistemon lanceolatus

A new triterpenoid, 30-hydroxyalphitolic acid 1, and eight known triterpenoids, alphitolic acid 2, lupenol 3, 3-acetoxy-olean-18-en-28-oic acid 4, betulinic acid 5, ursolic acid 6, betulinic acid 3-O-caffeate 7, morolic acid 3-O-caffeate 8, and ursolic acid 3-O-caffeate 9, were isolated from Callistemon lanceolatus. Their structures were determined using spectroscopic techniques, which included 1D- and 2D-NMR. All compounds were evaluated for the inhibition of LPS-induced nitric oxide production in murine macrophage RAW264.7 cells. Betulinic acid 3-O-caffeate 7 showed a moderate inhibitory effect on nitric oxide production with IC(50) value of 15.4 microM.

Inflexinol inhibits colon cancer cell growth through inhibition of nuclear factor-kappaB activity via direct interaction with p50

Kaurane diterpene compounds have been known to be cytotoxic against several cancer cells through inhibition of nuclear factor-kappaB (NF-kappaB) activity. Here, we showed that inflexinol, a novel kaurane diterpene compound, inhibited the activity of NF-kappaB and its target gene expression as well as cancer cell growth through induction of apoptotic cell death in vitro and in vivo. These inhibitory effects on NF-kappaB activity and on cancer cell growth were suppressed by the reducing agents DTT and glutathione and were abrogated in the cells transfected with mutant p50 (C62S). Sol-gel biochip and surface plasmon resonance analysis showed that inflexinol binds to the p50 subunit of NF-kappaB. These results suggest that inflexinol inhibits colon cancer cell growth via induction of apoptotic cell death through inactivation of NF-kappaB by a direct modification of cysteine residue in the p50 subunit of NF-kappaB.

A new furofuran lignan from Isodon japonicus

A new sesamin type furofuran lignan, (-)-sesamin-2,2'-diol (1), along with two known flavonoids (2 and 3) and three phenolic compounds (4-6) were isolated from the aerial parts of Isodon japonicus. The structures of these compounds were determined by analysis of spectroscopic data (1D-, 2D-NMR, HRMS and CD) and by comparison of the data with those of related metabolites.

The inhibitory effect of quercitrin gallate on iNOS expression induced by lipopolysaccharide in Balb/c mice

Quercetin 3-O-β-(2"-galloyl)-rhamnopyranoside (QGR) is a naturally occurring quercitrin gallate, which is a polyphenolic compound that was originally isolated from Persicaria lapathifolia (Polygonaceae). QGR has been shown to have an inhibitory effect on nitric oxide (NO) production in lipopolysaccharide (LPS)-stimulated macrophage RAW 264.7 cells. Therefore, this study was conducted to investigate the inhibitory effect of QGR on nitric oxide production and inducible nitric oxide synthases (iNOS) expression in LPS-stimulated Balb/c mice. To accomplish this, 10 mg/kg of QGR was administered via gavage once a day for 3 days. iNOS was then induced by intraperitoneal injection of LPS. Six hours after the LPS treatment the animals were sacrificed under ether anethesia. The serum levels of NO were then measured to determine if QGR exerted an inhibitory effect on NO production in vivo. LPS induced an approximately 6 fold increase in the expression of NO. However, oral administration of QGR reduced the LPS induced increase in NO by half. Furthermore, RT-PCR and western blot analysis revealed that the increased levels of iNOS expression that occurred in response to treatment with LPS were significantly attenuated in response to QGR pretreatment. Histologically, LPS induced the infiltration of polymorphonuclear neutrophils in portal veins and sinusoids and caused the formation of a large number of necrotic cells; however, pretreatment with QGR attenuated these LPS induced effects. Taken together, these results indicate that QGR inhibits iNOS expression in vivo as well as in vitro and has antiinflammatory potentials.

ent-Kaurane diterpenoids from Isodon japonicus

Five ent-kaurane diterpenoids, 6beta,7beta,14beta-trihydroxy-1alpha,19-diacetoxy-7alpha,20-epoxy- ent-kaur-16-en-15-one (1), 1alpha,6beta,7beta-trihydroxy-11alpha,19-diacetoxy-7alpha,20-epoxy-ent-kaur-16-en-15-one (2), 6-hydroxy-1alpha,19-diacetoxy-6,7-seco-ent-kaur-16-en-15-one-7,20-olide (3), 19-hydroxy-1alpha,6-diacetoxy-6,7-seco- ent-kaur-16-en-15-one-7,20-olide (4), and 6-aldehyde-1alpha,19-diacetoxy-6,7-seco- ent-kaur-16-en-15-one-7,20-olide (5), along with 10 known ent-kaurane diterpenoids, pseurata C (6), longikaurin C (7), effusanin C (8), longikaurin B (9), longikaurin D (10), effusanin D (11), excisanin B (12), lasiokaurin (13), megathyrin A (14), and loxothyrin A (15), were isolated from the aerial parts of Isodon japonicus. Their structures were determined on the basis of spectroscopic (1D-, 2D-NMR and MS) and chemical evidence. The isolates were evaluated for their inhibitory effects on LPS-induced production of nitric oxide in murine macrophage RAW264.7 cells.

Kaurane diterpenes protect against apoptosis and inhibition of phagocytosis in activated macrophages

BACKGROUND AND PURPOSE

The kaurane diterpenes foliol and linearol are inhibitors of the activation of nuclear factor kappaB, a transcription factor involved in the inflammatory response. Effects of these diterpenes on apoptosis and phagocytosis have been analysed in cultured peritoneal macrophages and in the mouse macrophage cell line, RAW 264.7.

EXPERIMENTAL APPROACH

Macrophages were maintained in culture and activated with pro-inflammatory stimuli in the absence or presence of diterpenes. Apoptosis and the phagocytosis in these cells under these conditions were determined.

KEY RESULTS

Incubation of macrophages with a mixture of bacterial lipopolysaccharide (LPS)/interferon-gamma (IFN-gamma) induced apoptosis through a NO-dependent pathway, an effect significantly inhibited by foliol and linearol in the low muM range, without cytotoxic effects. Apoptosis in macrophages induced by NO donors was also inhibited. The diterpenes prevented apoptosis through a mechanism compatible with the inhibition of caspase-3 activation, release of cytochrome c to the cytosol and p53 overexpression, as well as an alteration in the levels of proteins of the Bcl-2 family, in particular, the levels of Bax. Cleavage of poly(ADP-ribose) polymerase, a well-established caspase substrate, was reduced by these diterpenes. Treatment of cells with foliol and linearol decreased phagocytosis of zymosan bioparticles by RAW 264.7 cells and to a greater extent by peritoneal macrophages.

CONCLUSIONS AND IMPLICATIONS

Both diterpenes protected macrophages from apoptosis and inhibited phagocytosis, resulting in a paradoxical control of macrophage function, as viability was prolonged but inflammatory and phagocytic functions were impaired.

Relationships between inhibitory activity against a cancer cell line panel, profiles of plants collected, and compound classes isolated in an anticancer drug discovery project

In an attempt to determine the relationships between the plant profiles (country of collection, taxonomy, plant part) and the compound classes isolated with cytotoxic activity against a panel of human tumor cell lines, the data compiled from a 15-year anticancer drug-discovery project were subjected to an analysis of variance (ANOVA). The results indicate significant trends in cytotoxic activity relative to collection location, taxonomy, plant part, and compound classes isolated. Plant collections were made in tropical forests in six countries, with collections from Ecuador resulting in higher activity than those from Indonesia and Peru. Interestingly, collections from Florida were not statistically different than those from the countries with higher biodiversity. One hundred and forty-five families were represented in the collections, with the Clusiaceae, Elaeocarpaceae, Meliaceae, and Rubiaceae having low ED50 (half maximal effective dose) values. Especially active genera included Aglaia, Casearia, Exostema, Mallotus, and Trichosanthes. Roots and below-ground plant materials were significantly more active than above-ground materials. Cucurbitacins, flavaglines, anthraquinones, fatty acids, tropane alkaloids, lignans, and sesquiterpenoids were significantly more active than xanthones and oligorhamnosides. The results from this study should serve as a guide for future plant collection endeavors for anticancer drug discovery.

Inhibitory effect of inflexinol on nitric oxide generation and iNOS expression via inhibition of NF-kappaB activation

Inflexinol, an ent-kaurane diterpenoid, was isolated from the leaves of Isodon excisus. Many diterpenoids isolated from the genus Isodon (Labiatae) have antitumor and antiinflammatory activities. We investigated the antiinflammatory effect of inflexinol in RAW 264.7 cells and astrocytes. As a result, we found that inflexinol (1, 5, 10 μM) suppressed the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) as well as the production of nitric oxide (NO) in LPS-stimulated RAW 264.7 cells and astrocytes. Consistent with the inhibitory effect on iNOS and COX-2 expression, inflexinol also inhibited transcriptional and DNA binding activity of NF-κB via inhibition of IκB degradation as well as p50 and p65 translocation into nucleus. These results suggest that inflexinol inhibits iNOS and COX-2 expression through inhibition of NF-κB activation, thereby inhibits generation of inflammatory mediators in RAW 264.7 cells and astrocytes, and may be useful for treatment of inflammatory diseases.

PTP1B inhibitory activity of kaurane diterpenes isolated from Siegesbeckia glabrescens

Protein tyrosine phosphatase 1B (PTP1B) is considered as a therapeutic target for the treatment of diabetes and obesity. In our preliminary screening study, a MeOH extract of the aerial part of Siegesbeckia glabrescens was found to inhibit PTP1B activity at 30 microg/mL. Bioassay-guided fractionation led to the isolation of two active diterpenes, ent-16betaH, 17-isobutyryloxy-kauran-19-oic acid (1) and ent-16betaH, 17-acetoxy-18-isobutyryloxy-kauran-19-oic acid (2), along with ent- 16betaH, 17-hydroxykauran-19-oic acid (3). Compounds 1 and 2 inhibited the PTP1B activity with IC50 values of 8.7 +/- 0.9 and 30.6 +/- 2.1 microM, respectively. Kinetic studies suggest that both 1 and 2 are non-competitive inhibitors of PTP1B. However, compound 3 substituted with a hydroxyl group at C-17 in kaurane-type showed no inhibitory effects towards PTP1B.