Anti-inflammatory effect and mechanism of action of ellagic acid-3,3',4-trimethoxy-4'-O-α-L-rhamnopyranoside isolated from Hopea parviflora in lipopolysaccharide-stimulated RAW 264.7 macrophages.

Phytochemical investigation of the stem bark of Hopea parviflora resulted in the isolation of 9 compounds; which includes friedelin (1), friedelin-3ß-ol (2), (-)-ampelopsin A (3), (-)-ɛ-viniferin (4), (-)-hopeaphenol (5), vaticaphenol A (6), 2,4,8-trihydroxyphenanthrene-2-O-glucoside (7), ellagic acid-3,3',4-trimethoxy-4'-O-α-L-rhamnopyranoside (8) and ß-sitosterol-ß-D-glucoside (9). Among them, compounds 1, 2, 6, 7, 8 and 9 are isolated for the first time from this species. Further, we evaluated the anti-inflammatory activity of compounds 4, 5, 6, 7 and 8. In this study, compound 8 inhibited the activity of proinflammatory mediators like NO, TNF-α, IL-6, 5-LOX and COX-2, also promoted the action of anti-inflammatory mediator like IL-10 via inhibition of the NF-κB pathway in LPS-stimulated RAW 264.7 macrophages.

Isolation and characterization of resveratrol oligomers from the stem bark of Hopea ponga (Dennst.) Mabb. And their antidiabetic effect by modulation of digestive enzymes, protein glycation and glucose uptake in L6 myocytes.

ETHNOPHARMACOLOGICAL RELEVANCE: Hopea ponga (Dennst.) Mabb. Is used in traditional herbal formulations for diabetes complications. The aim of this study is to evaluate the antidiabetic effect of extracts and compounds from H. ponga. MATERIALS AND METHODS: Silica gel column chromatography was performed to identify various chemical components of the plant extract. Different extracts of H. ponga and isolated compounds were screened for their antidiabetic effect by modulation of digestive enzymes and protein glycation. The effect of glucose uptake by the compounds and the pathways through which the compounds mediate the glucose uptake potential were confirmed by fluorescent microscopy, flow cytometry and western blot analysis. RESULTS: Acetone and ethanol extracts of the stem bark of Hopea ponga (Dennst.) Mabb. Afforded six resveratrol oligomers namely, E-resveratrol (1), (-)-ε-viniferin (2), (-)-α-viniferin (3), trihydroxyphenanthrene glucoside (THPG) (4), vaticaphenol A (5), (-)-hopeaphenol (6), along with four phytosterols. The structures were determined on the basis of spectroscopic analyses including nuclear magnetic resonance (NMR) spectroscopy and high resolution mass spectrometry (HRMS) data. Compounds 1-5 and 7-10 were tested for their α-glucosidase, α-amylase and glycation inhibitiory activities. All the resveratrol oligomers (1-5) showed prominent α-glucosidase inhibition with IC50 values, 12.56 ±â€¯1.00, 23.98 ±â€¯1.11, 7.17 ±â€¯1.10, 31.74 ±â€¯0.42 and 16.95 ±â€¯0.39 µM, respectively. Molecular docking studies also supported the observed α-glucosidase inhibition. Compound 3 displayed IC50 values of 4.85 ±â€¯0.06 and 27.10 ±â€¯0.04 µM in α-amylase and glycation inhibitory assays activity. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay revealed that the compounds 3 and 4 were found to be less toxic at a concentration of 100 µM (<10%) and 25 µM (<20%), respectively. The effect of glucose uptake performed by 2-(N-(7-Nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-2-deoxyglucose (2-NBDG) in L6 myoblast were measured by fluorescent microscopy and flow cytometry. The compounds 3 and 4 showed 2-NBDG uptake of 49.6% and 38.8% respectively. By examining the molecular pathway through which the compounds elicit their glucose uptake potential, it was observed that both the compounds mainly act via AMPK pathway. CONCLUSION: This is the first report on the isolation of compounds from H. ponga. Altogether, the results of this study reveal the antidiabetic effects of H. ponga extracts and isolated compounds promoting traditional use of this plant in the treatment of diabetes.