α-mangostin improves glucose uptake and inhibits adipocytes differentiation in 3T3-L1 cells via PPARgamma, GLUT4, and leptin expressions

Obesity has been often associated with the occurrence of cardiovascular diseases, type 2 diabetes, and cancer. The development of obesity is also accompanied by significant differentiation of preadipocytes into adipocytes. In this study, we investigated the activity of α-mangostin, a major xanthone component isolated from the stem bark of G. malaccensis, on glucose uptake and adipocyte differentiation of 3T3-L1 cells focusing on PPARγ, GLUT4, and leptin expressions. α-Mangostin was found to inhibit cytoplasmic lipid accumulation and adipogenic differentiation. Cells treated with 50 μM of α-mangostin reduced intracellular fat accumulation dose-dependently up to 44.4% relative to MDI-treated cells. Analyses of 2-deoxy-D-[3H] glucose uptake activity showed that α-mangostin significantly improved the glucose uptake ( P < 0.05 ) with highest activity found at 25 μM. In addition, α-mangostin increased the amount of free fatty acids (FFA) released. The highest glycerol release level was observed at 50 μM of α-mangostin. qRT-PCR analysis showed reduced lipid accumulation via inhibition of PPARγ gene expression. Induction of glucose uptake and free fatty acid release by α-mangostin were accompanied by increasing mRNA expression of GLUT4 and leptin. These evidences propose that α-mangostin might be possible candidate for the effective management of obesity in future

Antioxidant and antimicrobial activities of shorea kunstleri

Objective: To evaluate antioxidant and antimicrobial activities of stembark of Shorea kunstleri together with analysis of phytochemical and total phenolic contents. Methods: Extraction was conducted with different solvent polarity of n-hexane, dichloromethane (DCM) and methanol by using Soxhlet extraction. Total phenolic content was determined using Folin-Ciocalteu method. Free radical scavenging activity and inhibition of lipid peroxidation were evaluated with DPPH radical scavenging and ferric thiocyanate (FTC) assays, respectively. Antimicrobial activities were performed using disc diffusion method, minimum inhibition concentration (MIC), minimum bactericidal concentration (MBC), and minimum fungicidal concentration (MFC). Results: S. kunstleri stembark extracts revealed presence of steroids, terpenoids, saponins, flavonoids, and phenolic compounds. Methanol extract exhibited the highest total phenolic content and free radical scavenging activity result in phenolic content of 8.34±0.003 g GAE/100 g of extract and 95.9±1.07% DPPH inhibition (IC50 value of 18.6 µg/ml), respectively. FTC assay of n-hexane, DCM, and methanol extracts indicated lipid peroxidation inhibitory activity of 74.2±0.35%, 74.0±0.10%, and 72.8±0.27%, respectively. In antimicrobial and antifungal tests, methanol extract showed inhibition against S. aureus, C. albicans, and C. tropicalis with inhibition zones of 10-12, 18-22, and 18-19 mm, respectively. The MIC test of methanol extract showed highest inhibition against C. albicans and S. aureus (0.04 and 0.08 mg/ml, respectively) while DCM extract exhibited the highest activity towards C. tropicalis (MIC value of 0.63 mg/ml). Taken together, MBC test of methanol extract strongly demonstrated bactericidal effect against S. aureus with MBC value of 0.08 mg/ml. Conclusion: The study demonstrated that stembark extracts of S. kunstleri possessed antioxidant and antimicrobial properties

Flavonoids from Tetracera indica Merr. induce adipogenesis and exert glucose uptake activities in 3T3-L1 adipocyte cells

Background: Tetracera indica Merr. (Family: Dilleniaceae), known to the Malay as ‘Mempelas paya’, is one of the medicinal plants used in the treatment of diabetes in Malaysia. However, no proper scientific study has been carried out to verify the traditional claim of T. indica as an antidiabetic agent. Hence, the aims of the present study were to determine the in vitro antidiabetic potential of the T. indica stems ethanol extract, subfractions and isolated compounds. Methods: The ethanol extract and its subfractions, and isolated compounds from T. indica stems were subjected to cytotoxicity test using MTT viability assay on 3T3-L1 pre-adipocytes. Then, the test groups were subjected to the in vitro antidiabetic investigation using 3T3-L1 pre-adipocytes and differentiated adipocytes to determine the insulinlike and insulin sensitizing activities. Rosiglitazone was used as a standard antidiabetic agent. All compounds were also subjected to fluorescence glucose (2-NBDG) uptake test on differentiated adipocytes. Test solutions were introduced to the cells in different safe concentrations as well as in different adipogenic cocktails, which were modified by the addition of compounds to be investigated and in the presence or absence of insulin. Isolation of bioactive compounds from the most effective subfraction (ethyl acetate) was performed through repeated silica gel and sephadex LH-20 column chromatographies and their structures were elucidated through 1 H–and 13C–NMR spectroscopy. Results: Four monoflavonoids, namely, wogonin, norwogonin, quercetin and techtochrysin were isolated from the T. indica stems ethanol extract. Wogonin, norwogonin and techtochrysin induced significant (P < 0.05) adipogenesis like insulin and enhanced adipogenesis like rosiglitazone. Wogonin and norwogonin also exhibited significant (P < 0.05) glucose uptake activity. Conclusion: The present study demonstrated that the flavonoids isolated from the T. indica stems possess antidiabetic potential revealing insulin-like and insulin sensitizing effects which were significant among the compounds. This also rationalizes the traditional use of T. indica in the management of diabetes in Malaysia