Two new antidiabetic xanthones from the twigs of Garcinia oblongifolia.

Two new xanthones, oblongixanthones I (1) and J (2), and seven known compounds (3-9), were isolated from an EtOAc extract of the twigs of Garcinia oblongifolia. Their structures were elucidated using spectroscopic methods, mainly 1 D and 2 D NMR. The antidiabetic effects of the two new compounds were evaluated using α-glucosidase and PTP1B inhibition assays. Both compounds displayed strong inhibition towards α-glucosidase with IC50 values of 258.7 ± 49.3 and 187.1 ± 27.5 µM, respectively (compared with acarbose, IC50 = 900.0 ± 3.0 µM) and moderate effects against PTP1B with IC50 values of 93.9 ± 12.3 and 64.1 ± 5.8 µM, respectively (compared with RK682, IC50 = 4.4 ± 0.3 l µM).

In vitro and in silico antioxidant and α-glucosidase inhibitory potential of compounds isolated from Garcinia gaudichaudii.

Nine compounds including a new one, garcichaudiic acid (1), were isolated from the bark of G. gaudichaudii and their structures were characterized mainly by 1 D and 2 D NMR experiments. The antioxidant capacity of the isolated compounds was determined using DPPH radical scavenging assay and the anti-hyperglycemic activity was assessed by measuring the inhibitory effect against α-glucosidase. Among them, compound 4 showed higher antioxidant activity than the positive control, ascorbic acid, while both compounds 1 and 7 exhibited more significant α-glucosidase inhibitory activity than the reference drug acarbose. Molecular docking analysis of the bioactive compounds was also performed to examine the binding modes and key interactions with the catalytic site.

Triterpenoids from the bark of Entandrophragma angolense.

Two new triterpenoids, entanolide (1) and methyl 3,4-secotirucalla-23-oxo-4(28),7,24-trien-21-al-3-oate (2), together with nine known compounds (3-11), were isolated from the bark of Entandrophragma angolense. Their structures were elucidated based on spectroscopic analyses, mainly 1 D and 2 D NMR spectral data. Compounds 1-6 and 8 were evaluated for their cytotoxicity against HepG2 cells, and compounds 2-5 exhibited weak activities.

Antioxidant and Antimicrobial Activities of the Extracts from Different Garcinia Species.

BACKGROUND: Garcinia is a large genus which has promising bioactivities. However, the properties of many Garcinia species have not been investigated thoroughly. AIM: To determine the antioxidant and antimicrobial capabilities of the extracts from different Garcinia species. Methodology. Six Garcinia species, including Garcinia fusca, Garcinia hopii, Garcinia planchonii, Garcinia nigrolineata, Garcinia gaudichaudii, and Garcinia tinctoria were extracted using n-hexane, ethyl acetate, and methanol, producing n-hexane extract (HE), ethyl acetate extract (EAE), and methanol extract (ME). After that, the total polyphenol content was evaluated using Folin-Ciocalteu assay. DPPH, hydroxyl radical scavenging, and total antioxidant capacity assays were performed to test the antioxidant activity. Subsequently, the antimicrobial activities against Gram-positive (Staphylococcus aureus, Bacillus subtilis) and Gram-negative (Escherichia coli, Pseudomonas aeruginosa) bacterial strains were assessed using Kirby Bauer and the broth microdilution methods. RESULTS: Many Garcinia extracts contained high total polyphenol content consisting of ME of G. hopii ad G. tinctoria, and EAE of G. planchonii and G. tinctoria. The EAE of G. tinctoria showed effective antioxidant capacity (IC50 = 1.5 µg/mL). Additionally, the EAE of G. gaudichaudii was effective against Gram-positive bacteria with minimal inhibition concentration (MIC) of 15.625-25 µg/mL whereas ME of G. planchonii was effective against both Gram-positive bacteria (MIC = 160 µg/mL) and Gram-negative bacteria (MIC = 75 µg/mL). CONCLUSION: Several extracts of Garcinia species demonstrated valuable antioxidant and antimicrobial properties.

Cytotoxic limonoids from the bark of Walsura cochinchinensis.

Three new limonoids, walsucochinones A-C (1-3), along with eight known compounds, were isolated from an ethyl acetate extract of the bark of Walsura cochinchinensis. Their structures were determined using spectroscopic techniques, mainly 1-D and 2-D NMR. The ethyl acetate extract showed cytotoxic activity against MCF-7 human breast cancer cells and cytotoxicity of the isolated compounds were evaluated in vitro using the SRB assay. Walsucochinone C (3) exhibited the most active effect with IC50 value of 16.4 ±â€¯0.2 µM.