Phuong Thien Thuong

Stilbenes and oligostilbenes from leaf and stem of Vitis amurensis and their cytotoxic activity

Chromatographic separation of the EtOAc fraction from the leaf and stem of Vitis amurensis led to the isolation of six oligostilbenoids (i.e., r-2-viniferin (1), trans-amurensin B (2), trans-ɛ-viniferin (3), gnetin H (4), amurensin G (5), (+)-ampelopsin A (8)) and four stilbenoids (i.e., trans-resveratrol (6), (+)-ampelopsin F (7), piceatannol (9), and trans-piceid (10)). The structures have been identified on the basis of spectroscopic evidence and physicochemical properties. The isolates were investigated for cytotoxic activity against three cancer cell lines in vitro using the MTT assay method. Amurensin G (5) and trans-resveratrol (6) showed significant cytotoxic activity against L1210, K562 and HTC116 cancer cell lines with IC50 values ranging from 15.7 ± 2.1 to 30.9 ± 1.8 μM. (+)-Ampelopsin A (8) and trans-piceid (10) exhibited considerable cytotoxic activity against L1210 (IC50 values of 30.6 ± 4.1 and 28.7 ± 2.81 μM, respectively) and K562 (IC50 values of 38.6 ± 0.82 and 24.6 ± 0.76 μM, respectively). Gnetin H (4) showed only weak cytotoxic activity against L1210 with an IC50 value of 40.1 ± 4.23 μM. On the other hand, r-2-viniverin (1), trans-amurensin B (2), trans-ɛ-viniferin (3), (+)-ampelopsin F (7), and piceatannol (9) exhibited no activity on three cancer cell lines.

Cytotoxic and PTP1B inhibitory activities from Erythrina abyssinica.

Bioassay-guided fractionation of the EtOAc extract of the stem bark of Erythrina abyssinica (Leguminosae) resulted in the isolation of three new (1-3), along with 12 known (4-15) pterocarpan derivatives. Their chemical structures were determined by physicochemical and spectroscopic data analysis (IR, UV, [alpha](D), CD, 1D and 2D NMR, and MS data). All the isolates were evaluated for their inhibitory effects on protein tyrosine phosphatase-1B (PTP1B), as well as their growth inhibition on MCF7, tamoxifen-resistant MCF7 (MCF7/TAMR), adriamycin-resistant MCF7 (MCF7/ADR) and MDA-MB-231 breast cancer cell lines. Compounds which exhibited PTP1B inhibitory activity (IC(50) values ranging from 4.2+/-0.2 to 19.3+/-0.3 microM) showed strong cytotoxic activity (IC(50) values from 5.6+/-0.7 to 28.0+/-0.2 microM). Our data suggested that pterocarpans could be considered as new anticancer materials by PTP1B inhibition.

Stimulation of glucose uptake by triterpenoids from Weigela subsessilis

Four ursane‐type triterpenoids, corosolic acid (1), ilekudinol B (2), ursolic acid (3) and pomolic acid (4), were isolated from an EtOAc‐soluble extract of the leaves of Weigela subsessilis. These bioactive compounds were evaluated for their glucose uptake activity and produced moderate to strong enhancement both in basal‐ and insulin‐stimulated L6 muscle cells. In particular, corosolic acid exhibited the most potent activity, increasing uptake by basal‐ and insulin‐stimulated myotubes by 2.63‐ and 3.33‐fold, respectively; ilekudinol B produced 1.6‐ and 2.9‐fold, ursolic acid produced 1.84‐ and 2.64‐fold, and pomolic acid produced 1.6‐ and 2.8‐fold increases. No cytotoxicities were observed for corosolic acid, ursolic acid and ilekudinol B in myoblasts, while pomolic acid at doses of 25 and 50 µm reduced cell viability by 19% and 21.8% upon 24 h treatment and by 48.6% and 54.1% upon 48 h treatment, respectively. These results suggest that ursane‐type triterpenoids from W. subsessilis might enhance glucose uptake by acting as insulin mimics and as insulin sensitizers and that they could be useful as nontoxic diabetes treatment agents. Copyright

Flavanones from the stem bark of Erythrina abyssinica

Twelve new flavanones bearing a 2,2-dimethylpyrano ring were isolated from a MeOH extract of the stem bark of Erythrina abyssinica. Their structures were determined on the basis of spectroscopic (UV, CD, 1D and 2D NMR, HRMS) and physico-chemical analyses. Compounds 1, 3, 5, 6, 8, and 9 exhibited inhibitory effects on the enzyme activity of PTP1B in an in vitro assay with IC(50) values ranging from 13.9+/-2.1 to 19.0+/-1.8 microM. These results suggest that prenyl and methoxy groups on the B ring contribute to the inhibitory activity of flavanones against PTP1B.