Six new oligostilbenes, carastilphenols A-E (1-5) and (-)-hopeachinol B (6), with three reported oligostilbenes were obtained from the stems of Caragana sinica. The structures of compounds 1-6 were determined by comprehensive spectroscopy analysis, and their absolute configurations were determined by electronic circular dichroism calculations. Thus, natural tetrastilbenes were determined as absolute configuration for the first time. Also, we did several pharmacological essays. In the antiviral tests, compounds 2, 4 and 6 showed moderate anti-coxsackie virus B3 type (CVB3) effect on Vero cells activities in vitro with IC50 values of 19.2 ∼ 69.3 μM; and compounds 3 and 4 showed different levels of anti-respiratory syncytial virus (RSV) effect on Hep2 cells activities in vitro with IC50 values of 23.1 and 33.3 μM, respectively. As for hypoglycemic activity, compounds 6-9 (10 μM) showed the inhibition of α-glucosidase in vitro with IC50 values of 0.1 ∼ 0.4 μM; and compound 7 showed significant inhibition (88.8%, 10 μM) of protein tyrosine phosphatase 1B (PTP1B) with IC50 value of 1.1 μM in vitro.
Keywords: Caragana sinica; Carastilphenols A-E; Hypoglycemic activity; Oligostilbenes.
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