Protein tyrosine phosphatase 1B inhibitory activities of compounds isolated from Polygonum cuspidatum

Abstract

In the search for new natural PTP1B inhibitory compounds from medicinal plants, two 9,10-anthraquinones were isolated and structurally identitfed as physcion (1) and emodin (2) from the alcoholic extract of the root of Polygonum cuspidatum. Chemical structures of these isolates were identified by interpretation of spectroscopic data (¹H, ¹³C NMR and MS) as well as comparing with reported literatures. Compounds 1-2 possessed inhibitory activity on PTP1B enzyme with IC₅₀ values of 26.1 ± 0.7 and 13.3 ± 0.4 µM, respectively. Ursolic acid was used as positive control showing an IC₅₀ value of 3.5 ± 0.2 µM in this assay. This result reveals that these 9,10-anthraquinones might be considered as new natural compounds for development of antidiabetic agents.