Caged xanthones displaying protein tyrosine phosphatase 1B (PTP1B) inhibition from Cratoxylum cochinchinense

Abstract

Four new caged xanthones (1-4) and two known compounds (5, 6) were isolated from the roots of Cratoxylum cochinchinense, a polyphenol rich plant, collected in China. The structures of the isolated compounds (1-6) were characterized by obtaining their detailed spectroscopic data. In particular, compounds 1 and 6 were fully identified by X-ray crystallographic data. The isolated compounds (1-6) were evaluated against protein tyrosine phosphatase 1B (PTP1B), which plays an important role in diabetes, obesity, and cancer. Among these compounds, 3, 4, and 6 displayed significant inhibition with IC50 values of 76.3, 43.2, and 6.6 mu M, respectively. A detailed kinetic study was conducted by determining K-m, V-max, and the ratio of K-ik and K-iv, which revealed that all the compounds behaved as competitive inhibitors. (C) 2018 Elsevier Inc. All rights reserved.