Geranylated 2-arylbenzofurans from Morus alba var. tatarica and their alpha-glucosidase and protein tyrosine phosphatase 1B inhibitory activities

Ten new geranylated 2-arylbenzofuran derivatives, including two monoterpenoid 2-arylbenzofurans (1 and 2), two geranylated 2-arylbenzofuran enantiomers (3a and 3b), and six geranylated 2-alylbenzofurans (4-9), along with four known 2-arylbenzofurans (10-13) were isolated from the root bark of Morus alba var. tatarica. Their structures and relative configurations were established on the basis of spectroscopic data analysis. Compounds 3-7 with one asymmetric carbon at C-7 were supposed to be enantiomeric mixtures confirmed by chiral HPLC analysis, and the absolute configurations of each enantiomer in 3-7 were determined by Rh-2(OCOCF3)(4)-induced CD and Snatzke's method. The enantiomers with the substituting group at C-2' exhibited better resolutions on a Chiralpak AD-H column than those with the substituting group at C-4'. Compounds 1-7, 10, 11 and 13, showed alpha-glucosidase inhibitory activities with IC50 values of 11.9-131.9 mu M, and compounds 1 and 9-13 inhibited protein tyrosine phosphatase 1B (PTP1B) with IC50 values of 7.9-38.1 mu M. (C) 2013 Elsevier B.V. All rights reserved.