12.

A Trimeric Proanthocyanidin from the Bark of Acacia leucophloea Willd.

Sarfaraz Ahmed, Hsiao-Ching Lin, Iram Nizam, Nadeem Ahmad Khan, Shoei-Sheng Lee and Nizam Uddin Khan

Department of Chemistry, Aligarh Muslim University, Aligarh-202 002, India

School of Pharmacy, College of Medicine, National Taiwan University, Taipei 10051, Taiwan, Republic of China

GVK Biosciences, 28A, IDA, Nacharam, Hyderabad-500076, India

Department of Pharmacognosy, College of Pharmacy, King Saud University, Post box-2457, Riyadh-11451, Saudi Arabia

Abstract: (–)-Fisetinidol-(4α,8)-[(–)-fisetinidol-(4α,6) ]-(+)-catechin ( 1 ), a proanthocyanidin, was isolated from the bark of Acacia leucophloea . Its structure including absolute configuration was elucidated on the basis of spectroscopic analysis and chemical correlation . The 1H NMR spectrum of this compound, exhibiting exceptional complex signals attributable to rotational isomerism, and the reported data were obtained at elevated temperature in methyl ether acetate form. This work provided the 1H and 13C NMR assignments for 1 and its rotational isomer as the free phenolic form at ambient temperature for the first time. Compound 1 showed inhibitory activity against α-glucosidase type IV from Bacillus stearothermophilus with the IC 50 value of 102.3 μM.

Keywords: Acacia leucophloea ; Mimosaceae; α-Glucosidase inhibitor; proanthocyanidin. © 2014 ACG Publications. All rights reserved.