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Published on: July 5, 2017
Proanthocyanidins from the leaves of Machilus philippinensis
Hsiao-Ching Lin1, Shoei-Sheng Lee
1School of Pharmacy, College of Medicine, National Taiwan University, 1, Sec. 1, Jen-Ai Rd, Taipei 10051, Taiwan, Republic of China.
Abstract:
Seven proanthocyanidins (2-8) together with epicatechin (1) were isolated from the EtOH extract of the leaves of Machilus philippinensis. Of these, machiphilitannins A (7) and B (8) are new natural products, with respective IC(50) values of 31.3 (7) and 18.4 microM (8) against alpha-glucosidase type IV from Bacillus stearothermophilus. Their structures were elucidated mainly on the basis of CD and 2D NMR analyses. In addition, aesculitannin B (2) showed inhibitory activity against alpha-glucosidase with an IC(50) value of 3.5 microM. This work demonstrates for the first time that the purified proanthocyanidins possess inhibitory activity against alpha-glucosidase type IV.
