title: Proanthocyanidins from the leaves of Machilus philippinensis.
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.
authors.affiliation: School of Pharmacy, College of Medicine, National Taiwan University, 1, Sec. 1, Jen-Ai Rd, Taipei 10051, Taiwan, Republic of China.
authors.forename: Hsiao-Ching
authors.initials: HC
authors.lastname: Lin
authors.forename: Shoei-Sheng
authors.initials: SS
authors.lastname: Lee
mesh_terms: D002392:Catechin / Q000737:chemistry / Q000302:isolation & purification; D001411:Geobacillus stearothermophilus / Q000201:enzymology*; D065089:Glycoside Hydrolase Inhibitors; D006801:Humans; D020128:Inhibitory Concentration 50; D019770:Lauraceae / Q000737:chemistry*; D019906:Nuclear Magnetic Resonance, Biomolecular; D018515:Plant Leaves / Q000737:chemistry; D010946:Plants, Medicinal / Q000737:chemistry*; D044945:Proanthocyanidins / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D013624:Taiwan
chemical_list: D065089:Glycoside Hydrolase Inhibitors; D044945:Proanthocyanidins; C552130:machiphilitannin A; C552131:machiphilitannin B; D002392:Catechin