title: Acylated flavonol monorhamnosides, alpha-glucosidase inhibitors, from Machilus philippinensis.
abstract: Bioassay-guided fractionation and isolation of the active constituents from the leaf extract of Machilusphilippinense Merr. yielded two active compounds, kaempferol-3-O-alpha-L-rhamnopyranoside 3'',4''-di-E-P-coumaroic acid ester (1) and 3''-E,4''-Z-di-p-coumaroic acid ester (2) when tested against a Bacillus stearothermophilus, a alpha-glucosidase type IV. The IC50 values of 1 and 2 were 6.10 and 1.00microM, respectively. Further application of the HPLC-SPE-NMR hyphenated technique in the on-line characterization of other active ingredients present in the CH2Cl2 - soluble fraction led to identification of luteolin (3) and seven additional 3-O-(coumaroyl-rhamnopyranosyl)-flavonols (4-10). Their structures were determined mainly by 1H NMR spectroscopic analyses. Among the compounds identified, compounds 2, 4, 5, and 7 were hitherto unknown natural products.
authors.affiliation: School of Pharmacy, College of Medicine, National Taiwan University, 1, Sec. 1, Jen-Ai Road, Taipei 10051, Taiwan, ROC. shoeilee@ntu.edu.tw
authors.forename: Shoei-Sheng
authors.initials: SS
authors.lastname: Lee
authors.forename: Hsiao-Ching
authors.initials: HC
authors.lastname: Lin
authors.forename: Chien-Kuang
authors.initials: CK
authors.lastname: Chen
mesh_terms: D000215:Acylation; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology; D044948:Flavonols / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology; D001411:Geobacillus stearothermophilus / Q000187:drug effects / Q000201:enzymology; D065089:Glycoside Hydrolase Inhibitors; D006027:Glycosides / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology; D019684:Magnoliopsida / Q000737:chemistry*; D010936:Plant Extracts / Q000737:chemistry / Q000302:isolation & purification; D018515:Plant Leaves / Q000737:chemistry*
chemical_list: D001426:Bacterial Proteins; D004791:Enzyme Inhibitors; D044948:Flavonols; D065089:Glycoside Hydrolase Inhibitors; D006027:Glycosides; D010936:Plant Extracts