title: Inhibition of angiotensin-I-converting enzyme by tetrahydroxyxanthones isolated from Tripterospermum lanceolatum.
abstract: Five tetrahydroxyxanthones, 3,4,6,7-tetrahydroxyxanthone [1], 1,3,5,6-tetrahydroxyxanthone [2], 3,4,5,6-tetrahydroxyxanthone [3], 1,3,6,7-tetrahydroxyxanthone [4], and 2,3,6,7-tetrahydroxyxanthone [5] isolated from Tripterospermum lanceolatum inhibited angiotensin-I-converting-enzyme activity in a dose-dependent manner. The mode of inhibition of the tetrahydroxyxanthones (THXs) was found to be competitive inhibition. When the tetrahydroxy groups of THXs were blocked with acetyl groups, the angiotensin-I-converting-enzyme inhibitory activity was abolished, suggesting that the tetrahydroxy groups are indispensible for the inhibitory activity.
authors.affiliation: Institute of Biochemistry, College of Medicine, National Taiwan University, Taipei, Republic of China.
authors.forename: C H
authors.initials: CH
authors.lastname: Chen
authors.forename: J Y
authors.initials: JY
authors.lastname: Lin
authors.forename: C N
authors.initials: CN
authors.lastname: Lin
authors.forename: S Y
authors.initials: SY
authors.lastname: Hsu
mesh_terms: D000806:Angiotensin-Converting Enzyme Inhibitors / Q000302:isolation & purification / Q000494:pharmacology*; D000818:Animals; D004365:Drugs, Chinese Herbal / Q000737:chemistry*; D008297:Male; D051381:Rats; D011918:Rats, Inbred SHR; D014966:Xanthenes / Q000302:isolation & purification / Q000494:pharmacology*
chemical_list: D000806:Angiotensin-Converting Enzyme Inhibitors; D004365:Drugs, Chinese Herbal; D014966:Xanthenes