title: Scopadulcic acid B, a new tetracyclic diterpenoid from Scoparia dulcis L. Its structure, H+, K(+)-adenosine triphosphatase inhibitory activity and pharmacokinetic behaviour in rats.
abstract: The structure of scopadulcic acid B (2, SDB), a major ingredient of the Paraguayan herb "Typychá kuratũ" (Scoparia dulcis L.), was elucidated mainly by comparison of its spectral data with that of scopadulcic acid A (1). SDB inhibited both the K(+)-dependent adenosine triphosphatase (ATPase) activity of a hog gastric proton pump (H+, K(+)-ATPase) with a value of 20-30 microM for IC50 and proton transport into gastric vesicles. Pharmacokinetic studies of SDB in rats indicated that plasma SDB concentrations after i.v. injection of the sodium salt of SDB (SDB-Na) were described reasonably well by a two-compartment open model with Michaelis-Menten elimination kinetics. Plasma concentrations after oral administration of SDB-Na or SDB showed a much slower decline than what was expected following the i. v. study. It was suggested that the sustained plasma level of SDB after oral administration of SDB-Na or SDB was accounted for by relatively slow but efficient gastro-intestinal absorption in rats.
authors.affiliation: Faculty of Pharmaceutical Sciences, Toyama Medical and Pharmaceutical University, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Hayashi
authors.forename: K
authors.initials: K
authors.lastname: Okamura
authors.forename: M
authors.initials: M
authors.lastname: Kakemi
authors.forename: S
authors.initials: S
authors.lastname: Asano
authors.forename: M
authors.initials: M
authors.lastname: Mizutani
authors.forename: N
authors.initials: N
authors.lastname: Takeguchi
authors.forename: M
authors.initials: M
authors.lastname: Kawasaki
authors.forename: Y
authors.initials: Y
authors.lastname: Tezuka
authors.forename: T
authors.initials: T
authors.lastname: Kikuchi
authors.forename: N
authors.initials: N
authors.lastname: Morita
mesh_terms: D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors*; D000818:Animals; D000998:Antiviral Agents / Q000737:chemistry* / Q000493:pharmacokinetics / Q000494:pharmacology; D004224:Diterpenes / Q000737:chemistry* / Q000493:pharmacokinetics / Q000494:pharmacology; D017506:H(+)-K(+)-Exchanging ATPase; D008297:Male; D010239:Paraguay; D010946:Plants, Medicinal / Q000032:analysis*; D051381:Rats; D011919:Rats, Inbred Strains; D013270:Stomach / Q000187:drug effects / Q000201:enzymology; D013552:Swine; D014961:X-Ray Diffraction
chemical_list: D000998:Antiviral Agents; D004224:Diterpenes; C058658:scopadulcic acid B; D000251:Adenosine Triphosphatases; D017506:H(+)-K(+)-Exchanging ATPase