title: Chemical constituents of the aerial parts of Scutellaria lateriflora and their alpha-glucosidase inhibitory activities.
abstract: MeOH extracts of 37 herbs were tested in screening experiments for rat intestinal alpha-glucosidase. The MeOH extract of the aerial parts of Scutellaria lateriflora L. (Lamiaceae) significantly inhibited sucrase and maltase activities, using sucrose and maltase as the substrates. Enzyme inhibition guided-fractionation of the MeOH extract of S. lateriflora resulted in the isolation of a new diterpene glucoside, deacetylajugarin-IV 18-O-beta-D-glucopyranoside (1), along with 20 known phenolics (2-21). The structures of 1-21 were elucidated on the basis of MS and NMR data analyses. Baicalein (4) and baicalin (10), a glycoside of 4, showed moderate sucrase inhibitory activities at IC50 values of 14.9 and 36.3 microM, respectively, whereas luteolin (3), acteoside (16), leucosceptoside A (18), and isoacteoside (20) showed weak inhibitory activities at IC50 values of 811, 522, 727, and 443 microM, respectively. This is the first report on mammalian alpha-glucosidase inhibitory activities of S. lateriflora extract and identification of the constituents responsible for the activities. Apigenin (2), luteolin (3), 6-methoxyluteolin 4'-methyl ether (6), isoscutellarin 8-O-beta-D-glucuronide (7), luteolin 7-O-beta-D-glucuronide (9), wogonin 7-O-beta-D-glucuronide methyl ester (12), eriodictyol (13), naringenin (14), naringenin 7-O-beta-D-glucuronide (15), jionoside D (17), leucosceptoside A (18), and (+)-syringaresinol 4'-O-beta-D-glucopyranoside (21) were isolated from this plant for the first time. The inhibitory properties of S. lateriflora extract against alpha-glucosidase provide a prospect for its antidiabetic usage.
authors.affiliation: School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, 1432-1, Horinouchi, Hachioji, Tokyo 192-0392, Japan. kurodam@toyaku.ac.jp
authors.forename: Minpei
authors.initials: M
authors.lastname: Kuroda
authors.forename: Katsura
authors.initials: K
authors.lastname: Iwabuchi
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Mimaki
mesh_terms: D000818:Animals; D065089:Glycoside Hydrolase Inhibitors; D035261:Plant Components, Aerial / Q000737:chemistry; D051381:Rats; D031363:Scutellaria / Q000737:chemistry*; D013393:Sucrase / Q000037:antagonists & inhibitors*
chemical_list: D065089:Glycoside Hydrolase Inhibitors; D013393:Sucrase