No abstract

Nine flavonoids (1-9) were isolated from the leaves of Morus alba (Moraceae). The structures of compounds were determined to be kaempferol-3-O-beta-D-glucopyranoside (astragalin, 1) kaempferol-3-O-(6"-O-acetyl)-beta-D-glucopyranoside (2), quercetin-3-O-(6"-O-acetyl)-beta-D-glucopyranoside (3), quercetin-3-O-beta-D-glucopyranoside (4), kaempferol-3-O-alpha-L-rhamnopyranosyl-(1-->6)-beta-D-glucopyranoside (5), quercetin-3-O-alpha-L-rhamnopyranosyl-(1-->6)-beta-D-glucopyranoside (rutin, 6), quercetin-3-O-beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranoside (7), quercetin-3,7-di-O-beta-D-glucopyranoside (8) and quercetin (9) on the basis of spectroscopic and chemical studies. Compounds 7 and 9 exhibited significant radical scavenging effect on 1,1-diphenyl-2-picrylhydrazyl radical.

From Arisaema amurense, four new cerebrosides were isolated along with a known cerebroside. The new cerebrosides were characterized as 1-O-beta-D-glucopyranosyl- (2S,3R,4E,8Z)-2-[(2(R)- hydroxyicosanoyl)amido]-4,8-octadecadiene-1,3-diol (1), 1-O-beta-D- glucopyranosyl-(2S,3R,4E,8Z)- 2-[(2-hydroxyoctadecanoyl)amido]-4,8-octadecadiene-1,3-diol (2), 1-O-beta-D- glucopyranosyl- (2S,3R,4E,8E)-2-[(2-hydroxyicosanoyl)amido]-4,8-oct adecadiene-1,3-diol (4), and 1-O-beta-D- glucopyranosyl-(2S,3R,4E,8E)-2-[(2-hydroxyoctadecanoyl )amido]-4,8- octadecadiene-1,3-diol (5), respectively. These cerebrosides displayed significant antihepatotoxic activity.

Two new diastereomeric sauchinones (2, 3), along with the known sauchinone (1), a phenylpropanoid (sarisan), and two known lignans (galbacin and saucernetin), were isolated from the n-hexane fraction of Saururus chinensis using reversed-phase HPLC. The stereostructures of the lignans, sauchinone A (2) and 1'-epi-sauchinone (3), were established by analysis of spectroscopic data. Incubation of cultured rat hepatocytes intentionally injured by CCl(4) with each of the compounds 1, 2, and 3 significantly reduced the levels of glutamic pyruvic transaminase released by the damaged hepatocytes.

Eleven lignans (1-11) were isolated from the CH2Cl2 fraction of the bark of Machilus thunbergii Sieb. et Zucc. (Lauraceae). These were identified as (-)-acuminatin (1), (-)-isoguaiacin (2), meso-dihydroguaiaretic acid (3), (+)-galbacin (4), (-)-sesamin (5), (+)-galbelgin (6), machilin A (7), machilin G (8), licarin A (9), and nectandrin A (10) and B (11). Primary cultures of rat hepatocytes were co-incubated for 90 min with the hepatotoxin CCl4 and each of the 11 lignans (50 microM). Hepatoprotective activity was determined by measuring the level of glutamic pyruvic transaminase released into the medium from the primary cultures of rat hepatocytes. (-)-Acuminatin, (-)-isoguaiacin and meso-dihydroguaiaretic acid all significantly reduced the level of glutamic pyruvic transaminase released. Further investigation revealed that these three compounds significantly preserved the levels and the activities of glutathione, superoxide dismutase, glutathione peroxidase and catalase. (-)-Acuminatin, (-)-isoguaiacin and meso-dihydroguaiaretic acid also ameliorated lipid peroxidation as demonstrated by a reduction of malondialdehyde production. These results suggest that (-)-acuminatin, (-)-isoguaiacin and meso-dihydroguaiaretic acid exert diverse hepatoprotective activities, perhaps by serving as potent antioxidants.