We isolated and characterized 23 compounds, including a new iridoid named gentiolutelin and its dimethyl acetal, and a new lignan named gentioluteol from fresh roots (including small amounts of rhizome) of Gentiana lutea cultivated in Japan (Hokkaido). The structures of gentiolutelin and gentioluteol were determined as (1S,2R,3S,5R)-3-hydroxy-2-methyl-5-(2-oxoethyl)-cyclopentanecarboxylic acid methyl ester and (7R,8S,8¢S)-4,4¢,8,9-tetrahydroxy-3,3¢,5-trimethoxy-7,9¢-epoxylignan, respectively, on the basis of chemical and spectroscopic evidence. It was noteworthy that gentiopicroside, known to be a major secoiridoid glycoside in Gentian root, was not detected from the fresh roots of 3-year-old G. lutea.

Gentianae Radix, the dried root and rhizoma of Gentiana lutea L. (Gentianaceae), has long been used as a remedy for liver and stomach inflammation, eye troubles, etc. In this paper, the gastroprotective effects of the methanol extract of Gentian root (GM) were studied using different gastric lesion models. In pylorus-ligated rats, administration of GM in the duodenum suppressed gastric juice secretion and total acid output in a dosedependent manner. Oral or duodenum administration of GM showed significant protection against acute gastric ulcer induced by aspirin plus pylorus ligation, waterimmersion restraint stress-induced ulcers, and gastric mucosal injury induced by ethanol. Furthermore, four secoiridoid glycosides, amarogentin (A1), gentiopicroside (A2), amaroswerin (A3), and swertiamarin (A4), were obtained from Gentian root or Swertia herb, and their protective effects against stress-induced ulcers and ethanol-induced gastric mucosal injury were evaluated. The doses required for 50% inhibition (ID 50 ) of A1, A3, and A4 on stress-induced ulcers were calculated to be 5.76, 2.58, and 167 mg/kg respectively. The protective effect of A2 at 250 mg/kg was 26.5%. On ethanol-induced gastritis, 5.0 mg/kg of A1 and A3 showed remarkable suppressive effects (33.7 and 45.4%, respectively), and 20 mg/kg of A4 exhibited a suppressive effect (30.8%). The effects of A1, A3, and A4 on ethanol-induced gastric lesions were canceled by 5.0 mg/ kg indomethacin pretreatment. These results suggest that the therapeutic effects of Gentian root on gastric lesions are associated with enhanced mucosal defensive factors via the prostaglandin pathway in the cell membrane, and that secoiridoid glycosides contribute to this activity.

The flowers from Pueraria, which are called Puerariae Flos, have been used since ancient times for recovery from alcohol intoxication. We elucidated the microbial transformation of the main isoflavones (1, 1a and 2) by using 29 commercially available human intestinal bacterial strains together with the bioactivation of the hepatoprotective activity of their metabolites. Tectoridin (1a), which contains only one glucosyl moiety, was metabolized to its aglycone 1b by various bacterial strains. On the other hand, the metabolism of 1 and 2, which both have disaccharide groups, was limited to specific bacterial strains. The metabolites 1c and 2c obtained from the Peptostreptococcus productus strain were completely different from those produced by the other strains. These metabolites were identified as 6-hydroxygenistein and 6-hydroxybiochanin A, respectively. The glycosides 1, 1a and 2 did not show any hepatoprotective activity, whereas aglycones 1b and 2b showed moderate activity. Furthermore, the hepatoprotective activity of the demethylated metabolites 1c and 2c was extremely potent. Although not all people have P. productus in their gastrointestinal tract, the O-demethylated compounds might become one of the bioactivated metabolites when Puerariae Flos is administered orally.

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