The hepatoprotective effects and pharmacokinetics of trans-resveratrol and hydroxystilbenes of the garden rhubarb (Rheum rhaponticum L., R. rhaponticum) root ethanol extract were studied. Ethanol was administered to male BALB/c mice for 35 days in an inhalation chamber. During this time vehicle, trans-resveratrol (20 mg/kg per day) or R. rhaponticum extract was intraperitoneally (i.p.) administered and mice were sacrificed for the collection of liver and blood. In an additional experiment, the level of parent compounds and metabolites was estimated in the blood after acute i.p. administration of trans-resveratrol or R. rhaponticum extract. The levels of hydroxystilbenes, their metabolites and fatty acid oxy-metabolites (oxylipins) were studied by LC-tandem DAD-MS/MS. Ethanol induced hepatotoxicity, as evidenced by histological changes and accumulation of oxylipins in the blood. Both trans-resveratrol and R. rhaponticum extract reduced the extent of these changes. The pharmacokinetics of trans-resveratrol was characterized by a rapid removal from the blood and metabolism to sulfates and glucuronides. After the administration of R. rhaponticum extract, in addition to trans-resveratrol glucoside and its metabolites, several other hydroxystilbenes were found. Inhibition of oxidation of polyunsaturated fatty acids is proposed as a basis of the hepatoprotective effect of both trans-resveratrol and R. rhaponticum extract.

M. HAAS et al.: Nuclear Polaritom in the YBssbauer Absorber 283 phys. stat. 801. (b) 149, 283 (1988) Subject classification: 76.80 Inetitule of Phyeics, A d e m y of Sciences of the Eetonian SSR, Tartd) Nuclear Polaritom in the Mossbauer Absorber BY 35. HAAS, V. HIZHSYAXOV, E. REAM, and J. J~G I A transient pulse of theMBssbauer radiation in a thiok resonant absorber in the easo of a significant isomer shift is investigated theoretically and experimentally. It is shown that on transmission the inoident pulse docomposes into 1. a fast pulsean analog of the Sommcrfeld-Brillouin precursive pulse in optics and 2. 8 slow pulse connected with tho motion of a nuclear polariton packet. The group volocity of the polaritons is determined.

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