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Background: The stem bark ethyl acetate extract of Erythrina lysistemon was found to induce vaginal proliferation in ovariectomized rats orally treated. Alpinumisoflavone (AIF) and abyssinone V-4'-methyl-ether (AME), isolated as its major constituents, were reported to separately provoke uterine growth and/or vaginal proliferation. The present study aimed at evaluating the effects of the mixture of AIF and AME (51 mg/kg [AIF]+153 mg/kg [AME]) following their relative abundance in the extract, in order to compare these effects to those of E. lysistemon., Methods: The study was performed in ovariectomized rats treated intraperitoneally for 3 days. Estradiol valerate (E2 V) and AME were used for positive controls. Morphological and histological changes of animals' uterus and vagina were used as the hallmark of estrogenicity., Results: E. lysistemon extract induced estrogen-like effects only on the uterus and significantly increased uterine wet weight (p<0.01) and uterine epithelial height (p<0.01). These results suggest a tissue-selective action of E. lysistemon extract depending on the route of administration. The mixture of AIF and AME induced E. lysistemon-like effects only at a dose of 1 mg/kg BW/d (0.25 mg/kg+0.75 mg/kg), although these effects were lower in magnitude (p<0.05) compared to those induced by E. lysistemon extract., Conclusions: Effects induced by the mixture of AIF and AME are analogous to those of E. lysistemon, but the low magnitude of these effects suggests that there are minor metabolites that interact with AIF and AME to provoke the specific effects of E. lysistemon.

Erythrina lysistemon is an African medicinal plant used as a palliative for problems in women. The crude extract of this plant was shown to exhibit estrogenic effects on the female rat reproductive tract and on cell cuture. Using classic chromatographic methods, two compounds have been isolated as major constituents of this extract: alpinumisoflavone (1) and abyssinone V-4'-methyl ether (2). To determine whether both compounds are actives principles accounting for E. lysistemon effects, we applied the classic 3-day uterotrophic assay. We also carried out a ligand binding assay to determine whether the observed effects are estrogen receptor (ER) mediated. This study showed that whereas compound 1 displayed a fourfold preference for ERα, compound 2 bound ERα and ERβ with a same affinity. The in vivo study showed that compound 1 increased the uterine wet weight by 182.23% (p < 0.01) and 71.79% (p < 0.05) at doses of 0.1 and 1 mg/kg BW/day respectively. The uterine epithelium thickened dose-dependently. Vaginal epithelial height also increased by 369.97 and 226.76% respectively (p < 0.01). Compound 2 acted only on the vagina and increased vaginal epithelial height by 244.56% (p < 0.01) at 1 mg/kg BW/day. These results suggest that compounds 1 and 2 are endowed with estrogenic properties accounting, at least in part, for E. lysistemon effects., (Copyright © 2011 John Wiley & Sons, Ltd.)

To determine whether the two major compounds of Erythrina lysistemon are active principles accounting for Erythrina estrogenic effects, we used a postmenopause-like model of ovariectomized Wistar rats to evaluate their effects on some menopausal problems. Ovariectomized rats were orally treated either with compound 1 or compound 2 at 1 and 10 mg/kg BW for 28 days. Estradiol valerate served as the reference substance. As results, compounds 1 and 2 displayed estrogen-like effects on the uterus and the vagina, and reduced atherogenic risks by decreasing the two assessed atherogenic parameters, the total cholesterol/HDL-cholesterol ratio and the atherogenic index of plasma., (Copyright © 2011 Elsevier B.V. All rights reserved.)