RESUMO: "Efeito do extrato, frações e da 2,3-diidromiricetina-3-O-α-L-raminosídeo obtidos da Pradosia huberi (Ducke) Ducke em artéria mesentérica isolada de rato". Pradosia huberi (Ducke) Ducke (Sapotaceae), espécie Amazônica popularmente conhecida como "casca-doce" é utilizada na medicina tradicional no tratamento de gastrite. O extrato etanólico de suas cascas é rico em polifenóis que podem apresentar um grande número de atividades, incluindo efeito vasorelaxante e cardioprotetor. O objetivo deste estudo foi avaliar as propriedades farmacológicas do extrato etanólico (EPH), de frações e da 2,3-diidromiricetina-3-O-α-L-raminosídeo isolados de P. huberi, em artéria mesentérica isolada de rato. O EPH foi fracionado resultando nas seguintes frações: CHCl 3 , CHCl 3 :AcOEt (1:1), AcOEt, AcOEt:MeOH (1:1) e MeOH. Da fração MeOH foi isolada a 2,3-diidromiricetina-3-O-α-L-raminosídeo e identificada através de espectro de RMN de 1 H e 13 C, além de comparações com os dados de literatura. EPH (1-100 μg/mL) promoveu relaxamento dependente de concentração no tônus vascular induzido por 10 μM de fenilefrina (CE 50 =17,1±2,9 µg/ mL; E max =87,4±2,9 %, n=8). A fração MeOH também relaxou os anéis mesentéricos (CE 50 =31±2,0 µg/mL; E max =54±12,5%, n=6), porém com menor eficácia quando comparado ao efeito de EPH. Unitermos: Pradosia huberi, artéria mesentérica, vasodilatação, endotélio dependente, 2,3-diidromiricetina-3-O-α-L-raminosídeo, floresta amazônica.ABSTRACT: Pradosia huberi (Ducke) Ducke (Sapotaceae), an Amazonian species, is popularly known as "casca-doce" and used in the folk medicine for the treatment of gastritis. The ethanol extract of the bark contains mainly polyphenolic compounds, which are known to show a large number of activities, including cardioprotective and vasorelaxant effects. The aim of this study was to evaluate the pharmacological properties induced by P. huberi ethanol extract (PHEE) and fractions and 2-3-dihydromyricetin-3-O-α-L-rhamnoside derived from this extract, in isolated rat mesenteric arteries. PHEE was separated and the following fractions were obtained: CHCl 3 , CHCl 3 :AcOEt (1:1), AcOEt, AcOEt:MeOH (1:1) and MeOH. We isolated 2-3-dihydromyricetin-3-O-α-L-rhamnoside from the MeOH fraction, which was identified by 1 H and 13 C NMR spectra and compared with data in the literature. PHEE (1-100 μg/mL) induced concentration-dependent relaxations of 10 μM phenylephrine-induced tone (EC 50 =17,1±2,9 µg/mL; E max =87.4±2.9 %, n=8). The MeOH fraction also relaxed mesenteric rings (EC 50 =31±2.0 μg/mL; E max =54±12.5%, n=6) but less effectively when compared to PHEE. Both effects were completely abolished after removal of the vascular endothelium. The AcOEt:MeOH (1:1) fraction and the isolated flavonoid were ineffective in eliciting vasorelaxation. The study demonstrates that PHEE and MeOH fraction of Pradosia huberi possess a vasorelaxant effect, which may be completely dependent upon endothelium. The isolated flavonoid is not responsible for this vasorelaxant effect.

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Pradosia huberi is a species found in the Amazon region and used as an antiulcerogenic and gastroprotective agent; however, phytochemical analysis has revealed the presence of compounds with potential toxic effects on the reproductive system. For the evaluation of the toxicity of P. huberi on male fertility, male Wistar rats were divided into four groups: one control (distilled water p.o.) and three treated (hydroalcoholic extract of the stem bark of P. Huberi (PH-HAE) at doses of 1.22, 6.1, and 30.5 mg/kg p.o.) once daily, for 63 days. In the last week of treatment (from the 57th to the 63rd day), the rats were mated with untreated virgin females (n ¼ 30/group) and were killed on day 64. To investigate the toxic potential of PH-HAE on the reproductive system of rats the following parameters were evaluated: sperm production, genotoxicity, and general development. The production of gametes and their morphology did not differ between control and treated groups. Treatment with PH-HAE did not result in fewer vaginal plugs formed, indicating that the ability to mate was not impaired, but caused an increase of 14.3 and 10.8% in the preimplantation loss index, a reduction of 14.3 and 10.8% in the implantation index, and a reduction of 5.6 and 8.2% in the postimplantation loss index of female rats mated with rats treated with 6.1 and 30.5 mg/kg, respectively, indicating a possible toxic action of PH-HAE on the reproductive system of rats.