Effects of extract, fractions and 2,3-dihydromyricetin-3-O-α-L-rhamnoside from Pradosia huberi (Ducke) Ducke on rat isolated mesenteric arteries

Abstract

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.

Species tree phylogeny and biogeography of the Neotropical genus Pradosia (Sapotaceae, Chrysophylloideae)

“…Ducke (1942) highlighted the sweet taste of the inner bark in Pradosia and attributed it to the presence of glycyrrhizin. Other studies have found flavonoids in the sweet bark of some species (e.g., Pradosia huberi; not included), which may be related to protection against injuries (Medeiros et al, 2010). The ancestral reconstruction of this character revealed that the sweet taste first appears in the sweet-bark clade with a subsequent loss in P. decipiens, and involved independently further three times in the red-flowered clade (Fig.…”

Evaluation of the Toxicity ofPradosia huberiExtract during the Preimplantation in Wistar Rats

“…In addition, the medicinal plants are a source of active compounds able to exert therapeutic and toxic activities [26]. For example, P. huberi also has gastroprotective activity [6] but revealed high toxicity, causing behavioral changes, decreased weight of organs, and death in rodents [27]. …”

Extract and chloroform fraction from Syzygium cumini leaves with vasorelaxant effect mediated by inhibition of calcium channels

“…A particular feature of phytomedicines is their complex composition, that is, the "phytocomplex", with different specific effects, however a wider array of effects and healing properties are guaranteed only by the phytocomplex (Medeiros et al, 2008). In order to further characterize this effect, HESc was submitted to liquid partition, as described under material and methods.…”