Analgesic and Anti-Ulcerogenic Effects of a Polar Extract from Leaves ofVernonia condensata

Abstract

An aqueous crude extract and a polar fraction derived from this extract were prepared from leaves of Vernonia condensata Baker and assessed in standard rodent models of algesia and ulcerogenesis. Oral pretreatment with the lyophilized crude extract (200 mg/kg) significantly reduced mouse writhing counts caused by the i.p. injection of increasing concentrations (0.6-1.2%) of acetic acid (0.1 ml/10 g). In doses ranging from 50 to 400 mg/kg, the crude extract inhibited dose-dependently mouse writhing induced by acetic acid (0.6%) (ED50 = 241 mg/kg) and also markedly increased the sleeping time induced by thiopental. The polar fraction, prepared by washing out the crude extract with chloroform, did not alter sleeping time but kept the analgesic activity (ED50 = 154 mg/kg), indicating that these effects are indeed dissociated. In contrast, the tail flick response in the immersion test was not modified by the crude extract or the polar fraction. The relative potency with which polar fraction and non-steroidal anti-inflammatory drugs inhibited mouse writhing caused by acetic acid in mice was indomethacin >> dypirone > polar fraction > aspirin. Furthermore, the combined polar fraction/aspirin or polar fraction/indomethacin treatments presented a marked synergistic effect, in contrast to what was observed when submaximal doses of indomethacin and aspirin were coadministered, suggesting that polar fraction and aspirin like drugs may have complementary analgesic actions. Finally, despite being able to potentiate the analgesic effect of indomethacin in mouse writhing caused by acetic acid, the pretreatment with the polar fraction (200 mg/kg, oral) significantly prevented indomethacin-induced ulcers in rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Fitoconstituintes isolados da fração em diclorometano das folhas de Vernonia tweediana Baker

“…No Brasil, várias espécies de Vernonia são utilizadas empiricamente pela população, destacandose o macerado de folhas de V. condensata Baker, usado como analgésico, anti-ulcerogênico e para a prevenção de distúrbios no estômago e fígado (Frutuoso et al, 1994) e os extratos alcoólicos de V. scorpioides (Lam.) Pers., utilizados no tratamento dos mais variados ferimentos cutâneos (Dalazen et al, 2005).…”

Analgesic and antiinflammatory activities of vernonioside B2 from Vernonia condensata

“…Evidence from Brazilian folk medicine has shown that the crude extract from the leaves of this plant is able to prevent stomach and liver disturbances (Magalhães et al, 1990). Recent pharmacological study proved that a polar extract from the leaves of V. condensata presented analgesic and antiulcerogenic activities (Frutuoso et al, 1994). Only few reports on phytochemical studies about this species have been published, some triterpenes (Bohlmann et al, 1981) and sesquiterpene lactones (Jakupovic et al, 1987) having been isolated.…”

Antipyretic, analgesic, anti-inflammatory and antioxidant activities of two major chromenes from Melicope lunu-ankenda

“…Acetic acid-induced writhing. Analgesic activities of evodione and leptonol were evaluated by the acetic acid-induced writhing assay (Frutuoso et al, 1994). Writhes were induced by intra-peritoneal injection of 0.6% (v/v) acetic acid (10 ml/kg).…”