Contribuição ao estudo químico das espécies vegetais Palicourea rigida e Palicourea coriacea e avaliação das atividades antioxidante, antiinflamatória e moluscicida de Palicourea rigida

Abstract

Palicourea belongs to the Rubiaceae family which comprises about 230 species the majority of them occurring in Cerrado region, Brazil. Palicourea rigida, known by name douradão, it's used in popular medicine as purifying in renal diseases and in inflammations of the feminine reproductive apprel. Recents workshave reported the presence of iridoids, alkaloids and triterpenoids in P. rígida. Palicourea coriacea, popularly called douradinha, is well known in folk medicine as a potent diuretic and earlier works have revelead have the occurrence of alkaloids, steroids, cinnamic and benzoic acids derivatives in P. coriacea leaves. Taking into account the chemical importance of Palicourea genus the present work aimed to continue P. rígida and P. conacea chemical study seeking to isolate and identify the main constituents of the leaves and flowers from these species and the evaluation of the moliuciscidal, antioxidant and anti-inflammatory activities of P. rigida. The Palicoureas extracts were partitioned with solvents and the chromatography studies with column on silica gel or Sephadex LH-20 or Diaion HP2OS or preparative TLC were used for the isolation of the iridoids, unpublished in genus: sweroside; 6-O-caffeoyl-sweroside and secoxyloganine; the alkalois calicantine, strictosidinic acid and a supoposed calystegin Ni derivative; the flavonoids unpublished in genus: quercetin 3-O-3-D-glicoside, isorhamnetin-3- glicoside; quercetin 3-O-sophoroside and rutine; the anthraquinone, unpublished in genus, 7-hidroxy-tectoquinone; the coumarin scopoletin, the terpenoids phytol, unpublished in genus, oleanoic and ursolic acids and the steroids campesterol, stigmasterol and sitosterol. The compounds were dentified by spectroscopy analysis of their 1H, 13C and bidimensional NMR spectral data and by comparing spectroscopy data with those reported in literature. In the evaluation of the molluciscidal, the clams didn't have their heart beats altered by P. rígida crude extract, while the evaluation of the antinflamatory activity from leaves of this specie showed that hexane fraction; provoked a significant reduction of the ear edema induced by croton oil. In antioxidant assay and total phenoiic determination of the crude extract, polar and apoiar fractions from P. rigida, a larger phenolic concentration was observed in ethyl acetate fraction, which was also the source of the isolated fiavonoids. This fact could have contributed to the demonstrated antioxidant activity.