Estudo fitoquímico e atividade biológica de Pavonia distinguenda A.ST.- HILL. et naudin e Dorstenia brasiliensis LAM

Abstract

From the aerial parts of Pavonia distinguenda the glycosilated flavonoids, tirosilide and astragalina glycolilated flavonoids were isolated, among free b-sitosterol, lupeol, taraxerol, germanicol and from the roots of Dorstenia brasiliensis Lam, psolaren, bergapten and umbeliferone that were identified by the appliance of NMR 1D and 2D GC-MS techniques. The crude extract of P distinguenda presented a citotoxity index to Artemia salina Leach larvae with LD50 in 6.2 μg/mL, showing potential antitumoural and/or insecticide activity. In the intraperitoneal single dose acute toxicity tests it presented LD50 in 1004.9 mg/kg (confidence limits in 731.8 and 1422.7 mg/kg) and to oral administration one LD50 in 3002.1 mg/kg (lower and upper confidence limits respectively, in 2864.4 and 3153.1 mg/kg).The crude extract, the hexanic, dichloromethane, ethyl acetate, and buthanolic fractions and the tiroliside tested on nine different human tumour cell lines showed moderately cytostatic and/or cytocide in some concentrations, but no one of the samples showed high specificity to a single one type of tumour cell. Relating to the antimicrobial activity of the extracts, fractions and isolated compounds from these two plants , using the bioauthography method, diffusion and microdilution method against Gram-positive, Gram-negative bacteria and fungi one observed that they proved to be very active against the used bacteria only in the concentrations above 50 μg, with o activity against anyone of the tested fungi. The crude extract of P distinguenda presented a significant analgesic activity, of 30 mg/kg doses using the contortion method induced by acetic acid and in the hot plate method in the 30 and 100 mg/kg/dose. Relating to the antioxidant activity the crude extract, the hexanic fraction ,dichloromethane ,ethyl acetate and tirosilide showed themselves as trapping of the free radical DPPH, only in the concentrations above 6.25μg. The tiroliside presented a discrete inhibition on the AChE enzyme activity.