Estudo fitoquímico e avaliação biológica pioneiros da espécie Sida ciliaris L. (Malvaceae sensu lato)

Abstract

The medicinal use of plants to cure diseases is already an ancient practice, this has given humanity a great knowledge about the therapeutic effects and toxicity of some species. In global visibility, Brazil stands out, as it has the most outstanding differentiated qualities of plant species in the world. In this context, the study with the species Sida ciliaris L. from the family Malvaceae sensu lato, popularly known as “escova peluda” and “guanxuminha”, aimed to isolate and identify its chemical constituents, as well as to evaluate its photoprotective and antibacterial potential. First, the aerial parts of S. ciliaris were dried and ground in a mechanical mill, providing 1.8 kg of plant drug, which were subjected to maceration with hexane, hexane/ethyl acetate (1:1) and 95% ethanol, for 72 hours each, resulting in extractive solutions, which were filtered and concentrated in a rotary evaporator, providing their respective extracts. From the chromatographic fractionation using flash silica and/or sephadex LH-20 (Merk) as stationary phases and PA solvents as mobile phase, it was possible to isolate and structurally characterize, through analysis of the Nuclear Magnetic Resonance spectra (1H and 13C NMR) Uni and Bidimensional and also comparisons with models from the literature, the compounds: a mixture of pheophytins: (132-R)-pheophytin a (Sc-1a) and (132-S)-pheophytin (Sc-1b) isolated from Hexane/ethyl acetate extract (1:1); 5,7,3'-trihydroxy-4'-methoxyflavone (Diosmetin) (Sc-2) and 5,7,3',4'-tetrahydroxyflavone (luteolin) (Sc-3) isolated from the methanolic fraction of the crude ethanol extract , these being unpublished in the species S. ciliares. The results obtained for solar photoprotection of the extracts and methanolic phase, showed that the concentrations of 500 and 1000 μg.mL-1 were presented as photoprotective potential, with SPF > 25, mainly in the methanolic phase, being superior to the minimum factor of established sun protection. However, the antibacterial activity of these substances was not effective against the gram-positive strains Staphylococcus aureus and Staphylococcus epidermidis and the gram-negative ones, Klebsiella pneumoniae and Salmonella enterica typhimurium.