Antioxidant effects of different extracts from Melissa officinalis, Matricaria recutita and Cymbopogon citratus.

Considering the important role of oxidative stress in the pathogenesis of several neurological diseases, and the growing evidence of the presence of compounds with antioxidant properties in the plant extracts, the aim of the present study was to investigate the antioxidant capacity of three plants used in Brazil to treat neurological disorders: Melissa officinalis, Matricaria recutita and Cymbopogon citratus. The antioxidant effect of phenolic compounds commonly found in plant extracts, namely, quercetin, gallic acid, quercitrin and rutin was also examined for comparative purposes. Cerebral lipid peroxidation (assessed by TBARS) was induced by iron sulfate (10 microM), sodium nitroprusside (5 microM) or 3-nitropropionic acid (2 mM). Free radical scavenger properties and the chemical composition of plant extracts were assessed by 1'-1' Diphenyl-2' picrylhydrazyl (DPPH) method and by Thin Layer Chromatography (TLC), respectively. M. officinalis aqueous extract caused the highest decrease in TBARS production induced by all tested pro-oxidants. In the DPPH assay, M. officinalis presented also the best antioxidant effect, but, in this case, the antioxidant potencies were similar for the aqueous, methanolic and ethanolic extracts. Among the purified compounds, quercetin had the highest antioxidant activity followed by gallic acid, quercitrin and rutin. In this work, we have demonstrated that the plant extracts could protect against oxidative damage induced by various pro-oxidant agents that induce lipid peroxidation by different process. Thus, plant extracts could inhibit the generation of early chemical reactive species that subsequently initiate lipid peroxidation or, alternatively, they could block a common final pathway in the process of polyunsaturated fatty acids peroxidation. Our study indicates that M. officinalis could be considered an effective agent in the prevention of various neurological diseases associated with oxidative stress.

Fitoconstituintes isolados da fração em diclorometano das folhas de Vernonia tweediana Baker / Phytoconstituents isolated from dichloromethane fraction of Vernonia tweediana Baker leaves

Fracionamento cromatográfico da fração em diclorometano obtida do extrato etanólico das folhas de Vernonia tweediana Baker (Asteraceae) conduziu ao isolamento de α-amirina, β-amirina, lupeol, β-sitosterol, estigmasterol e espinasterol. As estruturas foram identificadas através de técnicas espectroscópicas usuais, além da comparação com dados relatados na literatura. Os compostos isolados são relatados pela primeira vez para a espécie V. tweediana.

Fractionation of the dichloromethane -soluble fraction from the ethanol extract of the leaves of Vernonia tweediana (Asteraceae) led to the isolation of α-amyrin, β-amyrin, lupeol, β-sitosterol, stigmasterol and spinasterol. The structures of the isolates were elucidated by spectroscopic analysis and comparison with literature data. The isolated compounds are reported for the first time to the species V. tweediana.