Free radical scavenging activity from Casimiroa spp. extracts

Free radicals, particularly reactive oxygen species (ROS), are involved in the pathogenesis of several chronical and degenerative diseases. This study was designed to investigate the antioxidative properties of natural extracts and isolated compounds of Casimiroa edulis and Casimiroa pubescens Llave et Lex (Rutaceae). The genus Casimiroa is widely spread in the tropical and subtropical areas of central America: the decoction of leaves and seeds, together with the consumption of the edible fruits are quite diffused as folk remedies to relieve hypertensive ailments, insomnia, rheumatisms and arthritic pains. To the best of our knowledge, there are no available scientific data directly related to the benefit of scavenging activity toward radical-mediated disease prevention, such as for coronary heart disease, cancer, Alzheimer, arthritis and diabetes as well as degenerative processes associated with aging (Haliwell et al. 1992), in consequence of membrane damage, protein modification, enzyme inactivation and DNA damage induced by free radicals. The antioxidant effect was evaluated by ,-diphenyl--picrylhydrazyl (DPPH.) decolorization, according to the method reported by Brand-Williams et al. (1995); the assay was performed first with TLC plate as positive antioxidant control and then with a spectrophotometric analysis to measure the effective in vitro scavenging activity. We used N-acetyl-L-cysteine, pyrogallic acid, -tocopherol, L-ascorbic acid and quercetin as antioxidative standards. Casimiroa edulis hexanic leaf extract (Ce5), seed extract (Ce7) and methanolic seed extract (Ce8) at 600 g/ml showed an antiradical activity of 77.09.2%, 24.22.9% and 72.05.6% respectively. Also C. pubescens methanolic leaf extract (Cp10) and seed extract (Cp12) at the same concentrations pointed out an antioxidant activity of 84.70.2% and 58.44.3% respectively. According to the phytochemical composition of the extracts, the DPPH. screening was performed also with several organic compounds specifically identified in the genus, such as imperatorin, herniarin, 7-methoxy-3-(2-methylbut-3-en-2-yl)cumarin and pentamethoxyflavone. Imperatorin and pentamethoxyflavone (5mM) revealed an antioxidant activity of 71.30.2% and 30.71.3%, while the cumarin derivatives showed a very low antioxidant profile. Experimental evidences indicated a non-linear relationship between the antioxidant concentration and the DPPH. radical scavenging activity: as a consequence, the measurement of the EC50 seemed quite problematic. For this reason we used a mathematical software to process the data and then to obtain a relation between antioxidant activity and sample concentration (Locatelli et al. 2009). Hence, Casimiroa extracts and some isolated constituents - mainly imperatorin and pentamethoxyflavone - have shown a remarkable radical scavenging activity; research is progressing to characterize their effects on LDL oxidation. References Brand-Williams W et al. (1995) LWT-Food Science and Technology 28:25 Haliwell B et al. (1992) J. Lab. Clin. Med. 119:598 Locatelli M et al. (2009) Food Chemistry 114:889