Search of antioxidant compounds from Dalea species

PERALTA MARIANA A; DEL GAUDIO MICAELA; CABRERA, JOSE L.; ORTEGA, M. GABRIELA

Córdoba

Congreso; I REUNIÓN INTERNACIONAL DE CIENCIAS FARMACÉUTICAS (RICiFA).; 2010

Facultad de Ciencias Químicas, Universidad Nacional de Córdoba

Introduction Reactive oxygen (ROS) and nitrogen species (RNS) include free radicals and molecules derived from oxygen and nitrogen, respectively. There are increasing suggestions by considerable evidence that free radicals induce oxidative damage to biomolecules, causing eventually atherosclerosis, ageing, cancer, inflammation, and degenerative diseases in humans.(1) There is an increasing interest in natural antioxidants, present in plants, which might help to prevent oxidative damage. Plant phenolic compounds are secondary metabolites with interesting antioxidant activity. Flavonoids are naturally occurring poliphenolic compounds found in the vegetal kingdom that have effect on a great variety of enzymatic systems, enclosing important pharmacological and biochemical activities such as antioxidant, antitumoral and anti-inflammatory ones.(2) Dalea is an exclusively American genus with more than 250 species. Different species of this genus were studied, and the isolation of compounds, including flavonoids, has been reported. There are four species described for Argentina, namely Dalea elegans Gillies ex Hook. & Arn., D. boliviana Britton, D. leporina (Aiton) Bullock, and D. elegans var. onobrychioides (Griseb.) Barneby(3) The first phytochemical and bioactivity studies on Argentinean Dalea species were made by our research group starting with D. elegans (4,5,6,7) and D. boliviana (8). In the present work, three crude extracts of Dalea species were studied (D. elegans, D. boliviana and D. leporina) regarding to their total phenols and flavonoids content and antioxidant activity. The results could impact in the research of new antioxidants compounds from autochthons species. Materials and methods Plant Material The dried plant material from Dalea elegans, Dalea boliviana and Dalea leporina were studied. The roots were powdered and extracted exhaustively with EtOH:H20 (70:30). Total phenols content Total phenols content were estimated by Folin-Ciocalteau reagent (9). The results were expressed as mg of gallic acid equivalents/g of extract (mgEqAG). Total flavonoids concentration The flavonoid concentration was estimated by the AlCl3  method (10). The results were expressed as mg of quercetin equivalents/g of extract (mgEqQ). Antioxidant  potential assay  The antioxidant potencial of the extracts was assessed with the phospomolybdenum reduction assay (FM) (9,11) The reducing capacity of the extracts were expressed as ascorbic acid equivalents/ mg of extract analyzed. Determination of ABTS radical-scavenging activity (TEAC) The ABTS radical-scavenging activity values were estimated by the Trolox equivalent antioxidant capacity (TEAC) test (12). The results were expressed as µg of Trolox equivalents/ of mg of analyzed extract. Results Results are shown in the Table 1. Conclusions The aim of the present work was to quantify and compare total phenols and flavonoids content in the ethanol/ H2O extracts of three Argentinean species from Dalea genus: D. elegans, D. boliviana and D. leporina as well as to assess their in vitro potential as new natural antioxidants source. Antioxidant activity was analyzed in two different test systems. According to the results, it can be concluded that all the tested extracts demonstrated important antioxidant potential and free radical scavenging activity compared with the positive control Quercetin, which could be due to their phenols and flavonoids content. The results show correlation between concentration of total phenolic and flavonoids compounds and antioxidant capacity of the extracts. Therefore, these values in Dalea extracts are relevant indicators of their antioxidant power. Further studies would focus on the isolation, purification, structural characterization and evaluation of new antioxidant substances from this genus.