Comparison of free radical scavenging activity of flowers and leaves from three Chuquiraga species that grow in different altitude of Argentine and its relation with polyphenol content.

MENDIONDO, MARÍA ELENA; ZAMPINI, IRIS CATIANA; JUÁREZ, BERTA ESTELA; ORDÓÑEZ, ROXANA MABEL; ISLA MARÍA INÉS

La Habana

Congreso; silae 2011; 2011

Sociedad Italo-americana de etnomedicina

Introduction:  The Chuquiraga genus includes 19 species of xerophytic shrub of South America. In Argentine can be found 15 of these species distributed in different geographical regions, between Patagonia and the Andes region. Chuquiraga atacamensis, C. straminea and C. longiflora are three traditionally species used as medicinal. C. atacamensis and C. longiflora growing in the Argentine Northwest at 3000-4500 meters above sea level (masl) and 2500-3000 masl, respectively. C. straminea, can be found in the southern region at lower altitudes, between 600 and 1000 masl. Each region has different environmental conditions that give intrinsic characteristics. UV-B radiation (UV-B) increases with altitude in consequence, the plants synthesize various phenolic compounds principally flavonoids. The aim of this study was to evaluate comparatively the free radical scavenging effect of flowers and leaves of three Chuquiraga species, which grow in extreme environments at different altitudes in Argentina. Methods: Extracts of flowers and leaves from Chuquiraga atacamensis, C. straminea and C. longiflora were prepared by maceration with ethanol 80°. Soluble phenolics and total flavonoids content were evaluated in each extract. Chromatographic profiles by RP-HPLC and TLC were obtained. The free radical scavenging activity of crude extracts was assessed following the autographic and spectrophotometric assay using the ABTS radical cation (2,2-azinobis-(3- etilbenzotioazolín 6- sulfonic acid)). The results were expressed as percentage of free radical scavenging and SC50 (concentration required to scavenge 50% of ABTS free radical). Results and discussion / conclusions: The leaves extracts had higher content of soluble phenolics and total flavonoids than flowers. There was a positive correlation between the content of soluble phenolics and flavonoids with altitudinal level. C. atacamensis, species that grows at higher altitudes was the richest in these compounds, which may be related to increased exposure to elevated UV-B radiation, dryness and other abiotic stresses. The profiles obtained by RP-HPLC and TLC shows that the three species have compounds in common. All extracts showed ability to reduce ABTS radical cation by concentration-dependent manner, and leaf extracts were more active than flowers extracts. It was also observed that the antioxidant activity is greater in species that grow at higher altitudes (C. atacamensis> C. longiflora> C. straminea). By autographic assays showed that several phenolic compounds present in the extracts have free radical scavenging activity. These results reveal the potential antioxidant (as scavenger and / or reductor) of flowers and leaves of these species and supporting their use for the prevention of chronic degenerative diseases and aging in the treatment of inflammatory or other diseases related with the oxidative stress. Financial support: CONICET, CIUNT.