Isolation and Biological Activities of Secondary Metabolites implicated in RUV Resistance in Plants of Argentine Puna.

ISLA M.I.,; ZAMPINI IRIS C.,; CUELLO SOLEDAD,; ORDOÑEZ ROXANA.

San Miguel de Tucum¨¢n. Tucum¨¢n. Argentina

Congreso; Coloquio de Fotoquimica y Fotobiologia.; 2006

CEBANOA

The plants that live in extreme ecosystems (dry climate, wide temperature range, low atmospheric pressure and high solar radiation)  defend themselves through a wide array of constitutive and induced defense mechanisms, which include, for example, expression of defense proteins and biosynthesis of secondary metabolites such as phytoalexins.  These genetic resources are a key source of natural products of biotechnological importance. In this context, we developed a research program to screen the plant resources of the Argentine Puna (3500-4500 (masl) to determine the biological activities and chemical nature of the compounds implicated in UVR resistance and to study their application in the pharmaceutical, cosmetic and food industries.  In botanical screenings at different levels from Taf¨ª del Valle to Laguna Huaca Huasi (4200 masl) and Antofagasta de la Sierra (4000 masl) we collected the following plant species: Zuccagnia punctata, Fabiana punensis, Baccharis boliviensis, Baccharis incarum, Baccharis rupestris, Chuquiraga atacamensis, Parastrephia lucida,  Parastrephia phylicaeformis, Parastrephia lepidophylla, Mulinum axilliflorum, Picnophyllum convexum, Tetraglochin alatum and Azorella compacta. Besides all the popularity some of them have enjoyed as ethnomedicinal and edible plants, we recently demonstrated that Chuquiraga atacamensis, Parastrephia lucida and Baccharis spp have important antiradical capacity and scavenging activity of O2¡ñ-, HO¡ñ and H2O2.The bioactive compounds obtained from Baccharis species may correspond to methoxylated flavones. These species markedly and dose dependently protected erythrocytes from UVB-induced hemolysis and lipids and proteins against oxidation. Zuccagnia punctata showed antimicrobial, free-radical scavenging, antioxidant and antimutagenic (Ames test) activities. Z. punctata extracts and 2¡¯,4¡¯  dihydroxychalcone (and antimicrobial agent isolated of Z.punctata) were able to diminish the DNA damage induced by benzo(a)pyrene (B(a)P) and 4-nitroquinoline-N-oxyde (4-NQO) in Hep G2 cells. These effects could be explained by their 2¡¯,4¡¯ dihydroxychalcone content. Since these plant species are xanthine oxidase inhibitors, they decrease both uric acid and O2¡ñ- production. Consequently, some of the analyzed plant extracts could be used as antibiotics of topical use to prevent states of oxidative stress and quimiopreventive.