Antibacterial, Cytotoxic and Antioxidant Activities of Extracts and secondary metabolities Obtained From Srubs and Lichens of Argentine

E.CORRECHE, R. KURDELAS, M.J, GOMEZ LECHON, D. CORTE, M.L. FREILE AND R.D.ENRIZ

Pharmacological Applications of South American Plants

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Lugar: Kerala; Año: 2008; p. 112 - 123

The main purpose of the work in this chapter has been to detect antibacterial, antifungal, citotoxic and antioxidant activities of extracts and secondary metabolites obtained from plants and lichens located in different zones of Argentine. The lichen Usnea densirostra Taylor (Usneaceae) is used in Argentinian folk medicine under the name “Barba de la Piedra”. Complete parts of U. densirostra were collected in the highland region “La Carolina”, 50 miles Northeast of San Luis (Argentine). We evaluate the antibacterial and citotoxic effects of the aqueous extract of the lichen. It appears that the presence of usnic acid would be the principal responsible for the antibacterial activity. Our results indicate that usnic acid possess antibacterial effect particularly against Gram positive bacteria; however this compound displayed a high citotoxic effect to the potentially therapeutic concentrations. In contrast, the aqueous extract of U. densirostra displayed a moderate but significant antibacterial activity without cytotoxic effect. Thus our results support the use of infusions of this lichen, which are commonly used in the Argentinean folk medicine. Leaves and stems and roots of Berberis heterophylla Juss were collected in Comodoro Rivadavia, Chubut, Patagonia-Argentina. The aqueous extracts of B. Heterophylla do not possess significant antifungal and antibacterial activity. These results explain why the Indian people of (Patagonia Austral) do not use this plant as a remedy. On the other hand, Berberine isolated from B. Heterophylla displayed an interesting in vitro/in vivo antifungal activity against a panel of pathogenic fungi. We evaluate the cytotoxic activity as well as the antioxidant effect of alkaloids obtained form different plants. Thus berberine, canadine, anonaine, and antioquine were tested. Our results indicate that canadine shows the most interesting antioxidant activity in this series of alkaloids. The antioxidant activity of canadine, combined with their low toxic effect, indicate that the potential of this alkaloid as a novel class of antioxidant agent should be investigated more fully.