Plant evaluation as a source of natural antimicrobial and antioxidant agents

VATTUONE M.A.; JAIME, G.S.; SOBERÓN, J.R.; MARTÍNEZ ARRIAZU, M.E.; SAMPIETRO, D.A.; SGARIGLIA, M.A.; SGROI, N.; SELIS, A.N.; QUIROGA, E.N.

Tucumán (Argentina)

Congreso; XXI Annual Meeting of Tucuman Biology Society; 2004

Tucuman Biology Society (publicado en Bio Cell 29 (1))

In the last century, an increasingly interest on the study of folk medicines (plants and propolis) appeared in the world. Several approaches can be taken to establish the scientific basis for the success of folk medicine. One method is to begin with an anthropological approach in order to appreciate how and why a particular medical practice became establish and then to explore the chemical and biological reasons for the success of the practice. A rich heritage of traditional knowledge of the uses of plants as medicines can be found in the northwest of Argentina. The purpose of our studies was the demonstration of the antimicrobial and antioxidant activities present in plant species of the Northwest of Argentina. The prolongued use of antimicrobials provoked problems of importance for the society in relation with the growing resistance in the pathogenic population and the increased dependence from the synthetic drugs. Our efforts were centered to the demonstration of the antimicrobial activity of plant extracts (infusions, decoctions and tinctures) on antibiotic multiresistant Gram + and Gram – bacteria, on phytopathogenic bacteria and on yeasts, xylophagous and phytopathogenic fungi. Several techniques were applied for the detection and quantification of each activity and were compared with that of synthetic drugs.  Bioauthographic methods allowed the easy and rapid demonstration of the antimicrobial activity of components of an extract and more refined methodologies the determination of the MIC and the MBC. With the use of co-chromatography on TLC, column chromatography on Silica gel, HPLC, uv-visible spectra and different staining methods on TLC we could detect  quercetine derivatives, a known flavanone and we isolated a new flavanone glycoside with high antifungal activity from Larrea divaricata ethanolic extract. Otherwise, L. divaricata extract showed lower cytotoxicity than ketoconazole and clortrimazole. The oxidation of biological molecules, membranes and tissues, induced by oxygen, mediated by free radicals or metallic ions is related with diverse pathologies (inflammation, carcinogenesis, aging, photobiologic effects, etc.). The main damaged molecules are DNA, proteins, carbohydrates and lipids. The damage on the DNA can be irreversible and consequently inheritable. Extracts from Jodina rhombifolia, Leonurus sibiricus, Psittacanthus cuneifolius, Tripodanthus acutifolius, L. divaricata and Zuccagnia punctata showed a high inhibition of the oxidative damage induced by ter-butilhydroperoxide on DNA. Their antioxidant activity was assayed by the inhibition of bacterial mutagenesis reversion in E. coli WP2 trp65 uvrA rfa/pKM 101 (IC 188) and its isogenic oxyR30 derivative (IC203) with and without metabolic activation to detect direct and indirect mutagens. Moreover, the photoprotective effect of extracts from L. divaricata and Z. punctata assayed with pBR322 also suggests the antioxidant effect of these extracts. Our results suggest that plants from the Northwest of Argentina are useful for their application as phytopharmaceuticals, in veterinary and as agrochemicals.