ANTIBACTERIAL AND ANTIFUNGAL ACTIVITIES OF PARASTREPHIA LUCIDA (ASTERACEAE), A PLANT SPECIE FROM THE ARGENTINE PUNA.

DALMEIDA R; ALBERTO MR, ZAMPINI I, ORDOÑEZ RM; ISLA MI

SM Tucumán

Congreso; VII Congreso Argentina de Microbiología General; 2011

Sociedad Argentina de Microbiologia

Parastrephia lucida Meyen Cabrera is one plant species that grow in the Argentine Puna, a place where extreme conditions like high altitude (3000-4200 meters above sea level), high exposure to UV radiation, low concentration of oxygen, temperature variations (30°C/day) induce particular adaptations on organisms that allow them to survive under these conditions. In the folklore medicine it is used as an antimicrobial, antipyretic and anti-inflammatory plant, also for bone fractures and hematomas. The antibacterial activity of ethanolic extracts on pathogenic human bacteria was previously demonstrated. The aim of this work was to isolate of fractions with antibacterial and antifungal activities from the aerial parts of them. Methanolic extract (ET); aqueous (Aq) and dichlormethanic (DCM) subextracts were obtained. The Minimal Inhibitory Concentration and Minimal Bactericidal Concentration (MIC/MBC) against methycillin resistant Staphylococcus aureus, methycillin resistant Staphylococcus coagulase negative, St. aureus ATCC29213, Enterococcus faecalis, E. faecalis ATCC29212, Proteus mirabilis, Klebsiella pneumonia, Pseudomonas aeruginosa, Escherichia coli, E. coli ATCC35218, Candida albicans, C. tropicalis, C. parasilopsis, C. glabrata and C. guilleirmondii were determined. DCM and Aq subextracts showed antimicrobial activity against all Gram positive bacteria and fungi strains with MIC values between 100 to 400 g/ml. DCM subextract showed the lowest MIC values for almost all the strains tested. According to these results, the DCM subextract was chosed for the isolation of the compound/s responsible of the antimicrobial activity. A chromatography column with Sephadex LH-20 on the DCM subextract was made and seven fractions (A-G) were obtained. The fractions C, D and E showed MIC values between 100 and 400 ug/ml against Gram positive bacteria. Fractions F and G were active not only against Gram positive bacteria, with MIC values of 100 ug/ml, but also against Gram negative bacteria with MIC values between 200 and 400 ug/ml. For all strains of Candida we found MIC and MBC values between 100 and 400 ug/ml. These results show that as we advance in the isolation of the subextract, the active compounds are more concentrated and show higher activity than the phytocomplex.