[Antimicrobial activity and interaction with DNA of medicinal plants from the Peruvian Amazon region].

Decoctions of four plants used for the treatment of different infections by indigenous groups of the Peruvian Amazon, i.e. Abuta grandifolia, Cyperus articulatus, Gnaphalium spicatum and Pothomorphe peltata were evaluated for antimicrobial activity by the "stroke method" in agar plates. Tested organisms included Staphylococcus aureus, Escherichia coli, Salmonella gallinarum, Klebsiella pneumoniae, Candida albicans, Pseudomonas aeruginosa and Mycobacterium gordonae. All decoctions showed antimicrobial activity against at least one of the tested organisms. The A. grandifolia and C. articulatis decoctions partially inhibited the growth of P. aeruginosa. S. aureus was completely inhibited by C. articulatus decoction and only partially inhibited by G. spicatum and P. peltata. The A. grandifolia decoction also showed a partial inhibition against M. gordonae, showing a clear correlation between the ethnopharmacological use and the observed activity. Methanolic extracts of plants were analyzed by using the DNA-methyl green bioassay. The methanolic extract of P. peltata (concentration 1000 micrograms/ml) showed a decrease of 30% regarding to the initial absorbance of the DNA-MG complex suggesting the possible interaction with DNA.