Antimicrobial activity of Amazon Astrocaryum aculeatum extracts and its association to oxidative metabolism

Several compounds present in fruits as polyphenols are able to kill or inhibit the growth of microorganisms. These proprieties are relevant mainly in tropical areas, as Amazonian region where infectious are highly prevalent. Therefore, this study investigated the antimicrobial activity of tucuma Amazonian fruit against 37 microorganisms. The potential role of oxidative metabolism imbalance was also studied as causal mechanism of antimicrobial activity. The results showed antibacterial effect of pulp and peel tucuma hydro-alcoholic extracts on three Gram-positive bacteria (Enterococcus faecalis, Bacillus cereus, Listeria monocytogenes) and antifungal effect against Candida albi cans. The antimicrobial contribution of main chemical compounds (quercetin, rutin, O-carotene and gallic, caffeic and chlorogenic acids) found in tucuma extracts was also investigated showing an inhibitory effect depending of the organism mainly by quercetin in bacteria and rutin in C. albi cans. Analysis of kinetic of DNA releasing in extracellular medium by fluorescence using DNA Pico Green assay and reactive oxygen species production (ROS) showed potential oxidative imbalance contribution on tucuma inhibitory effect. In B. cereus and C albicans this effect was clear since after 24 h the ROS levels were higher when compared to negative control group. In conclusion, tucuma extracts present antimicrobial activity to four microorganisms that have large problems of drug resistance, and the possible mechanism of action of this Amazon fruit is related to REDOX imbalance. (C) 2013 Elsevier GmbH. All rights reserved.