Antioxidant and antimicrobial activity of guarana seed extracts

The antioxidant and antibacterial activities of guarana (Paullinia cupana) seed extracts were determined. The seeds were extracted with water, methanol, 35% acetone and 60% ethanol at room (T-R) and at boiling (T-B) temperature of solvent. Extracts were analyzed for the contents of caffeine and catechins, epicatechin (EC), catechin (C) and epicatechin gallate (ECG), by high performance liquid chromatography (HPLC). The contents of total phenols (according to the Folin-Ciocalteu procedure) and proanthocyanidins were analysed by UV spectrophotometry. The guarana, seed water extract obtained at room temperature contained higher amounts of caffeine and catechins than did alcoholic guarana seed extracts. The antioxidant and radical-scavenging activities of guarana seed extracts were evaluated using the beta-carotene-linoleic acid emulsion system and the stable free radical 2.2-diphenyl-1-picrylhydrazy] (DPPH'). All tested guarana seed extracts displayed strong antioxidant and radical-scavenging properties. The guarana seed extracts were tested against three food-borne fungi: Aspergillus niger, Trichoderma viride and Penicillium cyclopium, and three health-damaging bacteria: Escherichia coli, Pseudomonasfluorescens and Bacillus cereus by the agar well diffusion and broth dilution assay. The alcoholic guarana seed extracts displayed stronger antimicrobial activity against all tested microorganisms than did water extracts. Results presented here may suggest that seed extracts of guarana possess strong antimicrobial and antioxidant properties, and they can therefore be used as a natural additive in food, cosmetic and pharmaceutical industries. (c) 2007 Elsevier Ltd. All rights reserved.