Antibacterial and antioxidant activities of grape (Vitis vinifera) seed extracts

Grape seeds were powdered and the fatty material was extracted in a Soxhlet extractor with petroleum ether (60-80 degreesC for 6 h. The defatted powder was extracted with acetone: water: acetic acid (90:9.5:0.5) and methanol:water: acetic acid (90:9.5:0.5) for 8 h each separately. The extracts were concentrated under vacuum to obtain crude extracts, which were analyzed by high performance liquid chromatography with UV detection at 280 nm. Monomeric procyanidin was found to be the major compound being at 48 and 40% in acetone: water: acetic acid (90:9.5:0.5) and methanol:water: acetic acid (90:9.5:0.5) extracts, respectively. These extracts were tested for antibacterial activity by pour plate method against Bacillus cereus, Bacillus coagulans, Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. It was found that, Gram-positive bacteria were completely inhibited at 850-1000 ppm, while Gram-negative bacteria were inhibited at 1250-1500 ppm concentration. Radical-scavenging activity of grape seed extracts of acetone: water: acetic acid (90:9.5:0.5) and methanol: water: acetic acid (90:9.5:0.5) were compared with BHA at 25 and 50 ppm concentrations by HPLC method using 1, 1-diphenyl-2-picrylhydrazyl (DPPH). The antioxidant capacities of grape seed extracts were determined by the formation of phosphomolybdenum complex method. It was found that acetone:water: acetic acid (90:9.5:0.5) extract was better radical scavenger than methanol: water: acetic acid (90:9.5:0.5) extract. (C) 2002 Elsevier Science Ltd. All rights reserved.