Chemical composition and antioxidative activity of Echinophora platyloba DC. essential oil, and its interaction with natural antimicrobials against food-borne pathogens and spoilage organisms.

This study was undertaken to determine the chemical composition and antioxidative capacity of Echinophora platyloba DC. essential oil, and its antimicrobial potency against Listeria monocytogenes, Bacillus cereus, Bacillus subtilis, Staphylococcus aureus, Salmonella typhimurium, Escherichia coli O157:H7, Pseudomonas aeruginosa, Candida albicans, Candida tropicalis, Rhodotorula rubra, and Rhodotorula mucilaginosa. The essential oil was analyzed by GC and GC-MS; and evaluated for its antioxidative and antimicrobial (singly or in combination with chitosan, nisin, monolaurin, or amphotericin B) activity. Thirty-three components were characterized representing 95.69% of the total oil composition in which thymol, trans-ocimene, carvacrol, and (E)-sesqui-lavandulol were the major constituents. The oil exhibited high scavenging (IC(50): 49.7 ± 2.3 µg/mL) and relative antioxidative activity (RAA%: 85.21 ± 0.4) in 1,1-diphenyl-2-picrylhydrazyl radicals and ß-carotene/linoleic acid bleaching assays, respectively. The oil showed antimicrobial activity against L. monocytogenes, B. cereus, B. subtilis, S. aureus, S. typhimurium, E. coli O157:H7, P. aeruginosa, C. albicans, C. tropicalis, R. Rubra, and R. mucilaginosa. Moreover, R. mucilaginosa and P. aeruginosa were the most susceptible and most resistant organisms, respectively. Regarding the checkerboard data, 47 fractional inhibitory concentration index (FICIs) (≤ 0.5) indicated synergistic, whereas 7 FICIs (>0.5 to 1) indicated additive effect. Consequently, E. platyloba DC. essential oil could be used as a recommended natural antioxidant and antimicrobial substance for food preservation.

Arsenic and mercury in commercially valuable fish species from the Persian Gulf: influence of season and habitat.

This study was undertaken to determine the concentrations of arsenic and mercury in edible muscle of pelagic (Scomberomorus commerson, Chirocentrus dorab, Sphyraena jello, Rachycentron conadum, Thunus tonggol), benthopelagic (Trichiurus lepturus, Caranx sem, Pampus argenteus, Parastromateus niger) and demersal (Nemipterus japonicas, Epinephelus coioides, Platycephalus indicus, Psettodes erumei, Pomadasys argenteus, Acanthopagrus latus) fish species from the Persian Gulf during summer and winter. The samples were analyzed by graphite furnace atomic absorption spectrometry (GFAAS) for arsenic and cold vapor atomic absorption spectrometry (CVAAS) for mercury after wet-ashing digestion. The results were expressed as µg/g of wet weight. The resulted range of contamination in fish species was between 0.156-0.834 µg/g for arsenic; and 0.120-0.527 µg/g for mercury. Also study revealed that seasonal variation influenced the concentration of the metals in the fish samples. The highest concentration of arsenic and mercury was found in Epinephelus coioides (1.011 µg/g) and Thunus tonggol (0.548 µg/g) in winter, respectively. Moreover, demersal fish species had the highest arsenic (0.481 µg/g) and mercury (0.312 µg/g) concentrations. Our study demonstrates that estimated daily and weekly intakes of arsenic and mercury via consumption of fish flesh were far below the PTDI and PTWI values established by FAO/WHO.