Leaves of Adenanthera pavonina, Moringa oleifera and Annona squamosa are used in traditional Thai medicine to treat dysentery and other diseases. This study investigated the antibacterial activity of these plants against six species of foodborne pathogen. Methods and solvents employed to extract active constituents were optimised using the disc diffusion assay. Phytochemical analysis of the optimised extracts was performed by thin layer chromatography (TLC). Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) were determined by broth microdilution. A. pavonina contained flavonoids, terpines and tannins, and was the most active extract against Campylobacter jejuni, inhibiting growth at 62.5-125 µg mL(-1). The A. squamosa extract contained flavonoids, terpines, tannins and alkaloids, and had the broadest spectrum of antibacterial activity, inhibiting Bacillus cereus, Listeria monocytogenes, Staphylococcus aureus and C. jejuni between 62.5 and 500 µg mL(-1). MBCs were 2- to 4-fold higher than MICs against C. jejuni and B. cereus, suggesting the extracts are bactericidal against these species. Negligible activity was detected from M. oleifera. The data presented here show that A. pavonina and A. squamosa could potentially be used in modern applications aimed at the treatment or prevention of foodborne diseases.
Foodborne disease is a major public health problem. The present study examined Annona squamosa leaves, which are traditionally used to treat diarrhea and other infections, for their potential to be used in modern food safety or medicine. Active constituents were partially purified by ethanol extraction and column chromatography. MICs of the extract were 62.5 to 125 μg/mL against Bacillus cereus, Listeria monocytogenes and Staphylococcus aureus, and 250 μg/mL against Campylobacter jejuni. In time-kill assays, 500 μg/mL of the extract reduced colony forming unit numbers of C. jejuni almost 10 000-fold within 12 hours. Similar decreases were seen against B. cereus, but over a longer time-frame. LC-MS analysis indicated the presence of reticuline and oxophoebine. Assessment of stability by MIC assay showed activity was heat-labile, with loss of activity greatest following high temperature treatments. Activity was relatively stable at refrigeration temperature. These results indicate A. squamosa has broad-spectrum but heat-labile activity against foodborne bacterial pathogens, and bactericidal activity against B. cereus and C. jejuni. This bactericidal activity is not sufficiently rapid for A. squamosa to be used as a food sanitizer, but the extract could potentially be developed as an additive for refrigerated foods, or a modern treatment for foodborne illness.
Abstract-This paper proposed an efficient local search (LS) technique for solving optimal assignment of food exchange lists problem under these constraints, energy and quantity limits. The proposed LS is improved by backtracking mechanism (BT). The objective function and its constraints were explained and conducted how to map into a real value for LS to minimize subjected to constraints. Experimental tests were divided into three cases, underweight-male, normal weight-female and overweight-female. Computational efforts were set to 20 trials for each case. The results show that the proposed LS can confirm significantly reduction of searching time for each complete assignment of a food exchange list, many thousands times with respect to a man doing.Index Terms-Food exchange list, ideal body weight, local search technique, backtracking mechanism.
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