Growth Inhibitory Activity of Selected High Antioxidant Australian Syzygium Species Against the Food Poisoning and Tissue Necrotic Pathogen Clostridium Perfringens
Abstract:Introduction: Clostridium perfringens is a gram positive pathogen which is an etiological agent in Clostridial myonecrosis and enteritis necroticans. Unless promptly treated, C. perfringens infections may result in tissue necrosis and death. Syzygium australe (brush cherry) and Syzygium luehmannii (riberry) fruit and leaves have documented therapeutic properties as general antiseptic agents against an extensive panel of bacteria. Despite this, studies are yet to test the growth inhibitory activity of these spe… Show more
“…Our study reported that all the extracts with LC 50 values < 1000 μg/mL had relatively high antioxidant capacities. Furthermore, previous studies 35 reported that the high antioxidant capacities of these Syzygium spp. is largely due to their high ascorbic acid contents.…”
Section: Quantification Of Toxicitymentioning
confidence: 90%
“…34,35 Briefly, each individual plant extract was diluted in deionised water and tested across a decreasing concentration gradient. Discs were impregnated with 10 µL of the extract dilutions, allowed to dry and placed onto plates inoculated with B. linens or C. jeikeium.…”
“…Furthermore, recent laboratory studies have reported potent growth inhibitory activity for S. australe and S. luehmannii fruit. 27,35,49 and leaf extracts 35,50 against extensive microbial panels. The same studies also reported low toxicity for all extracts, further supporting their safety.…”
Background: Extracts produced from S. australe and S. luehmannii fruit and leaves are potent growth inhibitors of many bacterial pathogens. They may also inhibit the growth of malodour producing bacteria and thus be useful deodorant components, although this is yet to be tested. Methods: S. australe and S. luehmannii fruit and leaf solvent extracts were investigated by disc diffusion assays against significant bacterial contributors to axillary and plantar malodour formation. Toxicity was determined using the Artemia franciscana nauplii bioassay. Results: S. australe and S. luehmannii solvent extracts were good inhibitors of B. linens and C. jeikeium growth, with zones of inhibition up to 10 mm measured. S. australe extracts were generally better inhibitors of both bacterial species compared with the S. luehmannii extracts. Ethyl acetate extracts were particularly potent, with MIC values of 300 and 857 µg/mL for the S. australe fruit and leaf extracts respectively against B. linens, and 1000 and 311 µg/mL against C. jeikeium. The S. luehmannii fruit ethyl acetate extracts were similarly potent growth inhibitors, with MIC values of 571 and 203 µg/mL against B. linens and C. jeikeium respectively. S. australe aqueous and methanolic leaf extracts were also potent inhibitors of C. jeikeium (MIC's of 285 and 306 µg/mL respectively). All other extracts had moderate or low inhibitory activity. All of the most potent ethyl acetate extracts were nontoxic in the Artemia franciscana bioassay. In contrast, the methanolic and aqueous S. australe leaf extracts, as well as the aqueous and methanolic S. luehmannii fruit extracts displayed apparent toxicity. However, these results may be fallacious and instead result from the high antioxidant content of these extracts. Conclusion: The potent growth inhibition of axillary and plantar malodour producing bacteria by the Syzygium spp. extracts indicate their potential as deodorant components.
“…Our study reported that all the extracts with LC 50 values < 1000 μg/mL had relatively high antioxidant capacities. Furthermore, previous studies 35 reported that the high antioxidant capacities of these Syzygium spp. is largely due to their high ascorbic acid contents.…”
Section: Quantification Of Toxicitymentioning
confidence: 90%
“…34,35 Briefly, each individual plant extract was diluted in deionised water and tested across a decreasing concentration gradient. Discs were impregnated with 10 µL of the extract dilutions, allowed to dry and placed onto plates inoculated with B. linens or C. jeikeium.…”
“…Furthermore, recent laboratory studies have reported potent growth inhibitory activity for S. australe and S. luehmannii fruit. 27,35,49 and leaf extracts 35,50 against extensive microbial panels. The same studies also reported low toxicity for all extracts, further supporting their safety.…”
Background: Extracts produced from S. australe and S. luehmannii fruit and leaves are potent growth inhibitors of many bacterial pathogens. They may also inhibit the growth of malodour producing bacteria and thus be useful deodorant components, although this is yet to be tested. Methods: S. australe and S. luehmannii fruit and leaf solvent extracts were investigated by disc diffusion assays against significant bacterial contributors to axillary and plantar malodour formation. Toxicity was determined using the Artemia franciscana nauplii bioassay. Results: S. australe and S. luehmannii solvent extracts were good inhibitors of B. linens and C. jeikeium growth, with zones of inhibition up to 10 mm measured. S. australe extracts were generally better inhibitors of both bacterial species compared with the S. luehmannii extracts. Ethyl acetate extracts were particularly potent, with MIC values of 300 and 857 µg/mL for the S. australe fruit and leaf extracts respectively against B. linens, and 1000 and 311 µg/mL against C. jeikeium. The S. luehmannii fruit ethyl acetate extracts were similarly potent growth inhibitors, with MIC values of 571 and 203 µg/mL against B. linens and C. jeikeium respectively. S. australe aqueous and methanolic leaf extracts were also potent inhibitors of C. jeikeium (MIC's of 285 and 306 µg/mL respectively). All other extracts had moderate or low inhibitory activity. All of the most potent ethyl acetate extracts were nontoxic in the Artemia franciscana bioassay. In contrast, the methanolic and aqueous S. australe leaf extracts, as well as the aqueous and methanolic S. luehmannii fruit extracts displayed apparent toxicity. However, these results may be fallacious and instead result from the high antioxidant content of these extracts. Conclusion: The potent growth inhibition of axillary and plantar malodour producing bacteria by the Syzygium spp. extracts indicate their potential as deodorant components.
“…24,25 Briefly, each individual plant extract was diluted in deionised water and tested across a decreasing concentration gradient. Discs were impregnated with 10 µL of the extract dilutions, allowed to dry and placed onto plates inoculated with Y. enterocolitica.…”
Introduction: Yersinia enterocolitica is a major cause of food poisoning through contaminated meat products, causing the acute gastrointestinal disease yersiniosis. Many Terminalia spp. have documented therapeutic properties as general antiseptics, inhibiting the growth of a wide variety of bacterial species. Despite this, Indian Terminalia spp. extracts have not been tested for the ability to inhibit the growth of Y. enterocolitica. Methods: T. arjuna, T. catappa and T. chebula extracts were extracted by maceration and the extracts were investigated by disc diffusion assay for growth inhibitory activity against a clinical strain of Y. enterocolitica. The MIC values of the extracts were determined to quantify and compare their efficacies. Toxicity was determined using the Artemia franciscana nauplii bioassay. Results: T. chebula fruit extracts displayed potent growth inhibitory activity in the disc diffusion assay against Y. enterocolitica. The methanolic and ethyl acetate T. chebula fruit extracts were particularly potent growth inhibitors, with MIC values of 85 and 64 µg/mL respectively. The aqueous fruit extract also displayed good growth inhibitory activity against Y. enterocolitica, albeit with a higher MIC value (653 µg/mL). The T. arjuna branch extract was moderately active (3000 µg/mL). All other extracts were either low efficacy, or completely devoid of growth inhibitory activity. All Indian Terminalia spp. extracts were nontoxic (LC 50 values <1000 µg/mL) in the Artemia franciscana bioassay. Conclusions: The lack of toxicity and the potent growth inhibitory bioactivity of the T. chebula extracts against Y. enterocolitica indicates their potential as medicinal agents in the treatment and prevention of yersiniosis.
“…[25][26][27] Briefly, 100 µL of each bacterial culture was grown in 10 mL of fresh nutrient broth until they reached a count of ~10 8 cells/mL. A volume of 100 µL of the bacterial suspension was spread onto nutrient agar plates and extracts were tested for antibacterial activity using 5 mm sterilised filter paper discs.…”
Section: Evaluation Of Antimicrobial Activitymentioning
Introduction:A. auriculiformis, A. disparrima and A. leptoloba are native Australian Acacia spp. which were used as both foods and medicines by the first Australians. Infusions and decoctions produced from leaves and bark have reputed antiseptic properties and were used traditionally to treat a variety of bacterial diseases. Despite this, Australian Acacia spp. solvent extractions have not been rigorously examined for antibacterial properties against food spoilage and food poisoning bacteria. Methods: The antimicrobial activity of A. auriculiformis, A. disparrima and A. leptoloba leaf extracts extractions was investigated by disc diffusion and growth time course assays against a panel of food spoilage and food poisoning bacteria. The growth inhibitory activity was quantified by MIC determination. Toxicity was determined using the Artemia franciscana nauplii bioassay. Results: A. auriculiformis, A. disparrima and A. leptoloba leaf extracts inhibited the growth of a wide range of bacterial species which cause food spoilage and food poisoning. A. auriculiformis extracts were generally more potent growth inhibitors than extracts prepared from the other species, although A. disparrima extracts were also potent inhibitors of bacterial growth. With few exceptions, the methanolic extracts were more potent growth inhibitors than the other solvent extractions. The methanolic A. auriculiformis leaf extract was a particularly potent inhibitor of K. pneumoniae and P. mirabilis, B. cereus and S. aureus growth, with MIC values of 97, 132, 178 and 109 µg/mL respectively. This extract was also a good inhibitor of A. faecalis, A. hydrophilia and S. newport growth (MIC's <1000 µg/mL range). The A. disparrima extracts had a similar, albeit slightly less potent activity profiles. In contrast, the A. leptoloba leaf extracts were substantially less potent. All extracts were determined to be nontoxic in the Artemia franciscana nauplii bioassay, indicating their safety for use as natural food preservatives. Conclusions: The lack of toxicity of the A. auriculiformis, A. disparrima and A. leptoloba leaf extracts and their growth inhibitory bioactivity against a panel of food spoilage and food poisoning bacteria indicate their potential in the development of natural food preservatives.
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