The low toxicity of the T. ferdinandiana leaf extracts and their potent growth inhibition of axillary and plantar malodour-producing bacteria indicate their potential as deodorant components.

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.

Introduction: Acronychia acidula F. Muell. (lemon aspen, pigeon berry) has been previously recognized for its antimicrobial properties against a broad panel of pathogenic bacteria. This study assessed the effectiveness of A. acidula as an inhibitory agent against bacteria associated with malodour formation. Methodology: A. acidula fruit extracts were prepared using methanol or water as the extraction solvent. Growth inhibition and minimal inhibitory concentrations were determined against C. jeikeium, P. acnes and B. linens through disc diffusion assays. MIC values were quantified to evaluate their efficacies as antimicrobials. Toxicity of each extract was determined using the Artemia franciscana nauplii bioassay. Results: A. acidula aqueous fruit extracts inhibited the growth of B. linens (MIC = 1258 µg/mL), C. jeikeium (MIC = 1630 µg/mL) and P. acnes (MIC = 1455 µg/mL) in the disc diffusion assay. Similarly, the methanolic fruit extracts inhibited the growth of B. linens (MIC = 2608 µg/mL) and C. jeikeium (MIC = 3044 µg/mL), although no growth inhibition of P. acnes was observed. Both aqueous and methanolic A. acidula extracts were nontoxic towards Artemia nauplii (LC 50 values of 1872 µg/mL and 1500 µg/mL). Conclusion:A. acidula fruit extracts were non-toxic and also displayed moderate growth inhibitory bioactivity against B. linens, C. jeikeium and P. acnes, highlighting their potential as additives to deodorants.

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