The Growth Inhibitory Activity of Tasmannia lanceolata (Poir.) A.C. Sm against the Food-poisoning Pathogen Yersinia enterocolitica

Introduction: Yersinia enterocolitica is a major source of food poisoning via the consumption of contaminated meat products, causing acute gastroenteric yersiniosis. Tasmannia lanceolata has been widely documented for its antiseptic properties, repressing the growth of an extensive range of bacteria. Despite this, Tasmannia lanceolata has yet to be been tested for its inhibitory capacity against Y. enterocolitica. Methods: T. lanceolata leaf and berry extracts were prepared by maceration and growth inhibitory activity against a clinical strain of Y. enterocolitica was examined by disc diffusion assays. The MIC values of the extracts were determined to quantify and compare their relative efficacies. Toxicity was determined using an Artemia franciscana nauplii bioassay. Results: T. lanceolata leaf and berry extracts displayed potent growth inhibitory activity in the disc diffusion assay against Y. enterocolitica. The ethyl acetate and chloroform leaf extracts (MICs of 30 and 53 μg/mL respectively) and the hexane berry extract (MIC = 34 μg/mL) were particularly potent growth inhibitors. The methanol and water extracts of both the berry and leaf, as well as the leaf ethyl acetate extract, also had strong growth inhibitory activity against Y. enterocolitica, albeit with a higher MIC values (250-300μg/mL). All other extracts had lower efficacy, although their MIC values also indicated good inhibitory activity (with the exception of the chloroform berry extract). When assessed for toxicity, all T. lanceolata extracts were non-toxic (LC₅₀ values >1000 μg/mL) in the Artemia franciscana bioassay. Conclusion: The non-toxicity of the T. lanceolata berry and leaf extracts, combined with the potent inhibitory bioactivity observed against Y. enterocolitica, demonstrates their potential as therapeutic agents in the prevention and treatment of yersiniosis.