Pouteria australis (R.Br.) Baehni Leaf Extracts Lack Antibacterial Activity and are Non-toxic in vitro

Introduction: Closely related plant species often share similar secondary metabolites and bioactivities and are therefore good targets for bioactivity testing when one or more species within a family are known to possess therapeutic properties. The genus Pouteria (family Sapotaceae) has a long history of medicinal usage in many areas of the world. Many species are known to have therapeutic properties, several of which have well established antibacterial bioactivities. Methods: The ability of P. australis leaf extracts to inhibit the growth of a panel of bacterial pathogens was investigated by disc diffusion assay. Toxicity was examined using the Artemia franciscana nauplii bioassay. Results: P. australis methanolic and aqueous extracts were completely ineffective at inhibiting the growth of gram-positive and gram-negative panels of bacteria. The extracts were nontoxic to Artemia nauplii following 24 hr exposure. Conclusion: Despite the taxonomic relationship with several bioactive Pouteria spp., P. australis leaf extracts were completely ineffective bacterial growth inhibitors. However, these extracts may have other therapeutic properties and testing against protozoa, fungi, virus and tumour cells is required.