Heritiera actinophyllum (F.M.Bailey) Kosterm. Leaf Extracts Lack Antibacterial Activity and are non-toxic in vitro

Introduction: The development of bacterial strains that are resistant to multiple antibiotics has made the discovery of new antibiotics a priority for medical research. Examination of plants for new antimicrobial agents is an attractive prospect and numerous recent studies have screened plants for antibacterial activity. Despite this, Australian native plants have been relatively neglected. Heritiera actinophyllum (F.M.Bailey) Kosterm. is a rainforest tree that is native to eastern coastal regions of Australia. Material from this species has not yet been examined for antibacterial properties against human pathogens. Materials and Methods: The ability of H. actinophyllum 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: H. actinophyllum methanolic and aqueous extracts were ineffective at inhibiting the growth of gram-positive and gram-negative panels of bacteria. The extracts were non-toxic or of low toxicity following 24 h exposure. Conclusion: The H. actinophyllum leaf extracts lacked growth inhibitory bioactivity against a panel of pathogenic bacteria and were nontoxic in the Artemia nauplii assay. However, these extracts may have other therapeutic properties and testing against protozoa, fungi, and virus and tumour cells is required.