Tasmannia lanceolata (Poir.) A.C. Sm. Berry Extracts Inhibit the Growth of the Skin Pathogens Staphylococcus aureus and Staphylococcus epidermidis

Veronica Winnett^1,2, Ian Edwin Cock^1,2,*

¹Centre for Planetary Health and Food Security, Nathan Campus, Griffith University, Nathan, Queensland, AUSTRALIA.

²School of Environment and Science, Nathan Campus, Griffith University, Nathan, Queensland, AUSTRALIA.

DOI: 10.5530/pc.2024.4.26

ABSTRACT

Background: Tasmannia lanceolata (Poir.) A.C. Sm. pepper berries were used as a nutritious food and natural medicine by the first Australians. This study focuses on the growth inhibitory activity of T. lanceolata pepper berry extracts against the bacterial skin pathogens Staphylococcus aureus and Staphylococcus epidermidis. Materials and Methods: Tasmannia lanceolata pepper berry powder was extracted with solvents of varying polarity and screened for inhibition of bacterial growth against S. aureus and S. epidermidis. Inhibition on agar was assessed by disc diffusion techniques, while the minimum inhibitory concentrations (MICs) were also quantified by liquid dilution assays. Extract toxicities was examined using Artemia nauplii bioassays and therapeutic indexes (TIs) were calculated as a measure of therapeutic safety. Results: All Tasmannia lanceolata pepper berry extracts inhibited the growth of S. aureus and S. epidermidis. The ethyl acetate extract was the best inhibitor of both bacteria, with LD MIC values of 563 and 750 μg/mL against S. aureus and S. epidermidis respectively. The methanolic (LD MICs of 891 μg/mL against both bacteria) and aqueous extracts (LD MICs of 1031 and 1375 μg/mL against S. aureus and S. epidermidis respectively) also displayed noteworthy antibacterial activity. All extracts were determined to be non-toxic in the Artemia nauplii bioassays. Conclusion: Methanolic, aqueous and ethyl acetate T. lanceolata pepperberry extracts had noteworthy inhibitory activity against S. aureus and S. epidermidis. These extracts were also non-toxic in the Artemia nauplii bioassay, indicating their potential for topical and oral treatment against infections of these bacteria.

Keywords: Winteraceae, Mountain pepper berry, Tasmanian pepper, Bacterial skin infections, Antioxidant, Australian plants, Traditional medicine.