Chemical and biological investigations of Yaegl medicinal plants

The Yaegl Aboriginal people of northern New South Wales, Australia, have used plants as medicines for centuries. Alphitonia excelsa leaves have been used topically by the Yaegl community to treat sores, wounds and skin infections, while Smilax australis leaves have been used as a blood cleanser and for diabetes. Biological testing aligned with the customary uses of these plants was conducted on the n-hexane, dichloromethane, ethyl acetate, methanol, n-butanol and water extracts of the plants. The ethyl acetate and n-hexane extracts of A. excelsa showed moderate activity against Staphylococcus aureus and Streptococcus pyogenes, while the dichloromethane, ethyl acetate and n-hexane partitions of S. australis showed good activity against S. aureus and S. pyogenes. The ethyl acetate and dichloromethane partitions of S. australis also showed promising antioxidant activity, and total phenolic, flavonoid and condensed tannin assays identified high phenolic and flavonoid content in these extracts. The extracts of A. excelsa and S. australis were also investigated, using a metabolomics approach, by high performance liquid chromatography-quadrupole time-of-flight mass spectrometry, gas chromatography-mass spectrometry and database searches. This tentatively identified known antioxidant and antibacterial phenols, flavonoids, terpenes and their derivatives. Most of the compounds have not been previously reported in these plants.