Bush medicine of the Mbabaram Aboriginal community in Far North Queensland demonstrates strong antioxidant and anti-inflammatory activities.

INTRODUCTION: The Mbabaram Aboriginal community lives in Atherton Tableland of Far North Queensland, Australia. While most of the knowledge had been lost due to colonial influences, this community still has remnants of traditional biocultural knowledge, which is critically endangered. They have been closely working with the Tropical Indigenous Ethnobotany Centre (Queensland Herbarium, James Cook University) in the areas of documenting traditional biocultural knowledge and biodiscovery projects. The current study investigated five medicinal plants used by the Mbabaram Aboriginal community for treating wounds, and inflammation-associated diseases. METHODS: In this study, crude extracts of five medicinal plants from the Mbabaram community (Breynia oblongifolia, Cajanus reticulatus, Dodonaea lanceolata, Exocarpos latifolius, and Coleus amoenus) were assessed for their phytochemical contents. The antioxidant activity was determined using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. Furthermore, crude extracts were evaluated for their effect on cell viability and anti-inflammatory activities using the human peripheral blood mononuclear cells (PBMC) assay. RESULTS: While some plants tested positive for flavonoids and saponins, B. oblongifolia and C. amoenus did not test positive for saponins. Only C. reticulatus and E. latifolius tested positive for alkaloids. The water extract of C. amoenus and the ethanol extract of B. oblongifolia exhibited the highest TPC with 99.88 ± 4.47 GAE/g extract and 128.36 ± 14.09 GAE/g extract, respectively. While the crude water extract of E. latifolius stems showed the best antioxidant activity with EC50 value of 0.024 μg/mL, the water extract of B. oblongifolia leaf showed the best anti-inflammatory activity by significantly reducing the levels of four pro-inflammatory cytokines, namely IL-1β, IL-6, IL-8, and TNF, which are known for instigating IBD pathogenesis. CONCLUSIONS: Of the five aqueous crude extracts studied here, E. latifolius stems showed the best antioxidant activity and B. oblongifolia leaf showed the best anti-inflammatory activity. This result validated the traditional uses of medicinal plants, which is used for treating inflammation-related conditions including wounds and sores. B. oblongifolia has potential to yield drug lead molecules for developing treatment for inflammation and sores/ulcers related diseases such as IBD.