ETHNOPHARMACOLOGICAL RELEVANCE: The tropical ulcer is a debilitating bacterial infection that is common in Papua New Guinea. Deploying healthcare infrastructure to remote and inaccessible rainforest locations is not practical, therefore local plants may be the best treatment option. Here we present an ethnobotanical survey of the tropical ulcer plant medicines used by the semi-nomadic Apsokok who roam the remote central mountains of Papua New Guinea's West New Britain Province. The bio-activity of their plant medicines in assays relevant to tropical ulcer wound healing is also presented.
MATERIALS AND METHODS: Focus groups and semi-structured interviews were used to acquire information on the uses of plants, vouchers of which were collected and identified by comparison with authentic herbarium specimens. Antibacterial disc diffusion assays with Staphylococcus aureus and Fusobacterium ulcerans, MMP-9 enzyme inhibition, stimulation of dermal fibroblast proliferation and SMAD signalling assays were carried out on samples of plant sap and aqueous extracts of plant material.
RESULTS: The ethnobotanical survey identified sixteen species that were used to treat tropical ulcers, all of which were applied topically. The aqueous extracts of a subset of twelve species were investigated further in vitro. Four species produced zones of inhibition with S. aureus and all species provided low level inhibition of MMP-9 when tested at 0.01% v/v. Eight species exhibited concentration dependent stimulation of dermal fibroblasts which was independent of SMAD signalling. The extract of Homalium foetidum Benth. inhibited S. aureus and MMP-9 while at lower sub-cytotoxic concentrations stimulated fibroblast proliferation.
CONCLUSIONS: Topical application of plant saps to wounds results in very high localised concentrations of plant metabolites which is likely to result in inhibition of MMP proteases. Homalium foetidum Benth. is a candidate for tropical ulcer treatment in remote areas.
- Journal Article