A method of selecting plants with anti-inflammatory potential for pharmacological study

In searching for anti-inflammatory agents from Australian medicinal plants, a method of selecting plants with anti-inflammatory potential for chemical and pharmacological study was developed and is described in this paper. The method was based on the cross-referencing of ethnopharmacological information documented in Australian bush medicine and Chinese herbal medicine. Our hypothesis was that plants that have been used in several geographically different cultures for the same or similar medicinal purposes would be highly probable to possess some common chemical and pharmacological properties, and therefore might warrant scientific investigation. The Chinese ethnopharmacological information was used as "standard" references to select Australian plants with anti-inflammatory potential. From 284 plants documented in Australian bush medicine and 882 plants in Chinese herbal medicine, 58 Australian plants and 41 Chinese plants were identified to have potential anti-inflammatory activity. The traditional use of the identified Australian and Chinese plants to treat inflammatory conditions, botanical names, modes of preparation and administration, and chemical constituents were compiled to form a Chinese and an Australian dataset using Microsoft Access. By cross-referencing the ethnobotany, ethnopharmacology and phytochemistry of the plants in the two datasets, fourteen Australian plants were selected for laboratory study. Testing of these plants with respect to inhibitory activity against cyclooxygenases (COX) and lipoxygenases (LOX) showed that the majority of the plants (>85%) exhibited anti-inflammatory activity. Bioassay-guided isolation and spectroscopic identification of active constituents in three species were conducted. Racemosic acid was characterised as a new compound with anti-inflammatory activity from Ficus racemosa, together with a known compound bergenin. Triterpene-fatty acid esters were identified in Tinospora smilacina. HPLC fractions from Clematis pickeringii inhibited COX and LOX and also triggered peroxisome proliferator activated receptors (PPARs). This method of cross-referencing ethnopharmacological information to select plants with anti-inflammatory potential appears to be productive, and may be more widely applicable for the selection of plants for other pharmacological and chemical studies.