Anti-inflammatory, antioxidant, anti-tyrosinase and phenolic contents of four Podocarpus species used in traditional medicine in South Africa

Ethnopharmacological relevance: Species of Podocarpus are used traditionally in their native areas for the treatment of fevers, asthma, coughs, cholera, chest complaints, arthritis, rheumatism, venereal diseases and distemper in dogs. Aims of the study: To investigate the antioxidant, anti-inflammatory and anti-tyrosinase activities of four Podocarpus species, Podocarpus elongatus, Podocarpus falcatus, Podocarpus henkelii and Podocarpus latifolius, used in traditional medicine in South Africa. Phytochemical analysis to determine the phenolic contents was also carried out. Materials and methods: DPPH, FRAP and beta-carotene-linoleic acid assays were used to determine the antioxidant/radical scavenging activities of these species. Anti-inflammatory activity of these species was assayed against two cyclooxygenase enzymes (COX-1 and COX-2). Tyrosinase inhibition activity was analysed using the modified dopachrome method with L-DOPA as the substrate. Phenolics were quantitatively determined using spectrophotometric methods. Results: Stems of Podocarpus latifolius exhibited the lowest EC50 (0.84 mu g/ml) inhibition against DPPH. The percentage antioxidant activity based on the bleaching rate of beta-carotene ranged from 96% to 99%. High ferric reducing power was observed in all the extracts. For COX-1, the lowest EC50 value was exhibited by stem extracts of Podocatpus elongatus (5.02 mu g/ml) and leaf extract of Podocarpus latifolius showed the lowest EC50 against COX-2 (5.13 mu g/ml). All extracts inhibited tyrosinase activity in a dose-dependent manner with stem extract of Podocarpus elongatus being the most potent with an EC50 value of 0.14 mg/ml. The total phenolic content ranged from 2.38 to 6.94 mg of GAE/g dry sample. Conclusion: The significant pharmacological activities observed support the use of these species in traditional medicine and may also be candidates in the search for modern pharmaceuticals in medicine, food and cosmetic industries. (C) 2010 Elsevier Ireland Ltd. All rights reserved.