Browsing by Author "Staden, J.Van"

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    Anti-inflammatory, antioxidant,anti-tyrosinase and phenolic contents off our Podocarpus species used in traditional medicine in South Africa
    (Elsevier Ireland, 2010-07-06) Abdillahi, Halima Saado; Finnie, J.F.; Staden, J.Van
    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 off our Podocarpus species, Podocarpus elongatus, Podocarpus falcatus, Podocarpus henkelii and Podocarpus lati-folius, used in traditional medicine in South Africa. Phytochemical analysis to determine the phenolic contents was also carried out. Materials and methods: DPPH, FRAPand -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 thelowestEC50 (0.84 g/ml) inhibition against DPPH.The percentage antioxidant activity based on the bleaching rate of -carotene rangedfrom96%to99%.High ferric reducing power was observed in all the extracts.For COX-1,the lowest EC50 value was exhibited by stem extracts of Podocarpus elongatus (5.02 g/ml) and leaf extract of Podocarpus latifolius showed the lowest EC50 against COX-2(5.13 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 0.14mg/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.
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    Ethnobotany, phytochemistry and pharmacology of Podocarpus sensu latissimo (s.l.)
    (Elsevier, 2009-09-02) Abdillahi, H. S.; Stafford, G.I.; Finnie, J.F.; Staden, J.Van
    The genus Podocarpus sensu latissimo (s.l.) was initially subdivided into eight sections. However, based on new information from different morphological and anatomical studies, these sections were recognised as new genera. This change in nomenclature sometimes is problematic when consulting ethnobotanical data especially when selecting plants for pharmacological screening, thus there is a need to clear any ambiguity with the nomenclature. Species of Podocarpus s.l. are important timber trees in their native areas. They have been used by many communities in traditional medicine and as a source of income. Podocarpus s.l. is used in the treatment of fevers, asthma, coughs, cholera, distemper, chest complaints and venereal diseases. Other uses include timber, food, wax, tannin and as ornamental trees. Although extensive research has been carried out on species of Podocarpus s.l over the last decade, relatively little is known about the African species compared to those of New Zealand, Australia, China and Japan. Phytochemical studies have led to the isolation and elucidation of various terpenoids and nor- and bisnorditerpenoid dilactones. Biflavonoids of the amentoflavone and hinokiflavone types have also been isolated. Nor- and bis-norditerpenes are said to be taxonomic markers for this genus. Recent in vitro and in vivo studies have shown antitumor, antimicrobial, anti-inflammatory, antioxidant, larvicidal, plant and insect growth regulation activities. Various studies have yielded important natural bioactive products and two of them are worth mentioning. Taxol, a significant anticancer agent has been isolated from Podocarpus gracilior and totarol, a diterpenoid isolated from various species and now commercially produced as a potent antibacterial and antioxidant agent. Findings from this review supports the use of an ethnobotanical and chemotaxonomical approach in selecting plants for pharmacological screening since most of the species in the differentmorphological groups have similar uses. Also the isolated compounds have chemotaxonomic value amongst the groups. Some of the biological activities identified from extracts and compounds isolated from Podocarpus s.l. support the rationale behind the medicinal uses of these species.