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DOI: 10.1055/s-2007-986930
Biological activities of South African Salvia species and isolated compounds
Salvia L. species are traditionally used in South Africa to treat various ailments. The antibacterial, antimalarial and anticancer activities of the extracts of sixteen species were investigated. The extracts exhibited moderate to good antimalarial activity against the chloroquine-resistant Plasmodium falciparum (FCR-3) strain (3.9µg/ml < IC50 values <26.1µg/ml). Salvia radula Benth. exhibited the best activity and bioassay-guided fractionation lead to the isolation of betulafolientriol oxide and salvigenin (IC50 values: 4.9 and 24.6µg/ml, respectively). The antibacterial and antimycobacterial activities were evaluated using the microdilution and BACTEC TM 460 radiometric methods, respectively. Nearly all the solvent extracts displayed good to moderate activity against the Gram-negative and Gram-positive bacteria (0.03mg/ml < MIC values <8.0mg/ml). The extracts also exhibited promising activity against Mycobacterium tuberculosis (MIC values <0.50mg/ml). Four compounds with antibacterial activity were isolated from S. chamelaeagnea P.J. Bergius and characterized as carnosol, ursolic acid, oleanolic acid and 7-O-methylepirosmanol). The potential of the solvent extracts to inhibit cell proliferation of three cancer cell lines (MCF-7, HT-29 and SF-268) and Graham cells was evaluated using the SRB and MTT assays, respectively. The concentration required to inhibit 50% of cell growth ranged from 9.6 to 43.7 and between 8.7 and 59.1µg/ml against the MCF-7 and SF-268 cell lines, respectively. The IC50 values against the HT-29 cell line ranged from 17.1 to 57.0µg/ml. The toxicity of the solvent extracts on Graham cells ranged from 12.1 to 53.3µg/ml. The in vitro pharmacological properties of these plants support the traditional medicinal uses of these plants. However, considering the toxicity that may be associated with high doses, these plants should be used with caution.
Acknowledgements: National research Foundation (South Africa); South Africa National Biodiversity Institute (Pretoria).