Indigenous Salvia species : an investigation of their pharmacological activities and phytochemistry
Year: 2008
Type: dissertation
Abstract: The genus Salvia belongs to the family Lamiaceae and encompasses 900 species \nworldwide of which 26 are found in southern Africa and many of them are used in local \ntraditional medicine. However, the phytochemistry and pharmacological activities of the \nSouth African species have not been extensively investigated. \nThe leaf trichome morphology that may be used to distinguish species was investigated \nwith the scanning electron and light microscopy. Both glandular (capitate or peltate) and \nnon-glandular trichomes were identified in all species. \nThe essential oils were isolated by hydro-distillation and analysed by GC and GC-MS \nmethods. The oil yield was relatively low and ranged from 0.004 (S. radula) to 0.50% (S. \nmuirii) (w/w). Major components identified include α-pinene, 1,8-cineole, linalool, \nlimonene, myrcene, β-caryophyllene, spathulenol, β-caryophyllene oxide, viridiflorol, δ-3- \ncarene and α-bisabolol. High performance liquid chromatography analysis was used to \nidentify phenolic compounds in 17 solvent extracts. Betulafolientriol oxide was detected \nin all species. Rosmarinic acid was only absent in S. verbenaca, while S. garipensis and S. \nradula were the only species which lacked oleanolic acid/ursolic acid. \nVarious in vitro biological activities were investigated. Nearly all the solvent extracts \ndisplayed anti-oxidant activity with IC50 values ranging from 1.61 to 74.50 μg/ml using the \nDPPH· radical, while the IC50 values ranged from 11.88 to 69.26 μg/ml with the ABTS·+ \nradical. The solvent extract of S. schlechteri was three times more active than vitamin C. \nTotal phenolic content based on gallic acid equivalents (GAE) revealed the presence of \ntotal soluble phenolics in the extract at 45 to 211 mg of GAE dry sample. Almost all the \nessential oils exhibited promising anti-inflammatory activity (5-lipoxygenase assay) with \nIC50 values ranging from 22.81 to 77.32 μg/ml. The antimalarial activity was determined \nusing [3H]-hypoxanthine method on the Plasmodium falciparum (FCR-3) strain. The IC50 \nvalues of the essential oils ranged from 1.20 to 13.50 μg/ml and were low compared to the \nsolvent extracts (IC50 values ranging from 3.91 to 26.01 μg/ml). Betulafolientriol oxide \nand salvigenin isolated from S. radula inhibited the growth of malaria parasites with IC50 \nvalues of 4.95 and 24.60 μg/ml, respectively. With the exception of S. radula, all the \nsolvent extracts displayed moderate to good activity against Staphylococcus aureus, \nvii \nBacillus cereus, Klebsiella pneumoniae, Escherichia coli and Mycobacterium tuberculosis \nwith the MIC values ranging from 0.03 to 8.00 mg/ml. Four compounds, namely carnosol, \n7-O-methylepirosmanol, oleanolic acid and its isomer ursolic acid were isolated from S. \nchamelaeagnea as the active principles against S. aureus. The solvent extracts of Salvia \nspecies were tested for in vitro anticancer activity against human breast adenocarcinoma \n(MCF-7), colon adenocarcinoma (HT-29) and glioblastoma (SF-268) using the \nsulforhodamine B assay. The extracts inhibited cell proliferation of all three cell lines to \nvarying degrees, with the IC50 values ranging between 9.69 and 43.65 μg/ml and 8.72 and \n59.12 μg/ml against the MCF-7 and SF-268 cell lines, respectively. The IC50 values \nagainst the HT-29 cell line ranged from 17.05 to 57.00 μg/ml. The in vitro toxicity profile \nof 28 samples (17 solvent extracts and 11 essential oils) was evaluated on human kidney \nepithelial cells using the 3-(4,5-dimethylthiazol-2-yl)-2,5 dimethyl tetrazolium bromide \nmethod. The samples displayed some degree of toxicity with IC50 values ranging from \n1.79 to 22.9 μg/ml for the essential oils and from 12.12 to 53.34 μg/ml for the solvent \nextracts. The essential oil composition of S. africana-caerulea, S. africana-lutea and S. \nlanceolata, collected at the same locality throughout the 2004/2005 growing season, was \ncompared in terms of essential oil yields, chemical composition and biological activities. \nMostly quantitative, rather than qualitative variation was observed. Major seasonal \nfluctuations of certain essential oil compounds were observed in all three species. \nVariations in biological activities of the solvent extracts over seasons were noted. The \nbiological activities of the solvent extracts of three Salvia species (Salvia africanacaerulea, \nS. africana-lutea and S. lanceolata) were evaluated in the presence and absence \nof essential oils. The solvent extract of S. africana-caerulea without essential oil exhibited \nthe best activity against Gram-positive bacteria (MIC value: 0.1 mg/ml), while the solvent \nextract containing essential oil of S. africana-lutea was the most active against Gramnegative \nbacteria. The toxicity profile of all three species was significantly higher (P < \n0.05) with the solvent extracts containing essential oils. The in vitro biological activities \nadd scientific support to the use of Salvia species in traditional medicine.
Author: Guy Kamatou
Language: English
Subfield: Food Science
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W118948902