In vitro evaluation of the comprehensive antimicrobial and antioxidant properties of curtisia dentata (Burm.f) C.A. Sm: Toxicological effect on the human embryonic kidney (HEK293) and human hepatocellular carcinoma (HepG2) cell lines
Department of Chemistry, University of Zululand, Private Bag X1001, KwaDlangezwa, South Africa; College of Agriculture and Environmental Sciences (CAES) Laboratories, University of South Africa, Private Bag X6, Florida, South Africa; Department of Biochemistry and Microbiology, University of Zululand, Private Bag X1001, KwaDlangezwa, South Africa
Curtisia dentata is used in African traditional medicine to treat variety of infections. C. dentata leaves were collected from Buffelskloof Nature Reserve, South Africa. The ethanol, chloroform, ethyl acetate and acetone extracts were evaluated for antimicrobial activity using micro dilution assay against Escherichia coli, Pseudomonas aeruginosa, Mycobacterium smegmatis, Mycoplasma hominis, Candida albicans and some clinical isolates of Moraxella catarrhalis, Proteus mirabilis and Staphylococcus aureus isolated from HIV patient. Acetone extract exhibited lowest MIC of 0.01 mg/ml against Candida albicans compared to other extracts. Besides lupeol, betulinic acid and ursolic acid, β-sitosterol was isolated for the first time from C. dentata leaves and exhibited antimicrobial activity with MIC values ranging from 0.20 to 6.25 mg/ml. Furthermore, the ethanol extract and the four isolated compounds revealed microbicidal effect, with MIC index of less than 4. Ethanol extract revealed the best total activity of 2400 ml/g against Mycoplasma hominis. Cytotoxicity of the isolated compounds was further investigated against the Human embryonic kidney (HEK293) and Human hepatocellular carcinoma (HepG2) cell lines using the MTT assay. Ursolic acid exhibited the lowest LD<inf>50</inf> of 122.4 μg/ml against HEK293 cell line while lupeol exhibited LD<inf>50</inf> of 278.8 and 289.4 μg/ml against HEK293 and HepG2 respectively. Lupeol exhibited low selectivity index. Ethyl acetate and acetone extracts were further investigated for antioxidant activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH). The acetone extract exhibited potent inhibition of DPPH compared to ethyl acetate extract. The findings of the current work validate the use of the plant species in the treatment of various human infections. © 2015 Leibniz Research Centre for Working Environment and Human Factors. All rights reserved.
1,1 diphenyl 2 picrylhydrazyl; antiinfective agent; antioxidant; ascorbic acid; betulic acid; Curtisia dentata extract; lupeol; plant extract; sitosterol; streptomycin sulfate; unclassified drug; ursolic acid; antimicrobial activity; antioxidant activity; Article; Candida albicans; controlled study; Curtisia dentata; drug cytotoxicity; drug isolation; Escherichia coli; HEK293 cell line; HepG2 cell line; human; human cell; in vitro study; LD50; minimum bactericidal concentration; minimum fungicidal concentration; minimum inhibitory concentration; Moraxella catarrhalis; Mycobacterium smegmatis; Mycoplasma hominis; nonhuman; plant leaf; Proteus mirabilis; Pseudomonas aeruginosa; Staphylococcus aureus; Candida albicans; Curtisia dentata; Escherichia coli; Moraxella catarrhalis; Mycobacterium smegmatis; Mycoplasma hominis; Proteus mirabilis; Pseudomonas aeruginosa; Staphylococcus aureus