Fractions and isolated compounds from Oxyanthus speciosus subsp. stenocarpus (Rubiaceae) have promising antimycobacterial and intracellular activity

BMC Complementary and Alternative Medicine

Mamoalosi A. Selepe¹  Jacobus N. Eloff²  Abimbola O. Aro²  Lyndy J. McGaw²  Jean P. Dzoyem³  Maurice D. Awouafack⁴ 

[1] 0000 0001 2107 2298, grid.49697.35, Department of Chemistry, University of Pretoria, Pretoria, South Africa;0000 0001 2107 2298, grid.49697.35, Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, 0110, Onderstepoort, South Africa;0000 0001 2107 2298, grid.49697.35, Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, 0110, Onderstepoort, South Africa;0000 0001 0657 2358, grid.8201.b, Department of Biochemistry, Faculty of Science, University of Dschang, P.O. Box 67, Dschang, Cameroon;0000 0001 2107 2298, grid.49697.35, Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, 0110, Onderstepoort, South Africa;0000 0001 0657 2358, grid.8201.b, Laboratory of Natural Products Chemistry, Department of Chemistry, Faculty of Science, University of Dschang, P.OBox 67, Dschang, Cameroon;

关键词: Oxyanthus speciosus;    Mycobacterium tuberculosis;    Rotundic acid;    Lutein;    Intracellular;    Nitric oxide inhibition;   

DOI  :  10.1186/s12906-019-2520-x

来源: publisher

【 摘 要 】

BackgroundTuberculosis is a deadly disease caused by Mycobacterium species. The use of medicinal plants is an ancient global practice for the treatment and prevention of diverse ailments including tuberculosis. The aim of this study was to isolate and characterize antimycobacterial compounds by bioassay-guided fractionation of the acetone leaf extract of Oxyanthus speciosus.MethodsA two-fold serial microdilution method was used to determine the minimum inhibitory concentration (MIC) against mycobacteria. Cytotoxicity and nitric oxide inhibitory activity of the isolated compounds was determined to evaluate in vitro safety and potential anti-inflammatory activity. Intracellular efficacy of the crude extract against Mycobacterium-infected macrophages was also determined.ResultsTwo compounds were isolated and identified as lutein (1) and rotundic acid (2). These had good antimycobacterial activity against the four mycobacteria tested with MIC values ranging from 0.013 to 0.1 mg/mL. Rotundic acid had some cytotoxicity against C3A human liver cells. Lutein was not cytotoxic at the highest tested concentration (200 μg/mL) and inhibited nitric oxide production in RAW 264.7 macrophages by 94% at a concentration of 25 μg/mL. The acetone crude extract (120 μg/mL) of O. speciosus had intracellular antimycobacterial activity, reducing colony forming units by more than 90%, displaying bactericidal efficacy in a dose and time-dependent manner.ConclusionThis study provides good proof of the presence of synergism between different compounds in extracts and fractions. It is also the first report of the antimycobacterial activity of lutein and rotundic acid isolated from Oxyanthus speciosus. The promising activity of the crude extract of O. speciosus both in vitro and intracellularly in an in vitro macrophage model suggests its potential for development as an anti- tuberculosis (TB) herbal medicine.

【 授权许可】

CC BY