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Some South African Rubiaceae Tree Leaf Extracts Have Antimycobacterial Activity Against Pathogenic and Non‐pathogenic Mycobacterium Species
Author(s) -
Aro Abimbola O.,
Dzoyem Jean P.,
Hlokwe Tiny M.,
Madoroba Evelyn,
Eloff Jacobus N.,
McGaw Lyndy J.
Publication year - 2015
Publication title -
phytotherapy research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.019
H-Index - 129
eISSN - 1099-1573
pISSN - 0951-418X
DOI - 10.1002/ptr.5338
Subject(s) - antimycobacterial , mycobacterium tuberculosis , mycobacterium bovis , biology , mycobacterium , microbiology and biotechnology , broth microdilution , mycobacterium smegmatis , tuberculosis , rubiaceae , minimum inhibitory concentration , traditional medicine , bacteria , medicine , antimicrobial , botany , pathology , genetics
Tuberculosis (TB) caused by Mycobacterium tuberculosis remains an ongoing threat to human health. Many plant species contain antimycobacterial compounds, which may serve as template molecules for new anti‐TB drugs. The Rubiaceae family is the largest family of trees in southern Africa, and preliminary evidence revealed antimycobacterial activity in several species of the genus, motivating further studies. Leaf extracts of 15 tree species from the Rubiaceae family were screened for antimycobacterial activity against pathogenic M. tuberculosis and non‐pathogenic Mycobacterium smegmatis, Mycobacterium aurum and Mycobacterium bovis BCG (Bacillus Calmette‐Guérin) using a twofold serial microdilution assay. Cytotoxicity was determined using a tetrazolium‐based colorimetric assay against C3A liver cells and Vero kidney cells. Minimum inhibitory concentration values as low as 0.04 mg/mL against M. smegmatis and M. tuberculosis were recorded. Activity against M. aurum was the best predictor of activity against pathogenic M. tuberculosis (correlation coefficient = 0.9). Bioautography indicated at least 40 different antimycobacterial compounds in the extracts. Cytotoxicity of the extracts varied, and Oxyanthus speciosus had the most promising selectivity index values. Copyright © 2015 John Wiley & Sons, Ltd.