<i>Sutherlandia frutescens</i> (Fabaceae) extracts used for treating tuberculosis do not have high activity against <i>Mycobacterium smegmatis</i>

  • Itumeleng H. Mabusa Department of Biochemistry, Microbiology and Biotechnology, University of Limpopo
  • Rachmond Howard Planning & Institutional Support, University of Mpumalanga
  • Peter Masoko Department of Biochemistry, Microbiology and Biotechnology, University of Limpopo
Keywords: Sutherlandia frutescens, Mycobacterium tuberculosis, shikimate kinase, High Performance Liquid Chromatography- Mass Spectroscopy, Mycobacterium smegmatis

Abstract

Sutherlandia frutescens (L) R. Br. contains several essential, bioactive compounds with clinically proven pharmacological activities. Sutherlandia is prescribed for people with tuberculosis but it is still not known what compounds in this plant act against Mycobacterium tuberculosis and its mode of action. This study is aimed at determining if S. frutescens extracts contain antimycobacterial compounds. Aerial parts of S. frutescens were dried, ground and extracted with ethanol, dichloromethane: methanol 1:1 (v/v) and water. The chemical profiling was done using high-performance liquid chromatography-mass spectroscopy (HPLC-MS) and thin layer chromatography (TLC). TLC plates were developed in butanol:acetic acid:water (BAW) to the ratio of 21:6:3; chloroform:methanol:water:formic acid (CMWF1) [60:15:2:1] and (CMWF2) [21:9:1:0.3]. Qualitative antioxidant activity was done, using 2.2-diphenylpacryl-1-hydrazyl (DPPH). Antimycobacterial activity of the plant extracts was evaluated, using micro-dilution and bioautographic methods against Mycobacterium smegmatis. Low antimycobacterial activity against M. smegmatis was observed on the bioautograms. The ethanol extracts contained more compounds compared to water extracts on HPLC-MS chromatographic profiles. The average Minimum Inhibitory Concentration (MIC) values for all the extracts were 0.61 mg/mL units and the DCM:MeOH (1:1) extract had the lowest MIC value of 0.28 mg/mL. The results showed that the plant could be further explored for possible antimycobacterial agents. Low activity was observed, possibly due to low replication of bacilli and non-replicating organisms. The study provides preliminary scientific validation of the traditional medicinal use of this plant. Further studies are required to identify the bioactive compounds in the DCM:MeOH 1:1 extract which showed significant antimycobacterial activities.

 

Research correlation: This article is the original version, of which an Afrikaans translation was made available to provide access to a larger readership, available here: https://doi.org/10.4102/satnt.v36i1.1494

Author Biographies

Itumeleng H. Mabusa, Department of Biochemistry, Microbiology and Biotechnology, University of Limpopo
Student
Rachmond Howard, Planning & Institutional Support, University of Mpumalanga
Deputy Vice-Chancellor
Peter Masoko, Department of Biochemistry, Microbiology and Biotechnology, University of Limpopo
Professor
Published
2017-12-12
Section
Original Research