Evaluation of Cytotoxicity, Antimicrobial Activities and Minerals Composition of Vigna subterranea (L.) Verdc. (Bambara Groundnut) Extracts

Wanyama A. W. ,Orwa J.A. , Njenga  P. K. , Irungu B.N

Wanyama A. W.  [1],Orwa J.A. [2], Njenga  P. K.[3]. Irungu B.N [4]

  1. Department of Institute of Tropical Medicine and Infectious Diseases, College of Health, Sciences, Jomo Kenyatta University of Agriculture and Technology.
  2. Centre for Traditional Medicine and Drug Research (CTMDR), Kenya Medical Research.

Corresponding authors:  Jennifer A. Orwa, Peter K. Njenga, Beatrice Irungu.


Introduction: Bambara nuts have phytochemicals noted to have different roles in nutrition, physiology and control of diseases.

Objectives: Nuts were investigated for their phytochemicals, cytotoxicity, antimicrobial activity and minerals presence.

Materials and Methods: The nuts were extracted with methanol-dichloromethane solvent. The extracts were   qualitatively analyzed for the presence of phytochemicals.  Cytotoxicity was evaluated against Hep 2, DU 145 and Vero cell lines using MTT assay. Bambara extract activity against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa was done using diffusion test and micro dilution method to determine the inhibitory effect as well as minimum inhibitory concentration (MIC). Colony growth diameter for Candida albicans was measured and percent inhabitation of mycelial growth calculated. Mineral composition was determined through qualitative analysis.

Results: Alkaloids, saponins, terpenoids and tannins were identified. The dark brown cultivar cytotoxicity against Hep 2, Vero and DU 145 cell lines showed IC 50’s of 15.5 μg/ml, 19.2 μg/ml, and 41.1 μg/ml respectively. MIC for E. coli was 7.72± 0.35 μg/ml, S. aureus, 12.5± 0.32 μg/ml, and P. aeruginosa was 7.95± 0.10 μg/ml. At 100 μg/ml; E. coli, S. aureus and P. aeruginosa showed zone of inhibition of 27± 0.74 mm, 25.3 ± 0.40 mm and 25.1± 0.24 mm respectively but these values were less as compared to those of ceftriaxone which were 37.0±0.5, 41.3±0.9 and 42.3±0.9 respectively The extract had the minimum inhibitory effect of 62.44% at 1 μg/ml but the greatest effect against mycelial growth was 91.12% at 4 μg/ml. The control drug clotrimazole however showed increased efficacy. The minerals present in the extracts were manganese, magnesium and potassium, sodium, iron and calcium.

Conclusion: The Bambara nuts extract showed appreciable efficacy against cell lines and microbes hence signifying their possible potential use as cytotoxic and antimicrobial agents as well as a plant with higher nutritional value to improve health.

Key words: Bambara nuts, antimicrobial activity, cytotoxic, minimum inhibitory concentration

[Afr J Health Sci. 2017; 30(2):88-104]

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