African Journal of
Biotechnology

  • Abbreviation: Afr. J. Biotechnol.
  • Language: English
  • ISSN: 1684-5315
  • DOI: 10.5897/AJB
  • Start Year: 2002
  • Published Articles: 12405

Full Length Research Paper

Synthesis of silver nanoparticles using crude leaf extracts of Acacia nilotica, Azadirachta indica, Carissa spinarum, Melia azedarach, Senna didymobotrya and Warburgia ugandensis, and their antifungal activity against Sporisorium scitamineum

Nkhabindze Bongani Z.
  • Nkhabindze Bongani Z.
  • Department of Molecular Biology and Biotechnology, Pan African University Institute for Basic Science, Technology and Innovation (PAUISTI), Nairobi, Kenya.
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Wanyika Harrison N.
  • Wanyika Harrison N.
  • Department of Chemistry, Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya.
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Earnshaw Diana M.
  • Earnshaw Diana M.
  • Department of Crop Production, Faculty of Agriculture, University of Eswatini, Luyengo, Eswatini.
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Ateka Elijah M.
  • Ateka Elijah M.
  • Department of Molecular Biology and Biotechnology, Pan African University Institute for Basic Science, Technology and Innovation (PAUISTI), Nairobi, Kenya.
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  •  Received: 14 March 2022
  •  Accepted: 01 June 2022
  •  Published: 31 July 2022

Abstract

Bio-synthesised silver nanoparticles are effective in controlling several micro-organisms. They are correspondingly environmentally friendly, affordable, and easy to synthesise when compared with chemically synthesised silver nanoparticles. This study investigated the efficacy of biosynthesized silver nanoparticles against the fungus Sporisorium scitamineum, the causal agent of sugarcane smut. The reduction of silver nitrate upon mixing with the plants’ crude extracts was evidenced by the change in colour of the mixture to dark brown. Optimization of the mixtures using ultraviolet-visual spectroscopy showed peaks in the range of 340 to 450 nm. The Fourier transform infrared spectroscopy analysis identified proteins to be essential capping agents, and reducing sugars were responsible for the reduction of silver nitrate to nanoparticles and stabilizing the nanoparticles. The transmission electron microscope analysis showed the sizes of the nanoparticles to vary between 3 and 70 nm. Carissa spinarum and Melia azedarach had the most antifungal activity against S. scitamineum as observed from the inhibition-zone assay. Silver nanoparticles were successfully synthesized using the selected botanicals. All the synthesized nanoparticles showed varying antifungal effects against the S. scitamineum. C. spinarum and M. azedarach exhibited the highest antifungal activity, while Azadirachta indica showed the least.

 

Key words: Sporisorium scitamineum, Acacia nilotica, Carissa spinarum, Senna didymobotrya, Warburgia ugandensis, Melia azedarach, Azadirachta indica, bio-synthesised silver nanoparticles, antifungal activity.