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International Journal of Microbiology
Volume 2017, Article ID 5273893, 9 pages
https://doi.org/10.1155/2017/5273893
Research Article

Effects of Medicinal Plant Extracts and Photosensitization on Aflatoxin Producing Aspergillus flavus (Raper and Fennell)

School of Biological Sciences, University of Nairobi, P.O. Box 30197-00100, Nairobi, Kenya

Correspondence should be addressed to Loise M. Njoki; moc.liamg@0302ibmumesiolofni

Received 12 January 2017; Revised 29 March 2017; Accepted 13 April 2017; Published 2 May 2017

Academic Editor: Todd R. Callaway

Copyright © 2017 Loise M. Njoki et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

This study was undertaken with an aim of exploring the effectiveness of medicinal plant extracts in the control of aflatoxin production. Antifungal properties, photosensitization, and phytochemical composition of aqueous and organic extracts of fruits from Solanum aculeastrum, bark from Syzygium cordatum, and leaves from Prunus africana, Ocimum lamiifolium, Lippia kituiensis, and Spinacia oleracea were tested. Spores from four-day-old cultures of previously identified toxigenic fungi, UONV017 and UONV003, were used. Disc diffusion and broth dilution methods were used to test the antifungal activity. The spores were suspended in 2 ml of each extract separately and treated with visible light (420 nm) for varying periods. Organic extracts displayed species and concentration dependent antifungal activity. Solanum aculeastrum had the highest zones of inhibition diameters in both strains: UONV017 (mean =  mm) and UONV003 (mean =  mm) at 600 mg/ml. Aqueous extracts had no antifungal activity because all diameters were below 8 mm. Solanum aculeastrum had the lowest minimum inhibitory concentration at 25 mg/ml against A. flavus UONV017. All the plant extracts in combination with light reduced the viability of fungal conidia compared with the controls without light, without extracts, and without both extracts and light. Six bioactive compounds were analyzed in the plant extracts. Medicinal plant extracts in this study can control conidia viability and hence with further development can control toxigenic fungal spread.