Microbiological and Chemical Analysis of Neem (Azadirachta indica) Extracts: New Data on Antimicrobial Activity |
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| Authors: | E Coventry E J Allan |
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| Institution: | (1) Dept. of Agriculture & Forestry, University of Aberdeen, AB24 5UA Aberdeen, UK;(2) Present address: Plant Pathology and Microbiology Department, Present address: Horticulture Research International, CV35 9EF Welles-bourne, Warwick, UK |
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| Abstract: | The antimicrobial effects of extracts of neem seed (Azadirachta indica A. Juss.) were investigated using microbial growth inhibition assays. A laboratory-prepared neem seed extract along with
a commercially available formulated product, were characterized using HPLC, and shown to be effective against a range of bacteria
in an agar diffusion assay. The active ingredient,i.e., the unformulated seed extract of the commercial product, also showed activity and this was further investigated in a biochromatogram,
using the sensitive bacteriumBacillus mycoides. Results showed antibacterial activity as three discrete inhibition zones that did not correspond to the Rf of the major neem metabolites, azadirachtin, nimbin and salannin. This suggests that these compounds were not antibacterial.
The colony radial growth rates of the fungal pathogens that cause ‘take-all’ and ‘snow mould’ disease were both significantly
affected when the commercial, unformulated, neem seed extract was incorporated into the growth medium. Experiments in liquid
culture suggested that the effect was fungistatic. Conidial germination of the commercially important obligate pathogenSphaerotheca fuliginea (powdery mildew) was reduced to 11%. The results show that neem seed extracts possess antimicrobial activity with notable
effects on some fungal phytopathogens. This Work demonstrates that neem seed extracts have potential for controlling both
microbial and insect pests.
http://www.phytoparasitica.org posting Sept. 16,2001. |
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| Keywords: | Neem antibacterial antifungal biochromatogram phytopathogens azadirachtin |
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