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Enhancement of fungicidal and insecticidal activity by reductive alkylation of chitosan
Author(s) -
Rabea Entsar I,
Badawy Mohamed EI,
Rogge Tina M,
Stevens Christian V,
Steurbaut Walter,
Höfte Monica,
Smagghe Guy
Publication year - 2006
Publication title -
pest management science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.296
H-Index - 125
eISSN - 1526-4998
pISSN - 1526-498X
DOI - 10.1002/ps.1263
Subject(s) - spodoptera littoralis , botrytis cinerea , bioassay , chitosan , noctuidae , fungicide , magnaporthe grisea , biology , mycelium , botany , stereochemistry , chemistry , lepidoptera genitalia , biochemistry , oryza sativa , gene , genetics
A series of N ‐alkyl chitosan (NAC) derivatives were synthesized using a reductive alkylation reaction to examine their fungicidal and insecticidal activity. The chemical structures were characterized by IR and 1 H NMR spectroscopy, and the degree of substitution (DS) ranged from 0.02 to 0.37. Their fungicidal activity was evaluated against the grey mould Botrytis cinerea Pers ex Fr (Leotiales: Sclerotiniaceae) and the rice leaf blast pathogen Pyricularia grisea Sacc [Teleomorph: Magnaporthe grisea (Hebert) Barr] by a radial growth bioassay. It was of interest that most of the NAC derivatives were more active against both fungi than chitosan itself. The most active derivative was N ‐(2,2‐diphenylethyl)chitosan with EC 50 values of 0.031 and 0.23 g L −1 against B. cinerea and P. grisea respectively. In addition, some derivatives, at higher concentrations up to 1.0 g L −1 , inhibited the mycelial growth and spore formation of P. grisea . Bioassays against larvae of the cotton leafworm, Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae) with the NAC derivatives at a rate of 5.0 g kg −1 in artificial diet demonstrated that N ‐(3‐phenylbutyl)chitosan was the most active compound. In addition, N ‐propylchitosan, N ‐undecanylchitosan and N ‐(3‐phenylpropyl)chitosan derivatives strongly inhibited larval weight gain in S. littoralis , with respective reductions of 76, 66 and 65% after 4 days of feeding on treated diet. Copyright © 2006 Society of Chemical Industry