QUANTITATIVE STRUCTURE-ACTIVITY-RELATIONSHIPS OF FLUAZINAM AND RELATED FUNGICIDAL N-PHENYLPYRIDINAMINES - PREVENTIVE ACTIVITY AGAINST SPHAEROTHECA-FULIGINEA, PYRICULARIA-ORYZAE AND RHIZOCTONIA-SOLANI
T. Akagi et al., QUANTITATIVE STRUCTURE-ACTIVITY-RELATIONSHIPS OF FLUAZINAM AND RELATED FUNGICIDAL N-PHENYLPYRIDINAMINES - PREVENTIVE ACTIVITY AGAINST SPHAEROTHECA-FULIGINEA, PYRICULARIA-ORYZAE AND RHIZOCTONIA-SOLANI, Nippon Noyaku Gakkaishi, 21(1), 1996, pp. 23-29
Quantitative structure-activity relationships (QSAR) analyses of fungi
cidal activity of 3-chloro-2[N-(3-substituted-2, uoromethylphenyl)]ami
no-5-trifluoromethylpyridines against Sphaerotheca fuliginea, Pyricula
ria oryzae and Rhizoctonia solani were carried out and the results wer
e compared. In the case of S. fuliginea, a usual QSAR equation with Ha
mmett's electronic parameter (sigma(m)) and hydrophobicity (pi) was ob
tained, suggesting that the uncoupling mechanism might be involved in
the mode of action. In the cases of P. oryzae and R. solani, QSAR equa
tions were consisted of sigma(m), pi and the activity rank against Bot
rytis cinerea as independent variables, indicating both of uncoupling
and SH-inhibition were working in the action mechanism. Molecular orbi
tal calculations clarified that the charge delocalization coupled with
structural relaxations of the torsion angles between the C-N-C plane
and the benzene and pyridine rings were responsible for strong acidity
of fluazinam even in the less polar environment, which was reported a
s an important feature of shuttle-type uncoupling mechanism. More than
one mode of action may be working behind the broad fungicidal spectru
m of fluazinam.