Differential susceptibility ofSclerotium cepivorum Berk. to some synthesized visnagin sulfonamide derivates

Abstract

Twenty-five visnagin sulfonamide derivatives were testedin vitro against sclerotial germination, growth and cellulolytic activity ofSclerotium cepivorum Berk. The effectiveness of the derivatives depends on the concentration and the substituent introduced to the title compounds. The introduction of SO2Cl2 to C9 of visnagin induced high toxicity than introducing SO2NH2. Compounds with sulfonyl piperidine or sulfonyl morpholine gave small toxicity only at 30 and 75 μg cm−3. Addition of N-aryl ring to visnagin-9-sulfonamide rendered the title compound to be more toxic. The substitution of the N-aryl ring bym-CH3,m-Cl orp-Cl enhanced the toxicity, while its substitution witho-CH3,p-CH3,p-Br,o-OCH3 orm-OCH3 caused a drop in the toxicity as compared to compounds with unsubstituted aryl ring. Visnagin sulfonamide derivatives having azole rings were strongly inhibitory for sclerotial germination, growth, sclerotial formation and cellulolytic activity, even when applied at 4 μg cm−3. The most toxic one was that having dimethyl isoxazole. The cleavage of γ-pyrone ring led to a decline in the toxicity as compared with the other sulfonamide derivatives.