Mechanism of Antifungal Action of 2,4,5,6‐Tetrachloroisophthalonitrile

Abstract

AbslractStudies of the toxicity of 2,4,5,6-tetrachloroisophthalonitrile (TCIN) to cells of Stucluiromyce.s paslorianiis and ^'^•tlroHpora crasm showed that 2 to 4 [ig/ml of the tnxirant were required to inhihit giowth. Several thiol compounds reversed toxicity tn h tdticose oxidation was severely impaired in treated cells of both test organisms. The to.xicant at '2 or 4 ug/ml markedly reduced soluble thiol content of these cells. Unuiul thiol content was less affected in S. pastoritmus cells than soluble thiol content.I'ptake of toxicant by yeast cells was accompuniyd by lorination of derivatives, some of wliich ri'stMiihlcd tliosc formed by reaction of glutathionr with TCIN in vitro. Cot-nzynio A. glutathione, and 2-merca|)toethanol readily formed derivatives with TCIN in oitro. The nature of these derivatives was studied using 2-mercaptoethanol products as model suhstituents. Four derivatives were formed with '2-niercaptoethanol each with similar functional groups but showing dis.similar degree.s of mohility during silica gel chroniatogrii|)hy. Evidence indicaled tliat these are derivatives of I'CIN in which 1 to 4 of the halogens has been substituted by 2-mercaptoethanol.The mechanism of fungicidal action of TCIN is attributed to thiol inaclivalion. InlroductionA iiilrile derivative, 2,4,5,(>tetrachloroisophlhalonitrile (TCIN). ha.s recently been introduced as a lunjiicide active aj,'ainst a broad .spectrum of phylopatho^'enic fungi (13). Chemically related to TCIN are tbe herbicide.s ;i5-dii()do-4-bydroxybenzonitrile. 2,6-dichiorobenzonitriIe (2,8,15), and 2,0dicbloro-3-bydroxybenzonitrile (10): an insecticide, p-cblorobenzonitrile (2); "Physiol. Plant., 21, 1068 [1249]

Soil Enzyme: The State-of-Art

“…These include temperature, soil pH, water, and oxygen contents (abiotic conditions), the chemical structure of organic matter and its location in the soil profile horizon (Rubidge 1977;Gomah 1980;Tabatabai 1982;Klein 1989;Deng and Tabatabai 1994;Alf and Nannipieri 1995), quality of organic matter/plant debris and soil mineral elements (Burns 1978;Hope and Burns 1987;Klein 1989;Sinsabaugh and Linkins 1989;Deng and Tabatabai 1994) and the trace elements from fungicides (Deng and Tabatabai 1994;Petker and Rai 1992;Arinze and Yubedee 2000;Atlas et al 1978;Vincent and Sisler 1968).…”

Environmental Fate and Toxicology of Chlorothalonil

“…Gallagher et al (1992) recorded a depletion of glutathione, resulting in the inhibition of glucose oxidation in exposed channel catfish. A study, in which Saccharomyces pastorianus and Neurospora crassa were exposed to chlorothalonil confirmed that glucose oxidation was impaired and soluble thiol content was reduced from chlorothalonil treatment (Vincent and Sisler 1968). Tillman et al (1973) concluded that the mechanism of chlorothalonil's toxic action resembles that of the trichoromethylsulfenyl fungicides.…”

“…The fungicidal activity exhibited by chlorothalonil is attributed to the inactivation of cell sulfhydryl enzymes (Vincent and Sisler 1968;Sherrard et al 2003). Gallagher et al (1992) recorded a depletion of glutathione, resulting in the inhibition of glucose oxidation in exposed channel catfish.…”

Formation of a Methylthiolated Metabolite from the Fungicide Chlorothalonil by Soil Bacteria

“…In the past, the formation of a methylthiolated metabolite from chlorothalonil has been reported in soil,5) and in cultures of such eucaryotic microorganisms as Saccharomyces pastorianus and Neurospora crassa. 3 ) The methylthiolation process has also been observed in the degradation of pentachloronitrobenzene 7) and fthalide. 8 ) However, there has been no previous report that bacteria could transform chlorinated aromatic compounds to methylthiolated metabolites.…”