Background: Topoisomerase II poisons are in clinical use as anti-cancer therapy for decades and work by stabilizing the enzyme-induced DNA breaks. In contrast, catalytic inhibitors block the enzyme before DNA scission. Although several catalytic inhibitors of topoisomerase II have been described, preclinical concepts for exploiting their anti-proliferative activity based on molecular characteristics of the tumor cell have only recently started to emerge. Topoisomerase II is an ATPase and uses the energy derived from ATP hydrolysis to orchestrate the movement of the DNA double strands along the enzyme. Thus, interfering with ATPase function with low molecular weight inhibitors that target the nucleotide binding pocket should profoundly affect cells that are committed to undergo mitosis.

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A panel of monoclonal antibodies (MAbs) specific to triasulfuron was obtained by using two different hapten-protein conjugates as immunogens. MAbs generated with a simple hapten corresponding only to the chloroethoxy sulfonamide moiety of triasulfuron with an additional succinic acid spacer showed much higher affinity for triasulfuron as compared to those obtained with a hapten consisting of the complete molecule with an aminoalkyl spacer attached to the triazine ring. The cross-reactivity of the MAbs was limited to only a few structurally related compounds as determined by competitive ELISA. Most of the MAbs cross-reacted with the phenylhydroxylated degradation products of triasulfuron, whereas a few others cross-reacted with cinosulfuron and a fluoroethylthio analogue of triasulfuron. The competitive enzyme immunoassay based on these MAbs detected triasulfuron in aqueous media ranging from 0.01 to 1 #tg/L. The ELISA was tested on fortified soil samples. The extraction procedure was optimized to reduce the soil matrix effects to a minimal level, allowing the detection of triasulfuron down to 0.1 Mg/kg of soil.

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