Novel dynamic flow cytoenzymological determination of intracellular esterase inhibition by BCNU and related isocyanates

Caroline Dive, Paul Workman, James V. Watson

    Research output: Contribution to journalArticlepeer-review

    Abstract

    We present a novel dynamic flow cytoenzymological demonstration of the potent inhibition by the antitumour chloroethylnitrosourea BCNU of the intracellular hydrolysis of fluorescein diacetate by esterases of viable, intact murine and human tumour cells in vitro. The BCNU metabonate chloroethyl isocyanate and the related compound n-butyl isocyanate were also potent inhibitors. I50 values were in the range 4.2 × 10-5-2.0× 10-4 M. Generally similar quantitative results were obtained for intact cells and sonicates by conventional spectrofluorimetry, and inhibition of purified porcine liver carboxyl esterase (EC 3.1.1.1) was demonstrated. Little or no inhibitory activity was seen with the alkylating agents methyl methane-sulphonate, melphalan and nitrogen mustard. The results are consistent with carbamoylation of the esterase molecules by isocyanates, and this may provide a basis for the flow cytometric determination of intracellular carbamoylation in discrete subpopulations of heterogeneous samples. © 1987.
    Original languageEnglish
    Pages (from-to)3731-3738
    Number of pages7
    JournalBiochemical Pharmacology
    Volume36
    Issue number21
    Publication statusPublished - 1 Nov 1987

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