RAPID AND SPECIFIC ENZYME-IMMUNOASSAY FOR MAKISTERONE-A

A new, sensitive enzyme immunoassay (EIA) for makisterone A (MaA) is d escribed. The assay is based on the competition between MaA (standard or in the sample to be assayed) and an enzymatic tracer, a MaA-6-carbo xymethoxime derivative coupled to acetylcholinesterase (MaA-CMO-AChE), for binding to rabbit polyclonal antibody directed against a primary antibody coated onto the wells of microtiter plates. The antibody is r aised against an immunogen obtained by coupling MaA-CMO to bovine seru m albumin (BSA), The EIA permits the accurate measurement of as little MaA as 440 pmol/l (33 pg/well) in biological samples. While no signif icant cross reactivity was observed with 20-hydroxyecdysone and ecdyso ne, makisterone C (MaC) was recognized as well as MaA. This characteri stic has the advantage of allowing the measurement of these latter ecd ysteroids in Dysdercus fasciatus eggs known to contain both MaA and Ma C.