Abstract
Starfish oocytes are naturally arrested at the prophase stage of the first meiotic division and resume meiosis in response to the maturation-inducing hormone 1-methyladenine. Five analogs of 1-methyladenine including three novel ones were synthesized and tested for biological activities as 1-methyladenine agonists or antagonists in triggering reinitiation of meiosis of starfish Asterina pectinifera oocytes, as well as for competition in binding to putative 1-methyladenine receptors with respect to 1-methyladenine. 1-Ethyladenine was an effective agonist, but 1-propyladenine served as a weak antagonist to 1-methyladenine, indicating strict specificity for a relatively small N-1 substituent. Analogs in which carboxymethyl or methyl group substitutes for a hydrogen of 6-amino group still retained oocyte maturation-inducing activity, but to a much lesser degree. The results of the competitive binding assay with cortices of oocytes demonstrated that these agonists or antagonist inhibited the binding of [3H]1-methyladenine to receptors. 8-methylamino-1-methyladenine competed only weakly with [3H]1-methyladenine for the binding to cortices, although it behaved as a potent antagonist.
