Abstract
ABSTRACTMembrane progestin receptors (mPRs) are members of the progestin and adipoQ (PAQR) receptor family that are stimulated by endogenous steroids to initiate rapid intracellular signalling through a nongenomic pathway. Previously, water-soluble compounds with mPRα-binding activity from the marine algaePadina arborescenswere fractionated by HPLC steps. In this study, the structure of one of the major compounds in the fraction was identified as 2-hydroxypentanoic acid (2-HPA) using Nuclear Magnetic Resonance spectroscopy. 2-HPA showed a substantial competitive binding affinity for hmPRα in the GQD-hmPRα binding assay. In contrast, synthetic structural analogues of 2-HPA showed no competitive binding activity. The physiological activity of 2-HPA and its analogues was then investigated usingin vitrogoldfish andin vivozebrafish oocyte maturation and ovulation assays. As with the hmPRα binding assay, only 2-HPA showed inhibitory activity on oocyte maturation and ovulation of fish oocytes. Furthermore, the inhibitory activity of 2-HPA was compared between S- and R-type 2-HPA. The results showed that both types had the same level of activity. These results indicate that 2-HPA, found as a secreted compound fromPadina arborescens, is a novel mPRα antagonist and its chemical structure is highly restricted to show its activity.
Publisher
Cold Spring Harbor Laboratory