Physiological role and clinical utility of inositols in polycystic ovary syndrome

During the last decades, a substantial body of research has focused on the role of the two major inositol (Ins) stereoisomers, myoinositol (myoIns) and D-chiroinositol (D-chiroIns), both second messengers of insulin, in insulin-dependent processes, including polycystic ovary syndrome (PCOS). MyoIns has been shown to affect different pathways at both ovarian and non-ovarian level. On the contrary, D-chiroIns alone is unable to exert significant improvements in the ovarian cell functions, as its beneficial effects are mainly limited to the non-ovarian tissue in which it may significantly inhibit the negative cellular consequences of hyperinsulinemia. However, both Ins isomers can be positively associated in the management of PCOS patients in a ratio corresponding to their physiological plasma ratio (40:1). This appears to exert a synergistic effect according to a multi-targeted design. In this respect, new fundamental insights into the biological mechanisms displayed by Ins, as well as clinical trials based on the myoIns + D-chiroIns formulations, have already provided encouraging results.