Wikipedia
D-chiro-Inositol (commonly abbreviated DCI) is a member of a family of related substances often referred to collectively as " inositol," although that term encompasses several isomers of questionable biological relevance. It is known to be an important secondary messenger in insulin signal transduction.
DCI is not abundant in most diets. It can be found in carob tree (Cearatonia siliqua L.) pods. It is likely that in higher vertebrates DCI is made from myo-inositol via the action of an epimerase. DCI is commercially available to the public as a nutritional supplement in several countries. Caronositol is natural D-chiro-Inositol obtained from carob extract by a patented process. Caronositol is used in treatment of metabolic and hormonal polycystic ovarian syndrome.