Inositol formation by cyclization of glucose chain in rat testis

A homogenate of rat testis capable of incorporating carbon from glucose-U-C14 into inositol has been described in a previous publication (Eisenberg and Bolden, 1963). In an attempt to differentiate1 between a hexose moiety (Imai, 1963; Loewus and Kelly, 1962) and hexose fragments (Charalampous, 1957; Hauser and Finelli, 1963) as precursors of inositol, the conversion of specifically labeled glucose to inositol has now been studied in rat testis homogenate with the aid of a combined plant and chemical degradative system described previously (Loewus et al, 1962). Experimental evidence to be presented in this paper points unequivocally to a pathway of biosynthesis of inositol in the mammal involving cyclization of a six-carbon unit.