Pinitol is a cyclitol, a cyclic polyol. It is a known anti-diabetic agent isolated from Sutherlandia frutescens leaves. Gall plant tannins can be differentiated by their content of pinitol. It was first identified in the sugar pine (Pinus lambertiana). It is also found in other plants, such as in the pods of the carob tree.
A cyclitol derivative can be found in the marine sponge Petrosia sp.
Biosynthesis
D-pinitol is the most widely distributed inositol ether in plants. In Angiosperms, D-pinitol has a relatively straight forward and short biosynthesis which proceeds via the Loewus pathway. The precursor to the biosynthesis pathway is glucose-6-phosphate, which is converted to D-ononitol (1-D-4-O-methyl-myo-inositol) via myo-inositol. Ononitol is epimerized to yield D-pinitol via a D-ononitol epimerase using NADPH as a cofactor.
↑Sanz ML, Martínez-Castro I, Moreno-Arribas MV (2008). "Identification of the origin of commercial enological tannins by the analysis of monosaccharides and polyalcohols". Food Chemistry. 111 (3): 778–783. doi:10.1016/j.foodchem.2008.04.050. S2CID84922451.
↑Ley SV, Sternfeld F, Taylor S (1987). "Microbial oxidation in synthesis: A six step preparation of (±)-pinitol from benzene". Tetrahedron Letters. 28 (2): 225–226. doi:10.1016/S0040-4039(00)95692-2. S2CID83944164.