Phlorizin


Phlorizin is a glucoside of phloretin, a dihydrochalcone, a family of bicyclic flavonoids, which in turn is a subgroup in the diverse phenylpropanoid synthesis pathway in plants.

Occurrence

Phlorizin is found primarily in unripe Malus root bark of apple, and trace amounts have been found in strawberry. In Malus, it is most abundant in vegetative tissues and seeds. Closely related species, such as pear, cherry, and other fruit trees in the Rosaceae do not contain phloridzin. Phloridzin is a phytochemical that belongs to the class of polyphenols. In natural sources, it may occur with other polyphenols such as quercetin, catechin, epicatechin, procyanidins, and rutin.

Properties

Phlorizin is a white to yellow crystalline solid with a melting point of 106–109 °C. It is of sweet taste and contains four molecules of water in the crystal. Above 200 °C, it decomposes. It is poorly soluble in ether and cold water, but soluble in ethanol and hot water. Upon prolonged exposure to aqueous solutions phlorizin hydrolyzes to phloretin and glucose.

Pharmacology

Phlorizin is a competitive inhibitor of SGLT1 and SGLT2 because it competes with D-glucose for binding to the carrier; this reduces renal glucose transport, lowering the amount of glucose in the blood. Phlorizin was studied as a potential pharmaceutical treatment for type 2 diabetes, but has since been superseded by more selective and more promising synthetic analogs, such as empagliflozin, canagliflozin and dapagliflozin. Phlorizin is not an effective drug because when orally consumed, it is nearly entirely converted into phloretin by hydrolytic enzymes in the small intestine.