Phlorizin

Phlorizin, or phloretin-2'-O-glucoside, is a natural dihydrochalcone glycoside found in various fruit trees, especially in the skin and bark of apples and other members of the Rosaceae family. It exists as the glucoside form of phloretin and is produced in plants through glycosylation. In human digestion, phlorizin is hydrolyzed by intestinal glycosidases to phloretin and glucose, which limits systemic exposure to intact phlorizin.

Phlorizin is best known in pharmacology as a competitive inhibitor of glucose transporters SGLT1 (intestinal) and SGLT2 (renal). By blocking sodium-glucose cotransport, it prevents glucose reabsorption and uptake. This property made phlorizin a valuable tool in early studies of glucose transport and contributed to the development of modern SGLT inhibitors used to treat type 2 diabetes, although phlorizin itself is not suitable as a drug due to poor bioavailability and nonselectivity.

Occurrence and applications: In plants, phlorizin is found in the bark and fruit tissues of several Malus and related species and may contribute to plant defense against pathogens and herbivores. In research, phlorizin is used to probe glucose transport mechanisms, and its aglycone, phloretin, has various reported biological activities, including antimicrobial and antioxidant effects.

Chemical and safety notes: Phlorizin is a glycoside distinct from pharmaceutical SGLT inhibitors. It is primarily used in laboratory studies, with limited clinical data on long-term human effects. Derivatives and related compounds inform the ongoing design of selective, orally bioavailable SGLT inhibitors.