Metabolism of stearoyl propylene glycol hydrogen succinate

Abstract

Metabolism of stearoyl propylene glycol hydrogen succinate (SPGHSu) has been studied in vivo in the rat and to a limited extent in man, and in vitro with pancreatic enzymes. Both 1- 14C-stearic acid-labeled and 1- 14C-succinic acid-labeled SPGHSu were used. Data from rat metabolism studies were compared with those obtained when either 1- 14C-stearic acid-labeled soybean oil, or free 1- 14C-succinic acid was fed. The data show that SPGHSu is efficiently metabolized by the animal body. Hydrolysis of SPGHSu takes place to a large extent prior to absorption. About 86% of the stearic acid moiety was absorbed via the thoracic duct, while more than 90% of the succinic acid moiety was absorbed by another pathway. Respiratory CO 2 was the major end product of catabolism, and no intact SPGHSu was deposited in the animal body. The metabolic fate of the stearic acid moiety of SPGHSu was similar to that of stearic acid in 1- 14C-stearic acid-labeled soybean oil. The rate of hydrolysis of the succinic acid-propylene glycol bond in SPGHSu was such that some propylene glycol hydrogen succinate (PGHSu) was excreted in the urine. During digestion in vitro of SPGHSu, both stearic acid and succinic acid were liberated, indicating that the pancreatic enzymes were capable of attacking either end of the molecule. Propylene glycol monostearate and PGHSu were also shown to be products of the digestion.