Extracellular and intracellular esterase processing of SCFA-hexosamine analogs: implications for metabolic glycoengineering and drug delivery.

This report provides a synopsis of the esterase processing of short chain fatty acid (SCFA)-derivatized hexosamine analogs used in metabolic glycoengineering by demonstrating that the extracellular hydrolysis of these compounds is comparatively slow (e.g., with a t(1/2) of ∼4 h to several days) in normal cell culture as well as in high serum concentrations intended to mimic in vivo conditions. Structure-activity relationship (SAR) analysis of common sugar analogs revealed that O-acetylated and N-azido ManNAc derivatives were more refractory against extracellular inactivation by FBS than their butanoylated counterparts consistent with in silico docking simulations of Ac(4)ManNAc and Bu(4)ManNAc to human carboxylesterase 1 (hCE1). By contrast, all analogs tested supported increased intracellular sialic acid production within 2h establishing that esterase processing once the analogs are taken up by cells is not rate limiting.