Monopalmitolein, also known as 1-monopalmitolein or glyceryl monopalmitoleate, is a monounsaturated monoacylglycerol formed by esterification of glycerol with palmitoleic acid (16:1 n-7, cis-9) at the sn-1 position. This lipid, naturally present in bitter melon and other biological sources, exhibits antimicrobial activity and inhibitory effects on P-glycoprotein. Its functional profile and physicochemical behavior are comparable to other monoacylglycerols such as monoolein, which are widely used in membrane protein studies and bioactive lipid research.
Chemical Structure
Monopalmitolein has the molecular formula C19H36O4 and a molecular weight of approximately 328.5 g/mol. The molecule consists of a glycerol backbone esterified with a single C16 fatty acyl chain containing one cis double bond. This structural feature confers a conical molecular geometry, favoring the formation of non-lamellar lipid phases such as lipidic cubic phases (LCP) and inverse mesophases, similarly to monoolein.
Physical Properties
At room temperature, monopalmitolein appears as a clear liquid to waxy solid. It is soluble in non-polar organic solvents such as hexane and chloroform and is typically supplied at high purity levels (>99%) for research applications. Its amphiphilic character enables spontaneous self-assembly into organized nanostructures, including bicontinuous cubic phases. In combination with lipids such as DSPG, it can form ultraswollen cubic phases with enlarged aqueous channels, which are advantageous for membrane protein crystallization and structural biology studies.
Biological Role
In biological systems, monopalmitolein has been reported to inhibit P-glycoprotein activity in intestinal Caco-2 cells, suggesting a potential role in modulating drug absorption and bioavailability. It also induces apoptotic responses in T lymphocytes and contributes to the antimicrobial properties observed among monoglycerides by disrupting microbial membrane integrity, in a manner comparable to compounds such as monocaprin. Furthermore, it is metabolically related to palmitoleic acid and may participate in lipid signaling and host–pathogen interactions.