Monoerucin, also known as 1-monoerucin or glyceryl monoerucate, is a monounsaturated monoacylglycerol formed by esterification of glycerol with erucic acid (C22:1 cis-13) at the sn-1 position. This long-chain lipid, typically derived from rapeseed sources, exhibits distinct lyotropic phase behavior and emulsifying properties. These characteristics are consistent with those reported for structurally related monoacylglycerols such as monobehenin, monoolein, and monopalmitolein.
Chemical Structure
Monoerucin has the molecular formula C25H48O4 and a molecular weight of 412.65 g/mol. Its glycerol backbone is esterified with an erucoyl chain containing a single cis double bond at the Δ13 position. This configuration leads to a predominantly cylindrical molecular geometry, which favors the formation of lamellar liquid-crystalline phases rather than the inverse cubic or hexagonal phases commonly observed for shorter unsaturated monoacylglycerols such as monoolein.
Physical Properties
Monoerucin typically appears as a white to off-white powder or waxy solid, with a melting point of approximately 52 °C, a density of about 0.951 g/cm³, and a boiling point exceeding 530 °C. It displays high thermal stability and is practically insoluble in water, while being readily soluble in organic solvents such as chloroform and hot ethanol. In hydrated systems, it forms lamellar (Lα) and isotropic fluid phases, with phase transitions commonly characterized using synchrotron X-ray diffraction techniques.
Phase Behavior
Hydrated monoerucin–water systems exhibit pronounced polymorphism, with stable lamellar phases persisting over a wide range of water concentrations. This behavior contrasts with the cubic and hexagonal phase preferences of monoolein and is attributed to the longer acyl chain length and the position of the single unsaturation. These properties support established structure–property relationships linking chain length, degree and position of unsaturation, and interfacial curvature in monoacylglycerol self-assembly.
