Monomyristin, also known as 1-monomyristoyl-rac-glycerol or glycerol monomyristate (C₁₇H₃₄O₄, MW 302.46 g/mol), is a long-chain saturated monoacylglycerol (MAG) formed by esterification of myristic acid (tetradecanoic acid, C14:0) at the sn-1 position of glycerol. It represents the final compound in the monoacylglycerol series and contributes to broader lipid research applications in biochemical and pharmaceutical sciences.
Chemical Structure
Monomyristin consists of a glycerol backbone esterified with a 14-carbon saturated fatty acyl chain (-CO(CH₂)₁₂CH₃) at the primary sn-1 hydroxyl group, while the sn-2 and sn-3 positions remain as free hydroxyls. Its IUPAC name is 2,3-dihydroxypropyl tetradecanoate (CH₂(OCOC₁₃H₂₇)-CH(OH)-CH₂OH). The compound typically appears as a white to off-white crystalline powder. Structural identity is confirmed by InChI=1S/C17H34O4/c1-2-3-4-5-6-7-8-9-10-11-12-13-17(20)21-15-16(19)14-18/h16,18-19H,2-15H2,1H3. It exhibits low solubility in water but good compatibility with common organic solvents.
Physicochemical Properties
Monomyristin displays a melting point in the range of 68–72 °C and an estimated boiling point of approximately 363 °C. Its density is about 0.97 g/cm³, with a refractive index of 1.423 and a pKa of approximately 13.16. Due to its amphiphilic character (HLB ≈ 3–5), the compound is capable of forming mesophases such as lamellar and cubic structures. It shows high thermal stability up to 150 °C and moderate resistance to hydrolysis under mild conditions. The compound is soluble in methanol, ethanol, and DMSO (with slight turbidity) but insoluble in water, and is typically stored in sealed containers at 2–8 °C to ensure stability.
Synthesis and Stability
Monomyristin is commonly synthesized through enzymatic glycerolysis of trimyristin or by lipase-catalyzed transesterification of ethyl myristate with glycerol, frequently using Candida antarctica lipase as a biocatalyst. These processes can yield product purities exceeding 97% following distillation and crystallization. In biological systems, the C14 ester bond undergoes gradual hydrolysis mediated by lipases, enabling sustained release of myristic acid. This controlled hydrolysis profile provides functional advantages over free fatty acids in formulation stability and biological availability.