Triarachidin , also known as glyceryl triarachidate or 1,2,3-triarachidonoyl glycerol, is a saturated very-long-chain triacylglycerol (TAG) composed of three arachidic acid (eicosanoic acid, C20:0) chains esterified to a glycerol backbone. Found in peanut oil and fish fats, this high-melting lipid extends the saturated TAG series beyond tristearin, serving as a model for studying fat crystallization and thermal stability in lipid research.
Chemical Structure
Triarachidin has the molecular formula C63H122O6 and a molecular weight of 975.6 g/mol. Its symmetric sn-glycerol core with three straight-chain eicosanoyl groups at sn-1, sn-2, and sn-3 positions yields extreme hydrophobicity (XLogP3-AA ~23), promoting tight β-crystalline packing and hydrolysis to arachidic acid by pancreatic lipases.
Physical Properties
A white powder or crystalline solid (melting point 75–80°C, density ~0.90 g/cm³), triarachidin shows collision cross-sections of 349.1–349.3 Ų [M+NH4]+ for IMS identification, with solubility in chloroform (10 mg/mL) but insolubility in water. Stable at room temperature or -20°C, its high ΔfusH supports polymorphism studies.
Biological Functions
Hydrolyzed to arachidic acid—which incorporates into sphingolipids and modulates membrane rigidity—triarachidin stores energy efficiently in specialized fats, digesting slower than medium-chain TAGs for sustained release while contributing to very-long-chain fatty acid metabolism.
