In Vitro hydrolysis of fungal oils: Distribution of arachidonic acid‐containing triacylglycerol molecular species

Abstract

AbstractFour commercially prepared arachidonic acidrich oils from the fungus Mortierella alpina were analyzed by high‐performance liquid chromatography and gas chromatography. The levels of arachidonic acid and the distribution of triacylglycerol (TG) molecular species varied significantly among these oils. The major arachidonate‐containing TG species were AAA, LAA, DAA, OAA, PAA, SAA, OLA, PGA, PLA, POA, and SOA where the abbreviations A, D, G, L, O, P, and S represent arachidonic (20:4n‐6), dihomo‐γ‐linolenic (20:3n‐6), γ‐linolenic (18:3n‐6), linoleic (18:2n‐6), oleic (18:1n‐9), palmitic (16:0), and stearic (18:0) acids, respectively. In vitro incubation of the TG fractions, purified from these oils with porcine pancreatic lipase for 5 min, yields a mixture of intermediate products, such as 1,2‐ and 2,3‐diacylglycerols (1,2‐ and 2,3‐DG), 2‐monoacylglycerol (2‐MG) and free fatty acids (FFA), as well as residual TG. The degrees of hydrolysis varied significantly among the four oil preparations, ranging from 35 to 57%. The levels of arachidonic acid in the residual TG and 1,2(2,3)‐DG were significantly higher than those in the original TG, whereas those in the FFA fraction were significantly lower than those in 1,2(2,3)‐DG and 2‐MG. Results from this study suggest that the bioavailability of arachidonic acid differs among fungal oils prepared by different suppliers. These differences could be attributed to the arachidonic acid content of the oil as well as to the association of arachidonic acid with other fatty acids in the same TG molecule.