Intestinal absorption of specific structured triacylglycerols.
To clarify the intestinal absorption pathway of medium-chain fatty acids from MLM-type structured triacylglycerols containing both medium- and long-chain fatty acids, we studied the lymphatic transport of 1,3-dioctanoyl-2-linoleoyl-sn-glycerol (8:0/18:2/8:0), 1,3-didecanoyl-2-linoleoyl-sn-glycerol (10:0/18:2/10:0), and 1,3-didodecanoyl-2-linoleoyl-sn-glycerol (12:0/18:2/12:0) in a rat model. Safflower oil was used in the absorption study in order to compare the absorption of medium-chain fatty acids and long-chain fatty acids. The triacylglycerol species of lymph lipids were separated on a reversed-phase high performance liquid chromatograph (RP-HPLC) and identified by atmospheric pressure chemical ionization mass spectrometry. The composition of triacylglycerols was quantified by RP-HPLC with evaporative light scattering detection. The intact MLM-type triacylglycerols were detected in the lymph lipids after administration of the specific structured triacylglycerols (STAG). The recoveries of 8:0/18:2/8:0, 10:0/18:2/10:0, and 12:0/18:2/12:0 were 0.6%, 12%, and 5%, respectively. Several new triacylglycerol species were detected in the lymph lipids, including MLL-, LLL-, and MMM-type triacylglycerols. From the present study we conclude that the medium-chain fatty acids from STAG, in addition to absorption into the portal blood as free fatty acids, are absorbed by the same pathway as the conventional long-chain triacylglycerols, that is, they are hydrolyzed into free fatty acids, absorbed and activated into CoA, and reacylated into triacylglycerols in the enterocyte. The hydrolysis of MLM-type STAG is predominantly partial hydrolysis, whereas part of the STAG can also be hydrolyzed to free glycerol and free fatty acids.
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Department of Biochemistry and Nutrition, Center for Advanced Food Studies, Technical University of Denmark, 2800 Lyngby, Denmark. huiling.mu@biocentrum.dtu.dk
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D000818:Animals; D002851:Chromatography, High Pressure Liquid; D005227:Fatty Acids / Q000737:chemistry / Q000378:metabolism*; D007408:Intestinal Absorption; D008196:Lymph / Q000737:chemistry*; D008297:Male; D013058:Mass Spectrometry / Q000379:methods; D051381:Rats; D017208:Rats, Wistar; D012450:Safflower Oil / Q000008:administration & dosage* / Q000737:chemistry; D014280:Triglycerides / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*
D005227:Fatty Acids; D014280:Triglycerides; D012450:Safflower Oil