Gastrointestinal digestion fates of lipids based on pH-stat and Caco-2 cells models: Superior bioavailability of triglyceride monomer derived from silkworm pupae oil

Silkworm pupae oil (SPO) was regarded as a good alternative to alpha-linolenic acid supplements, which contain a variety of triacylglyceride with high nutritional value. To investigate the connections between triacylglyceride composition and lipid gastrointestinal digestive absorption profiles, isolation and bioavailability of triacylglyceride monomers from silkworm pupae oil was analyzed. In this study, two triacylglyceride monomers rich in α-linolenic acid were separated by preparative liquid chromatography, namely LnLnLn (1,2,3- α-linolenic acid triacylglyceride) and LnLnL (1,2- α-linolenic acid, 3- linoleic acid triacylglyceride). The in vitro digestion in the pH-stat model results showed the digestive rate of LnLnLn was 0.4101 ± 0.0089 s−1, which was significantly higher than that of SPO (0.2494 ± 0.0108 s−1) (p < 0.05). The in vitro absorption in the Caco-2 cells model results showed the absorptivity of LnLnLn and LnLnL were 6.40 ± 0.19% and 6.06 ± 0.54%, which were significantly higher than SPO (5.43 ± 0.51%) (p < 0.05). In addition, the mRNA expression levels of lipid metabolism-related proteins provide evidence for the absorption superiority of LnLnLn and LnLnL. The present work provides novel structural lipids for rapid and efficient supplementation of α-linolenic acid.