Recent reports have shown that n-3 PUFA-enriched phospholipids have various beneficial effects. The proportion of DHA and eicosapentaenoic acid (EPA) in the phospholipids might affect their biological functions. In the present study, marine DHA-enriched phospholipids (DHA-PL) and EPA-enriched phospholipids (EPA-PL) were administered to high fat (HF) diet-induced obese C57BL/6J mice for 8 weeks to compare their effects on obesity-related metabolic disorders. DHA-PL and EPA-PL significantly decreased epididymal and perirenal adipose tissue weights, reduced blood pressures and lowered serum and hepatic triacylglycerol levels in HF diet-induced obese mice. Serum insulin, MCP-1 and IL-6 levels were also efficiently reduced by treatment with DHA-PL and EPA-PL. The anti-obesity and lipid-lowering effects of EPA-PL were superior to DHA-PL, while DHA-PL exhibited better anti-hypertension effects than EPA-PL. The effects of DHA-PL and EPA-PL on glucose intolerance and inflammation were basically equivalent. DHA-PL and EPA-PL up-regulated genes involved in insulin-sensitizing actions in the adipose tissue and suppressed hepatic SREBP-1c mediated lipogenesis. EPA-PL also significantly activated PPARα mediated fatty acid β-oxidation in the liver. These results indicate that DHA-PL and EPA-PL could efficaciously alleviate obesity-related metabolic disorders but the ameliorative degree and regulatory mechanisms are not identical.
Practical applications: This investigation would be useful in the selective development of functional foods containing DHA-PL or EPA-PL contributing to the prevention and treatment of chronic metabolic disease in humans. The study also showed the chemical compositions of phospholipids fractions of squid (Sthenoteuthis oualaniensis) egg and sea cucumber (Cucumaria frondosa) that may be useful for further studies.