The in vitro antioxidant activity of water extract from Dictyophora indusiate was evaluated by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, hydroxyl radical and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonate) (ABTS) cation radical scavenging assays. Caenorhabditis elegans was used as a model organism to observe the effects of the extract at high (1.0 mg/mL), medium (0.5 mg/mL) and low (0.25 mg/mL) doses on oxidative and heat stress. In addition, the effects of the extract on fat deposition was analyzed by oil red O staining, and the level of triglyceride (TG) and the expression of fat metabolism-related genes in C. elegans were determined. The results showed that the extract enhanced antioxidant capacity in C. elegans. Its half maximal inhibitory concentrations on DPPH radical, hydroxyl radical and ABTS cation radical were 2.36, 1.44 and 0.86 mg/mL, respectively. The average life span of C. elegans under oxidative and heat stress was prolonged by 54.6% (P < 0.01) and 19.8% (P < 0.05) in the high-dose group, respectively. Compared with the control group, lipid deposition and TG level in the high-dose group decreased by 57.0% (P < 0.01) and 40.5% (P < 0.01), respectively. The mechanism may be that the water extract can down-regulate the regulation of mod-1, daf-1, fat-7, acs-2, daf-16 and mdt-15, up-regulate the expression levels of daf-2, sbp-1, nhr-49, fat-5 and fat-6, thereby improving lipid metabolism. These results show that the water extract of D. indusiate has antioxidant properties and can improve lipid metabolism.

In this study, pancrelipase inhibitory peptides (PES) from an enzymatic protein hydrolysate of Chlorella pyrenoidosa were isolated and purified by ultrafiltration and Sephadex gel chromatography. The in vivo hypolipidemic activity of PES was evaluated by fat deposition and the levels of triglyceride (TG) and total cholesterol (TC) in Caenorhabditis elegans fed a high sugar diet. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to identify the peptide sequence of PES, and molecular docking was used to select potential pancreatic lipase inhibitory peptides, and the pancreatic lipase inhibitory activity of the synthesized peptides was verified. The results showed that PES had good hypolipidemic activity at a concentration of 1 mg/mL; it inhibited lipid deposition by 22.5%, and reduced the levels of TG and TC by 27.4% and 29.4%, respectively. In total, 999 peptides were identified, and four potential lipase inhibitory peptides were obtained. Among them, FLGPF had the best inhibitory effect on pancreatic lipase, with an inhibition rate of 50.12% at 8 mg/mL. The inhibition was reversible and non-competitive, with an inhibition constant of 5.23 mg/mL. Molecular docking showed that FLGPF could better bind to human pancreatic triacylglycerol lipase (PTL) via π-hydrogen, π-cation and hydrogen bond interactions. This study can provide a theoretical reference for the development and utilization of C. pyrenoidosa protein-derived hypolipidemic peptide.