Lactiplantibacillus plantarum fermented barley extracts ameliorate high-fat-diet-induced muscle dysfunction via mitophagy

Heterologous expression and enzymatic characteristics of sulfatase from Lactobacillus plantarum dy-1

Barley, rich in bioactive components including dietary fiber, polyphenolic compounds and functional proteins, exhibits health benefits such as regulating glucose and lipid metabolism. Previous studies have found that the content and composition of free phenolic acids in barley may be significantly changed by fermentation with the laboratory patented strain Lactobacillus plantarum dy-1 (L. p dy-1), but the mechanism of enzymatic release of phenolic acid remains to be elucidated. Based on this, this study aimed to identify the key enzyme in L. p dy-1 responsible for releasing the bound phenolic acid and to further analyze its enzymatic properties. The Carbohydrate-Active enZYmes database revealed that L. p dy-1 encodes 7 types of auxiliary enzymes, among which we have identified a membrane sulfatase. The enzyme gene LPMS05445 was heterologous to that expressed in E. coli, and a recombinant strain was induced to produce the target protein and purified. The molecular weight of the purified enzyme was about 59.9 kDa, with 578.21 U mg-1 enzyme activity. The optimal temperature and pH for LPMS05445 expression were 40 °C and 7.0, respectively. Furthermore, enzymatic hydrolysis by LPMS05445 can obviously change the surface microstructure of dietary fiber from barley bran and enhance the release of bound phenolic acid, thereby increasing the free phenolic acid content and improving its physiological function. In conclusion, sulfatase produced by Lactobacillus plantarum dy-1 plays a key role in releasing bound phenolic acids during the fermentation of barley.

Identification, characterization and hypolipidemic effect of novel peptides in protein hydrolysate from Protaetia brevitarsis larvae

The proteins were mainly derived from Protaetia brevitarsis larval extracts obtained using two empty intestine methods (traditional static method: TSM or salt immersion stress method: SISM) and extraction solvents (water: W or 50 % water-ethanol: W:E), and the proteins were used as objects to investigate the effect of emptying intestine methods on hypolipidemic peptides. The results revealed that the F-2 fractions of protein hydrolysate had stronger in vitro hypolipidemic activity, with the peptides obtained by SISM possessing a stronger cholesterol micelle solubility inhibition rate, especially in SISM-W:E-P. Moreover, a total of 106 peptides were tentatively identified, among which SISM identified more peptides with an amino acid number < 8. Meanwhile, five novel peptides (YPPFH, YPGFGK, KYPF, SPLPGPR and VPPP) exhibited good hypolipidemic activity in vitro and in vivo, among which YPPFH, VPPP and KYPF had strong inhibitory activities on pancreatic lipase (PL) and cholesteryl esterase (CE), and KYPF, SPLPGPR and VPPP could significantly reduce the TG content in Caenorhabditis elegans. Thus, P. brevitarsis can be developed as a naturally derived hypolipidemic component for the development and application in functional foods.

Responses of bitter melon saponins to oxidative stress and aging via the IIS pathway linked with sir-2.1 and hlh-30

Saponins from bitter melon (BMS) exert potential bioactivities and pharmacological activities, including anti-oxidation and lifespan extension. However, the exact mechanisms of BMS in response to oxidative stress remain unknown. Results demonstrated that bitter melon saponins could strengthen locomotive activities (body bend and head thrashing) accompanied by delaying the muscle fiber damage with age in Caenorhabditis elegans. In addition, BMS inhibited the ROS accumulation, improved the activities of antioxidant enzymes like SOD (by 57.90% and 94.34% for 100 μg/ml and 200 μg/ml BMS, respectively) and CAT (by 51.45% and 56.91% for 100 μg/ml and 200 μg/ml BMS, respectively), and extend the lifespan of N2 and CL2006 worms under paraquat-induced oxidative stress. Mechanism study suggested that BMS modulated the mRNA expressions of oxidation-related regulators, like the upregulation of cat-1, hsf-1, sir-2.1, and hlh-30. Furthermore, gene-deficient mutants verified that IIS (insulin/insulin-like growth factor-1 signaling) pathway linked with sir-2.1 and hlh-30 factors were involved in the BMS's lifespan-extension effects under oxidative stress. In general, this study supplemented the explanation of BMS in promoting oxidation-resistance and lifespan-extension activities, which could be served as a potential candidate for anti-aging. PRACTICAL APPLICATIONS: Our previous studies have suggested that saponins from bitter melon exhibited fat-lowering activity in C. elegans. However, little was known about the mechanism underlying the anti-oxidation effects of BMS in C. elegans. Current results indicated that the IIS pathway linked with sir-2.1 and hlh-30 transcriptional factors jointly to increase the lifespan in BMS' responses to oxidative stress. Our findings are beneficial to understand the main nutritional ingredients in bitter melon, which are ideal and expected in functional foods for aging.