Immunomodulatory activity and protective effect of a capsular polysaccharide in Caenorhabditis elegans, isolated from Lactobacillus fermentum GBJ.

A capsular polysaccharide, namely CPS-2, was isolated from Lactobacillus fermentum GBJ, purified using DEAE-52 anion exchange chromatography, and structurally characterized. We found that CPS-2 is homogenous, has an average molecular weight of 377 KDa, and is mainly composed of galactose and glucose at a molar ratio of 1.54:1.00. Its backbone comprises α-D-Galp-(1 â†’ 3), α-D-Galp-(1 â†’ 3,6), ß-D-Glcp-(1 â†’ 2), ß-D-Galp-(1 â†’ 6), and α-D-Galp-(1 â†’ 4) residues with a side chain of ß-D-Glcp-(1→). CPS-2 exerts an immunomodulatory effect by improving the proliferation and phagocytosis of macrophage RAW264.7 and promoting the secretion of NO and cytokines. The maximum secretion levels of IL-1ß, IL-6, IL-10, and TNF-α were 1.96-, 0.11-, 0.22-, and 0.46-fold higher than those of the control, respectively. Furthermore, CPS-2 could significantly enhance the antioxidant system, extend lifespan, and improve stress tolerance of Caenorhabditis elegans at both exposure doses of 31.25 and 62.5 µg/mL. The average lifespan of nematodes reached a maximum in the 62.5 µg/mL-treated group after 10.39 days, 6.56 h, and 23.56 h in normal, oxidative stress, and heat shock environment, with extension percentages of 16.61 %, 43.23 %, and 15.77 %, respectively; therefore, CPS-2 displays an anti-aging effect. The significant bioactivity of CPS-2 promotes its application as a promising immunomodulatory and anti-aging ingredient in the food or pharmaceutical field.

Active Nrf2 signaling flexibly regulates HO-1 and NQO-1 in hypoxic Gansu Zokor (Eospalax cansus).

Gansu zokor (Eospalax cansus) is a typical subterranean rodent species with resistance to ambient hypoxia. The nuclear factor erythroid 2-related factor 2 (Nrf2) signaling plays a key role in regulating redox homeostasis. However, little is known about the regulation of Nrf2 signaling in Gansu zokor. We exposed Gansu zokors and SD rats to chronic hypoxia (44 h at 10.5% O2) or acute hypoxia (6 h at 6.5% O2) andmeasured the activities of heme oxygenase-1 (HO-1) and NAD(P)H quinone oxidoreductase-1 (NQO-1)，gene expression of HO-1, NQO-1, Nrf2, Kelch-like ECH-associated protein-1 (KEAP1), and ß-transducin repeat-containing protein (ß-TRCP) in the brain and liver. We found that Gansu zokor increased the NQO-1 protein content and activity, HO-1 protein content in the brain, and increased HO-1 activity and mRNA level, NQO-1 activity and protein content in the liver by up regulating Nrf2 gene expression under chronic hypoxia. Although acute hypoxia enhanced the expression of Nrf2 gene, only the level of HO-1 mRNA in the liver increased. Besides, the HO-1 and NQO-1 genes in the brain, HO-1 genes and NQO-1 mRNA in the Gansu zokor liver were significantly higher than those in SD rats under normoxia. Negative regulators of Nrf2 signaling were tissue specific: KEAP1 protein decreased in the brain, and ß-TRCP decreased in the liver. The Nrf2 signaling and expression of downstream antioxidant enzymes were different under different oxygen concentrations, reflecting the flexible characteristics of Gansu zokor to deal with the hypoxic environment.

Effects of in vitro digestion on protein degradation, phenolic compound release, and bioactivity of black bean tempeh.

The nutritional value and bioactivity of black beans are enhanced when fermented as tempeh, but their bioaccessibility and bioactivity after ingestion remain unclear. In this study, black bean tempeh and unfermented black beans were digested in vitro and changes in protein degradation, phenolic compound release, angiotensin I-converting enzyme (ACE)-inhibitory activity, and antioxidant activity between the two groups were compared. We observed that the soluble protein content of digested black bean tempeh was generally significantly higher than that of digested unfermented black beans at the same digestion stage (P < 0.05). The degree of protein hydrolysis and the content of <10 kDa peptides were also significantly higher in the digested black bean tempeh than in digested unfermented black beans (P < 0.05). SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and reversed-phase high-performance liquid chromatography (RP-HPLC) analysis showed that most macromolecular proteins in tempeh had been degraded during fermentation and more of the small peptides were released from black bean tempeh during digestion, respectively. Compared to that of the unfermented black beans, the level of ACE inhibition of black bean tempeh was lower, but this significantly increased to 82.51% following digestion, closing the gap with unfermented black beans. In addition, the total respective levels of phenolics, flavonoids, and proanthocyanidins released from black bean tempeh were 1.21, 1.40, and 1.55 times those of unfermented black beans following in vitro digestion, respectively. Antioxidant activity was also significantly higher in digested black bean tempeh than in digested unfermented black beans and showed a positive correlation with phenolic compound contents (P < 0.05). The results of this study proved that, compared to unfermented black beans, black bean tempeh retained protein and phenolic compound bioaccessibility and antioxidant activity and showed an improved ACE-inhibitory activity even after consumption.