Catfish bone collagen peptide-calcium (F₃-Ca) chelatate, which had been prepared in our laboratory, was evaluated for its effect on calcium transport and absorption using a Caco-2 cell model. Its effect on the alkaline phosphatase (ALP) activity of osteoblast hFoB1.19 and the expression of the key genes and proteins involved in osteoblast differentiation was also investigated. The results indicated that the chelate increased calcium transport in Caco-2 cells to 0.31 mg/mL, and promoted the mineralization of osteoblasts. The chelate at a concentration of 100 μg/mL increased the ALP activity of osteoblasts by 53.68% compared with the control group. Reverse transcription-polymerase chain reaction (RTPCR) and protein immunoblot analysis showed that F₃-Ca chelate increased the gene and protein expression levels of osteoprotegerin (OPG), osteocalcin (OCN) and Runt-related transcription factor 2 (RUNX2) in osteoblasts, reduced those of receptor activator for nuclear factor-κB ligand (RANKL), and increase the ratio of OPG/RANKL, thus activating the OPG/RANKL/receptor activator for nuclear factor-κB (RANK) signaling pathway, promoting the proliferation, differentiation and mineralization of osteoblasts, and ultimately resulting in enhanced calcium absorption and anti-osteoporosis activity. This study provides a scientific basis for the high-value utilization of catfish bone and the development of new calcium supplements.

To elucidate the differences in the antioxidant and antidiabetic activities of different phenolic fractions from Rubus chingii Hu, aqueous-soluble, alcohol-soluble, free and bound polyphenols from the fruits of R. chingii Hu were extracted using different solvents and methods. The difference in the contents of total phenolic compounds, total flavonoids, and hydrolyzable tannins in the different extracts were compared, and the radical scavenging, α-glucosidase inhibitory and antiglycation activity of the extracts were determined. The major chemical components in the extract with the highest activity were determined using mass spectrometry (MS). The results indicated that the alcohol-soluble polyphenol-rich extract had the highest contents of total phenols and hydrolysable tannins (414.95 μg/mg and 182.47 μg/mg (expressed as gallic acid equivalent in per milligram of extract), respectively). Meanwhile, it also presented the strongest ability to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and 2,2’-azino-bis (3-ethylbenzothiazoline-6-sulfonate) (ABTS) cation radical and to inhibit α-glucosidase activity with half maximal inhibitory concentration (IC₅₀) values of 40.68, 23.90 μg/mL and 1.65 μg/mL, respectively. But the highest total flavonoid content and antiglycation activity were observed in the bound polyphenol-rich extract. Totally, 31 compounds were tentatively identified from the bound polyphenol-rich extract, and tannins and flavonoids were the major bioactive constituents. Therefore, the R. chingii Hu residues left after the extraction of free polyphenols and aqueous-soluble constituents can be further utilized to develop bioactive constituents with high antioxidant and antidiabetic activities.

Tannin is the major active ingredient of the dried unripe fruits of Chinese raspberry (Rubus chingii Hu), Fupenzi in Chinese, and has the functions of lowering blood sugar, reducing blood lipid, resisting inflammation, delaying aging and preventing cardiovascular and cerebrovascular diseases. In this study, a tannin-enriched fraction was prepared from Fupenzi, and the changes in its tannin content, antioxidant activity and α-glucosidase inhibitory activity before and after in vitro simulated digestion were investigated. Its regulatory effect on the intestinal microflora was analyzed by in vitro anaerobic fermentation. Finally, ultra-high performance liquid chromatography-quadrupole time of flight-tandem mass spectrometry (UPLC-ESI-QTOF-MS/MS) was used to compare the changes in the contents of tannin and its metabolite after in vitro digestion and fermentation. The results showed that the content of hydrolyzed tannin increased first and then decreased during both gastric and intestinal digestion. Gastrointestinal digestion increased 1,1-dipheny1-2-picryl-hydrazyl (DPPH) radical scavenging capacity of the tannin-enriched fraction, with half-maximal inhibitory concentration (IC₅₀) values ranging from 29.15 to 39.65 µg/mL, but had no significant effect on 2,2’-azino-bis(3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS) cation radical scavenging capacity (P > 0.05). In addition, after simulated intestinal digestion, the α-glucosidase inhibitory activity increased by 7.16–7.86 times. In vitro colonic fermentation experiments showed that tannin-enriched fraction significantly increased the relative abundance of beneficial bacteria such as Coprococcus, Anaerostipes, Ruminococcus and Faecalibaterium. Simulated gastrointestinal digestion reduced its effect in improving beneficial bacteria such as bifidobacteria. UPLC-ESI-QTOF-MS/MS analysis showed that the content of tannin metabolites decreased first and then increased during gastrointestinal digestion; the contents of urolithin A and urolithin B decreased significantly after colon fermentation, and neither urolithin C nor urolithin D was detected. Therefore, this study provides a theoretical basis for the establishment of stable tannin delivery system to improve its bioavailability.

Ulcerative colitis is a chronic inflammatory bowel disease with unclear pathogenesis, and its incidence is increasing gradually. Recently, with the popularization of the concept of healthy diet, reducing the risk of ulcerative colitis through dietary intervention has become increasingly popular. In this paper, we report on the protective effect of Gallus gallus domesticlus Brisson peptides on dextran sodium sulfate (DSS)-induced ulcerative colitis in mice. For this purpose, we measured changes in body mass, disease activity index (DAI), colon length, hematoxylin-eosin (HE) stained colon sections, the levels of pro-inflammatory cytokines such as interleulin-6 (IL-6), IL-10, IL-1β and tumor necrosis factor-α (TNF-α), intestinal microbial community composition and the levels of short-chain fatty acids in cecal contents. The results indicated that G. gallus domesticlus Brisson peptides significantly alleviated the symptoms of ulcerative colitis such as body mass loss, hematochezia, diarrhea, and the shortening of colon length and colon tissue injury in mice, and significantly decreased the levels of TNF-α, IL-1β and IL-6. In addition, G. gallus domesticlus Brisson peptides alleviated intestinal microflora disturbance induced by DSS, down-regulated the relative abundance of Shigella and Clostridiaceae_Clostridium, increased the relative abundance of Akkermansia, Ruminococcus and Oscillospira, and significantly increased the contents of acetic acid, propionic acid and butyric acid in cecal contents, thereby alleviating colon inflammation induced by DSS in mice.

In this study, the effect of quercetin-3-O-β-D-glucuronide (Q3G) on the formation of fructosamine and 5-hydroxymethylfurfural (5-HMF), the amount of free amino groups and browning degree in a non-enzymatic glycosylation model consisting of bovine α-lactalbumin (α-La) and fructose were evaluated. In addition, the inhibitory mechanism of Q3G against non-enzymatic glycosylation was explored by molecular docking and mass spectrometry (MS). The results indicated that Q3G could significantly reduce the browning degree, increase the free amino groups, inhibit the formation of fructosamine and 5-HMF, and delay the process of glycosylation reaction. The effect was most pronounced at 2 mmol/L Q3G. Molecular docking analysis indicated that Q3G could bind with the active amino acid residues of α-La through hydrogen bonds, van der Waals force and hydrophobic interactions, delaying the process of glycosylation reaction. Meanwhile, by ultra-high performance liquid chromatography-quadrupole-orbitrap tandem mass spectrometry (UPLC-Q-Orbitrap MS/MS) analysis, it was found that Q3G shielded the potential glycosylation sites Lys93 and Lys108, and the activity of the glycosylation site Lys98 was weak, indicating inhibited non-enzymatic glycosylation reaction. This study can provide a theoretical basis for the development of Q3G as a potential anti-glycosylation agent.

Effect of ellagitannins gut microbiota metabolites ellagic acid (EA) and urolithin A-urolithin D (UroA-UroD) on human serum albumin (HSA) glycation were firstly evaluated in this research. The inhibition mechanisms were investigated by methylglyoxal (MGO) trapping and radical scavenging ability assays, docking studies and nano LC-orbitrap-MS/MS technology. Results indicated that the inhibition of urolithins on HSA glycation was highly positive correlated with the number of phenolic hydroxy groups. Addition of UroD and EA could effectively enhance the content of free amino group, suppress dicarbonyl compounds and advanced glycation end-products (AGEs) formation, alleviated tryptophan and protein oxidation, inhibited HSA amyloid-like aggregation. They could also trap MGO and scavenge 1,1-diphenyl-2-picrylhydrazyl free radical (DPPH·) and 2,2’-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid free radical (ABTS⁺·). Molecular docking indicated that EA and UroA-UroD interact with HSA mainly through hydrogen bound and hydrophobic interaction, among which 2 or 3 hydrogen bonds were formed. The number of glycation sites were reduced from 11 to 10, 10, 7, and 10, respectively, when 90 μmol/L of EA, UroA, UroC and UroD were added. However, weak inhibition was observed on UroA and UroB. These findings can provide scientific evidence for the application of ellagitannins-rich foods in alleviating diabetic complications.

Frozen storage is a prevalent technique for maintaining the freshness of fish. However, fish quality is susceptible to decline throughout the freezing period, substantially impacting its flavor and nutritive content. Hence, this article examines the mechanisms behind the quality degradation and the control strategies employed to preserve fish during frozen storage. Firstly, the formation of ice crystals and the reasons for the decline of fish meat quality were clarified. Secondly, the factors that may lead to quality deterioration during frozen storage were analyzed, including protein denaturation, fat oxidation and enzymatic reaction. Furthermore, the novel freezing control technologies for the deterioration of fish frozen storage quality were reviewed, including the technology of adjusting the nucleation, growth behavior, and recrystallization of ice crystals, and the technology of improving the freezing rate. Finally, the development direction of the research on the deterioration of frozen fish quality in the future was prospected, and novel technologies and methods to improve the quality of frozen fish were pointed out, which is expected to lay a foundation for higher quality frozen fish meat in the future.

The unripe palmleaf raspberry, namely Fupenzi (FPZ), is an important medicinal and edible food. This study aims to evaluate the potential of FPZ extracts prepared with different approaches in attenuating hyperglycemia, gout, Alzheimer's disease, and pigmentation, to obtain the enriching fraction and to identify the major active compounds. Results indicated that FPZ extracts showed weak activity against acetylcholinesterase, considerable ability against tyrosinase and xanthine oxidase, but excellent inhibition on α-glucosidase. Ultrasound-assisted 40 % ethanol extract (40EUS) gave the highest phenolics content, and the best α-glucosidase inhibition (IC₅₀ = 0.08 μg/mL), which is 877-fold higher than that of positive control acarbose. The 40 % ethanol eluting fraction of 40EUS showed the strongest a-glucosidase inhibition with the IC₅₀ value of 37.79 ng/mL, it could also effectively attenuate the fasting blood glucose level and oral glucose tolerance of C57BL/6 mice. Twenty-six compounds were identified from 40 % ethanol fraction by using HPLC-QTOF-MS/MS, hydrolysable tannins (including 11 ellagitannins and 4 gallotannins) were the major compounds, phenolic acids came to the second. Above results could provide important technical supporting for the further application and research of FPZ in health foods and drugs against diabetes.