Structural characterization and calcium absorption-promoting effect of sucrose-calcium chelate in Caco-2 monolayer cells and mice.

Sucrose emerges as a chelating agent to form a stable sucrose-metal-ion chelate that can potentially improve metal-ion absorption. This study aimed to analyze the structure of sucrose-calcium chelate and its potential to promote calcium absorption in both Caco-2 monolayer cells and mice. The characterization results showed that calcium ions mainly chelated with hydroxyl groups in sucrose to produce sucrose-calcium chelate, altering the crystal structure of sucrose (forming polymer particles) and improving its thermal stability. Sucrose-calcium chelate dose dependently increased the amount of calcium uptake, retention, and transport in the Caco-2 monolayer cell model. Compared to CaCl2 , there was a significant improvement in the proportion of absorbed calcium utilized for transport but not retention (93.13 ± 1.75% vs. 67.67 ± 7.55%). Further treatment of calcium channel inhibitors demonstrated the active transport of sucrose-calcium chelate through Cav1.3. Cellular thermal shift assay and quantitative reverse transcription-polymerase chain reaction (qRT-PCR) assays indicated that the ability of sucrose-calcium chelate to promote calcium transport was attributed to its superior ability to bind with PMCA1b, a calcium transporter located on the basement membrane, and stimulate its gene expression compared to CaCl2 . Pharmacokinetic analysis of mice confirmed the calcium absorption-promoting effect of sucrose-calcium chelate, as evident by the higher serum calcium level (44.12 ± 1.90 mg/L vs. 37.42 ± 1.88 mmol/L) and intestinal PMCA1b gene expression than CaCl2 . These findings offer a new understanding of how sucrose-calcium chelate enhances intestinal calcium absorption and could be used as an ingredient in functional foods to treat calcium deficiency. PRACTICAL APPLICATION: The development of high-quality calcium supplements is crucial for addressing the various adverse symptoms associated with calcium deficiency. This study aimed to prepare a sucrose-calcium chelate and analyze its structure, as well as its potential to enhance calcium absorption in Caco-2 monolayer cells and mice. The results demonstrated that the sucrose-calcium chelate effectively promoted calcium absorption. Notably, its ability to enhance calcium transport was linked to its strong binding with PMCA1b, a calcium transporter located on the basement membrane, and its capacity to stimulate PMCA1b gene expression. These findings contribute to a deeper understanding of how the sucrose-calcium chelate enhances intestinal calcium absorption and suggest its potential use as an ingredient in functional foods for treating calcium deficiency.

Effects of Different Sources of Calcium in the Diet on Growth Performance, Blood Metabolic Parameters, and Intestinal Bacterial Community and Function of Weaned Piglets.

Despite a well-documented effect of calcium on the piglet's intestinal microbiota composition, it is less known about changes in microbial function or the effect of different sources of calcium. The experiment was designed to study the effects of dietary calcium from different sources on production, immune indexes, antioxidant capacity, serum biochemical indexes, and intestinal microflora of weaning piglets. A total of 1,000 piglets were randomly assigned to five groups (10 replicate pens per treatment with 20 pigs per pen) and fed diets supplemented with calcium carbonate, calcium citrate, multiple calcium, organic trace minerals, and different concentrations of acidifier. The results showed that the replacement of calcium carbonate with calcium citrate and multiple calcium had almost no significant difference in the growth performance of pigs compared with the control group, and only the diet of multiple calcium dramatically decreased the average daily feed intake (ADFI) compared to the calcium citrate diet on days 15-28 (p < 0.05). The five groups did not change the content of MDA, SOD, and GSH-Px (p > 0.10). A similar situation occurs in the immune function of the blood. There was no significant effect in immune indexes (IgA, IgG, and IgM) among different treatments after weaning at 6 weeks for piglets (p > 0.10). The 16S rRNA sequencing of ileal and cecal microbiota revealed that only the relative abundance of Actinobacteriota at the phyla level was significantly greater in the ileum of the A group compared to the other treatments (p < 0.05). There was a clear effect on seven bacteria in the top 30 genera of ileum and cecum for five groups (p < 0.05). The result of PICRUSt predicted that the intestinal microbe was mainly involved in carbohydrate and amino acid metabolism, membrane transport, and metabolism of cofactors and vitamins. Besides, adding calcium citrate to a weaned piglet diet is better than other choices from the third week to the fourth week. In conclusion, diets with different calcium sources changed ADFI and some intestinal microbial composition of weaned piglets but had little effect on intestinal microbial function.

Daptomycin and AgNP co-loaded rGO nanocomposites for specific treatment of Gram-positive bacterial infection in vitro and in vivo.

In order to improve the stability of AgNPs and decrease the dosage of Daptomycin for killing bacteria, a reduced graphene oxide (rGO) was used for simultaneously anchoring AgNPs and Daptomycin to prepare rGO@Ag@Dap nanocomposites. In vitro experiments showed that the nanocomposites can efficiently kill four kinds of pathogenic bacteria, especially two kinds of Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis) through damaging cell integrity, producing ROS, decreasing ATP and GSH and disrupting bacterial metabolism. Against Gram-positive bacteria, the rGO@Ag@Dap nanocomposites showed a cooperative antibacterial effect. Moreover, in vivo experiments showed that rGO@Ag@Dap can improve the healing of wounds infected with bacteria by efficiently killing the bacteria on the wounds and further promoting skin regeneration and dense collagen deposition. In summary, the above results suggest that the cooperative function of AgNPs with Daptomycin can significantly improve antibacterial efficiency against infectious diseases caused by bacteria, especially for therapies made ineffective due to the drug resistance of pathogenic bacteria.