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.

Identification of OLA1 as a Novel Protein Target of Vitexin to Ameliorate Dextran Sulfate Sodium-Induced Colitis with Tissue Thermal Proteome Profiling.

Vitexin, which exists in various medicinal plants and food sources, has recently received increasing attention because of its anti-inflammatory properties. This study aims to identify the protein target of vitexin that ameliorates dextran sulfate sodium (DSS)-induced colitis. The results showed that vitexin not only alleviated the clinical symptoms and colonic damage in mice with DSS-induced colitis but also suppressed the colonic production of inflammatory cytokines (IL-1ß, IL-6, ICAM, and VCAM) and enhanced the expression of barrier-associated proteins (ZO-1, Occludin, and E-cadherin). Based on tissue thermal proteome profiling (Tissue-TPP) and molecular docking, OLA1 was creatively identified as a potential protein target for vitexin. Further siRNA-mediated knockdown of the OLA1 gene in Caco-2 cells demonstrated the ability of OLA1 to increase Nrf2 protein expression and, thus, mediated the anti-inflammatory effects of vitexin. Interaction of the OLA1-vitexin complex with Keap1 protein to disrupt the Keap1-Nrf2 interaction may be required for activating Nrf2. Our findings revealed a novel role for OLA1 as a protein target of vitexin that contributes to its anti-inflammatory action by activating Nrf2, which may provide a promising molecular mechanism for novel therapeutic strategies to treat colitis and the associated systemic inflammation.

Intense pulsed light protects fibroblasts against the senescence induced by 8-methoxypsoralen plus ultraviolet-A irradiation.

OBJECTIVE: The purpose of this study was to evaluate the influence of intense pulsed light (IPL) irradiation on 8-methoxypsoralen plus ultraviolet-A irradiation (PUVA)-induced senescence of fibroblasts in vitro. BACKGROUND DATA: Exposure to PUVA may result in stress-induced senescence in fibroblasts. IPL has been widely used to treat photo-aged skin, but the mechanism is not clear. METHODS: The expression of senescence-associated ß-galactosidase (SA-ß-gal) was determined by histochemical staining, cell viability was assessed via an MTT assay, telomere length was determined by real-time polymerase chain reaction (PCR), and changes in the generation of reactive oxygen species (ROS) were determined by flow cytometry (FCM). RESULTS: In comparison with the control cells, cells irradiated with PUVA and PUVA+IPL showed a general elevation in SA-ß-gal activity (p<0.05). The number of SA-ß-gal-positive fibroblasts in the PUVA+IPL group was clearly lower than that in the PUVA group (p<0.05). Cell viability showed a time-dependent decrease in both the PUVA and PUVA+IPL groups, in comparison with the viability in the control group, and there was no difference in viability between the PUVA and PUVA+IPL groups. PUVA treatment shortened telomere length and increased the level of ROS, in comparison with the corresponding findings for the control cells (p<0.05), whereas irradiation with IPL after PUVA exposure prevented telomere shortening and decreased the ROS level, in comparison with PUVA treatment only (p<0.05). CONCLUSIONS: PUVA treatment induced fibroblast senescence, and irradiation with IPL after PUVA exposure partially rejuvenated the cells, demonstrating a protective effect against PUVA-induced fibroblast senescence.