Calcium bioaccessibility as affected by strontium. Temperature effect on citrate binding to strontium and calcium alone and in combination

Xiao-Chen Liu, Ruixia Chen, Weizheng Sun*, Leif H. Skibsted*

*Corresponding author af dette arbejde

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Abstract

Strontium as a bone health promoter was found to increase the bioaccessibility of essential calcium from solid calcium citrate tetrahydrate in aqueous suspensions. This is unexpected since calcium citrate binds calcium stronger than strontium with ΔH0ass,c = 5.07 kJ⋅mol−1, ΔS0ass,c = 78.0 J⋅mol−1⋅K−1 for 1:1 Ca-Citrate complex formation and ΔH0ass,c = 1.67 kJ⋅mol−1, ΔS0ass,c = 58.3 J⋅mol−1⋅K−1 for 1:1 Sr-Citrate complex formation as determined both electrochemically and by isothermal titration calorimetry. Calcium citrate tetrahydrate has reverse solubility around physiological temperature in contrast to strontium citrate pentahydrate. This difference results in opposite effect of strontium upon calcium ion liberation from calcium citrate suspensions at both low and high temperature compared to physiological temperature, for which strontium was found to stabilize solid calcium citrate tetrahydrate. This effect, confirmed by quantum mechanical calculation and by comparison of spontaneous aqueous supersaturation of calcium citrate and strontium citrate, is suggested to be involved in the positive effect of strontium on bone and teeth health. The conclusions provide a theoretical foundation for the research of molecular mechanisms among calcium, strontium, and citrate ions in relation to bone and teeth health.

OriginalsprogEngelsk
Artikelnummer123961
TidsskriftJournal of Molecular Liquids
Vol/bind396
Antal sider9
ISSN0167-7322
DOI
StatusUdgivet - 2024

Bibliografisk note

Funding Information:
This work was supported by the National Natural Science Foundation of China (32172257), the Science and Technology Program of Qingyuan (2022KJJH018, 2021SJXM032), and the China Scholarship Council [CSC, No. 201806360266].

Publisher Copyright:
© 2024 The Author(s)

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