Dietrich Jaume, Costa-Bauza Antònia, Grases Félix
Renal Lithiasis and Pathological Calcification Group, Research Institute of Health Sciences (IUNICS), University of the Balearic Islands, 07122 Palma, Spain.
Health Research Institute of the Balearic Islands (IdISBa), 07010 Palma, Spain.
Biomolecules. 2025 Aug 7;15(8):1141. doi: 10.3390/biom15081141.
Thermodynamic factors (supersaturation of substances that form crystals) and kinetic factors (heterogeneous nucleants and crystallization inhibitors) affect the formation of crystals and stones in the urinary tract. We studied the effect of five different polyhydroxycarboxylic acids and phytate on the formation of calcium oxalate crystals in artificial urine. All tested molecules are known to inhibit the crystallization of this calcium salt, and to also form complexes with calcium ions. Considering the typical concentration of polyhydroxycarboxylic acids in urine (similar to that of the calcium ion) and their ability to inhibit crystallization, their most important effect is the capacity to complex calcium-a thermodynamic effect. For phytate and its metabolites, which are present in concentrations much lower than that of the calcium ion, the most important effect is as a crystallization inhibitor-a kinetic effect. Among the five polyhydroxycarboxylic acids examined here, hydroxycitrate had the strongest complexing capacity, and the addition of phytate to hydroxycitrate led to greater inhibition of crystallization. Therefore, because oral consumption of hydroxycitrate does not increase the urinary pH, it is likely that the combined consumption of hydroxycitrate and phytate can provide certain benefits for patients with increased risk of developing calcium oxalate stones. We also discussed the effects of these different molecules on the different calcium oxalate stones, including papillary calcium oxalate monohydrate stones, cavity calcium oxalate monohydrate stones, calcium oxalate dihydrate stones, and mixed calcium oxalate dihydrate/hydroxyapatite stones.
热力学因素（形成晶体的物质的过饱和度）和动力学因素（异质成核剂和结晶抑制剂）会影响尿路中晶体和结石的形成。我们研究了五种不同的多羟基羧酸和植酸对人工尿液中草酸钙晶体形成的影响。所有测试的分子都已知能抑制这种钙盐的结晶，并且还能与钙离子形成络合物。考虑到尿液中多羟基羧酸的典型浓度（与钙离子浓度相似）及其抑制结晶的能力，它们最重要的作用是络合钙的能力——一种热力学效应。对于植酸及其代谢产物，其浓度远低于钙离子浓度，最重要的作用是作为结晶抑制剂——一种动力学效应。在这里研究的五种多羟基羧酸中，羟基柠檬酸盐具有最强的络合能力，并且向羟基柠檬酸盐中添加植酸会导致对结晶的更大抑制。因此，由于口服羟基柠檬酸盐不会增加尿液pH值，羟基柠檬酸盐和植酸的联合摄入可能会为患草酸钙结石风险增加的患者带来一定益处。我们还讨论了这些不同分子对不同草酸钙结石的影响，包括乳头状一水合草酸钙结石、空洞状一水合草酸钙结石、二水合草酸钙结石以及混合的二水合草酸钙/羟基磷灰石结石。
