Calcitroic acid was isolated and characterized almost four decades ago, but little is known about this important vitamin D metabolite. Four reported synthetic strategies to generate calcitroic acid are presented that highlight the scientific progress in the field of chemistry directed to vitamin D analog synthesis. The most recent synthesis described the generation of calcitroic acid with an overall yield of 12.8% in 13 steps. The endogenous formation of calcitroic acid has been demonstrated in perfused rat kidney using 24,25,26,27-tetranor-1,23(OH)₂D₃. Although, the majority of vitamin D metabolism is mediated by 24-hydoxylase (CYP24A1), it is not clear why the formation of calcitroic acid was not observed in the presence of recombinant CYP24A1 enzyme. Furthermore, it is not known if enzyme 1α-hydroxylase (CYP27B1) can convert calcioic acid into calcitroic acid. In addition to the lack of research investigating the endogenous formation of calcitroic acid, the physiological role of calcitroic acid remains unknown. Only a few reports mentioned the biological activity of calcitroic acid in connection with the vitamin D receptor (VDR). When administered subcutaneously, calcitroic acid has anthracitic properties and elevates calcium blood levels when administered intravenously. In vitro, calcitroic acid at higher concentrations has been shown to bind VDR and induce gene transcription. However, these studies were not carried out in cells derived from target organs of calcitroic acid such as kidney, liver, and intestine. We can conclude that our current knowledge of calcitroic acid is limited, and more studies are needed to identify its physiological role.

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钙柠檬酸–综述

钙酸是在大约四十年前分离并鉴定的，但对这种重要的维生素D代谢物知之甚少。提出了四种报道的生成钙柠檬酸的合成策略，这些策略突出了针对维生素D类似物合成的化学领域的科学进展。最新的合成方法描述了生成十三碳三酸的总产率为12.8％。在使用24,25,26,27-tetranor-1,23（OH）₂ D ₃灌注的大鼠肾脏中已证明了钙磷的内源性形成。尽管大多数维生素D代谢是由24-羟化酶（CYP24A1）介导的，但尚不清楚为什么在重组CYP24A1存在的情况下未观察到钙柠檬酸的形成酶。此外，还不清楚酶1α-羟化酶（CYP27B1）是否能够将钙碘酸转化为钙柠檬酸。除了缺乏研究钙柠檬酸的内源性形成的研究外，钙柠檬酸的生理作用仍然未知。只有少数报告提到钙维甲酸与维生素D受体（VDR）的生物学活性。皮下注射时，钙柠檬酸具有无烟特性，静脉内注射时钙血水平升高。体外已经显示，较高浓度的钙柠檬酸结合VDR并诱导基因转录。但是，这些研究未在源自钙柠檬酸靶器官（例如肾脏，肝脏和肠）的细胞中进行。我们可以得出结论，我们目前对降钙酸的了解是有限的，需要更多的研究来确定其生理作用。