A series of N‐(5‐(alkylthio)‐1,3,4‐oxadiazol‐2‐yl)methyl)benzamides 6a–i were synthesized as alkaline phosphatase inhibitors. The intermediate 5‐substituted 1,3,4‐oxadiazole‐2‐thione 4 was synthesized starting with hippuric acid. Hippuric acid in the first step was converted into corresponding methyl ester 2 which upon reaction with hydrazine hydrate furnished the formation of hydrazide 3. The hippuric acid hydrazide was then cyclized into 5‐substituted 1,3,4‐oxadiazole‐2‐thione 4. The intermediate 4 was then reacted with alkyl or aryl halides 5a–5i to afford the title compounds N‐(5‐(methylthio)‐1,3,4‐oxadiazol‐2‐yl)methyl)benzamides 6a–i. The bioassay results showed that compounds 6a–i exhibited good to excellent alkaline phosphatase inhibitory activity. The most potent activity was exhibited by the compound 6i having IC₅₀ value 0.420 μM, whereas IC₅₀ value of standard (KH₂PO₄) was 2.80 μM. Molecular docking studies was performed against alkaline phosphatase enzyme (PDBID 1EW2) to check binding affinity of the synthesized compounds 6a–i against target protein. The docking results showed that three compounds 6c, 6e, and 6i have maximum binding interactions with binding energy values of −8 kcal/mol. The compound 6i displayed the interactions of oxadiazole ring nitrogen with amino acid His265 having a binding distance 2.13 Ǻ. It was concluded from our results that synthesized compounds, especially compound 6i may serve as lead structure to design more potent inhibitors of human alkaline phosphatase.

中文翻译：

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N-（5-（烷硫基）-1,3,4-恶二唑-2-基）甲基）苯甲酰胺类似物作为潜在的碱性磷酸酶抑制剂的合成和对接研究。

合成了一系列N-（5-（烷硫基）-1,3,4-恶二唑-2-基）甲基）苯甲酰胺6a-i作为碱性磷酸酶抑制剂。中间体5-取代的1,3,4-恶二唑-2-硫酮4是从马尿酸开始合成的。将第一步中的马尿酸转化为相应的甲酯2，其与水合肼反应后形成酰肼3。然后将马尿酸酰肼环化为5-取代的1,3,4-恶二唑-2-硫酮4。然后将中间体4与烷基或芳基卤化物5a-5i反应，得到标题化合物N-（5-（甲硫基）-1,3,4-恶二唑-2-基）甲基）苯甲酰胺6a–i。生物测定结果表明，化合物6a–i表现出良好至优异的碱性磷酸酶抑制活性。具有IC ₅₀值为0.420μM的化合物6i表现出最有效的活性，而标准品（KH ₂ PO ₄）的IC ₅₀值为2.80μM。针对碱性磷酸酶（PDBID 1EW2）进行了分子对接研究，以检查合成的化合物6a-1对靶蛋白的结合亲和力。对接结果显示三种化合物6c，6e和6i具有最大的结合相互作用，结合能值为-8 kcal / mol。化合物6i显示了恶二唑环氮与结合距离为2.13Ǻ的氨基酸His265的相互作用。从我们的结果可以得出结论，合成的化合物，尤其是化合物6i可以充当先导结构，以设计更有效的人碱性磷酸酶抑制剂。