The genes GLB1 and GALC encode GLB1 isoform 1 and galactocerebrosidase, respectively, which exhibit β-galactosidase activity in human lysosomes. GLB1 isoform 1 has been reported to play roles in rare lysosomal storage diseases. Further, its β-galactosidase activity is the most widely used biomarker of senescent and aging cells; hence, it is called senescence-associated β-galactosidase. Galactocerebrosidase plays roles in Krabbe disease. We previously reported a novel β-galactosidase activity in the Golgi apparatus of human cells; however, the protein responsible for this activity could not be identified. Inhibitor-derived chemical probes can serve as powerful tools to identify the responsible protein. In this study, we first constructed a cell-based high-throughput screening (HTS) system for Golgi β-galactosidase inhibitors, and then screened inhibitors from two compound libraries using the HTS system, in vitro assay, and cytotoxicity assay. An isoflavone derivative was identified among the final Golgi β-galactosidase inhibitor compound hits. Molecular docking simulations were performed to redesign the isoflavone derivative into a more potent inhibitor, and six designed derivatives were then synthesized. One of the derivatives, ARM07, exhibited potent inhibitory activity against β-galactosidase, with an IC₅₀ value of 14.8 µM and competitive inhibition with K_i value of 13.3 µM. Furthermore, the in vitro and cellular inhibitory activities of ARM07 exceeded those of deoxygalactonojirimycin. ARM07 may contribute to the development of affinity-based chemical probes to identify the protein responsible for the newly discovered Golgi β-galactosidase activity. The therapeutic relevance of ARM07 against lysosomal storage diseases and its effect on senescent cells should be evaluated further.

基因GLB1和GALC分别编码GLB1同工型1和半乳糖脑苷脂酶，它们在人溶酶体中表现出β-半乳糖苷酶活性。已报道GLB1同工型1在罕见的溶酶体贮积病中起作用。此外，其β-半乳糖苷酶活性是衰老和衰老细胞中使用最广泛的生物标记。因此，它被称为衰老相关的β-半乳糖苷酶。半乳糖脑苷脂酶在克拉伯病中起作用。我们之前曾报道过人类细胞的高尔基体中有一种新型的β-半乳糖苷酶活性。然而，无法鉴定出负责此活性的蛋白质。抑制剂衍生的化学探针可以用作识别负责蛋白质的强大工具。在这项研究中，我们首先为高尔基β-半乳糖苷酶抑制剂构建了基于细胞的高通量筛选（HTS）系统，体外测定和细胞毒性测定。在最终的高尔基体β-半乳糖苷酶抑制剂化合物中发现了异黄酮衍生物。进行分子对接模拟以将异黄酮衍生物重新设计为更有效的抑制剂，然后合成了六种设计的衍生物。衍生物之一ARM07对β-半乳糖苷酶表现出有效的抑制活性，IC ₅₀值为14.8 µM，竞争性抑制作用的K _i值为13.3 µM。此外，体外并且ARM07的细胞抑制活性超过了脱氧半乳糖苷。ARM07可能有助于开发基于亲和力的化学探针，以鉴定负责新发现的高尔基β-半乳糖苷酶活性的蛋白质。应进一步评估ARM07对溶酶体贮积病的治疗意义及其对衰老细胞的作用。