Target cancer drug therapy is an alternative treatment for advanced hepatocellular carcinoma (HCC) patients. However, the treatment using approved targeted drugs has encountered a number of limitations, including the poor pharmacological properties of drugs, therapy efficiency, adverse effects, and drug resistance. As a consequence, the discovery and development of anti-HCC drug structures are therefore still in high demand. Herein, we designed and synthesized a new series of 1,2,3-triazole-cored structures incorporating aryl urea as anti-HepG2 agents. Forty-nine analogs were prepared via nucleophilic addition and copper-catalyzed azide-alkyne cycloaddition (CuAAC) with excellent yields. Significantly, almost all triazole-cored analogs exhibited less cytotoxicity toward normal cells, human embryonal lung fibroblast cell MRC-5, compared to Sorafenib and Doxorubicin. Among them, 2m’ and 2e exhibited the highest selectivity indexes (SI = 14.7 and 12.2), which were ca. 4.4- and 3.7-fold superior to that of Sorafenib (SI = 3.30) and ca. 3.8- and 3.2-fold superior to that of Doxorubicin (SI = 3.83), respectively. Additionally, excellent inhibitory activity against hepatocellular carcinoma HepG2, comparable to Sorafenib, was still maintained. A cell-cycle analysis and apoptosis induction study suggested that 2m’ and 2e likely share a similar mechanism of action to Sorafenib. Furthermore, compounds 2m’ and 2e exhibit appropriate drug-likeness, analyzed by SwissADME. With their excellent anti-HepG2 activity, improved selectivity indexes, and appropriate druggability, the triazole-cored analogs 2m’ and 2e are suggested to be promising candidates for development as targeted cancer agents and drugs used in combination therapy for the treatment of HCC.

The anticancer activity of Euphorbia lactea Haw. (E. lactea) has been observed by our lab and other research groups; however, the identity of the bioactive compounds harboring the anticancer effect remains unknown. Here, we report the first isolation of four triterpenoidal compounds, i.e., friedelin [1], friedelan-3β-ol [2], taraxerol [3], and friedelan-3α-ol [4], from the n-hexane fraction of the E. lactea extract. The cytotoxic activities of these compounds were investigated in several cancer cell lines, including HN22, HepG2, HCT116, and HeLa. These compounds exhibited a dose-dependent cytotoxic activity against HN22, HepG2, and HCT116, while the marginal cytotoxic effect was observed in HeLa cells. Among the four bioactive compounds, compound 2 exhibited the most prominent anticancer effect against HN22 cells. Flow cytometry analysis of HN22 cells treated with the compound revealed that compound 2 induced a cell cycle arrest at the S-phase, while apoptosis was not induced at the same concentration and exposure time. In summary, our results highlighted E. lactea as an attractive candidate for anticancer research and identified compound 2 as a chemical constituent of E. lactea harboring anticancer activity.

Hepatocellular carcinoma (HCC) is a major public health problem and the leading cause of death of people around the world with a tendency to increase every year, leading to a large investigation on the development of HCC drugs. In this work, novel sorafenib derivatives containing 1,2,3-triazole moiety, M1-M5 were designed as potential HCC cancer inhibitors by targeting B-rapidly accelerated fibrosarcoma (B-RAF) and vascular endothelial growth factor receptor 2 (VEGFR-2). The bindings of M1-M5 in the cavity of B-RAF and VEGFR-2, which are kinases related to HCC cell growth, were investigated by molecular docking using iGEMDOCK v2.1 software. The results illustrated that M1-M5 bound in the binding site of B-RAF and VEGFR-2 in a similar manner to sorafenib. It was also found that the 1,2,3-triazole moiety of M1-M5 interacted well by hydrogen bonding with key amino acids in the binding site of B-RAF and VEGFR-2 which could inhibit the cancer cell growth. Although the binding energies of M1-M5 in B-RAF (-148.51 to -126.19 kcal/mol) were rather higher to that of sorafenib (-176.75 kcal/mol), the binding energies of M1-M5 in VEGFR-2 (-127.00 to -116.48 kcal/mol) were comparable to that of sorafenib (-127.03 kcal/mol). As a result, M1-M5 containing 1,2,3-triazole moiety were promising molecules to study in vitro on VEGFR-2 inhibitory assay and be leading compounds for the development as the anticancer drugs against HCC in the future.

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