Design, Synthesis And Biological Evaluation Of Novel 1,2,4-triazole Derivatives As Tubulin

Microtubules, a polar cytoskeleton, exsit in eukaryocytes, and consist of many tubulin subunits. With other proteins, microtubules can form spindle, centrosome and other organelles. Therefore, they are of great significance in keeping cell morphology and ensuring the normal life activities of cells. As is well known, the main difference between tumor and normal cells is that tumor cells is able to split without restrictions and the mitosis of cells must rely on spindles composed with microtubules. Moreover, the proliferation of tumor cells and the transfer and diffusion of cancer tissue all depend on a large number of new blood vessels in surrounding tissue to supply nutrients. However, the growth of vascular endothelial cells is not mature. They also need to rely on mesh skeletons made up with microtubules to maintain its basic forms and the basic life activities. If the formation of microtubules is prevented, the formation of spindles and blood vessels will also be stopped. The former will cause the tumor cells to apoptosis and the latter will cause the ischemia of tumor tissues. Hence, microtubules play an important role in the growth and diffusion of tumor cells. With the development of medicinal chemistry and molecular pharmacology, medical workers have a more clear understanding in the biology essences and characteristics of malignant tumors. It also provides more in-depth understanding for the relationship between the tubes and cancer for us, which turns tubulin inhibitors into a hot area of anticancer drugs in recent years.The initial tubulin inhibitors are some natural products with good activities, such as colchicine, vinblastine, paclitaxel, etc. Although the activity of natural products is good, many serious adverse reactions still happen in the clinical application, and thus the clinical applications of them are restricted. With the rapid development of organic synthesis and computer aided drugs, a large number of small molecule novel antitumor reagents as tubulin inhibitors were designed. Among them, most of compounds reported belong to heterocycles, including triazoles, indoles, pyrazoles, pyrimidines, imidazoles and sulfonamides. Meanwhile, the triazole ring has attracted increasing attentionsdue to the better biological diversity, simple structure and easy synthesis.Based on the above research background, using our previously reported compound TR33 possessing significant antiproliferative activity as a lead, and in view of the structural feature of CA-4, this paper designed and synthesised seventy-eight novel 1,2,4-triazole derivatives (series Ⅰ, Ⅱ, Ⅲ). The specific research contents were preliminary summarized as follows:1. The literatures about tubulin inhibitors which are reported in recent years are summarized systematically. The structure types of the compounds, the antitumor activities and the mechanism of action are introduced in details.2. Based on the compound TR-33 which showed strong antitumor activity in our previous studies, this paper designed and synthesised twenty-two novel 1,2,4-triazole derivatives (series Ⅰ), through the extension trimethoxy phenyl chain of 5-position of the triazole ring and replacement benzene by heterocycle. In addition, we designed and synthesized 30 new structure of 3,4,5-three substituted 1,2,4 triazole derivatives (Series II), by changing the isoindole ring as benzene ring. All target compounds were characterized by nuclear magnetic resonance hydrogen spectrum (’H-NMR), carbon-13 nuclear magnetic resonance spectroscopy (13C-NMR), EI low resolution mass spectrometry (ESI-MS), and elemental analysis or high resolution mass spectrometer (HRMS).3. Our previous reported compound TR-33 was selected as the leading compound and CA-4 was kept in mind. Pharmacophore group 3,4, 5-trimethoxyphenyl was maintained and the ethylene bridge of CA-4 was replaced with triazolo[3,4-b][1,3,4]thiadiazine ring. Moreover, the six ring was introduced some heterocycles, such as furan ring, thiophene ring. And a total of 26 compounds (series Ⅲ) were designed and synthesized. All target compounds were characterized by 1H-NMR,13C-NMR, ESI-MS, and elemental analysis.4. Cytotoxic activities of all synthesized compounds were tested by MTT method. Human colcnic carcinoma cell line (HT-29), Human colcnic carcinoma cell line (HCT-116), human prostate cancer cell line (PC-3), human breast cancer cells line (MCF-7), human liver cancer cell lines (HepG-2), human lung cancer cell line (A-549), human cervical cancer cell lines (Hela) and human gastric cancer cell line (MKN-45) were selected for antitumor experiments in vitro. The results indicated that most of these compounds possessed significant antiproliferative activities against four cancer cell lines. Particularly, the most promising compound Ⅲz displayed the ICso values of 5.09,3.70,12.74 and 28.40 μmol·L-1 in inhibiting PC-3, HepG-2, A-549 and MCF-7, respectively. Moreover, compound Ⅱ-23 showed a better inhibitory activity on PC-3 than the positive control drug CA-4.5. Some compounds with potant antiproliferative activities were selected for further evaluation for tubulin polymerization inhibition. And the results suggested that most of the compounds displayed a certain inhibiting effect on tubulin polymerization.6. Compounds of series I were chosen for the test of fungicidal activity. The results showed that most compounds exhibited good fungicidal activities against botryosphaeria dothidea, pitaya shading germs, mango stem end rot pathogen and physalospora piricala.