Synthesis, antiproliferative activity evaluation and structure-activity relationships of novel aromatic urea and amide analogues of N-phenyl-N'-(2-chloroethyl)ureas

Design, Synthesis and Evaluation of the Biological Activities of Some New Carbohydrazide and Urea Derivatives

Objectives

Urea and carbohydrazide derivatives are important compounds exhibiting cytotoxic activities. In this study, a series of new urea and carbohydrazide derivatives containing an pyridine ring were synthesized and evaluated for cytotoxic activity.

Materials and Methods

The proposed structures of the synthesized compounds were confirmed using elemental analysis, IR, and ¹H-NMR spectroscopic techniques. The cytotoxic potencies of synthesized compounds were determined using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay (MTT) on BRCA mutant-carrying HCC1937 and Capan-1 cell lines, as well as on MCF7, HeLa, and MRC5 cells.

Results

3a, 3b, 3c and 3d showed cytotoxic activity against all cancer cell lines.

Conclusion

Our data indicate that compounds 3a-d are more selective to cancer cells compared with nontumoral fibroblasts; however, these compounds are not more potent on HR defective cells with BRCA mutants.

Fragment-Based Approach to Targeting Inosine-5'-monophosphate Dehydrogenase (IMPDH) from Mycobacterium tuberculosis

Tuberculosis (TB) remains a major cause of mortality worldwide, and improved treatments are needed to combat emergence of drug resistance. Inosine 5′-monophosphate dehydrogenase (IMPDH), a crucial enzyme required for de novo synthesis of guanine nucleotides, is an attractive TB drug target. Herein, we describe the identification of potent IMPDH inhibitors using fragment-based screening and structure-based design techniques. Screening of a fragment library for Mycobacterium thermoresistible (Mth) IMPDH ΔCBS inhibitors identified a low affinity phenylimidazole derivative. X-ray crystallography of the Mth IMPDH ΔCBS–IMP–inhibitor complex revealed that two molecules of the fragment were bound in the NAD binding pocket of IMPDH. Linking the two molecules of the fragment afforded compounds with more than 1000-fold improvement in IMPDH affinity over the initial fragment hit.

Synthesis, Biological Evaluation, and Autophagy Mechanism of 12N-Substituted Sophoridinamines as Novel Anticancer Agents

A series of 12N-substituted sophoridinamine derivatives were synthesized and evaluated for their cytotoxic activities in human HepG2 hepatoma cells. Structure-activity relationship revealed that introduction of a suitable arylidene or arylethyl at the N'-end could greatly enhance antiproliferation potency. Among them, compound 6b possessing a N'-trimethoxyphenyl methylene exhibited potent antiproliferation effect against three human tumor cell lines including HepG2, leukemia (K562), and breast cancer (HMLE), with IC₅₀ between 0.55 and 1.7 μM. The underlying mechanism of 6b against tumor cells is to block autophagic flux, mainly through neutralizing lysosomal acidity. Our results indicated that compound 6b is a potent lysosomal deacidification agent and is accordingly able to block autophagic flux and inhibit tumor cell growth.

Novel isoniazid–amidoether derivatives: synthesis, characterization and antimycobacterial activity evaluation

A series of isoniazid–amidoether derivatives was synthesized and screened for their antimycobacterial activity in vitro and in vivo.

Intramolecular cyclization of N-phenyl N'(2-chloroethyl)ureas leads to active N-phenyl-4,5-dihydrooxazol-2-amines alkylating β-tubulin Glu198 and prohibitin Asp40

The cyclization of anticancer drugs into active intermediates has been reported mainly for DNA alkylating molecules including nitrosoureas. We previously defined the original cytotoxic mechanism of anticancerous N-phenyl-N'-(2-chloroethyl)ureas (CEUs) that involves their reactivity towards cellular proteins and not against DNA; two CEU subsets have been shown to alkylate β-tubulin and prohibitin leading to inhibition of cell proliferation by G₂/M or G₁/S cell cycle arrest. In this study, we demonstrated that cyclic derivatives of CEUs, N-phenyl-4,5-dihydrooxazol-2-amines (Oxas) are two- to threefold more active than CEUs and share the same cytotoxic properties in B16F0 melanoma cells. Moreover, the CEU original covalent binding by an ester linkage on β-tubulin Glu198 and prohibitin Asp40 was maintained with Oxas. Surprisingly, we observed that Oxas were spontaneously formed from CEUs in the cell culture medium and were also detected within the cells. Our results suggest that the intramolecular cyclization of CEUs leads to active Oxas that should then be considered as the key intermediates for protein alkylation. These results will be useful for the design of new prodrugs for cancer chemotherapy.