Introduction: Hybrid drug design has developed as a prime method for the development of novel anticancer therapies that can theoretically solve much of the pharmacokinetic disadvantages of traditional anticancer drugs. Thus a number of studies have indicated that thiazole-thiophene hybrids and their bis derivatives have important anticancer activity. Mammalian Rab7b protein is a member of the Rab GTPase protein family that controls the trafficking from endosomes to the TGN. Alteration in the Rab7b expression is implicated in differentiation of malignant cells, causing cancer. Methods: 1-(4-Methyl-2-(2-(1-(thiophen-2-yl) ethylidene) hydrazinyl) thiazol-5-yl) ethanone was used as building block for synthesis of novel series of 5-(1-(2-(thiazol-2-yl) hydrazono) ethyl) thiazole derivatives. The bioactivities of the synthesized compounds were evaluated with respect to their antitumor activities against MCF-7 tumor cells using MTT assay. Computer-aided docking protocol was performed to study the possible molecular interactions between the newly synthetic thiazole compounds and the active binding site of the target protein Rab7b. Moreover, the in silico prediction of adsorption, distribution, metabolism, excretion (ADME) and toxicity (T) properties of synthesized compounds were carried out using admetSAR tool. Results: The results obtained showed that derivatives 9 and 11b have promising activity (IC₅₀ = 14.6 ± 0.8 and 28.3 ± 1.5 μM, respectively) compared to Cisplatin (IC₅₀ = 13.6 ± 0.9 μM). The molecular docking analysis reveals that the synthesized compounds are predicted to be fit into the binding site of the target Rab7b. In summary, the synthetic thiazole compounds 1– 17 could be used as potent inhibitors as anticancer drugs. Conclusion: Promising anticancer activity of compounds 9 and 11 compared with cisplatin reference drug suggests that these ligands may contribute as lead compounds in search of new anticancer agents to combat chemo-resistance.

In our endeavor towards the development of effective anticancer agents, a novel series of pyridine-ureas 8a–n were synthesized. All the newly prepared derivatives were evaluated in vitro for their growth inhibitory activity towards the proliferation of breast cancer MCF-7 cell line. Compounds 8e and 8n were found to be the most active congeners against MCF-7 cells (IC₅₀ = 0.22 and 1.88 µM after 48 h treatment; 0.11 and 0.80 µM after 72 h treatment, respectively) with increased activity compared to the reference drug doxorubicin (IC₅₀ = 1.93 µM). Moreover, eight selected pyridines 8b, 8d, 8e, 8i, 8j and 8l–n were evaluated for their in vitro anticancer activity according to the US-NCI protocol. Pyridines 8b and 8e proved to be the most effective anticancer agents in the NCI assay with mean inhibition = 43 and 49%, respectively. Both 8b and 8e exhibited anti-proliferative activity against all tested cancer cell lines from all subpanels growth inhibition (GI for 8b; 12–78%, GI for 8e; 15–91%). Pyridines 8b and 8e were screened in vitro for their inhibitory activity against VEGFR-2. Both compounds inhibited VEGFR-2 at micromolar IC₅₀ values 5.0 ± 1.91 and 3.93 ± 0.73 µM, respectively. The most active pyridines were filtered according to the Lipinski and Veber rules and all of them passed these filters. Finally, several ADME descriptors were predicted for the active pyridines through a theoretical kinetic study.

In connection with our research program on the development of new isatin-based anticancer candidates, herein we report the synthesis of two novel series of thiazolidinone-isatin conjugates (4a–n) and thiazolo[3,2-a]benzimidazolone-isatin conjugates (7a–d), and in vitro evaluation of their antiproliferative activity towards two breast cancer cell lines; triple negative MDA-MB-231, and MCF-7. Compounds 4m and 7b emerged as the most active congeners against MDA-MB-231 cells (IC₅₀ = 7.6 ± 0.5 and 13.2 ± 1.1 µM, respectively). Compounds 4m and 7b were able to provoke apoptosis in MDA-MB-231 cells, evidenced by the up-regulation of Bax and down-regulation of Bcl-2, besides boosting caspase-3 levels. Hybrid 4m induced a fourfold increase in the percentage of cells at Sub-G₁, with concurrent arrest in G₂-M phase by 2.5-folds. Furthermore, hybrid 4m resulted in a sixfold increase in the percentage of annexin V-FITC positive apoptotic MDA-MB-231 cells as compared with the control. Moreover, the cytotoxic activities of the active conjugates were assessed towards two nontumorigenic cell lines (breast MCF-10A and lung WI-38) where both conjugates 4m and 7b displayed mean tumor selectivity index: 9.6 and 13.9, respectively. Finally, several ADME descriptors were predicted for the active conjugates via a theoretical kinetic study.

A new series of 5-(3,5-dinitrophenyl)-1,3,4-thiadiazole derivatives were prepared and evaluated for their in vitro antimicrobial, antitumor, and DHFR inhibition activity. Compounds 9, 10, 13, and 16 showed strong and broad-spectrum antimicrobial activity comparable to Amoxicillin and Fluconazole as positive antibiotic and antifungal controls, respectively. Compounds 6, 14, and 15 exhibited antitumor activity against four human cancer cell lines, CCRF-CEM leukemia, HCT-15 colon, PC-3 prostate, and UACC-257 melanoma cell lines using Doxorubicin as a reference drug. Compounds 10, 13, 14, and 15 proved to be the most active DHFR inhibitors with an IC₅₀ range of 0.04 ± 0.82–1.00 ± 0.85 µM, in comparison with Methotrexate (IC₅₀ = 0.14 ± 1.38 µM). The highly potent DHFR inhibitors shared a similar molecular docking mode and made a critical hydrogen bond and arene‒arene interactions via Ser59 and Phe31 amino acid residues, respectively.

A series of novel quinazolinone derivatives (2–13) was synthesized and examined for their cytotoxicity to HepG2, MCF-7, and Caco-2 in an MTT assay. Among these derivatives, compounds 4 and 9 exhibited significant cytotoxic activity against Caco-2, HepG2, and MCF-7 cancer cells. Compound 4 had more significant inhibitory effects than compound 9 on Caco-2, HepG2, and MCF-7 cell lines, with IC₅₀ values of 23.31 ± 0.09, 53.29 ± 0.25, and 72.22 ± 0.14µM, respectively. The AKT pathway is one of human cancer’s most often deregulated signals. AKT is also overexpressed in human cancers such as glioma, lung, breast, ovarian, gastric, and pancreas. A molecular docking study was performed to analyze the inhibitory action of newly synthetic quinazolinone derivatives against Homo sapiens AKT1 protein. Molecular docking simulations were found to be in accordance with in vitro studies, and hence supported the biological activity. The results suggested that compounds 4 and 9 could be used as drug candidates for cancer therapy via its potential inhibition of AKT1 as described by docking study.

A series of N-aryl-7-aryl-pyrazolo[1,5-a]pyrimidines 18a–u and N-aryl-pyrazolo[1,5-a]quinazolines 25a–c were designed and synthesized via the reaction of 5-aminopyrazoles 11a–c with enaminones 12a–g or 19, respectively. The new compounds were screened for their in vitro antitumor activity toward liver (HepG-2) and breast (MCF-7) human cancer cells using 3-[4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide MTT assay. From the results, it was found that all compounds showed dose-dependent cytotoxic activities against both HepG-2 and MCF-7 cells. Two compounds 18o and 18a were selected for further investigations. Cell cycle analysis of liver (HepG-2) cells treated with 18o and breast (MCF-7) cells treated with 18a showed cell cycle arrest at G2/M phase and pro-apoptotic activity as indicated by annexin V-FITC staining.