Synthesis, modeling studies and evaluation of E-stilbene hydrazides as potent anticancer agents

Medicinal chemistry perspective on the structure-activity relationship of stilbene derivatives

Stilbenes are a small family of polyphenolic secondary metabolites produced in a variety of closely related plant species. These compounds function as phytoalexins, aiding plant defense against phytopathogens and plants' adaptation to abiotic environmental factors. Structurally, some important phenolic compounds have a 14-carbon skeleton and usually have two isomeric forms, Z and E. Stilbenes contain two benzene rings linked by a molecule of ethanol or ethylene. Some derivatives of natural (poly)phenolic stilbenes such as resveratrol, pterostilbene, and combretastatin A-4 have shown various biological activities, such as anti-microbial, anti-cancer, and anti-inflammatory properties as well as protection against heart disease, Alzheimer's disease, and diabetes. Among stilbenes, resveratrol is certainly the most popular and extensively studied for its health properties. In recent years, an increasing number of stilbene compounds have been investigated for their bioactivity. This review focuses on the assessment of synthetic stilbene derivatives in terms of their biological activities and structure-activity relationship. The goal of this study is to consider the structural changes and different substitutions on phenyl rings that can improve the desired medicinal effects of stilbene-based compounds beyond the usual standards and subsequently discover biological activities by identifying effective alternatives of the evaluated compounds.

Design, Synthesis, and Biological Evaluation of Novel Dihydropyridine and Pyridine Analogs as Potent Human Tissue Nonspecific Alkaline Phosphatase Inhibitors with Anticancer Activity: ROS and DNA Damage-Induced Apoptosis

Small molecules with nitrogen-containing scaffolds have gained much attention due to their biological importance in the development of new anticancer agents. The present paper reports the synthesis of a library of new dihydropyridine and pyridine analogs with diverse pharmacophores. All compounds were tested against the human tissue nonspecific alkaline phosphatase (h-TNAP) enzyme. Most of the compounds showed excellent enzyme inhibition against h-TNAP, having IC₅₀ values ranging from 0.49 ± 0.025 to 8.8 ± 0.53 µM, which is multi-fold higher than that of the standard inhibitor (levamisole = 22.65 ± 1.60 µM) of the h-TNAP enzyme. Furthermore, an MTT assay was carried out to evaluate cytotoxicity against the HeLa and MCF-7 cancer cell lines. Among the analogs, the most potent dihydropyridine-based compound 4d was selected to investigate pro-apoptotic behavior. The further analysis demonstrated that compound 4d played a significant role in inducing apoptosis through multiple mechanisms, including overproduction of reactive oxygen species, mitochondrial dysfunction, DNA damaging, and arrest of the cell cycle at the G1 phase by inhibiting CDK4/6. The apoptosis-inducing effect of compound 4d was studied through staining agents, microscopic, and flow cytometry techniques. Detailed structure–activity relationship (SAR) and molecular docking studies were carried out to identify the core structural features responsible for inhibiting the enzymatic activity of the h-TNAP enzyme. Moreover, fluorescence emission studies corroborated the binding interaction of compound 4d with DNA through a fluorescence titration experiment.

Design and syntheses of 7-nitro-2-aryl-4H-benzo[d][1,3]oxazin-4-ones as potent anticancer and antioxidant agents

A group of new nitro substituted benzoxazinones (3a-k) were synthesized from easily available 4-nitroanthranilic acid. All the synthesized compounds were characterized by FT-IR, ¹H NMR, ¹³C NMR, mass spectrometry and elemental analysis. Anti-proliferative and pro-apoptotic potential of all the synthesized compounds (3a-k) was evaluated by MTT and Hoechst 33258 staining assay respectively whereas their antioxidant properties were determined via DPPH free radical scavenging assay. The most active compounds (3a, 3c and 3k) showed significant cytotoxic potential against HeLa cells with an inhibition of cell viability that ranged between 28.54 and 44.67% (P < 0.001). Albeit statistically different, the anti-proliferative effect of 3c was in close match with that of the reference drug doxorubicin. Likewise, the test compounds showed profound pro-apoptotic potential with an apoptotic index that ranged between 52.86 and 75.61%. Besides, the docking studies revealed a higher efficiency for compounds (3a and 3h) owing to their better affinity and inhibition constant (K_i = 4.397 and 3.713 nmol) respectively. The antioxidant potential of synthesized benzoxazinones (3a-k) was in close agreement with the experimental anticancer results with a percent inhibition from 34.45 to 85.93% as compared to standard (90.56%).