Synthesis and Antitumor Activity of Novel [1,2,4,5]-tetrazepino[6,7-b] indole Derivatives: Marine Natural Product Hyrtioreticuline C and D Analogues

Synthesis, Biological Evaluation, and Molecular Docking Studies of Indole-Based Heterocyclic Scaffolds as Potential Antibacterial Agents

Indole-based heterocyclic scaffolds have become increasingly important in medicinal chemistry due to their notable pharmacological and biological properties. Their role in the discovery and development of innovative drugs for treating various diseases highlights their value. This study aimed to synthesize C3-indole derivatives linked to various heterocyclic scaffolds, including thiophenes, thiazolidine-4-ones, and 1,3,4-thiadiazoles, via the reaction of ethylthioacetanilide 2 with different α-haloketones.The structures of the target compounds were established using 1H and 13C nuclear magnetic resonance spectroscopy, mass spectrometry, infrared spectroscopy, and elemental analysis. The synthesized compounds were tested for antimicrobial activity against different microbes: S. aureus ATCC 6538 (Gram-positive bacteria), E. coli ATCC 25933 (Gram-negative bacteria), C. albicans ATCC 10231 (yeast), and fungi (A. niger NRRL-A326). Thiophene 6a, thiazolidine-4-one 8, and compound 10d exhibited the highest antimicrobial activities. The molecular docking study showed that compounds 2, 4, 6a, and 6c had good binding energy and favorable binding modes of interactions with the DNA gyrase B enzymes (PDB: 3 U2D) and (PDB: 1S14). The results showed that the NH group of the indole in compounds 2 and 4, together with the nitrile group (CN), played an important role in inhibiting DNA gyrase B of S. aureus, PDB: 3 U2D. Furthermore, the NH of the indole ring, together with the ethylamino group of compound 2, was crucial in inhibiting DNA gyrase B of E. coli, PDB: 1S14. These findings may encourage researchers to develop more effective C3-indole derivatives in their search for antimicrobial drugs.

Novel thiazole derivatives incorporating phenyl sulphonyl moiety as potent BRAFV600E kinase inhibitors targeting melanoma

Novel thiazole derivatives possessing phenyl sulfonyl moiety were designed and synthesized as B-RAFV600E kinase inhibitors based on the clinically-approved anticancer drug, dabrafenib. All target compounds showed significant inhibition of B-RAFV600E kinase enzyme at nanomolar levels. Compounds 7b and 13a revealed excellent B-RAFV600E inhibitory activity, superior to that of dabrafenib with IC₅₀ values of 36.3 ± 1.9, 23.1 ± 1.2, and 47.2 ± 2.5 nM, respectively. Moreover, the title compounds were much more selective toward B-RAFV600E kinase than B-RAF wild type. In addition, the most potent compounds were further evaluated for their anticancer activity against B-RAFV600E-mutated and wild type melanoma cells. A positive correlation between the cytotoxic activity and selectivity for B-RAF V600E over B-RAF wild type was clearly observed for compounds 7b, 11c, 13a, and 17. All the screened compounds potently inhibited the growth of WM266.4 melanoma cells with IC₅₀ values in the range from 1.24 to 17.1 μM relative to dabrafenib (IC₅₀ = 16.5 ± 0.91 μM). Compounds 7b, 11a and 11c, 13a, and 17 were much more potent than dabrafenib against B-RAFV600E-mutated WM266.4 melanoma cells. Furthermore, compound 7b suppressed the phosphorylation of downstream ERK1/2 from WM266.4 cells. Also, the docking study revealed the proper orientation and well-fitting of the title compounds into the ATP binding site of B-RAFV600E kinase.

Thiazole derivatives 7b and 13a were superior to dabrafenib against B-RAFV600E kinase and potently inhibited the growth of WM266.4 melanoma cells. Compound 7b suppressed the phosphorylation of downstream ERK1/2 from WM266.4 cells.

Discovery of novel indolyl-1,2,4-triazole hybrids as potent vascular endothelial growth factor receptor-2 (VEGFR-2) inhibitors with potential anti-renal cancer activity

Targeting VEGFR-2 signaling pathway is well-established as an important approach for the treatment of solid tumors, particularly renal cancer. Herein, novel indolyl-1,2,4-triazole hybrids were designed and synthesized as VEGFR-2 kinase inhibitors with potential anti-renal cancer activity. The structures of the newly synthesized compounds were confirmed based on their spectral and elemental analyses. The results of in vitro kinase assay indicated that all target compounds revealed submicromolar inhibition of VEGFR-2 kinase enzyme. Analogs 5c, 5d and 9b emerged as the most active compounds (IC₅₀ = 0.034-0.064 µM), showing VEGFR-2 inhibitory activity much superior to that of sunitinib reference drug (IC₅₀ = 0.075 µM). Moreover, compounds 5a, 8c, 9d, 12c were equipotent to sunitinib against VEGFR-2 kinase. Additionally, the most potent compounds were further examined for their anticancer activity against two human renal cancer cell lines. All screened compounds effectively inhibited the growth of the two tested cell lines with IC₅₀ values spanning from sub-micromolar to low micromolar levels. Compounds 5b, 5d, 11c and 12c were three to five-fold more potent than sunitinib against CAKI-1 cell line. Analogue 8c was superior/comparable to sunitinib against CAKI-1/A498 cell lines. Moreover, compound 9d showed double potency of sunitinib against A498 cell line. Besides, compounds 8c and 12c demonstrated a safety profile much better than that of sunitinib against non-cancer human renal cells. As well, the docked models of title compounds revealed strong interactions with key residues within the active site of VEGFR-2 kinase.

Novel 2-indolinone thiazole hybrids as sunitinib analogues: Design, synthesis, and potent VEGFR-2 inhibition with potential anti-renal cancer activity

Novel 2-indolinone thiazole hybrids were designed and synthesized as VEGFR-2 inhibitors based on sunitinib, an FDA-approved anticancer drug. The proposed structures of the prepared 2-indolinone thiazole hybrids were confirmed based on their spectral data and CHN analyses. The target compounds were screened in vitro for their anti-VEGFR-2 activity. All tested compounds exhibited a potent submicromolar inhibition of VEGFR-2 kinase with IC₅₀ values ranging from 0.067 to 0.422 μM, relative to sunitinib reference drug (IC₅₀ = 0.075 ± 0.002 μM). Compounds 5, 15a, 15b, 17, 19c displayed excellent VEGFR-2 inhibitory activity, comparable or nearly equipotent to sunitinib. Compound 13b stood out as the most potent against VEGFR-2 showing IC₅₀ value of 0.067 ± 0.002 μM, lower than that of sunitinib. In addition, the most potent derivatives were assessed for their anticancer activity against two renal cancer cell lines. Compound 13b (IC₅₀ = 3.9 ± 0.13 μM) was more potent than sunitinib (IC₅₀ = 4.93 ± 0.16 μM) against CAKI-1 cell line. Moreover, thiazole 15b displayed excellent anticancer activity against CAKI-1 cell line (IC₅₀ = 3.31 ± 0.11 μM), superior to that of sunitinib (IC₅₀ = 4.93 ± 0.16 μM). Thiazole 15b was also equipotent to sunitinib (IC₅₀ = 1.23 ± 0.04 μM) against A498 cell line. Besides, compound 15b revealed a safety profile much better than that of sunitinib against normal human renal cells. Furthermore, a docking study revealed a proper fitting of the most active compounds into the ATP binding site of VEGFR-2, rationalizing their potent anti-VEGFR-2 activity.

The Acetone Indigo Red Dehydrating Agent IF203 Induces HepG2 Cell Death Through Cell Cycle Arrest, Autophagy and Apoptosis

Background

Isatin derivatives have extensive biological activities, such as antitumor. IF203, a novel isatin derivative, has not previously been reported to have antitumor activity.

Methods

Acid phosphatase assays (APAs) and Ki-67 immunohistochemistry were used to detect the proliferation of HepG2 cells. Transmission electron microscope (TEM) was applied to detect ultrastructural changes. Flow cytometry (FCM) was used to detect cell cycle, apoptosis, reactive oxygen species (ROS) and mitochondrial membrane potential (MMP) of HepG2 cells in vitro. TUNEL, MMP and ROS immunofluorescence assays were applied to assess apoptosis, MMP, and ROS of HepG2 cells in vivo. Western Blotting was applied to assess the levels of apoptosis- and autophagy-related proteins.

Results

In this study, in vivo and in vitro experiments showed that IF203 possesses antitumor activity. The results of APAs and Ki-67 immunohistochemistry demonstrated that IF203 could inhibit the proliferation of HepG2 cells. Cell cycle assays, downregulation of Cyclin B1 and Cdc2, and upregulation of P53 suggested that IF203 could lead to G2/M cell cycle arrest. In addition, ultrastructural changes, apoptosis assays, TUNEL immunofluorescence results, upregulated expression of Bax, and downregulated expression of Bcl-2 suggest that IF203 can induce apoptosis in HepG2 cells. After IF203 treatment, intracellular ROS levels increased, MMP decreased, JC-1 green fluorescence was enhanced, and the levels of Caspase-9, Caspase-3 and Cytochrome C expression were upregulated, suggesting that IF203 could induce apoptosis of HepG2 cells through the mitochondrial apoptosis pathway. Moreover, characteristic apoptotic ultrastructural changes were accompanied by the appearance of many autophagy bubbles and upregulation of Atg5, Atg12, ULK1, Beclin-1 and LC3-II proteins, suggesting that IF203 could induce autophagy in HepG2 cells.

Conclusion

This study showed that IF203 leads to the death of HepG2 cells through cell cycle arrest, apoptotic induction, and autophagy promotion.