How the structural properties of the indole derivatives are important in kinase targeted drug design?: A case study on tyrosine kinase inhibitors

Development of 3-indolyl substituted phenyl pyrazolo-carboxamide hybrids as potential type II VEGFR-2 inhibitors and in vitro cytotoxicity studies

The progression of tumors is intricately linked to angiogenesis, the formation of new blood vessels, driven primarily by the release of growth factors such as Vascular Endothelial Growth Factor (VEGF). Targeting VEGF signaling through its receptor kinase (VEGFR-2) has emerged as a promising anti-angiogenic strategy for cancer therapy. In this study, we designed and synthesized a series of novel chemical entities based on 3-indolyl substituted phenyl pyrazole-carboxamides through docking studies upon considering the structure of sorafenib and its pattern of type II inhibition of VEGFR-2. Among the synthesized hybrids, 7b was able to significantly inhibit the growth of cancer cell lines, specifically against MCF-7 at 2.12 ± 0.19 μM. Compound 7b also efficiently inhibited VEGFR-2 kinase at a concentration of 2.83 ± 0.86 μM during the in vitro studies. Mechanistic studies revealed that 7b induced apoptosis evidenced by AO/EB, DAPI, and DCFDA staining, and its impact on the migratory ability of the cancer cells were also studied. These findings highlight the potential of 7b as a lead candidate for further development of anti-angiogenic therapies targeting VEGFR-2.

Indole Compounds in Oncology: Therapeutic Potential and Mechanistic Insights

Cancer remains a formidable global health challenge, with current treatment modalities such as chemotherapy, radiotherapy, surgery, and targeted therapy often hindered by low efficacy and adverse side effects. The indole scaffold, a prominent heterocyclic structure, has emerged as a promising candidate in the fight against cancer. This review consolidates recent advancements in developing natural and synthetic indolyl analogs, highlighting their antiproliferative activities against various cancer types over the past five years. These analogs are categorized based on their efficacy against common cancer types, supported by biochemical assays demonstrating their antiproliferative properties. In this review, emphasis is placed on elucidating the mechanisms of action of these compounds. Given the limitations of conventional cancer therapies, developing targeted therapeutics with enhanced selectivity and reduced side effects remains a critical focus in oncological research.

Discovery of 9H-pyrimido[4,5-b]indole derivatives as dual RET/TRKA inhibitors

Aberrant RET kinase signaling is activated in numerous cancers including lung, thyroid, breast, pancreatic, and prostate. Recent approvals of selective RET inhibitors, pralsetinib and selpercatinib, has shifted the focus of RET kinase drug discovery programs towards the development of selective inhibitors. However, selective inhibitors invariably lose efficacy as the selective nature of the inhibitor places Darwinian-like pressure on the tumor to bypass treatment through the selection of novel oncogenic drivers. Further, selective inhibitors are restricted for use in tumors with specific genetic backgrounds that do not encompass diverse patient classes. Here we report the identification of a pyrimido indole RET inhibitor found to also have activity against TRK. This selective dual RET/TRK inhibitor can be utilized in tumors with both RET and TRK genetic backgrounds and can also provide blockade of NTRK-fusions that are selected for from RET inhibitor treatments. Efforts towards developing dual RET/TRK inhibitors can be beneficial in terms of encompassing more diverse patient classes while also achieving blockade against emerging resistance mechanisms.

Antineoplastic indole-containing compounds with potential VEGFR inhibitory properties

Cancer is one of the most significant health challenges worldwide. Various techniques, tools and therapeutics/materials have been developed in the last few decades for the treatment of cancer, together with great interest, funding and efforts from the scientific society. However, all the reported studies and efforts seem insufficient to combat the various types of cancer, especially the advanced ones. The overexpression of tyrosine kinases is associated with cancer proliferation and/or metastasis. VEGF, an important category of tyrosine kinases, and its receptors (VEGFR) are hyper-activated in different cancers. Accordingly, they are known as important factors in the angiogenesis of different tumors and are considered in the development of effective therapeutic approaches for controlling many types of cancer. In this case, targeted therapeutic approaches are preferable to the traditional non-selective approaches to minimize the side effects and drawbacks associated with treatment. Several indole-containing compounds have been identified as effective agents against VEGFR. Herein, we present a summary of the recent indolyl analogs reported within the last decade (2012-2023) with potential antineoplastic and VEGFR inhibitory properties. The most important drugs, natural products, synthesized potent compounds and promising hits/leads are highlighted. Indoles functionalized and conjugated with various heterocycles beside spiroindoles are also considered.

Synthesis, Cytotoxic, and Computational Screening of Some Novel Indole-1,2,4-Triazole-Based S-Alkylated N-Aryl Acetamides

Molecular hybridization has emerged as the prime and most significant approach for the development of novel anticancer chemotherapeutic agents for combating cancer. In this pursuit, a novel series of indole-1,2,4-triazol-based N-phenyl acetamide structural motifs 8a-f were synthesized and screened against the in vitro hepatocellular cancer Hep-G2 cell line. The MTT assay was applied to determine the anti-proliferative potential of novel indole-triazole compounds 8a-f, which displayed cytotoxicity potential as cell viabilities at 100 µg/mL concentration, by using ellipticine and doxorubicin as standard reference drugs. The remarkable prominent bioactive structural hybrids 8a, 8c, and 8f demonstrated good-to-excellent anti-Hep-G2 cancer chemotherapeutic potential, with a cell viability of (11.72 ± 0.53), (18.92 ± 1.48), and (12.93 ± 0.55), respectively. The excellent cytotoxicity efficacy against the liver cancer cell line Hep-G2 was displayed by the 3,4-dichloro moiety containing indole-triazole scaffold 8b, which had the lowest cell viability (10.99 ± 0.59) compared with the standard drug ellipticine (cell viability = 11.5 ± 0.55) but displayed comparable potency in comparison with the standard drug doxorubicin (cell viability = 10.8 ± 0.41). The structure-activity relationship (SAR) of indole-triazoles 8a-f revealed that the 3,4-dichlorophenyl-based indole-triazole structural hybrid 8b displayed excellent anti-Hep-G2 cancer chemotherapeutic efficacy. The in silico approaches such as molecular docking scores, molecular dynamic simulation stability data, DFT, ADMET studies, and in vitro pharmacological profile clearly indicated that indole-triazole scaffold 8b could be the lead anti-Hep-G2 liver cancer therapeutic agent and a promising anti-Hep-G2 drug candidate for further clinical evaluations.

Indole Antitumor Agents in Nanotechnology Formulations: An Overview

The indole heterocycle represents one of the most important scaffolds in medicinal chemistry and is shared among a number of drugs clinically used in different therapeutic areas. Due to its varied biological activities, high unique chemical properties and significant pharmacological behaviors, indole derivatives have drawn considerable interest in the last decade as antitumor agents active against different types of cancers. The research of novel antiproliferative drugs endowed with enhanced efficacy and reduced toxicity led to the approval by U.S. Food and Drug Administration of the indole-based anticancer agents Sunitinib, Nintedanib, Osimertinib, Panobinostat, Alectinib and Anlotinib. Additionally, new drug delivery systems have been developed to protect the active principle from degradation and to direct the drug to the specific site for clinical use, thus reducing its toxicity. In the present work is an updated review of the recently approved indole-based anti-cancer agents and the nanotechnology systems developed for their delivery.

Interaction study with DNA/HSA, anti-topoisomerase IIα, cytotoxicity and in vitro antiproliferative evaluations and molecular docking of indole-thiosemicarbazone compounds

In this work we will discuss the antiproliferative evaluation and the possible mechanisms of action of indole-thiosemicarbazone compounds LTs with anti-inflammatory activity, previously described in the literature. In this perspective, some analyzes were carried out, such as the study of binding to human serum albumin (HSA) and to biological targets: DNA and human topoisomerase IIα (topo). Antiproliferative study was performed with DU-145, Jukart, MCF-7 and T-47D tumor lines and J774A.1, besides HepG2 macrophages and hemolytic activity. In the HSA interaction tests, the highest binding constant was 3.70 × 10⁶ M^-1, referring to LT89 and in the fluorescence, most compounds, except for LT76 and LT87, promoted fluorescent suppression with the largest Stern-Volmer constant for the LT88 3.55 × 10⁴. In the antiproliferative assay with DU-145 and Jurkat strains, compounds LT76 (0.98 ± 0.10/1.23 ± 0.32 μM), LT77 (0.94 ± 0.05/1.18 ± 0.08 μM) and LT87 (0.94 ± 0.12/0.84 ± 0.09 μM) stood out, due to their IC₅₀ values mentioned above. With the MCF-7 and T-47D cell lines, the lowest IC₅₀ was presented by LT81 with values of 0.74 ± 0.12 μM and 0.68 ± 0.10 μM, respectively, followed by the compounds LT76 and LT87. As well as the positive control amsacrine, the compounds LT76, LT81 and LT87 were able to inhibit the enzymatic action of human Topoisomerase IIα.