Synthesis and Cytotoxicity Evaluation of Novel Indole Derivatives as Potential Anti-Cancer Agents

Identification of indole-grafted pyrazolopyrimidine and pyrazolopyridine derivatives as new anti-cancer agents: Synthesis, biological assessments, and molecular modeling insights

In the current medical era, developing new PIM-1 inhibitors stands as a significant approach to cancer management due to the pivotal role of PIM-1 kinase in promoting cell survival, proliferation, and drug resistance in various cancers. This study involved designing and synthesizing new derivatives of pyrazolo[1,5-a]pyrimidines (6a-i) and pyrazolo[3,4-b]pyridines (10a-i) as potential anti-cancer agents targeting PIM-1 kinase. The cytotoxicity was screened on three cancer cell lines: A-549 (lung), PANC-1 (pancreatic), and A-431 (skin), alongside MRC5 normal lung cells to assess selectivity. Several pyrazolo[1,5-a]pyrimidines (6b, 6c, 6g, 6h, and 6i) and pyrazolo[3,4-b]pyridine (10f) demonstrated notable anticancer properties, particularly against A-549 lung cancer cells (IC50 range: 1.28-3.52 μM), also they exhibited significantly lower toxicity towards MRC5 normal cells. Thereafter, the compounds were evaluated for their inhibitory activity against PIM-1 kinase. Notably, 10f, bearing a 4-methoxyphenyl moiety, demonstrated good inhibition of PIM-1 with an IC50 of 0.18 μM. Additionally, 10f induced apoptosis and arrested cell cycle progression in A-549 cells. Molecular docking and dynamics simulations provided insights into the binding interactions and compounds' stability with PIM-1 kinase. The results highlight these compounds, especially 10f, as promising selective anticancer agents targeting PIM-1 kinase.

A Review: Meridianins and Meridianins Derivatives

Meridianins are a family of indole alkaloids derived from Antarctic tunicates with extensive pharmacological activities. A series of meridianin derivatives had been synthesized by drug researchers. This article reviews the extraction and purification methods, biological activities and pharmacological applications, pharmacokinetic characters and chemical synthesis of meridianins and their derivatives. And prospects on discovering new bioactivities of meridianins and optimizing their structure for the improvement of the ADMET properties are provided.

Target-based anticancer indole derivatives and insight into structure‒activity relationship: A mechanistic review update (2018‒2021)

Cancer, which is the uncontrolled growth of cells, is the second leading cause of death after heart disease. Targeting drugs, especially to specific genes and proteins involved in growth and survival of cancer cells, is the prime need of research world-wide. Indole moiety, which is a combination of aromatic-heterocyclic compounds, is a constructive scaffold for the development of novel leads. Owing to its bioavailability, high unique chemical properties and significant pharmacological behaviours, indole is considered as the most inquisitive scaffold for anticancer drug research. This is illustrated by the fact that the U.S. Food and Drug Administration (FDA) has recently approved several indole-based anticancer agents such as panobinostat, alectinib, sunitinib, osimertinib, anlotinib and nintedanib for clinical use. Furthermore, hundreds of studies on the synthesis and activity of the indole ring have been published in the last three years. Taking into account the facts stated above, we have presented the most recent advances in medicinal chemistry of indole derivatives, encompassing hot articles published between 2018 and 2021 in anticancer drug research. The recent advances made towards the synthesis of promising indole-based anticancer compounds that may act via various targets such as topoisomerase, tubulin, apoptosis, aromatase, kinases, etc., have been discussed. This review also summarizes some of the recent efficient green chemical synthesis for indole rings using various catalysts for the period during 2018–2021. The review also covers the synthesis, structure‒activity relationship, and mechanism by which these leads have demonstrated improved and promising anticancer activity. Indole molecules under clinical and preclinical stages are classified into groups based on their cancer targets and presented in tabular form, along with their mechanism of action. The goal of this review article is to point the way for medicinal chemists to design and develop effective indole-based anticancer agents.

Synthesis and Cytotoxic Activity of Novel Mono- and Bis-Indole Derivatives: Analogues of Marine Alkaloid Nortopsentin

BACKGROUND

The oceans cover more than 70% of the earth's surface, which represents over 95% of the biosphere. Therefore, oceans provide a wealth of marine invertebrates, especially sponges, ascidians, bryozoans and molluscs that produce structurally unique bioactive metabolites such as alkaloids. The bioactive scaffolds of marine alkaloids exhibit cytotoxic activities against human cancer cell lines.

OBJECTIVE

To prepare analogues of the marine alkaloid nortopsentin [having 2,4-bis(3'- indolyl)imidazole scaffold] as cytotoxic agents via structural modification of the core imidazole ring and one of the side indole rings.

METHODS

Four series of nortopsentin analogues were synthesized in which the imidazole ring was replaced by pyrazole, pyrido[2,3-d]pyrimidinone and pyridine rings. Furthermore, one of the side indole rings was replaced by substituted phenyl moiety. The target compounds were tested for their in vitro cytotoxic activity against HCT-116 cell-line and the most potent compound was subjected to further investigation on its effect on HCT-116 cell cycle progression.

RESULTS

The cytotoxic screening of the synthesized compounds revealed that bis-indolylpyridinedicarbonitriles 8a-d exhibited the most potent cytotoxic activity with IC50=2.6-8.8 μM. Compound 8c was further tested by flow cytometry analysis to explore its effect on HCT-116 cell cycle progression that, in turn, indicated its anti-proliferative effect.

CONCLUSION

Marine-derived bis-indole alkaloids (nortopsentins) have emerged as a new class of indole-based antitumor agents. The design of new analogues involved several modifications in order to obtain more selective and potent cytotoxic agents. Indole derivatives bearing a pyridine core displayed more potent cytotoxic activity than those containing pyrido[2,3-d]pyrimidin-4(1H)-one moiety.