Benzimidazole based hybrids against complex diseases: A catalogue of the SAR profile

Benzimidazole(s): synthons, bioactive lead structures, total synthesis, and the profiling of major bioactive categories

Benzimidazole, a fused bicyclic compound with benzene and pentacyclic 1,3-diazole moeities, has a simple aromatic heterocyclic structure. The moiety has become an indispensable anchor for the development of new pharmacologically active products, and has yielded several therapeutic agents with anticancer, antihypertensive, antimicrobial, antifungal and antiulcer effects. Benzimidazoles, as synthetically feasible and pharmacophoric synthons, have been relentlessly pursued for the preparation of new analogues and derivatives, and they have successfully developed into some of the most sought-after and vital pharmacophores for drug discovery. The use of varied substituents and differing patterns around the benzimidazole nucleus has provided a wide spectrum of biological activities. In addition, the benzimidazole moiety constitutes a building block for the production of several drugs, drug candidates, new chemical entities, and lead molecules. The importance of this nucleus for bioactivity, e.g., antibacterial, antitubercular, antidiabetic, anticancer, antifungal, anti-inflammatory, analgesic, antioxidant, antihistaminic, and antimalarial activity, has led us to take note and provide an overview of the synthetic development approaches for various benzimidazole derivatives together with their biological actions. This review is projected to further assist in the design and development of new benzimidazole-based compounds for new and optimized pharmacologically active products towards new drug-development strategies.

Benzimidazole Conjugates as Multi-target Anticancer Agents - A Comprehensive Review

Cancer is the second leading cause of mortality globally and is characterized by a multifactorial etiology. Drug resistance and multidrug resistance are the reasons for the failure of many anticancer drugs that are in clinical practice now. The current review is a complete review of benzimidazole hybrids with different heterocyclic rings, which are potential anticancer agents. We reviewed around 70 research works of benzimidazole hybrids published in high-impact journals, along with a short discussion of structural features responsible for its activity against various cancers. This review highlighted benzimidazole hybrids as targeted anticancer agents with effects on multiple targets. Researchers working on targeted medications for cancer treatment will benefit from this review when designing new scaffolds with benzimidazole moieties.

Emerging Role of Natural Topoisomerase Inhibitors as Anticancer agents

Topoisomerases I and II are the functionally two forms of DNA topoisomerase. In anticancer research, novel anticancer chemotherapeutical capable of blocking topoisomerase enzymes have been discovered. Most commonly, topoisomerase causes replication fork arrest and doublestrand breaks, and this is how a clinically successful topoisomerase-targeting anticancer medicines work. Unfortunately, this novel mechanism of action has been linked to the development of secondary malignancies as well as cardiotoxicity. The specific binding locations and mechanisms of topoisomerase poisons have been identified by studying the structures of topoisomerase-drug-DNA ternary complexes. Recent breakthroughs in science have revealed that isoform-specific human topoisomerase II poison could be created as safer anticancer drug molecules. It may also be able to develop catalytic inhibitors of topoisomerases by focusing on their inactive conformations. In addition to this, the discovery of new bacterial topoisomerase inhibitor molecules and regulatory proteins could lead to the discovery of new human topoisomerase inhibitors. As a result, biologists, organic chemists, and medicinal chemists worldwide have been identifying, designing, synthesizing, and testing a variety of novel topoisomerase-targeting bioactive compounds. This review focused on topoisomerase inhibitors, their mechanisms of action, and different types of topoisomerase inhibitors that have been developed during the last ten years.

Recent Progresses in Development of Heterocyclic Compounds for Epilepsy Treatment: Key Research Highlights from 2019-2024

Epilepsy which is a chronic neurological disorder is characterized by recurrent seizure poses a significant challenge to healthcare professionals worldwide. Most of antiepileptic drugs have serious side effects that might affect the quality of life such as fatigue, dizziness, weight gain and cognitive impairments. In this context, the search for more effective and potential antiepileptic drug candidate has led to a growing interest in the field of synthesis of heterocyclic compounds. This review will focus on the utilization of heterocyclic moieties including imidazole, indole, thiazole, triazine, quinazoline and oxazole which show remarkable anticonvulsant properties. Furthermore, the exploration of various methodologies for the synthesis of heterocyclic anticonvulsant drugs such as green methodologies and microwave assisted protocols have contributed to the development of environment friendly, more efficient and potential approaches. The review will distinguish from previous ones by specifically focusing on innovative synthetic methodologies, including greener methodologies and micro-assisted techniques, that contribute to eco-friendly and environment benign approaches during 2019-2024. In addition to this, the review will focus on the Structure Activity Relationship (SAR) studies of heterocyclic compounds in order to offer insight into the design of next generation antiepileptic drugs with improved efficacy and reduced side effects.

An Insight into the Structure-activity Relationship of Benzimidazole and Pyrazole Derivatives as Anticancer Agents

INTRODUCTION

Cancer is a leading cause of death worldwide, driving the urgent need for new and effective treatments. Benzimidazole and pyrazole derivatives have gained attention for their potential as anticancer agents due to their diverse biological activities. The development of resistance in cancer cells, toxicity concerns, and inconsistent efficacy across different types of cancer are a few of the challenges. To overcome these challenges, optimisation of these nuclei using the structure-activity relationships is necessary.

OBJECTIVES

This review aimed to examine various benzimidazole, pyrazole, and their hybrid derivatives by focusing on their structure-activity relationships (SAR) as anticancer agents. Results of the most potent and least potent benzimidazole, pyrazole compounds, and their hybrid derivatives published by researchers were compiled.

METHODS

The findings of different researchers working on benzimidazole and pyrazole nuclei were reviewed and analysed for different targets and cell lines. Moreover, substitutions on different positions of pyrazole, benzimidazole, and their hybrid were summarised to derive an optimised pharmacophore.

RESULTS

Based on our analysis of existing studies, we anticipate that this review will guide researchers in creating potent pyrazole, benzimidazole, and hybrid derivatives crucial for combating cancer effectively.

CONCLUSION

Structure-Activity Relationship (SAR) studies can help in developing pyrazolebenzimidazole hybrids that are more powerful and selective in targeting specific aspects of cancer.

Exploring antimalarial potential: Conjugating organometallic moieties with organic fragments for enhanced efficacy

In the search for novel ligands with efficacy against various diseases, particularly parasitic diseases, molecular hybridization of organometallic units into biologically active scaffolds has been hailed as an appealing strategy in medicinal chemistry. The conjugation to organometallic fragments can be achieved by an appropriate linker or by directly coordinating the existing drugs to a metal. The success of Ferroquine (FQ, SR97193), an effective chloroquine-ferrocene conjugate currently undergoing the patient-exploratory phase as a combination therapy with the novel triaminopyrimidine ZY-19489 for malaria, has sparked intense interest in organometallic compound drug discovery. We present the evolution of organometallic antimalarial agents over the last decade, focusing on the parent moiety's class and the type of organometallics involved. Four main organometallic antimalarial compounds have been chosen based on conjugated organic moieties: existing antimalarial drugs, other clinical drugs, hybrid drugs, and promising scaffolds of thiosemicarbazones, benzimidazoles, and chalcones, in particular. The presented insights contribute to the ongoing discourse on organometallic compound drug development for malaria diseases.

Exploring the Synthetic and Antioxidant Potential of 1,2-Disubstituted Benzimidazoles Using [Et3NH][HSO4] Ionic Liquid Catalyst

An [Et3NH][HSO4] ionic-liquid catalyzed, intermolecular C-N bond formation for 1,2-disubstituted benzimidazole synthesis was achieved by the reaction of OPD and substituted aldehydes at ambient reaction conditions. Operational simplicity, use of easily available substrate and reagents, good yields (74-95 %) in short reaction time (4-18 min), simple work-up, and column chromatographic free synthesis are the remarkable features of this new protocol. The applicability of [Et3NH][HSO4] ionic-liquid as a green and inexpensive catalyst with good recyclability and compatibility with a broad range of functional group having heteroatom, electron-withdrawing, and electron-releasing groups manifested the sustainability, eco-friendliness, and efficiency of the present methodology. Moreover, the antioxidant studies of the synthesized compounds using DPPH and ABTS assays were appealing and several synthesized compounds showed significant antioxidant activity.

State-of-the-art Review on the Antiparasitic Activity of Benzimidazolebased Derivatives: Facing Malaria, Leishmaniasis, and Trypanosomiasis

Protozoan parasites represent a significant risk for public health worldwide, afflicting particularly people in more vulnerable categories and cause large morbidity and heavy economic impact. Traditional drugs are limited by their toxicity, low efficacy, route of administration, and cost, reflecting their low priority in global health management. Moreover, the drug resistance phenomenon threatens the positive therapy outcome. This scenario claims the need of addressing more adequate therapies. Among the diverse strategies implemented, the medicinal chemistry efforts have also focused their attention on the benzimidazole nucleus as a promising pharmacophore for the generation of new drug candidates. Hence, the present review provides a global insight into recent progress in benzimidazole-based derivatives drug discovery against important protozoan diseases, such as malaria, leishmaniasis and trypanosomiasis. The more relevant chemical features and structure-activity relationship studies of these molecules are discussed for the purpose of paving the way towards the development of more viable drugs for the treatment of these parasitic infections.

Dual Photochemistry of Benzimidazole

Monomers of benzimidazole trapped in an argon matrix at 15 K were characterized by vibrational spectroscopy and identified as 1H-tautomers exclusively. The photochemistry of matrix-isolated 1H-benzimidazole was induced by excitations with a frequency-tunable narrowband UV light and followed spectroscopically. Hitherto unobserved photoproducts were identified as 4H- and 6H-tautomers. Simultaneously, a family of photoproducts bearing the isocyano moiety was identified. Thereby, the photochemistry of benzimidazole was hypothesized to follow two reaction pathways: the fixed-ring and the ring-opening isomerizations. The former reaction channel results in the cleavage of the NH bond and formation of a benzimidazolyl radical and an H-atom. The latter reaction channel involves the cleavage of the five-membered ring and concomitant shift of the H-atom from the CH bond of the imidazole moiety to the neighboring NH group, leading to 2-isocyanoaniline and subsequently to the isocyanoanilinyl radical. The mechanistic analysis of the observed photochemistry suggests that detached H-atoms, in both cases, recombine with the benzimidazolyl or isocyanoanilinyl radicals, predominantly at the positions with the largest spin density (revealed using the natural bond analysis computations). The photochemistry of benzimidazole therefore occupies an intermediate position between the earlier studied prototype cases of indole and benzoxazole, which exhibit exclusively the fixed-ring and the ring-opening photochemistries, respectively.

Design, Synthesis, Docking Study, and Antiproliferative Evaluation of Novel Schiff Base-Benzimidazole Hybrids with VEGFR-2 Inhibitory Activity

A new series of Schiff-benzimidazole hybrids 3a-o has been designed and synthesized. The structure of the target compounds was proved by different spectroscopic and elemental analysis tools. The target compounds were evaluated for their in vitro cytotoxic activity against 60 cancer cell lines according to NCI single- and five-dose protocols. Consequently, four compounds were further examined against the most sensitive lung cancer A549 and NCI-H460 cell lines. Compounds 3e and 3g were the most active, achieving 3.58 ± 0.53, 1.71 ± 0.17 and 1.88 ± 0.35, 0.85 ± 0.24 against A549 and NCI-H460 cell lines, respectively. Moreover, they showed remarkable inhibitory activity on the VEGFR-2 TK with 86.23 and 89.89%, respectively, as compared with Sorafenib (88.17%). Moreover, cell cycle analysis of NCI-H460 cells treated with 3e and 3g showed cellular cycle arrest at both G1 and S phases (supported by caspases-9 study) with significant pro-apoptotic activity, as indicated by annexin V-FITC staining. The binding interactions of these compounds were confirmed through molecular docking studies; the most active compounds displayed complete overlay with, and a similar binding mode and pose to, Sorafenib, a reference VEGFR-2 inhibitor.