Benzothiazole-based apoptosis inducers: A comprehensive overview and future prospective

Cancer has become a major concern in healthcare globally, and over time, incidences and prevalence of cancer are increasing. To counter this, a lot of anticancer drugs are approved and are in clinical use, playing a pivotal role in its treatment. Due to drug resistance and adverse effects, a continuous demand for novel, potent, and safe candidates to treat cancer is always there. Over the last few decades, various heterocyclic ring-based derivatives have been explored and reported in the literature. In this regard, benzothiazole scaffold-based compound emerged as the versatile ring for developing novel and safe anticancer candidates. In this article, we have reported various benzothiazole heterocyclic ring-based derivatives demonstrating potent antiproliferative activity by induction of apoptosis via an intrinsic pathway in a dose-dependent manner. These compounds also displayed inhibition of different enzymes, for example, Aurora kinase, epidermal growth factor receptor, vascular endothelial growth factor receptor, phosphoinositide kinases, DNA topoisomerase, and tubulin polymerases. This study focused on a comprehensive overview of antiproliferative activity, structure-activity relationship, apoptosis induction activity, and enzyme inhibition by benzothiazole-based compounds.

Nitrogen-fused Heterocycles: Empowering Anticancer Drug Discovery

The worldwide impact of cancer is further compounded by the constraints of current anticancer medications, which frequently exhibit a lack of selectivity, raise safety apprehensions, result in significant adverse reactions, and encounter resistance mechanisms. The current situation highlights the pressing need to develop novel and more precise anticancer agents that prioritize safety and target specificity. Remarkably, more than 85% of drugs with physiological activity contain heterocyclic structures or at least one heteroatom. Nitrogen-containing heterocycles hold a significant position among these compounds, emerging as the most prevalent framework within the realm of heterocyclic chemistry. This article explores the medicinal chemistry behind these molecules, highlighting their potential as game-changing possibilities for anticancer medication development. The analysis highlights the inherent structural variety in nitrogen-containing heterocycles, revealing their potential to be customized for creating personalized anticancer medications. It also emphasizes the importance of computational techniques and studies on the relationships between structure and activity, providing a road map for rational medication design and optimization. Nitrogen- containing heterocycles are a promising new area of study in the fight against cancer, and this review summarises the state of the field so far. By utilizing their inherent characteristics and exploiting cooperative scientific investigations, these heterocyclic substances exhibit potential at the forefront of pioneering therapeutic approaches in combating the multifaceted obstacles posed by cancer.

Cu(ii)-catalyzed C-N coupling of 2-aminobenzothiazoles with boronic acids at room temperature

A Cu(ii)-catalyzed, effective C-N coupling of 2-aminobenzothiazoles with boronic acids in acetonitrile under open vessel chemistry was achieved. This protocol demonstrates the N-arylation of 2-aminobenzothiazoles with a broad range of differently substituted phenylboronic acids at room temperature and accomplishes moderate to excellent yields of the desired products. Under the optimized condition, phenylboronic acids bearing halogen at the para and meta positions were found to be more fruitful.

2-Aminobenzothiazoles in anticancer drug design and discovery

Cancer is one of the major causes of mortality and morbidity worldwide. Substantial research efforts have been made to develop new chemical entities with improved anticancer efficacy. 2-Aminobenzothiazole is an important class of heterocycles containing one sulfur and two nitrogen atoms, which is associated with a broad spectrum of medical and pharmacological activities, including antitumor, antibacterial, antimalarial, anti-inflammatory, and antiviral activities. In recent years, an extraordinary collection of potent and low-toxicity 2-aminobenzothiazole compounds have been discovered as new anticancer agents. Herein, we provide a comprehensive review of this class of compounds based on their activities against tumor-related proteins, including tyrosine kinases (CSF1R, EGFR, VEGFR-2, FAK, and MET), serine/threonine kinases (Aurora, CDK, CK, RAF, and DYRK2), PI3K kinase, BCL-XL, HSP90, mutant p53 protein, DNA topoisomerase, HDAC, NSD1, LSD1, FTO, mPGES-1, SCD, hCA IX/XII, and CXCR. In addition, the anticancer potentials of 2-aminobenzothiazole-derived chelators and metal complexes are also described here. Moreover, the design strategies, mechanism of actions, structure-activity relationships (SAR) and more advanced stages of pre-clinical development of 2-aminobenzothiazoles as new anticancer agents are extensively reviewed in this article. Finally, the examples that 2-aminobenzothiazoles showcase an advantage over other heterocyclic systems are also highlighted.

A minireview of 1,2,3-triazole hybrids with O-heterocycles as leads in medicinal chemistry

Over the past few decades, the dynamic progress in the synthesis and screening of heterocyclic compounds against various targets has made a significant contribution in the field of medicinal chemistry. Among the wide array of heterocyclic compounds, triazole moiety has attracted the attention of researchers owing to its vast therapeutic potential and easy preparation via copper and ruthenium-catalyzed azide-alkyne cycloaddition reactions. Triazole skeletons are found as major structural components in a different class of drugs possessing diverse pharmacological profiles including anti-cancer, anti-bacterial, anti-fungal, anti-viral, anti-oxidant, anti-inflammatory, anti-diabetic, anti-tubercular, and anti-depressant among various others. Furthermore, in the past few years, a significantly large number of triazole hybrids were synthesized with various heterocyclic moieties in order to gain the added advantage of the improved pharmacological profile, overcoming the multiple drug resistance and reduced toxicity from molecular hybridization. Among these synthesized triazole hybrids, many compounds are available commercially and used for treating different infections/disorders like tazobactam and cefatrizine as potent anti-bacterial agents while isavuconazole and ravuconazole as anti-fungal activities to name a few. In this review, we will summarize the biological activities of various 1,2,3-triazole hybrids with copious oxygen-containing heterocycles as lead compounds in medicinal chemistry. This review will be very helpful for researchers working in the field of molecular modeling, drug design and development, and medicinal chemistry.

2-Substituted Benzoxazoles as Potent Anti-Inflammatory Agents: Synthesis, Molecular Docking and In Vivo Anti-Ulcerogenic Studies

BACKGROUND

Non-steroidal anti-inflammatory drugs (NSAIDs) are the commonly used therapeutic interventions of inflammation and pain that competitively inhibit the cyclooxygenase (COX) enzymes. Several side effects like gastrointestinal and renal toxicities are associated with the use of these drugs. The therapeutic anti-inflammatory benefits of NSAIDs are produced by the inhibition of COX-2 enzymes, while undesirable side effects arise from the inhibition of COX-1 enzymes.

OBJECTIVES

In the present study, a new series of 2-substituted benzoxazole derivatives 2(a-f) and 3(a-e) were synthesized in our lab as potent anti-inflammatory agents with outstanding gastro-protective potential. The new analogs 2(a-f) and 3(a-e) were designed depending upon the literature review to serve as ligands for the development of selective COX-2 inhibitors.

METHODS

The synthesized analogs were characterized using different spectroscopic techniques (FTIR, 1HNMR, 13CNMR) and elemental analysis. All synthesized compounds were screened for their binding potential in the protein pocket of COX-2 and evaluated for their anti-inflammatory potential in animals using the carrageenan-induced paw edema method. Further 5 compounds were selected to assess the in vivo anti-ulcerogenic activity in an ethanol-induced anti-ulcer rat model.

RESULTS

Five compounds (2a, 2b, 3a, 3b and 3c) exhibited potent anti-inflammatory activity and significant binding potential in the COX-2 protein pocket. Similarly, these five compounds demonstrated a significant gastro-protective effect (p<0.01) in comparison to the standard drug, Omeprazole.

CONCLUSION

Depending upon our results, we hypothesize that 2-substituted benzoxazole derivatives have excellent potential to serve as candidates for the development of selective anti-inflammatory agents (COX-2 inhibitors). However, further assessments are required to delineate their underlying mechanisms.

1,2,3-Triazoles of 8-Hydroxyquinoline and HBT: Synthesis and Studies (DNA Binding, Antimicrobial, Molecular Docking, ADME, and DFT)

A new series of 1,2,3-triazole hybrids containing either 2- or 4-hydroxyphenyl benzothiazole (2- or 4-HBT) and naphthalen-1-ol or 8-hydroxyquinoline (8-HQ) was synthesized in high yields and fully characterized. In vitro DNA binding studies with herring fish sperm DNA (hs-DNA) showed that quinoline- and 2-HBT-linked 1,2,3-triazoles of shorter alkyl linkers such as 6a are better with a high binding affinity (3.90 × 105 L mol-1) with hs-DNA as compared to naphthol- and 4-HBT-linked 1,2,3-triazoles bound to longer alkyl linkers. Molecular docking of most active 1,2,3-triazoles 6a-f showed high binding energy of 6a (-8.7 kcal mol-1). Also, compound 6a displayed considerable antibacterial activity and superior antifungal activity with reference to ciprofloxacin and fluconazole, respectively. The docking results of the fungal enzyme lanosterol 14-α-demethylase showed high binding energy for 6a (-9.7 kcal mol-1) involving dominating H-bonds, electrostatic interaction, and hydrophobic interaction. The absorption, distribution, metabolism, and excretion (ADME) parameter, Molinspiration bioactivity score, and the PreADMET properties revealed that most of the synthesized 1,2,3-triazole molecules possess desirable physicochemical properties for drug-likeness and may be considered as orally active potential drugs. The electrophilicity index and chemical hardness properties were also studied by density functional theory (DFT) using the B3LYP/6-311G(d,p) level/basis set.

Design, synthesis, and biological evaluation of N-(4-substituted)-3-phenylisoxazolo[5,4-d]pyrimidin-4-amine derivatives as apoptosis-inducing cytotoxic agents

A library of new 3-phenylisoxazolo[5,4-d]pyrimidines (8-10) was designed based on a scaffold hybridization technique incorporating the important pharmacophoric features of 4-aminopyrimidine and phenyl isoxazole scaffold which is renowned for its BET inhibition activity. The designed molecules were synthesized and evaluated with the NCI-60 cell line panel. Examination by NCI-60 cell lines at single-dose and the five-dose study showed that compound 10h exhibited promising growth inhibitory effects with GI₅₀ values on various cancer cell lines such as HCT-15 (Colon Cancer)-0.0221 μM, MDA-MB-435 (Melanoma) - 0.0318 μM, SNB-75(CNS Cancer)-0.0263 μM, and MCF7 (Breast Cancer)-0.0372 μM. Further studies to know the mechanism of action of 10h based on the phase-contrast microscopic evaluation, DAPI, acridine orange/ethidium bromide (AO/EB) staining, and annexin V-FITC assays revealed that elevation in the intracellular ROS leads to alteration in mitochondrial membrane potential which in turn induced the apoptosis in BT-474 cancer cells, which could be the plausible mechanism of action for compound 10h.

Modern Approaches to the Synthesis and Transformations of Practically Valuable Benzothiazole Derivatives

The review is devoted to modern trends in the chemistry of 2-amino and 2-mercapto substituted benzothiazoles covering the literature since 2015. The reviewed heterocycles belong to biologically active and industrially demanded compounds. Newly developed synthesis methods can be divided into conventional multistep processes and one-pot, atom economy procedures, realized using green chemistry principles and simple reagents. The easy functionalization of the 2-NH2 and 2-SH groups and the benzene ring of the benzothiazole moiety allows considering them as highly reactive building blocks for organic and organoelement synthesis, including the synthesis of pharmacologically active heterocycles. The review provides a summary of findings, which may be useful for developing new drugs and materials and new synthetic approaches and patterns of reactivity.

Benzimidazole-1,2,3-triazole hybrid molecules: synthesis and study of their interaction with G-quadruplex DNA

A series of new benzimidazole-1,2,3-triazole hybrid derivatives have been synthesized via 'click' reaction and evaluated for their in vitro cytotoxicity as well as DNA binding affinity. MTT assay showed that all the six compounds are cytotoxic to PC3 and B16-F10 cancer cell lines. Though all the compounds showed moderate interaction with G4, c-Myc promoter DNA and dsDNA, 4f exhibited selective interaction with G-quadruplex DNA over duplex DNA as demonstrated by spectroscopic experiments like UV-vis spectroscopy, fluorescence spectroscopy, CD spectroscopy, thermal melting and fluorescence lifetime experiments. They also confirm the G-quadruplex DNA stabilizing potential of 4f. Viscosity measurements also confirm that 4f exhibits high G-quadruplex DNA selectivity over duplex DNA. Docking studies supported the spectroscopic observations. Cell cycle analysis showed that 4f induces G₂/M phase arrest and induces apoptosis. Hence, from these experimental results it is evident that compound 4f may be a G-quadruplex DNA groove binding molecule with anticancer activity.

Anticancer activity of benzoxazole derivative (2015 onwards): a review

Background

According to the report published recently by the World Health Organization, the number of cancer cases in the world will increase to 22 million by 2030. So the anticancer drug research and development is taking place in the direction where the new entities are developed which are low in toxicity and are with improved activity. Benzoxazole and its derivative represent a very important class of heterocyclic compounds, which have a diverse therapeutic area. Recently, many active compounds synthesized are very effective; natural products isolated with benzoxazole moiety have also shown to be potent towards cancer.

Main text

In the last few years, many research groups have designed and developed many novel compounds with benzoxazole as their backbone and checked their anticancer activity. In the review article, the recent developments (mostly after 2015) made in the direction of design and synthesis of new scaffolds with very potent anticancer activity are briefly described. The effect of various heterocycles attached to the benzoxazole and their effect on the anticancer activity are thoroughly studied and recorded in the review.

Conclusion

These compiled data in the article will surely update the scientific community with the recent development in this area and will provide direction for further research in this area.

Discovery of novel bis-sulfoxide derivatives bearing acylhydrazone and benzothiazole moieties as potential antibacterial agents

On the basis of the active substructure combination principle, 24 novel synthesis of novel bis-sulfoxide derivatives bearing acylhydrazone and benzothiazole moieties as potential antibacterial agents were designed and synthesized. The bioactivity assay results showed that many compounds had significant in vitro inhibitory effects against Xanthomonas oryzae pv. oryzae (Xoo) and Xanthomonas citri pv. citri (Xac). Notably, compound 4b had the best in vitro antibacterial activity against Xoo at an half-maximal effective concentration value of 11.4 μg/mL, which was superior to those of thiodiazole copper (TDC) and bismerthiazol (BMT). Compared with TDC and BMT, compound 4b was more effective in vivo controlling rice bacterial leaf blight with curative and protection activities of 42.5% and 40.3%, respectively. In addition, compound 4b can influence biofilm formation, inhibit extracellular polysaccharide production, and ultimately reduce the pathogenicity of Xoo. All the results indicated that bis-sulfoxide derivatives bearing acylhydrazone and benzothiazole moieties can be used for the development of small-molecule pesticides with high antibacterial activity.

1,2,3-Triazole-containing hybrids as leads in medicinal chemistry: A recent overview

The 1,2,3-triazole ring is a major pharmacophore system among nitrogen-containing heterocycles. These five-membered heterocyclic motifs with three nitrogen heteroatoms can be prepared easily using 'click' chemistry with copper- or ruthenium-catalysed azide-alkyne cycloaddition reactions. Recently, the 'linker' property of 1,2,3-triazoles was demonstrated, and a novel class of 1,2,3-triazole-containing hybrids and conjugates was synthesised and evaluated as lead compounds for diverse biological targets. These lead compounds have been demonstrated as anticancer, antimicrobial, anti-tubercular, antiviral, antidiabetic, antimalarial, anti-leishmanial, and neuroprotective agents. The present review summarises advances in lead compounds of 1,2,3-triazole-containing hybrids, conjugates, and their related heterocycles in medicinal chemistry published in 2018. This review will be useful to scientists in research fields of organic synthesis, medicinal chemistry, phytochemistry, and pharmacology.