Synthesis and Reactivity of [1,2,4]Triazolo-annelated Quinazolines

Significant pharmacological activities of benzoquinazolines scaffold

Benzoquinazolines, the essential constituents of numerous well-known heterocyclic systems, have occupied a prominent position and played a significant part in the synthesis of various pharmaceutical compounds. The wide range of pharmacological effects attributed to benzoquinazolines has been the subject of extensive study. These include their roles as anticancer, antimicrobial, anti-monoamine oxidase, anticonvulsant, antiviral, antinociceptive, antioxidant, antineoplastic, antituberculosis, antiplatelet, and antiphlogistic agents. This work provides an attempt at a literature review of the pharmacological activities of benzoquinazoline derivatives, including an up-to-date account of recent research findings, and suggests avenues for future exploration in the pursuit of more potent and specific analogues for a wide range of biological targets using this platform.

DFT Calculation, Hirshfeld Analysis and X-Ray Crystal Structure of Some Synthesized N-alkylated(S-alkylated)-[1,2,4]triazolo[1,5-a]quinazolines

The present work aimed to synthesize 2-methylthio-triazoloquinazoline derivatives and study their X-ray, NMR, DFT and Hirshfeld characteristics. The cyclocondensation of dimethyl-N-cyanodithiocarbonate with 2-hydrazinobenzoic acid hydrochloride resulted in an intermediate, 2-methylthio-[1,2,4]triazolo[1,5-a]quinazolin-5-one (A), which upon treatment with phosphorus pentasulfide, transformed into the 2-methylthio-[1,2,4]triazolo[1,5-a]quinazolin-5-thione (B). Reaction of 2-methylthio-triazoloquinazolines (A&B) with alkyl halides (allyl bromide and ethyl iodide) in basic medium afforded 4-allyl-2-methylthio-[1,2,4]triazolo[1,5-a]quinazolin-5-one (1; N-alkylated) and 5-ethylthio-2-methylthio-[1,2,4]triazolo[1,5-a]quinazoline (2; S-alkylated), respectively. Their molecular and supramolecular structures were presented. Unambiguously, the molecular structures of 1 and 2 were confirmed via NMR and single-crystal X-ray diffraction. The resulting findings confirmed the structures of 1 and 2 and determined their crystalized system (monoclinic system; P21/n space group). Hirshfeld analysis of 1 revealed the importance of the significantly short O···H (6.7%), S···S (1.2%) and C···C (2.8%); however, the short H···H (42.6%), S···H (16.3%) and C···C (4.3%) were showed in 2 by intermolecular interactions in the molecular packing. The 1,2,4-triazoloquinzolines (1&2) were anticipated to be relatively polar compounds with net dipole moments of 2.9284 and 4.2127 Debye, respectively. The molecular electrostatic potential, atomic charge distribution maps and reactivity descriptors for 1 and 2 were also determined. The calculated nuclear magnetic resonance spectra of the targets 1 and 2 were well correlated with the experimental data.

An overview of triazoloquinazolines: Pharmacological significance and recent developments

Nitrogen heterocyclic rings have participated to constitute most of the drugs and several pharmacologically related compounds. The existence of such hetero atoms/groups in heterocyclic systems privileged specificities in their biological objectives. Particularly, quinazoline and triazole are biologically imperative platforms known to be linked with various pharmacological activities. Some of the prominent pharmacological responses ascribed to these systems are analgesic, antiinflammatory, anticonvulsant, hypnotic, antihistaminic, antihypertensive, anticancer, antimicrobial, antitubercular, antiviral and antimalarial activities. This diversity in the pharmacological outputs for both triazole and quinazoline systems has encouraged the medicinal chemistry researchers to create several chemical routes aiming at the incorporation of two rings in one molecule named triazoloquinazoline system. This system has shown multiple potential activities against numerous targets. Correlation the specific structural features of triazoloquinazoline system with its pharmacological purposes has successively been achieved by performing several pharmacological examinations and structure-activity relationship studies. The development of triazoloquinazoline derivatives and the understanding of their pharmacological targets offer opportunities for novel therapeutics. This review mainly emphases on the medicinal chemistry aspects of triazoloquinazolines including synthesis, reactivity, biological activity and structure activity relationship studies (SARs). Moreover, this review collates literature reported by researchers on triazoquinazolines and provides detailed attention on their analogs pharmacological activities in the perspective of drug development and discovery.

Free radical scavengers: An overview on heterocyclic advances and medicinal prospects

In the present scenario, there has been a lot of consideration toward the field of free radical chemistry. Free radicals responsive oxygen species are produced by different endogenous frameworks, exposure to various physicochemical conditions, radiation, toxins, metabolized drug by-product, and pathological states. On the off chance that free radical overpowers the body's capacity, it generates a condition known as oxidative stress, which can alter physiological conditions of the body and results in several diseases. For appropriate physiological function, it is necessary to have a proper balance between free radicals and antioxidants. Antioxidants chemically inhibit the oxidation process; they are also known as free radical scavengers. For tackling the problem of oxidative stress application of an external source of antioxidant is helpful. A lot of antioxidants of natural, semi-synthetic and synthetic origin are in use, with time search of more effective, nontoxic, safe antioxidant is intensified. The present review, discuss different synthetic derivatives bearing various heterocyclic scaffolds as radical scavengers.

Triazoloquinazolines as a new class of potent α-glucosidase inhibitors: in vitro evaluation and docking study

Previously, we synthesized triazoloquinazolines 1–14 and characterized their structure. In this study, we aimed to evaluate the in vitro activity of the targets 1–14 as α-glucosidase inhibitors using α-glucosidase enzyme from Saccharomyces cerevisiae type 1. Among the tested compounds, triazoloquinazolines 14, 8, 4, 5, and 3 showed the highest inhibitory activity (IC₅₀ = 12.70 ± 1.87, 28.54 ± 1.22, 45.65 ± 4.28, 72.28 ± 4.67, and 83.87 ± 5.12 μM, respectively) in relation to that of acarbose (IC₅₀ = 143.54 ± 2.08 μM) as a reference drug. Triazoloquinazolines were identified herein as a new class of potent α-glucosidase inhibitors. Molecular docking results envisaged the plausible binding interaction between the target triazoloquinazolines and α-glucosidase enzyme and indicated considerable interaction with the active site residues.

Synthesis and biological evaluation of 4-(1H-1,2,4-triazol-1-yl)benzoic acid hybrids as anticancer agents

A series of 4-(1H-1,2,4-triazol-1-yl)benzoic acid hybrids (1-17) was successfully synthesized and their structures were established by NMR and MS analysis. In vitro cytotoxic evaluation indicated that some of the hybrids exhibited potent inhibitory activities against MCF-7 and HCT-116 cancer cell lines, with IC50 values ranging from 15.6 to 23.9 µM, compared with reference drug doxorubicin (19.7 and 22.6 µM, respectively). Notably, the most potent compounds, 2, 5, 14, and 15, not only exhibited an obvious improvement in IC50 values, but demonstrated very weak cytotoxic effects toward normal cells (RPE-1) compared with doxorubicin. A further investigation showed that compounds 2 and 14 clearly inhibited the proliferation of MCF-7 cancer cells by inducing apoptosis. In addition, these hybrids showed acceptable correlation with bioassay results in regression plots generated by 2D QSAR models. Our results indicated that 1,2,4-triazole benzoic acid hybrids could be used as a structural optimization platform for the design and development of more selective and potent anticancer molecules.

Screening and evaluation of antioxidant activity of some 1,2,4-triazolo[1,5-a]quinazoline derivatives

Aim: The present study was carried out to assess a new series of triazoloquinazolines 1–40 for their antioxidant activities using 1,1-diphenyl-2-picryl hydrazyl radical scavenging, ferric reduction antioxidant power and reducing power capability assays. Results: All triazoloquinazolines 1–40 exhibited antioxidant activity ranged from weak to moderate and high. The obtained findings revealed that the triazoloquinazolines 30, 36 and 38–40 have superiority among all compounds, demonstrating the highest capacity to deplete 1,1-diphenyl-2-picryl hydrazyl and free radicals, in relation to butylated hydroxyl toluene, as a synthetic antioxidant agent. Conclusion: Chemical modifications together with density functional theory study on the targets supplied us with some valuable clarifications about the required properties needed for the target compounds to be more active against free radicals.

Cytotoxicity evaluation of a new set of 2-aminobenzo[de]iso-quinoline-1,3-diones

A new series of 2-amino-benzo[de]isoquinoline-1,3-diones was synthesized and fully characterized in our previous paper. Here, their cytotoxic effects have been evaluated in vitro in relation to colon HCT-116, hepatocellular Hep-G2 and breast MCF-7 cancer cell lines, using a crystal violet viability assay. The IC₅₀-values of the target compounds are reported in µg/mL, using doxorubicin as a reference drug. The findings revealed that compounds 14, 15, 16, 21 and 22 had significant cytotoxic effects against HCT-116, MCF-7 and Hep-G2 cell lines. Their IC₅₀ values ranged between 1.3 and 8.3 μg/mL in relation to doxorubicin (IC₅₀ ≈ 0.45–0.89 μg/mL). Therefore, these compounds could be used as templates for furthering the development and design of more potent antitumor agents through structural modification.

Biological effects of a new set 1,2,4-triazolo[1,5-a]quinazolines on heart rate and blood pressure

BACKGROUND

Several quinazoline and triazole derivatives are reported to possess a wide-range of interesting pharmacological effects. Although various triazoloquinazoline subclasses having been synthesized and studied, the preparation of 1,2,4-triazolo[1,5-a]quinazolines as antihypertensive agent is still relatively unexplored. In continuation of our earlier research, we aimed at the synthesis and development of various potent antihypertensive 1,2,4-triazoloquinazoline derivatives.

RESULTS

A new series of 1,2,4-triazolo[1,5-a]quinazoline derivatives have been synthesized. Their structures were mainly established by spectroscopic methods of analysis (IR, MS, 1H and 13C NMR). Their in vivo antihypertensive activity was evaluated by tail cuff method using Muromachi Blood Pressure Monitor (Model MK 2000) for rats and mice. Some of the tested compounds were found to exhibit valuable effects in terms of heart rate and blood pressure. According to the biological results, some of tested derivatives have abolished completely the tachycardia of the parent compounds and may be studied and modified as potential adrenoblockers and cardiac stimulant.

CONCLUSION

New series of fifteen 1,2,4-triazolo[1,5-a]quinazolines were synthesized by convenient methodology from four key molecules, whereby their structures were established by advanced spectroscopic analyses. Some lead compounds have abolished completely the tachycardia of the parent compounds, that may be examined as potent adrenoblockers and some other compounds seem to be a cardiac stimulant or may be modified to enhance their hypotensive activity.

Antimicrobial activity of newly synthesized methylsulfanyl-triazoloquinazoline derivatives

OBJECTIVE

The aim of this research was to study and evaluate the antimicrobial activity of a novel 2-methylsulfanyl-[1,2,4]triazolo[1,5-a]quinazoline and its derivatives. Antibacterial activity of the target compounds was tested against a variety of species of Gram-positive bacteria such as Staphylococcus aureus ATCC 29213, Bacillus subtilis ATCC6633, and Gram-negative bacteria such as Pseudomonas aeruginosa ATCC27953 and Escherichia coli ATCC 25922. In addition some yeast and fungi, Candida albicans NRRL Y-477 and Aspergillus niger, respectively, were screened.

METHODS

Antimicrobial tests were carried out by the agar well diffusion method, using 100 μl of suspension containing 1 × 10(8)  CFU/ml of pathological tested bacteria, 1 × 10(6)  CFU/ml of yeast, and 1 × 10(4)  spore/ml of fungi spread on nutrient agar (NA), Sabourand dextrose agar (SDA), and potato dextrose agar (PDA), respectively.

KEY FINDINGS

The minimum inhibitory concentration (MIC) of the tested compounds was determined using the broth double dilution method (serially diluted technique) in proper nutrient. For comparison, ciprofloxacin and ketoconazole were used as antibacterial and antifungal reference drugs, respectively. Compounds 6, 9, 13, 14, and 11 were found to have the highest broad-spectrum antibacterial activity against S. aureus ATCC 29213, B. subtilis ATCC6633 and Gram-negative bacteria such as P. aeruginosa ATCC27953 and E. coli ATCC 25922 with MIC values of 6.25 and 12.50 μg/ml.

CONCLUSIONS

It was clear that many of the synthesized compounds exhibited good antimicrobial activity. This study has revealed that compounds 6, 9, 13, 14, and 11 have been disclosed as moderate antimicrobial agents. These compounds could be useful as templates for further development through modification or derivatization to design more potent antimicrobial agents.

2-Eth-oxy-5-methylbis[1,2,4]triazolo[1,5-a:4',3'-c]quinazoline

The title compound, C₁₃H₁₂N₆O, is a functionalized ditriazoloquinazoline with substituted eth­oxy and methyl groups attached at the 2-position of each triazole spacer. The fused-ring system is essentially planar [r.m.s. deviation = 0.016 (2) Å]. In the crystal, a weak C—H⋯N hydrogen bond connects the mol­ecules into a chain along [101].

2-Benz-yloxy-1,2,4-triazolo[1,5-a]quinazolin-5(4H)-one

The title compound, C₁₆H₁₂N₄O₂, is a functionalized triazoloquinazoline with a substituted benz­yloxy group attached at the 2-position of a triazole spacer. The triazoloquinazoline fused-ring system is approximately planar (r.m.s. deviation = 0.016 Å) while the benzyl substituent is perpendicular to the ring system, making a dihedral angle of 65.29 (6)°. The phenyl ring of the benz­yloxy moiety is equally disordered over two sets of sites. A centrosymmetric N—H⋯N hydrogen bond connects mol­ecules into dimers.