Synthesis and systemic toxicity assessment of quinine-triazole scaffold with antiprotozoal potency

Molecular Docking, Synthesis, and Characterization of Furanyl-Pyrazolyl Acetamide and 2,4-Thiazolidinyl-Furan-3-Carboxamide Derivatives as Neuroinflammatory Protective Agents

Microglia are key immune cells in the brain that maintain homeostasis and defend against immune threats. Targeting the dysfunctional microglia is one of the most promising approaches to inhibit neuroinflammation. In the current study, a diverse series of molecular hybrids were designed and screened through molecular docking against two neuroinflammatory targets, namely HMGB1 (2LY4) and HMGB1 Box A (4QR9) proteins. Based on the outcomes of docking scores fifteen compounds; ten furanyl-pyrazolyl acetamides 11(a-j), and five 2,4-thiazolidinyl-furan-3-carboxamide 15(a-e) derivatives were selected for further synthesis, followed by biological evaluation. The selected compounds, 11(a-j) and 15(a-e) were successfully synthesized with moderate to good yields, and structures were confirmed by IR, NMR, and mass spectra. The in-vitro cytotoxicity was evaluated on microglial cells namely BV-2, N-9, HMO6, leukemic HAP1, and human fibroblast cells. Further western-blot analysis revealed that 11h, 11f, 11c, 11j, 15d, 15c, 15e, and 15b compounds significantly suppressed anti-inflammatory markers such as TNF-α, IL-1, IL-6, and Bcl-2. All derivatives were moderate in potency compared to reference doxorubicin and could potentially act as novel anti-neuroinflammatory agents. This study can act as a beacon for further research in the application of furan-pyrazole and furan-2,4-thiazolidinediones as lead moieties for anti-neuroinflammatory and related diseases.

Synthesis, Molecular Docking, and Biological Evaluation of Novel Indole-triazole Conjugates

BACKGROUND

Indole-triazole conjugates have emerged as promising candidates for new drug development. Their distinctive structural characteristics, coupled with a wide array of biological activities, render them a captivating and promising field of research for the creation of novel pharmaceutical agents.

OBJECTIVE

This study aimed to synthesize indole-triazole conjugates to investigate the influence of various substituents on the functional characteristics of indole-triazole hybrids. It also aimed to study the binding modes of new hybrids with the DNA Gyrase using molecular docking studies.

METHODS

A new set of indole-triazole hybrids was synthesized and characterized using various physicochemical and spectral analyses. All hybrids underwent in-silico pharmacokinetic prediction studies. The antimicrobial efficacy of the hybrids was assessed using tube dilution and agar diffusion methods. Additionally, the in-vitro antioxidant activity of synthesized compounds was determined using the 1,1-diphenyl-2-picryl-hydrazyl free radical scavenging assay. Furthermore, in silico molecular docking studies were performed to enhance our comprehension of how the synthesized compounds interact at the molecular level with DNA gyrase.

RESULTS

Pharmacokinetic predictions of synthesized hybrids indicated favourable pharmacokinetic profiles, and none of the compounds violated the Lipinski rule of five. Notably, compound 6, featuring a cyclohexanol substituent, demonstrated superior antimicrobial and antioxidant activity (EC50 value = 14.23 μmol). Molecular docking studies further supported the in vitro antioxidant and antimicrobial findings, revealing that all compounds adeptly fit into the binding pocket of DNA Gyrase and engaged in interactions with crucial amino acid residues.

CONCLUSION

In summary, our research underscores the efficacy of molecular hybridization in shaping the physicochemical, pharmacokinetic, and biological characteristics of novel indole-triazole derivatives.

Molecular Hybridization of Alkaloids Using 1,2,3-Triazole-Based Click Chemistry

Alkaloids found in multiple species, known as 'driver species', are more likely to be included in early-stage drug development due to their high biodiversity compared to rare alkaloids. Many synthetic approaches have been employed to hybridize the natural alkaloids in drug development. Click chemistry is a highly efficient and versatile reaction targeting specific areas, making it a valuable tool for creating complex natural products and diverse molecular structures. It has been used to create hybrid alkaloids that address their limitations and serve as potential drugs that mimic natural products. In this review, we highlight the recent advancements made in modifying alkaloids using click chemistry and their potential medicinal applications. We discuss the significance, current trends, and prospects of click chemistry in natural product-based medicine. Furthermore, we have employed computational methods to evaluate the ADMET properties and drug-like qualities of hybrid molecules.

Triazole hybrid compounds: A new frontier in malaria treatment

Reviewing the advancements in malaria treatment, the emergence of triazole hybrid compounds stands out as a groundbreaking development. Combining the advantages of triazole and other moieties, these hybrid compounds offer a new frontier in the battle against malaria. Their potential as effective antimalarial agents has captured the attention of researchers and holds promise for overcoming the challenges posed by drug-resistant malaria strains. We focused on their broad spectrum of antimalarial activity of diverse hybridized 1,2,3-triazoles and 1,2,4-triazoles, structure-activity relationship (SAR), drug-likeness, bioavailability and pharmacokinetic properties reported since 2018 targeting multiple stages of the Plasmodium life cycle. This versatility makes them highly effective against both drug-sensitive and drug-resistant strains of P. falciparum, making them invaluable tools in regions where resistance is prevalent. The synergistic effects of combining the triazole moiety with other pharmacophores have resulted in even greater antimalarial potency. This approach has the potential to circumvent existing resistance mechanisms and provide a more sustainable solution to malaria treatment. While triazole hybrid compounds show great promise, further research and clinical trials are warranted to fully evaluate their safety, efficacy and long-term effects. As research progresses, these compounds can potentially revolutionize the field and contribute to global efforts to eradicate malaria, ultimately saving countless lives worldwide.

Current development of 1,2,3-triazole derived potential antimalarial scaffolds: Structure- activity relationship (SAR) and bioactive compounds

Malaria is among one of the most devastating and deadliest parasitic disease in the world claiming millions of lives every year around the globe. It is a mosquito-borne infectious disease caused by various species of the parasitic protozoan of the genus Plasmodium. The indiscriminate exploitation of the clinically used antimalarial drugs led to the development of various drug-resistant and multidrug-resistant strains of plasmodium which severely reduces the therapeutic effectiveness of most frontline medicines. Therefore, there is urgent need to develop novel structural classes of antimalarial agents acting with unique mechanism of action(s). In this context, design and development of hybrid molecules containing pharmacophoric features of different lead molecules in a single entity represents a unique strategy for the development of next-generation antimalarial drugs. Research efforts by the scientific community over the past few years has led to the identification and development of several heterocyclic small molecules as antimalarial agents with high potency, less toxicity and desired efficacy. Triazole derivatives have become indispensable units in the medicinal chemistry due to their diverse spectrum of biological profiles and many triazole based hybrids and conjugates have demonstrated potential in vitro and in vivo antimalarial activities. The manuscript compiled recent developments in the medicinal chemistry of triazole based small heterocyclic molecules as antimalarial agents and discusses various reported biologically active compounds to lay the groundwork for the rationale design and discovery of triazole based antimalarial compounds. The article emphasised on biological activities, structure activity relationships, and molecular docking studies of various triazole based hybrids with heterocycles such as quinoline, artemisinins, naphthyl, naphthoquinone, etc. as potential antimalarial agents which could act on the dual stage and multi stage of the parasitic life cycle.

Recent developments in the synthesis of hybrid antimalarial drug discovery

In this 21st century, Malaria remains a global burden and causes massive economic trouble to disease-endemic nations. The control and eradication of malaria is a major challenge that requires an urgent need to develop novel antimalarial drugs. To overcome the aforementioned situation, several researchers have given significant effort to develop hybrid antimalarial agents in the search for new antimalarial drugs. Hence, we have summarized those developments of hybrid antimalarial agents from 2017 to till date. This review illustrates the current progress in the recent synthesis of hybrid antimalarial agents along with focusing on their antimalarial evaluation to find the most potent hybrids. This present mini-review will also be useful for the scientific community for the development of new antimalarial drugs to eradicate malaria.

In Vitro Evaluation of Antiprotozoal Properties, Cytotoxicity Effect and Anticancer Activity of New Essential-Oil Based Phytoncide Mixtures

Protozoa, in both humans and animals, are one of the leading causes of disease. International programmes introduced in many countries have helped reduce the incidence of disease. However, it has recently become increasingly difficult to achieve the goals set for the coming years. One of the main reasons for this, as with other pathogenic organisms, such as bacteria and fungi, is the increasing resistance to current methods of treating and preventing infection. Therefore, new therapies with high efficacy are needed. In the present study, the novel mixtures of essential oils (EOs), clove, garlic, Ceylon cinnamon, and rosemary with organic acids (acetic, propionic, lactic) and metal ions (Cu, Mn, Zn) were tested against five selected model protozoa (Euglena gracilis, Gregarina blattarum, Amoeba proteus, Paramecium caudatum, Pentatrichomonas hominis). The cytotoxicity and potential anticancer activity of the obtained combinations were tested on the human fibroblasts (NHDF) and human cancer cell lines (A549, MCF7, LoVo, HT29). All of the mixtures showed very good antiprotozoal properties. The most efficient were the combination of clove and rosemary essential oils, mixtures of acids, and Mn ions. The LD₅₀ values were in the range of 0.001-0.006% and the LD₁₀₀ values were 0.002-0.008%. All of the tested mixtures did not show cytotoxicity against normal cells, but did show growth inhibition against cancer cell lines. The most cytotoxic against cancer cells were combinations with cinnamon essential oil. Nevertheless, the proposed combinations containing essential oils, organic acids, and metal ions have high antiprotozoal activity, with low toxicity to healthy human cells.

Mechanochemical Approach towards Multi-Functionalized 1,2,3-Triazoles and Anti-Seizure Drug Rufinamide Analogs Using Copper Beads

Highly regiospecific, copper-salt-free and neat conditions have been demonstrated for the 1,3-dipolar azide-alkyne cycloaddition (AAC) reactions under mechanochemical conditions. A group of structurally challenging alkynes and heterocyclic derivatives was efficiently implemented to achieve highly functionalized 1,4-disubstituted-1,2,3-triazoles in good to excellent yield by using the Cu beads without generation of unwanted byproducts. Furthermore, the high-speed ball milling (HSBM) strategy has also been extended to the synthesis of the commercially available pharmaceutical agent, Rufinamide, an antiepileptic drug (AED) and its analogues. The same strategy was also applied for the synthesis of the Cl-derivative of Rufinamide. Analysis of the single crystal XRD data of the triazole was also performed for the final structural confirmation. The Cu beads are easily recoverable from the reaction mixture and used for the further reactions without any special treatment.

Novel Formula of Antiprotozoal Mixtures

Antimicrobial resistance (AMR) is becoming more common in both bacteria and pathogenic protozoa. Therefore, new solutions are being sought as alternatives to currently used agents. There are many new ideas and solutions, especially compounds of natural origin, including essential oils. In the present study, the antiprotozoal activity of a mixture of essential oils (eucalyptus, lavender, cedar and tea tree), organic acids (acetic acid, propionic acid and lactic acid) and metal ions (Cu, Zn, Mn) were tested. As a model, protozoans were selected: Euglena gracilis, Gregarina blattarum, Amoeba proteus, Paramecium caudatum, Pentatrichomonas hominis. The tested concentrations of mixtures were in the range of 0.001-1.5%. The analyses show unexpected, very strong protozoicidal activity of combinations, presenting the synergy of compounds via determination of LD50 and LD100 values. Obtained mixtures showed significantly higher activity against protozoans, compared to chloramphenicol and metronidazole. Most of the analyzed samples show high antiprotozoal activity at very low concentration, in the range of 0.001-0.009%. The most effective combinations for all analyzed protozoans were the cedar essential oil and tea tree essential oil with a mixture of acids and manganese or zinc ions. Innovative combinations of essential oils, organic acids and metal ions are characterized by very high antiprotozoal activity at low doses, which, after further investigation, can be applicable for control of protozoan pathogens.

Green solvent-free synthesis of new N-heterocycle-L-ascorbic acid hybrids and their antiproliferative evaluation

Aim: The authors' aim was to improve the application of copper-catalyzed azide-alkyne cycloaddition in the synthesis of hybrids containing biologically significant nucleobases and L-ascorbic acid scaffolds by introducing an environmentally friendly and waste-free ball mill. Results: Two series of hybrids with a purine, pyrrolo[2,3- d]pyrimidine or 5-substituted pyrimidine attached to 2,3-dibenzyl-L-ascorbic acid via a hydroxyethyl- (15a–23a) or ethylidene-1,2,3-triazolyl (15b–23b) bridge were prepared by ball milling and conventional synthesis. The unsaturated 6-chloroadenine L-ascorbic acid derivative 16b can be highlighted as a lead compound and showed strong antiproliferative activity against HepG2 (hepatocellular carcinoma) and SW620 (colorectal adenocarcinoma) cells. Conclusion: Mechanochemical synthesis was superior in terms of sustainability, reaction rate and yield, highlighting the advantageous applications of ball milling over classical reactions.

Application of triazoles in the structural modification of natural products

Nature products have been extensively used in the discovery and development of new drugs, as the most important source of drugs. The triazole ring is one of main pharmacophore of the nitrogen-containing heterocycles. Thus, a new class of triazole-containing natural product conjugates has been synthesised. These compounds reportedly exert anticancer, anti-inflammatory, antimicrobial, antiparasitic, antiviral, antioxidant, anti-Alzheimer, and enzyme inhibitory effects. This review summarises the research progress of triazole-containing natural product derivatives involved in medicinal chemistry in the past six years. This review provides insights and perspectives that will help scientists in the fields of organic synthesis, medicinal chemistry, phytochemistry, and pharmacology.

Click Chemistry in Natural Product Modification

Click chemistry is perhaps the most powerful synthetic toolbox that can efficiently access the molecular diversity and unique functions of complex natural products up to now. It enables the ready synthesis of diverse sets of natural product derivatives either for the optimization of their drawbacks or for the construction of natural product-like drug screening libraries. This paper showcases the state-of-the-art development of click chemistry in natural product modification and summarizes the pharmacological activities of the active derivatives as well as the mechanism of action. The aim of this paper is to gain a deep understanding of the fruitful achievements and to provide perspectives, trends, and directions regarding further research in natural product medicinal chemistry.

Synthesis of Biologically Relevant 1,2,3- and 1,3,4-Triazoles: From Classical Pathway to Green Chemistry

Green Chemistry has become in the last two decades an increasing part of research interest. Nonconventional «green» sources for chemical reactions include micro-wave, mechanical mixing, visible light and ultrasound. 1,2,3-triazoles have important applications in pharmaceutical chemistry while their 1,2,4 counterparts are developed to a lesser extent. In the review presented here we will focus on synthesis of 1,2,3 and 1,2,4-triazole systems by means of classical and « green chemistry » conditions involving ultrasound chemistry and mechanochemistry. The focus will be on compounds/scaffolds that possess biological/pharmacophoric properties. Finally, we will also present the formal cycloreversion of 1,2,3-triazole compounds under mechanical forces and its potential use in biological systems.

Injectable In-Situ Forming Depot of Doxycycline Hyclate/α-Cyclodextrin Complex Using PLGA for Periodontitis Treatment: Preparation, Characterization, and In-Vitro Evaluation

BACKGROUND

Doxycycline (DOX) is used in treating a bacterial infection, especially for periodontitis treatment.

OBJECTIVE

To reduce irritation of DOX for subgingival administration and increase the chemical stability and against enzymatic, the complex of α-cyclodextrin with DOX was prepared and loaded into injectable in situ forming implant based on PLGA.

METHODS

FTIR, molecular docking studies, X-ray diffraction, and differential scanning calorimetry was performed to characterize the DOX/α-cyclodextrin complex. Finally, the in-vitro drug release and modeling, morphological properties, and cellular cytotoxic effects were also evaluated.

RESULTS

The stability of DOX was improved with complex than pure DOX. The main advantage of the complex is the almost complete release (96.31 ± 2.56 %) of the drug within 14 days of the implant, whereas in the formulation containing the pure DOX and the physical mixture the DOX with α-cyclodextrin release is reached to 70.18 ± 3.61 % and 77.03 ± 3.56 %, respectively. This trend is due to elevate of DOX stability in the DOX/ α-cyclodextrin complex form within PLGA implant that confirmed by the results of stability.

CONCLUSION

Our results were indicative that the formulation containing DOX/α-cyclodextrin complex was biocompatible and sustained-release with minimum initial burst release.

Bioisosteric Replacement of Amide Group with 1,2,3-Triazoles in Acetaminophen Addresses Reactive Oxygen Species-Mediated Hepatotoxic Insult in Wistar Albino Rats

Acetaminophen (AP) is a popularly recommended over-the-counter analgesic-antipyretic in clinical use. However, the drug is handicapped by the occurrence of hepatotoxic insult following acute ingestion. Consequently, AP-induced hepatotoxicity is often implicated in accidental or suicidal overdose. In the current study, we investigated the potential of bioisosteric replacement of amide in AP with 1,2,3-triazoles in curbing AP-induced hepatotoxicity. The therapeutic utility of synthesized bioisosteres was established by careful tailoring and optimization of the synthetic methodology along with detailed toxicological testing of pharmacologically potent acetaminophen-triazole derivatives (APTDs). Along the same lines, we herein report a series of 17 novel APTDs synthesized via aromatic substitution using sodium azide, l-proline, and copper iodide followed by click reaction with substituted alkynes using copper sulfate and sodium ascorbate. Pharmacological evaluation of synthesized APTDs revealed that, out of the series of 17 compounds, 5a and 5e were found to be most efficacious in exerting anti-inflammatory, analgesic, and antipyretic activity in an animal model. Further toxicity studies documented that, in both acute and sub-acute toxicology, AP administration caused significant hepatotoxicity, which was found to be a consequence of ROS-mediated oxidative stress. Potent APTDs (5a and 5e), on the other hand, revealed no adverse event in both acute and sub-toxicological analyses. Median lethal dose (LD₅₀) and no observed adverse effect level (NOAEL) values for 5a and 5e were found to be >1000 mg/kg and 2000 mg/kg, respectively. The human equivalent dose, defining the maximum safe concentration of a compound in a human's physiology, was found to be 27.68 mg/kg for the most potent APTDs (5a and 5e). Thus, it can be concluded that triazole incorporation into AP nucleus produced conjugates devoid of hepatotoxic manifestations, having the added advantage of anti-inflammatory efficacy along with analgesic and antipyretic potency.

Synthesis, Pharmacological and Toxicological Screening of Penicillin-Triazole Conjugates (PNTCs)

A series of hybrid antimicrobial compounds were prepared by carboxylic acid protection of 6-aminopenicillanic acid using benzyl alcohol and thionyl chloride succeeded by azide displacement using trifluoromethanesulfonyl azide in dichloromethane. The azide thus formed was reacted with substituted alkynes to furnish benzyl-protected penicillin-triazole conjugates. Benzyl deprotection of the conjugates resulted in furnishing PNTCs under water methanol mixture using Pd/C as a catalyst. The PNTCs (7a-j) formed were screened for in vitro antibacterial potency against pathogenic strains of Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Streptococcus pyogenes and antifungal potency against Candida albicans, Aspergillus niger, and Aspergillus clavatus. Further antimicrobial evaluation revealed compounds 7c, 7d, 7e, 7g, and 7i to be the most compounds of the series with minimum inhibitory concentration value for antibacterial in the range 0.5-50 μg/mL and for antifungal in the range 9-300 μg/mL. Toxicological analysis documented for compounds 7c, 7d, 7e, 7g, and 7i revealed compound 7i to be the most promising member of the series with 1000 and 500 mg/kg LD₅₀, and no-observed-adverse-effect level to facilitate future clinical studies of the same.