Quinolone-isoniazid hybrids: synthesis and preliminary in vitro cytotoxicity and anti-tuberculosis evaluation

Design and fabrication of dysprosium impregnated polyvinyl alcohol hydrogels. Physiochemical, mechanical, bioimaging and in vitro evaluation

Tissue engineering has gained prominence during the past decade since it offers a key solution to defects associated with the tissue regeneration. The limited healing potential of the cartilage tissue damage has significant clinical implications. Herein, dysprosium (Dy3+) impregnated polyvinyl alcohol (PVA) hydrogels have been developed to enhance the therapeutic efficacy, enabling simultaneous diagnostic imaging and antibacterial drug delivery for potential applications in articular cartilage. Based on the favorable imaging features, Dy3+ impregnated PVA hydrogels with enhanced stability were formed through successive steps of repeated cycles of freezing at - 30 °C for 21 h, thawing at 25 °C for 4 h and lyophilization. The tensile and compression tests of the hydrogels respectively determined a maximum of 3.88 and 1.58 MPa, which reflected better compatibility towards cartilage. The hydrogels fetched a sustained drug release for a period of 12 h with an associated swelling ratio of 80%. The potential of the resultant hydrogels in image diagnosis has been deliberated through their blue and yellow emissions in the visible region. Further, the computed tomography (CT) and magnetic resonance imaging characteristics of the hydrogels respectively accomplished a maximum of 343 Hounsfiled units (HU) and relaxivity of 7.25 mM-1s-1. The cytocompatibility of the hydrogels is also determined through in vitro tests performed in Murine pro B cell line (BA/F3) and human Megakaryocyte cell line (Mo7e) cell lines.

Synthesis, Biological, Spectroscopic and Computational Investigations of Novel N-Acylhydrazone Derivatives of Pyrrolo[3,4-d]pyridazinone as Dual COX/LOX Inhibitors

Secure and efficient treatment of diverse pain and inflammatory disorders is continually challenging. Although NSAIDs and other painkillers are well-known and commonly available, they are sometimes insufficient and can cause dangerous adverse effects. As yet reported, derivatives of pyrrolo[3,4-d]pyridazinone are potent COX-2 inhibitors with a COX-2/COX-1 selectivity index better than meloxicam. Considering that N-acylhydrazone (NAH) moiety is a privileged structure occurring in many promising drug candidates, we decided to introduce this pharmacophore into new series of pyrrolo[3,4-d]pyridazinone derivatives. The current paper presents the synthesis and in vitro, spectroscopic, and in silico studies evaluating the biological and physicochemical properties of NAH derivatives of pyrrolo[3,4-d]pyridazinone. Novel compounds 5a-c-7a-c were received with high purity and good yields and did not show cytotoxicity in the MTT assay. Their COX-1, COX-2, and 15-LOX inhibitory activities were estimated using enzymatic tests and molecular docking studies. The title N-acylhydrazones appeared to be promising dual COX/LOX inhibitors. Moreover, spectroscopic and computational methods revealed that new compounds form stable complexes with the most abundant plasma proteins-AAG and HSA, but do not destabilize their secondary structure. Additionally, predicted pharmacokinetic and drug-likeness properties of investigated molecules suggest their potentially good membrane permeability and satisfactory bioavailability.

Hydrazone-Tethered 5-(Pyridin-4-yl)-4H-1,2,4-triazole-3-thiol Hybrids: Synthesis, Characterisation, in silico ADME Studies, and in vitro Antimycobacterial Evaluation and Cytotoxicity

Compounds containing arylpyrrole-, 1,2,4-triazole- and hydrazone structural frameworks have been widely studied and demonstrated to exhibit a wide range of pharmacological properties. Herein, an exploratory series of new 1,2,4-triazole derivatives designed by amalgamation of arylpyrrole and 1,2,4-triazole structural units via a hydrazone linkage is reported. The synthesised compounds were tested in vitro for their potential activity against Mycobacterium tuberculosis (MTB) H₃₇ Rv strain. The most promising compound 13 - the derivative without the benzene ring appended to the pyrrole unit displayed acceptable activity (MIC₉₀ =3.99 μM) against MTB H₃₇ Rv, while other compounds from the series exhibited modest to weak antimycobacterial activity with MIC₉₀ values in the range between 7.0 and >125 μM. Furthermore, in silico results, predicated using the SwissADME web tool, show that the prepared compounds display desirable ADME profile with parameters within acceptable range.

Pyrazinamide–isoniazid hybrid: synthesis optimisation, characterisation, and antituberculous activity

Over time, the effective resistance mechanisms to various first- and second-line drugs against the disease of tuberculosis make its treatment extremely difficult. This work presents a new approach to synthesizing a hybrid of antituberculosis medications: isoniazid (INH) and pyrazinamide (PZA). The synthesis was performed using ultrasound-assisted synthesis to obtain an overall yield of 70%, minimizing the reaction time from 7 to 1 h. The evaluation of the biological activity of the hybrid (compound 2) was tested using the tetrazolium microplate assay (TEMA), showing inhibition in the growth of Mycobacterium tuberculosis H37Rv at a concentration of 0.025 mM at pH 6.0 and 6.7.

Biological Evaluation and Molecular Docking Studies of Novel 1,3,4-Oxadiazole Derivatives of 4,6-Dimethyl-2-sulfanylpyridine-3-carboxamide

To date, chronic inflammation is involved in most main human pathologies such as cancer, and autoimmune, cardiovascular or neurodegenerative disorders. Studies suggest that different prostanoids, especially prostaglandin E₂, and their own synthase (cyclooxygenase enzyme-COX) can promote tumor growth by activating signaling pathways which control cell proliferation, migration, apoptosis, and angiogenesis. Non-steroidal anti-inflammatory drugs (NSAIDs) are used, alongside corticosteroids, to treat inflammatory symptoms particularly in all chronic diseases. However, their toxicity from COX inhibition and the suppression of physiologically important prostaglandins limits their use. Therefore, in continuation of our efforts in the development of potent, safe, non-toxic chemopreventive compounds, we report herein the design, synthesis, biological evaluation of new series of Schiff base-type hybrid compounds containing differently substituted N-acyl hydrazone moieties, 1,3,4-oxadiazole ring, and 4,6-dimethylpyridine core. The anti-COX-1/COX-2, antioxidant and anticancer activities were studied. Schiff base 13, containing 2-bromobenzylidene residue inhibited the activity of both isoenzymes, COX-1 and COX-2 at a lower concentration than standard drugs, and its COX-2/COX-1 selectivity ratio was similar to meloxicam. Furthermore, the results of cytotoxicity assay indicated that all of the tested compounds exhibited potent anti-cancer activity against A549, MCF-7, LoVo, and LoVo/Dx cell lines, compared with piroxicam and meloxicam. Moreover, our experimental study was supported by density functional theory (DFT) and molecular docking to describe the binding mode of new structures to cyclooxygenase.

Updated Information on Antimicrobial Activity of Hydrazide-Hydrazones

Hydrazide-hydrazones possess a wide spectrum of bioactivity, including antibacterial, antitubercular, antifungal, anticancer, anti-inflammatory, anticonvulsant, antidepressant, antiviral, and antiprotozoal properties. This review is focused on the latest scientific reports regarding antibacterial, antimycobacterial, and antifungal activities of hydrazide-hydrazones published between 2017 and 2021. The molecules and their chemical structures presented in this article are the most active derivatives, with discussed activities having a hydrazide-hydrazone moiety as the main scaffold or as a side chain. Presented information constitute a concise summary, which may be used as a practical guide for further design of new molecules with antimicrobial activity.

Development and Validation of a Liquid Chromatographic Method for Aroylhydrazones at Hydrolytic Conditions

Background:

The indole-containing aroylhydrazone derivatives 3a-c with potent antimycobacterial activity against a referent strain M. tuberculosis H37Rv and low cytotoxicity were evaluated for their stability via the precise and accurate HPLC analytical method in aqueous media of different pH (2.0, 7.0, 9.0 and 12.0).

Objective:

The study describes the development and validation of a simple and reliable HPLC-UV procedure for the determination of aroylhydrazone derivatives and their hydrolytic stability. Additionally, to recognize if hydrolysis leads to generating undesired products, the degradation processes were identified.

Method:

The separation was achieved with a LiChrosorb®RP-18 (250 x 4.6 mm) column, at ambient temperature with isocratic mode with mobile phase containing mixture of component A (acetonitrile) and component B (0.001M NaH2PO4, with 5 mM 1-heptane sulfonic acid sodium salt, adjusted to pH 3.0) in a ratio 60:40 (v/v). The flow rate was 1.0 ml/min and the eluent was monitored at 297 nm. The proposed method was validated as per ICH guidelines.

Result:

The obtained results showed that the compounds were sensitive to hydrolytic decomposition in aqueous media, resulting in the splitting of the hydrazone bond. Rapid hydrolysis of substances was observed in the acid medium. The elevated temperature significantly accelerated the hydrolytic reaction. Relatively slow hydrolysis of 3a-c was observed in a neutral solution and aqueous solutions buffered to pH 9. The hydrolysis of 3a-c in neutral, alkaline and strong alkaline medium followed the pseudo- first-order reaction rate and showed a linear dependence of lnC versus time.

Conclusion:

A validated high-performance liquid chromatographic assay for the determination of the hydrolytic stability of a series of aroylhydrazones was developed and optimized for the first time. The methods devised are successfully applicable to the development of pharmaceutical formulations.

Easy-To-Access Quinolone Derivatives Exhibiting Antibacterial and Anti-Parasitic Activities

The cell wall of Mycobacterium tuberculosis (Mtb) has a unique structural organisation, comprising a high lipid content mixed with polysaccharides. This makes cell wall a formidable barrier impermeable to hydrophilic agents. In addition, during host infection, Mtb resides in macrophages within avascular necrotic granulomas and cavities, which shield the bacterium from the action of most antibiotics. To overcome these protective barriers, a new class of anti-TB agents exhibiting lipophilic character have been recommended by various reports in literature. Herein, a series of lipophilic heterocyclic quinolone compounds was synthesised and evaluated in vitro against pMSp12::GFP strain of Mtb, two protozoan parasites (Plasmodium falciparum and Trypanosoma brucei brucei) and against ESKAPE pathogens. The resultant compounds exhibited varied anti-Mtb activity with MIC₉₀ values in the range of 0.24–31 µM. Cross-screening against P. falciparum and T.b. brucei, identified several compounds with antiprotozoal activities in the range of 0.4–20 µM. Compounds were generally inactive against ESKAPE pathogens, with only compounds 8c, 8g and 13 exhibiting moderate to poor activity against S. aureus and A. baumannii.

Easily accessed nitroquinolones exhibiting potent and selective anti-tubercular activity

Nitro based DprE1 inhibitors exemplified by benzothiazinones have been reported to elicit potent anti-tubercular activity. Poor PK properties associated with benzothiazinones have inspired the discovery of alternative nitro based DprE1 inhibitors. Quinolone based antibiotics on the other hand have good PK properties. The potent anti-tubercular activity of nitro compounds and the good PK properties of the quinolones have elicited an interest in us to construct a new class of nitro containing compounds around the quinolone scaffold with the aim of identifying novel DprE1 inhibitors with potent anti-tubercular activity. Thus, we report herein the anti-tubercular activity of novel 6-nitroquinolone-3-carboxamide derivatives achieved using less than five cheap synthetic transformations. Among the 23 target compounds evaluated for anti-tubercular activity, 12 were active against Mtb─ exhibiting activity in the range of <0.244-31.865 μM. Compound 25 having a molecular weight of 399 Da and ClogP value of 2.7 is the most active (MIC₉₀: <0.244 μM) in this series. The SAR analyses suggest that anti-tubercular activity was influenced by substituents at position N-1 (R₂) and C-3 (R₃) of the quinolone ring. The activity data suggest that the nature of R₃ has a stronger influence on the SAR compared to R₂; with a fluorobenzyl and chlorobenzyl moiety at R₂ being the most favoured when R₃ is an aliphatic amine. Docking study confirms that compound 25 binds to the same hydrophobic pocket as does TCA1, and other nitro based DprE1 inhibitors, with its nitro group in close proximity with Cys387 residue.

Recent Highlights in Anti-infective Medicinal Chemistry from South Africa

Global advancements in biological technologies have vastly increased the variety of and accessibility to bioassay platforms, while simultaneously improving our understanding of druggable chemical space. In the South African context, this has resulted in a rapid expansion in the number of medicinal chemistry programmes currently operating, particularly on university campuses. Furthermore, the modern medicinal chemist has the advantage of being able to incorporate data from numerous related disciplines into the medicinal chemistry process, allowing for informed molecular design to play a far greater role than previously possible. Accordingly, this review focusses on recent highlights in drug-discovery programmes, in which South African medicinal chemistry groups have played a substantive role in the design and optimisation of biologically active compounds which contribute to the search for promising agents for infectious disease.

Discovery of hydrazone containing thiadiazoles as Mycobacterium tuberculosis growth and enoyl acyl carrier protein reductase (InhA) inhibitors

Tuberculosis, caused by Mycobacterium tuberculosis, is a serious infectious disease and remains a global health problem. There is an increasing need for the discovery of novel therapeutic agents for its treatment due to the emerging multi-drug resistance. Herein, we present the rational design and the synthesis of eighteen new thiadiazolylhidrazones (TDHs) which were synthesized by intramolecular oxidative N-S bond formation reaction of 2-benzylidene-N-(phenylcarbamothioyl)hydrazine-1-carboximidamide derivatives by phenyliodine(III) bis(trifluoroacetate) (PIFA) under mild conditions. The compounds were characterized by various spectral techniques including FTIR, ¹H NMR, ¹³C NMR and HRMS. Furthermore, the proposed structure of TDH12 was resolved by single-crystal X-ray analysis. The compounds were evaluated for their in vitro antitubercular activity against M. tuberculosis H37Rv. Among them, some compounds exhibited remarkable antimycobacterial activity, MIC = 0.78-6.25 μg/mL, with low cytotoxicity. Additionally, the most active compounds were screened for their biological activities against M. tuberculosis in the nutrient starvation model. Enzyme inhibition assays and molecular docking studies revealed enoyl acyl carrier protein reductase (InhA) as the possible target enzyme of the compounds to show their antitubercular activities.

Recent advances in the synthetic and medicinal perspective of quinolones: A review

In the modern scenario, the quinolone scaffold has emerged as a very potent motif considering its clinical significance. Quinolones possess wide range of pharmacological activities such as anticancer, antibacterial, antifungal, antiprotozoal, antiviral, anti-inflammatory, carbonic anhydrase inhibitory and diuretic activity etc. The versatile synthetic approaches have been successfully applied and several of the resulted synthesized compounds exhibit fascinating biological activities in numerous fields. This has prompted to discover quinolone-based analogues among the researchers due to its great diversity in biological activities. In the past few years, various new, efficient and convenient synthetic approaches (including green chemistry and microwave-assisted synthesis) have been designed and developed to synthesize diverse quinolone-based scaffolds which represent a growing area of interest in academic and industry as well as to explore their biological activities. In this review, an attempt has been made by the authors to summarize (1) One of the most comprehensive listings of quinolone-based drugs or agents in the market or under various stages of clinical development; (2) Recent advances in the synthetic strategies for quinolone derivatives as well as their biological implications including insight of mechanistic studies. (3) Further, the biological data is correlated with structure-activity relationship studies to provide an insight into the rational design of more active agents.

Effects of a new 1,2,3-thiadiazole containing hydrazone antimycobacterial agent on serum and liver biochemical parameters in female mice

Isoniazid (INH), a first-line drug in anti-tuberculosis therapy, is known to be potentially harmful and is associated with numerous side effects especially in the blood and liver. In the course of our previous investigations, 1,2,3-thiadiazole containing hydrazone (compound 3) showed excellent antimycobacterial activity against a referent strain M. tuberculosis H37Rv (MIC value 0.39 μM), low cytotoxicity, and did not have toxic effects when administered by oral or intraperitoneal routes to experimental animals (selectivity index SI > 1979, LD₅₀>2000 mg/kg b.w.) what revealed its suitability for further exploration. In the present study compound 3 was chosen to determine its effects on the liver and kidney functions in female mice. The compound was administered orally for 14 days at three doses (100, 200, and 400 mg/kg b.w.). The quantity of malondialdehyde (MDA), the level of reduced glutathione (GSH), blood hematological and biochemical parameters were assessed, and urine analysis was carried out. As a positive control INH was used orally at a dose of 50 mg/kg b.w. The investigated compound 3 did not affect the urine and serum hematological and biochemical parameters as INH did, compared to those of the control mice. The new compound did not affect significantly the MDA quantity and maintained its level near to the control values, though lower by 36% (p < 0.05) than in the INH treated animals. At the higher doses, 200 and 400 mg/kg, it depleted the GSH content by 25% (p < 0.05), compared to the control. However, its level remained 47% (p < 0.05) higher than in the INH treated animals.

New Quinolone-Based Thiosemicarbazones Showing Activity Against Plasmodium falciparum and Mycobacterium tuberculosis

Co-infection of malaria and tuberculosis, although not thoroughly investigated, has been noted. With the increasing prevalence of tuberculosis in the African region, wherein malaria is endemic, it is intuitive to suggest that the probability of co-infection with these diseases is likely to increase. To avoid the issue of drug-drug interactions when managing co-infections, it is imperative to investigate new molecules with dual activities against the causal agents of these diseases. To this effect, a small library of quinolone-thiosemicarbazones was synthesised and evaluated in vitro against Plasmodium falciparum and Mycobacterium tuberculosis, the causal agents of malaria and tuberculosis, respectively. The compounds were also evaluated against HeLa cells for overt cytotoxicity. Most compounds in this series exhibited activities against both organisms, with compound 10, emerging as the hit; with an MIC₉₀ of 2 µM against H37Rv strain of M. tuberculosis and an IC₅₀ of 1 µM against the 3D7 strain of P. falciparum. This study highlights quinolone-thiosemicarabazones as a class of compounds that can be exploited further in search of novel, safe agents with potent activities against both the causal agents of malaria and tuberculosis.