Synthesis of 2-sulfanyl-6-methyl-1,4-dihydropyrimidines as a new class of antifilarial agents

Synthesis, crystal structure and antibacterial studies of dihydropyrimidines and their regioselectively oxidized products

The syntheses and investigations of new biologically active derivatives of dihydropyrimidines by Biginelli reaction in the presence of copper triflate are reported. Due to the fact that salicylaldehyde and its derivatives under Biginelli reaction conditions can lead to the formation of 2 types of dihydropyrimidines, the influence of copper triflate on product formation was also investigated. In addition to this, regioselective oxidation of dihydropyrimidines was performed in the presence of cerium ammonium nitrate and novel oxidized dihydropyrimidines were obtained. Single crystals of some of them were obtained and as a result, the structures of them were investigated by X-ray diffraction method, which allows determining the presence of hydrogen bonds in their structures. In addition to this, the presence of hydrogen bonds in their structures affects the formation of the corresponding tautomer during oxidizing of dihydropyrimidines. Since dihydropyrimidines are claimed to be biologically active compounds, activities of the synthesized compounds were studied against Acinetobacter baumanii, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae and Staphylococcus aureus bacteria.

Known methods of synthesis of dihydropyrimidines and their oxidized products were modified, the impact of hydrogen bonds on stabilization of preferred tautomer and biological activities were studied.

Synthesis, Docking Studies into CDK-2 and Anticancer Activity of New Derivatives Based Pyrimidine Scaffold and Their Derived Glycosides

BACKGROUND & OBJECTIVE

New diaryl-substituted pyrimidinedione compounds, their thioxo derivatives as well as their bicyclic thiazole compounds were synthesized and characterized.

METHODS

The glycosylamino derivatives of the synthesized disubstituted derivatives of the pyrimidine scaffold were also prepared via reaction of the N3-amino derivatives with a number of monosaccharides followed by acetylation.

RESULTS

The anticancer activity of the synthesized compounds was studied against human liver cancer (HepG2) and RPE-1cell lines. Compounds 2a, 2b, 3a and 12 showed potent activities with IC50 results comparable to that of doxorubicin.

CONCLUSION

Docking investigations into Cyclin-dependent kinase 2 (CDK-2) enzyme, a potential target for cancer medication, were also reported showing the possible binding interaction into the enzyme active site to support their activity behavior.

Influence of autophagy, apoptosis and their interplay in filaricidal activity of C-cinnamoyl glycosides

The present work aims to explore the mechanism of action of C-cinnamoyl glycoside as an antifilarial agent against the bovine filarial nematode Setaria cervi. Both apoptosis and autophagy programmed cell death pathways play a significant role in parasitic death. The generation of reactive oxygen species, alteration of the level of antioxidant components and disruption of mitochondrial membrane potential may be the causative factors that drive the parasitic death. Monitoring of autophagic flux via the formation of autophagosome and autophagolysosome was detected via CYTO ID dye. The expression profiling of both apoptotic and autophagic marker proteins strongly support the initial findings of these two cell death processes. The increased interaction of pro-autophagic protein Beclin1 with BCL-2 may promote apoptotic pathway by suppressing anti-apoptotic protein BCL-2 from its function. This in turn partially restrains the autophagic pathway by engaging Beclin1 in the complex. But overall positive increment in autophagic flux was observed. Dynamic interaction and regulative balance of these two critical cellular pathways play a decisive role in controlling disease pathogenesis. Therefore, the present experimental work may prosper the chance for C-cinnamoyl glycosides to become a potential antifilarial therapeutic in the upcoming day after detail in vivo study and proper clinical trial.

Chemistry and Pharmacological Activities of Biginelli Product- A Brief Overview

Dihydropyrimidinones are extremely advantageous small sized molecules owning adaptable pharmaceutical properties. With a molecular formula C₄H₆N₂O, they hold a wide range of biological activities. It is a heterocyclic moiety having two N-atoms at positions 1 and 3. They are derivatives of pyrimidine containing an additional ketone group. They have inspired development of a wide range of synthetic methods for preparation and chemical transformations. Taking into consideration their structural similarity and involvement with DNA and RNA, they have become very imperative in the world of synthetic organic chemistry. Aryl substituted moieties and their derivatives are significant class of substances in medicinal and organic chemistry. Many alkaloids from natural marine sources comprising dihydropyrimidinones core have been isolated which possess fascinating biological properties. Intensive explorations have been carried out on these compounds because they possess close similitude to clinically used nifedipine, nicardipine etc. which are also Biginelli product analogues. Due to the interesting pharmacological properties associated with the privileged DHPM structures, the Biginelli reaction and related procedures have received increasing attention in recent years.

Recent synthetic and medicinal perspectives of dihydropyrimidinones: A review

Dihydropyrimidines are the most important heterocyclic ring systems which play an important role in the synthesis of DNA and RNA. Synthetically they were synthesized using Multi-component reactions like Biginelli reaction and Hantzschdihydropyridine. In the past decades, such Biginelli type dihydropyrimidones have received a considerable amount of attention due to the interesting pharmacological properties associated with this heterocyclic scaffold. In this review, we highlight recent developments in this area, with a focus on the DHPMs, recently developed as anti-inflammatory, anti-HIV, anti-tubercular, antifungal anticancer, antibacterial, antifilarial, antihyperglycemic, antihypertensive, analgesic, anti-convulsant, antioxidant, anti-TRPA1, anti-SARS, and anti-cancer activity and α_1a binding affinity.

•

This review is focused on synthetic prospective of dihydropyrimidinones.

•

This review is also focused on medicinal prospective of dihydropyrimidinones.

•

It includes structure-activity relationship study of different activities.

In vitro modulatory effects of functionalized pyrimidines and piperidine derivatives on Aryl hydrocarbon receptor (AhR) and glucocorticoid receptor (GR) activities

The development of biologically active molecules based on molecular recognition is an attractive and challenging task in medicinal chemistry and the molecules that can activate/deactivate certain receptors are of great medical interest. In this contribution, selected pyrimidine/piperidine derivatives were synthesized and tested for the ability to activate/deactivate Aryl hydrocarbon receptor (AhR) and Glucocorticoid receptor (GR). Tested compounds are shown to activate the receptors but to much lesser extent than positive controls, dioxin and dexamethasone for Ahr and GR, respectively. However, some of them antagonized the positive controls action. Although further in vivo studies are needed to fully characterize the bioactivities of these compounds, the reported in vitro evidences demonstrate that they might be used as the modulators of AhR and GR activities.

Two decades of antifilarial drug discovery: a review

Filariasis is one of the oldest, most debilitating, disabling, and disfiguring neglected tropical diseases with various clinical manifestations and a low rate of mortality, but has a high morbidity rate, which results in social stigma.

Dihydropyrimidones: As novel class of β-glucuronidase inhibitors

Dihydropyrimidones 1-37 were synthesized via a 'one-pot' three component reaction according to well-known Biginelli reaction by utilizing Cu(NO3)2·3H2O as catalyst, and screened for their in vitro β-glucuronidase inhibitory activity. It is worth mentioning that amongst the active molecules, compounds 8 (IC50=28.16±.056μM), 9 (IC50=18.16±0.41μM), 10 (IC50=22.14±0.43μM), 13 (IC50=34.16±0.65μM), 14 (IC50=17.60±0.35μM), 15 (IC50=15.19±0.30μM), 16 (IC50=27.16±0.48μM), 17 (IC50=48.16±1.06μM), 22 (IC50=40.16±0.85μM), 23 (IC50=44.16±0.86μM), 24 (IC50=47.16±0.92μM), 25 (IC50=18.19±0.34μM), 26 (IC50=33.14±0.68μM), 27 (IC50=44.16±0.94μM), 28 (IC50=24.16±0.50μM), 29 (IC50=34.24±0.47μM), 31 (IC50=14.11±0.21μM) and 32 (IC50=9.38±0.15μM) found to be more potent than the standard d-saccharic acid 1,4-lactone (IC50=48.4±1.25μM). Molecular docking study was conducted to establish the structure-activity relationship (SAR) which demonstrated that a number of structural features of dihydropyrimidone derivatives were involved to exhibit the inhibitory potential. All compounds were characterized by spectroscopic techniques such as (1)H, (13)C NMR, EIMS and HREI-MS.

Antifilarial activity of diterpenoids from Taxodium distichum

BACKGROUND

Lymphatic filariasis caused by Wuchereria bancrofti, Brugia malayi and B. timori, is a debilitating disease with an adverse social and economic impact. The infection remains unabated in spite of treatment with existing antifilarial drugs diethylcarbamazine (DEC) and ivermectin which are chiefly microfilaricides. There is therefore, need for macrofilaricides, embryostatic agents and better microfilaricides. In the present study we explored the antifilarial potential of crude extract and its molecular fractions of the plant Taxodium distichum using in vitro assay systems and rodent models of B. malayi infection.

METHODS

Ethanolic extract (A001) of aerial parts of T. distichum was solvent fractionated and sub-fractionated. Four molecules, 3-Acetoxylabda-8(20), 13-diene-15-oic acid (K001), Beta-sitosterol (K002), labda-8(20),13-diene-15-oic acid (K003) and Metasequoic acid A (K004) were isolated from the fractions and their structure determined by spectroscopic analysis. The extract, subfractions and molecules were evaluated for antifilarial activity against B. malayi by 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) reduction and motility assays in vitro and in two animal models, Meriones unguiculatus and Mastomys coucha, harbouring B. malayi infection.

RESULTS

A001 was effective in killing microfilariae (mf) and adult worms in vitro. The diterpenoid K003 produced 100 % reduction in motility of both mf and adult worms and > 80 % inhibition in MTT reduction potential of adult female worms. In B. malayi-M. unguiculatus model, A001 killed all the adult worms in > 80 % of infected animals. K003 was embryostatic (> 95 %) in this model. In the B. malayi-M. coucha model, K003 killed ~54 % of adult worms (macrofilaricidal activity) and rendered > 36 % female worms sterile; it also stopped any further rise in microfilaraemia after day 42 post-initiation of treatment.

CONCLUSION

Ethanolic extract of aerial parts of the plant T. distichum possesses potent antifilarial activity and the active principle was localised to K003 which showed significant macrofilaricidal activity and late suppression of peripheral microfilaraemia and some embryostatic activity. These findings indicate that labdane diterpenoid molecule(s) may provide valuable leads for design and development of new macrofilaricidal agent(s). To the best of our knowledge, this is the first report on antifilarial efficacy of products from the plant T. distichum.

Significance and biological importance of pyrimidine in the microbial world

Microbes are unique creatures that adapt to varying lifestyles and environment resistance in extreme or adverse conditions. The genetic architecture of microbe may bear a significant signature not only in the sequences position, but also in the lifestyle to which it is adapted. It becomes a challenge for the society to find new chemical entities which can treat microbial infections. The present review aims to focus on account of important chemical moiety, that is, pyrimidine and its various derivatives as antimicrobial agents. In the current studies we represent more than 200 pyrimidines as antimicrobial agents with different mono-, di-, tri-, and tetrasubstituted classes along with in vitro antimicrobial activities of pyrimidines derivatives which can facilitate the development of more potent and effective antimicrobial agents.

Synthesis, antifungal activity, and QSAR studies of 1,6-dihydropyrimidine derivatives

INTRODUCTION

A practical synthesis of pyrimidinone would be very helpful for chemists because pyrimidinone is found in many bioactive natural products and exhibits a wide range of biological properties. The biological significance of pyrimidine derivatives has led us to the synthesis of substituted pyrimidine.

MATERIALS AND METHODS

With the aim of developing potential antimicrobials, new series of 5-cyano-6-oxo-1,6-dihydro-pyrimidine derivatives namely 2-(5-cyano-6-oxo-4-substituted (aryl)-1,6-dihydropyrimidin-2-ylthio)-N-substituted (phenyl) acetamide (C1-C41) were synthesized and characterized by Fourier transform infrared spectroscopy (FTIR), mass analysis, and proton nuclear magnetic resonance ((1)H NMR). All the compounds were screened for their antifungal activity against Candida albicans (MTCC, 227).

RESULTS AND DISCUSSION

Quantitative structure activity relationship (QSAR) studies of a series of 1,6-dihydro-pyrimidine were carried out to study various structural requirements for fungal inhibition. Various lipophilic, electronic, geometric, and spatial descriptors were correlated with antifungal activity using genetic function approximation. Developed models were found predictive as indicated by their square of predictive regression values (r(2pred)) and their internal and external cross-validation. Study reveals that CHI_3_C, Molecular_SurfaceArea, and Jurs_DPSA_1 contributed significantly to the activity along with some electronic, geometric, and quantum mechanical descriptors.

CONCLUSION

A careful analysis of the antifungal activity data of synthesized compounds revealed that electron withdrawing substitution on N-phenyl acetamide ring of 1,6-dihydropyrimidine moiety possess good activity.

Antifilarial diarylheptanoids from Alnus nepalensis leaves growing in high altitude areas of Uttarakhand, India

Lymphatic filariasis continues to be a major health problem in tropical and subtropical countries. A macrofilaricidal agent capable of eliminating adult filarial parasites is urgently needed. Platyphyllenone (A), alusenone (B), hirustenone (C) and hirsutanonol (D) are important biologically active diarylheptanoids present in Alnus nepalensis. In the present study, we report the antifilarial activity in diarylheptanoids isolated from the leaves of A. nepalensis. Out of four compounds (A-D) tested in vitro one has shown promising anti-filarial activity both in vitro and in vivo studies. This is the first ever report on antifilarial efficacy of a compound of the plant and warrants further studies around this scaffold. In addition, a sensitive, selective and robust densitometric high-performance thin-layer chromatographic method was developed and validated for the above four biomarker compounds. The separation was performed on silica gel 60F(254) high-performance thin layer chromatography plates using chloroform:methanol (9:1, v/v) as mobile phase. The quantitation of marker compounds was carried out using densitometric reflection/absorption mode at 600 nm after post-chromatographic derivatization using vanillin-sulfuric acid reagent. The method was validated for peak purity, precision, robustness, limit of detection (LOD) and quantitation (LOQ) etc., as per the International Conference on Harmonization (ICH) guidelines.

Cellulose-Sulfuric Acid as an Efficient Biosupported Catalyst in One-Pot Synthesis of Novel Heteroaryl Substituted 1,4-Dihydropyridines

An efficient method for the synthesis of new heteroaryl substituted dihydropyridine derivatives via a one-pot four-component coupling reaction of heteroaldehyde, 1,3-diketone, ethylacetoacetate, and amonium acetate in the presence of cellulose-sulfuric acid as a biosupported solid acid catalyst was developed. The reaction gave the new derivatives of fused 1,4-dihydropyridines in lower reaction times and excellent yields (85–95%).

One pot efficient diversity oriented synthesis of polyfunctional styryl thiazolopyrimidines and their bio-evaluation as antimalarial and anti-HIV agents

An efficient one pot synthesis of a series of pluripotent (E)-1-(3-methyl-5-aryl-7-styryl-5H-thiazolo[3,2-a]pyrimidin-6-yl)-3-arylprop-2-en-1-ones is reported. It involves reaction of 5-acetyl-6-methyl-4-aryl-dihydropyrimidine-2-thiones, propargyl bromide and aromatic aldehydes in presence of ethanolic KOH. The newly synthesized compounds were evaluated for antimalarial activity against Plasmodium falciparum and as HIV-RT inhibitors. Most of the compound displayed potent antimalarial activity with IC(50)<2 μg/mL. Compounds 6, 11 and 20 showed better activity against P. falciparum K1 strains in comparison to standard drug chloroquine. Compounds 6, 11, and 16 exhibited 73.44, 66.92, and 70.81% HIV-RT inhibition at 100 μg/mL.

Inflammatory mediator release by Brugia malayi from macrophages of susceptible host Mastomys coucha and THP-1 and RAW 264.7 cell lines

OBJECTIVE

To investigate which life stage of the parasite has the ability to stimulate release of pro- or anti-inflammatory mediators from macrophages.

METHODS

The human macrophage/monocyte cell line THP-1, the mouse macrophage cell line RAW 264.7 and naive peritoneal macrophages (PM) from the rodent host Mastomys coucha (M. coucha) were incubated at 37 °C in 5% CO(2) atmosphere with extracts of microfilariae (Mf), third stage infective larvae (L(3)) and adult worms (Ad) of Brugia malayi. After 48 hr post exposure, IL-1β, IL-6, TNF-α, IL-10 and nitric oxide (NO) in cell-free supernatants were estimated.

RESULTS

Extracts of all the life stages of the parasite were capable of stimulating pro- (IL-1β, IL-6 and TNF-α) and anti-inflammatory (IL-10) cytokines in both the cell lines and peritoneal macrophages of M. coucha. Mf was the strongest stimulator of pro-inflammatory cytokines followed by L(3) and Ad; however, Ad was a strong stimulator of IL-10 release. Mf was found to have potential to modulate LPS-induced NO release in RAW cells. Ad-induced NO release was concentration dependent with maximum at 20 μg/mL in both RAW and PMs.

CONCLUSIONS

The results show that parasites at all life stages were capable of stimulating pro- (IL-1β, IL-6 and TNF-α) and anti-inflammatory (IL-10) cytokines and NO release from macrophages of susceptible host M. coucha, human and mouse macrophage cell lines. Mf can suppress the LPS-induced NO release in RAW cells. The findings also show that the two cell lines may provide a convenient in vitro system for assaying parasite-induced inflammatory mediator release.

Synthesis of novel 6-phenyl-2,4-disubstituted pyrimidine-5-carbonitriles as potential antimicrobial agents

New series of 6-phenyl-2,4-disubstituted pyrimidine-5-carbonitriles namely, 2-substitued thio-6-phenyl-3,4-dihydro-4-oxopyrimidine-5-carbonitriles (5a-d, 6, 7a-d, 8), 2-(4-chlorobenzylthio)-4-chloro-6-phenylpyrimidine-5-carbonitrile (9), 2-(4-chlorobenzylthio)-4-arylthio-6-phenylpyrimidine-5-carbonitriles (10a-d) and 2-(4-chlorobenzylthio)-4-arylamino-6-phenylpyrimidine-5-carbonitriles (11a-d) was synthesized and tested for in vitro activities against a panel of Gram-positive and Gram-negative bacteria and the yeast-like pathogenic fungus Candida albicans. Compounds 5b, 5c, 6, 7a, 7b, 7c, 9 and 11a displayed marked antibacterial activity particularly against the tested Gram-positive bacteria, while compounds 6, 7c, 7d and 9 were moderately or weakly active against C. albicans.

Antifilarial activity in vitro and in vivo of some flavonoids tested against Brugia malayi

We evaluated the antifilarial activity of 6 flavonoids against the human lymphatic filarial parasite Brugia malayi using an in vitro motility assay with adult worms and microfilariae, a biochemical test for viability (3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT)-reduction assay), and two animal models, Meriones unguiculatus (implanted adult worms) and Mastomys coucha (natural infections). In vitro, naringenin and hesperetin killed the adult worms and inhibited (>60%) MTT-reduction at 7.8 and 31.2 μg/ml concentration, respectively. Microfilariae (mf) were killed at 250-500 μg/ml. The half maximal inhibitory concentration (IC(50)) of naringenin for motility of adult females was 2.5 μg/ml. Flavone immobilized female adult worms at 31.2 μg/ml (MTT>80%) and microfilariae at 62.5 μg/ml. Rutin killed microfilariae at 125 μg/ml and inhibited MTT-reduction in female worms for >65% at 500 μg/ml. Naringin had adulticidal effects at 125 μg/ml while chrysin killed microfilariae at 250 μg/ml. In vivo, 50 mg/kg of naringenin elimiated 73% of transplanted adult worms in the Meriones model, but had no effect on the microfilariae in their peritoneal cavity. In Mastomys, the same drug was less effective, killing only 31% of the naturally acquired adult worms, but 51%, when the dose was doubled. Still, effects on the microfilariae in the blood were hardly detectable, even at the highest dose. In summary, all 6 flavonoids showed antifilarial activity in vitro, which can be classed, in a decreasing order: naringenin>flavone=hesperetin>rutin>naringin>chrysin. In jirds, naringenin and flavone killed or sterilized adult worms at 50mg/kg dose, but in Mastomys, where the parasite produces a patent infection, only naringenin was filaricidal. Thus naringenin and flavone may provide a lead for design and development of new antifilarial agent(s). This is the first report on antifilarial efficacy of flavonoids.

Towards novel antifilarial drugs: challenges and recent developments

Filariasis is caused by thread-like nematode worms, classified according to their presence in the vertebrate host. The cutaneous group includes Onchocerca volvulus, Loa loa and Mansonella streptocerca; the lymphatic group includes Wuchereria bancrofti, Brugia malayi and Brugia timori and the body cavity group includes Mansonella perstans and Mansonella ozzardi. Lymphatic filariasis, a mosquito-borne disease, is one of the most prevalent diseases in tropical and subtropical countries and is accompanied by a number of pathological conditions. In recent years, there has been rapid progress in filariasis research, which has provided new insights into the pathogenesis of filarial disease, diagnosis, chemotherapy, the host–parasite relationship and the genomics of the parasite. Together, these insights are assisting the identification of novel drug targets and the discovery of antifilarial agents and candidate vaccine molecules. This review discusses the antifilarial activity of various chemical entities, the merits and demerits of antifilarial drugs currently in use, their mechanisms of action, in addition to antifilarial drug targets and their validation.