Antimalarial activity of 2,4,6-trisubstituted pyrimidines

Development of carbazole-bearing pyridopyrimidine-substituted urea/thiourea as polyphenol oxidase inhibitors: synthesis, biochemistry, and theoretical studies

Polyphenol oxidase (Tyrosinase, PPO) has received considerable attention, since it is the key enzyme in melanin biosynthesis. In this study, we investigated prepared novel carbazole-containing pyridopyrimidine-substituted with urea and thiourea derivatives and their PPO activities on the diphenolase activity of banana tyrosinase. The structures of the compounds synthesized were confirmed by 1 H NMR, 13 C NMR, FTIR and elemental analysis. PPO enzyme was purified from banana on an affinity gel comprised of Sepharose 4B-L-tyrosine-p-amino benzoic acid. For evaluating the enzyme activity, the synthesised compounds were subjected to tyrosinase inhibition assay using catechol as substrate. While some of the compounds (6, 7, 8f, 8h, 8i, 8j) showed enzyme inhibitor effect, some of them (8a, 8b, 8c, 8d, 8e, 8g, 8k) activated the PPO enzyme activity. Gaussian software was used for the molecular calculations to explain the results for the prepared compounds.

DBU-Mediated Cyclization of Acylcyclopropanecarboxylates with Amidines: Access to Polysubstituted Pyrimidines

DBU-mediated cyclization of 2-acyl-1-cyanocyclopropanecarboxylates with amidines for the synthesis of multisubstituted pyrimidine derivatives is described. This reaction gives a practical method for producing a diverse set of pyrimidines, having simple experimentation, readily available starting materials, a wide substrate scope, and very good yields.

Synthesis and biological evaluation of new 2,4,6-trisubstituted pyrimidines and their N-alkyl derivatives

A series of new 2,4,6-trisubstituted pyrimidines and their N-alkyl bromide derivatives were prepared based upon methoxy substituted azachalcones as the starting materials. All newly synthesized compounds were screened for their anti-proliferative, cytotoxic, antibacterial activities and DNA/protein binding affinity. In vitro cell proliferation inhibitory and cell cytotoxic effects of 2,4,6-trisubstituted pyrimidines (1-9) and their N-alkyl bromide derivatives (2a-c, 3a-c,5a-c,6a-c, 8a-c, 9a-c) were obtained with the help of the 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) cell proliferation, LDH cytotoxicity detection, and microdilution assays. The antimicrobial activity for these compounds was also evaluated following the European Pharmacopoeia 8.0 protocol. The interactions of these compounds with DNA or bovine serum albumin were investigated by the spectrophotometric titration method. When the cytotoxic analysis and anticancer properties of the compounds were examined, most of the compounds significantly exhibited an anti-proliferative potency on cancer cells (IC₅₀ ∼ 2-10 µg/mL) and caused a cytotoxic effect as low as control drugs, 5-fluorouracil, and cisplatin (∼7-15%). Because the compound-DNA adducts are hyperchromic or hypochromic, they caused variations in their spectra. This situation shows they can be linked to DNA by the groove binding mode at a binding constant range of 2.0 × 104 and 2.4 × 105 M^-1. The antimicrobial screening results revealed that our new compounds for some human Gram(+) and Gram(-) pathogen bacteria showed remarkable activity with MIC values between <7.81 and 125 µg/mL. Overall, incorporation of alkyl chain to pyrimidines in the generation of N-alkyl bromides has resulted in showing differences in DNA/protein binding affinity, along with anti-proliferative and cytotoxic activity in favor of new compounds.

Antimony(III) complexes with 2-amino-4,6-dimethoxypyrimidines: Synthesis, characterization and biological evaluation

Novel pyrimidine compound bearing disulfide bridge, 5,5'-disulfanediylbis(2-amino-4,6-dimetoxypyrimidine) (3) was synthesized by reduction of 2-amino-4,6-dimethoxy-5-thiocyanatopyrimidine for the first time, and its structure was confirmed by X-ray crystallographic analysis. Novel binuclear antimony(III) compound of (3), {Sb[5,5'-disulfanediylbis(2-amino-4,6-dimetoxypyrimidine)]Cl3}2 (4) and mononuclear antimony(III) compounds, SbL2Cl3, [L: 2-amino-5-thiol-4,6-dimethoxy pyrimidine (2) and 2-amino-5-(1H-tetrazol-5-ylthio)-4,6-dimethoxypyrimidine (6)] were synthesized and characterized with the help of elemental analysis, molecular conductivity, FT-IR, (1)H-NMR and LC-MS techniques. The geometrical structures optimized by a DFT/B3LYP/LANL2DZ method of the compounds, indicated that monomeric compounds have square pyramidal shape. Both antileishmanial activity against Leishmania tropica promastigote and glutathione reductase inhibitory activity were determined in vitro. The results showed that (3) has the best biological activity.

Triazine as a promising scaffold for its versatile biological behavior

Among all heterocycles, the triazine scaffold occupies a prominent position, possessing a broad range of biological activities. Triazine is found in many potent biologically active molecules with promising biological potential like anti-inflammatory, anti-mycobacterial, anti-viral, anti-cancer etc. which makes it an attractive scaffold for the design and development of new drugs. The wide spectrum of biological activity of this moiety has attracted attention in the field of medicinal chemistry. Due to these biological activities, their structure-activity relationship has generated interest among medicinal chemists and this has culminated in the discovery of several lead molecules. The outstanding development of triazine derivatives in diverse diseases within very short span of time proves its magnitude for medicinal chemistry research. Therefore, these compounds have been synthesized as target structure by many researchers, and were further evaluated for their biological activities. In this review, we have compiled and discussed the biological potential of s-triazine derivatives, which could provide a low-height flying bird's eye view of the triazine derived compounds to a medicinal chemist, for a comprehensive and target oriented information for the development of clinically viable drugs.

Triazine–pyrimidine based molecular hybrids: synthesis, docking studies and evaluation of antimalarial activity

A series of novel triazine–pyrimidine hybrids have been synthesized and evaluated for their in vitro antimalarial activity.

Synthesis of novel 2-(substituted amino)alkylthiopyrimidin-4(3H)-ones as potential antimicrobial agents

5-Alkyl-6-(substituted benzyl)-2-thiouracils 3a,c were reacted with (2-chloroethyl) diethylamine hydrochloride to afford the corresponding 2-(2-diethylamino)ethylthiopyrimidin- 4(3H)-ones 4a,b. Reaction of 3a-c with N-(2-chloroethyl)pyrrolidine hydrochloride and/or N-(2-chloroethyl)piperidine hydrochloride gave the corresponding 2-[2-(pyrrolidin-1-yl)ethyl]-thiopyrimidin-4(3H)-ones 5a-c and 2-[2-(piperidin-1-yl)ethyl]thiopyrimidin-4(3H)-ones 6a,b, respectively. Treatment of 3a-d with N-(2-chloroethyl)morpholine hydrochloride under the same reaction conditions formed the corresponding 2-[2-(morpholin-4-yl)ethyl]thiopyrimidines 6c-f. On the other hand, 3a,b were reacted with N-(2-bromoethyl)phthalimide and/or N-(3-bromopropyl)phthalimide to furnish the corresponding 2-[2-(N-phthalimido)ethyl]-pyrimidines 7a,b and 2-[3-(N-phthalimido)-propyl]pyrimidines 7c,d, respectively. Compounds 3a-d, 4a,b, 5a-c, 6a-f and 7a-d were screened against Gram-positive bacteria (Staphylococcus aureus ATCC 29213, Bacillus subtilis NRRL 4219 and Bacillus cereus), yeast-like pathogenic fungus (Candida albicans ATCC 10231) and a fungus (Aspergillusniger NRRL 599). The best antibacterial activity was displayed by compounds 3a, 3b, 4a, 5a, 5b, 6d, 6f, 7b and 7d, whereas compounds 4b, 5b, 5c, 6a, 6b and 6f exhibited the best antifungal activity.

Synthesis of marine alkaloid: 8,9-dihydrocoscinamide B and its analogues as Novel class of antileishmanial agents

A series of marine alkaloid 8,9-dihydrocoscinamide B, its analogues and indolylglyoxylamide derivatives have been synthesized and screened for their in vitro antileishmanial activity profile in promastigote and amastigote models. Compounds 7 and 10 have shown 99-100% inhibition against promastigotes and 97-98% inhibition against amastigotes at a concentration of 10 microg/ml.

Synthesis of 2,4,6-trisubstituted pyrimidine and triazine heterocycles as antileishmanial agents

A series of 2,4,6 trisubstituted pyrimidines and triazines have been synthesized and screened for its in vitro antileishmanial activity profile in promastigote model. Nine compounds have shown > 94% inhibition against promastigotes at a concentration of 10 microg/mL.

Inhibitors of de novo folate enzymes in Plasmodium falciparum

Antifolates, inhibitors of folate synthesis or folate conversion, are used for malaria treatment. They are developed as synergistic combinations of inhibitors of dihydrofolate reductase (DHFR) and of dihydropteroate synthase (DHPS). DHPS inhibitors are sulfur-based drugs, analogs of sulfanilamide. These compounds compete with para-aminobenzoic acid in the active site of DHPS. The discovery of new antifolates is based on the identification of DHFR inhibitors; little work has been done on sulfur-based drugs because of their toxicity. As a result, only a few sulfur-based drugs are available. In this review, the hypothesis that compounds that compete with pteridine derivatives in active sites of de novo folate enzymes can be used as synergizers of DHFR inhibitors is discussed. If correct, this could lead to the identification of a new family of synergizers of DHFR inhibitors.

Antimalarial activity: A QSAR modeling using CODESSA PRO software

A quantitative structure-activity relationship (QSAR) modeling of the antimalarial activity of two diverse sets of compounds for each of two strains D6 and NF54 of Plasmodium falciparum is presented. The molecular structural features of compounds are presented by molecular descriptors (geometrical, topological, quantum mechanical, and electronic) calculated using the CODESSA PRO software. Satisfactory multilinear regression models were obtained for data sets of the D6 and NF54 strains, with R2 = 0.84 and 0.89, respectively. The models were also satisfactorily validated internally. The descriptors involved in these equations were related to the mechanism of antimalarial protection.

Dihydropyrido[2,3-d]pyrimidines as a new class of antileishmanial agents

A series of dihydropyrido[2,3-d]pyrimidines have been synthesized and screened for its in vitro antileishmanial activity profile in promastigote and amastigote models. Compounds 2a-2l have shown 83-100% inhibition against promastigotes and 79-100% inhibition against amastigotes at a concentration of 50 microg/mL.

Synthesis of 4-pyrido-6-aryl-2-substituted amino pyrimidines as a new class of antimalarial agents

A series of 2,4,6-trisubstituted pyrimidines were synthesized and evaluated for their in vitro antimalarial activity against Plasmodium falciparum. Of the 18 compounds synthesized, 14 compounds showed MIC in the range of 0.25-2 microg/mL. These compounds are in vitro several fold more active than pyrimethamine.

Synthesis of 2-[3,5-substituted pyrazol-1-yl]-4,6-trisubstituted triazine derivatives as antimalarial agents

A series of 22 compounds were synthesized and screened against Plasmodium falciparum NF-54 strain. Of the screened compounds, 6 compounds showed MIC in the range between 1 and 2 microg/mL. These compounds are 32 times more potent than the cycloguanil which was used as the standard drug.

Synthesis of substituted indole derivatives as a new class of antimalarial agents

A series of substituted indole derivatives were synthesized and evaluated for their in vitro antimalarial activity against P. falciparum. Out of the 24 compounds synthesized six compounds have shown MIC of 1 microg/mL. These compounds are in vitro several folds more active than pyrimethamine.