In vitro α-amylase and α-glucosidase inhibition study of dihydropyrimidinones synthesized via one-pot Biginelli reaction in the presence of a green catalyst

A green catalyst WELPSA-catalyzed three-component condensation (Biginelli) process involving an aldehyde, barbituric/thiobarbituric/1,3-dimethylbarbituric acid, and urea/thiourea/guanidine hydrochloride in a single pot in presence of a green solvent for the production of DHPM have been presented. The catalyst is reusable and this methodology is scalable. By using the in vitro experiments, the antidiabetic potentiality of synthesized compounds that inhibit α-amylase along with α-glucosidase efficiencies was assessed. All the synthesized compounds except for 4a and 4e, showed the most significant inhibition for α-amylase and α-glucosidase activities. Among the synthesized DHPM compounds, 4c and 4b exhibited significant inhibition profiles compared to the standard antidiabetic drug acarbose. Furthermore, synthesized substances' energy-minimized structures, 3D structures, and DFT calculations were performed using Gaussian 09 software, hybrid models, and MM2 force approaches. Strong hydrogen bonds with amino acid residues Arg-672, Arg-600, Trp-613, Asp-404, Asp-282, and Asp-616 indicate that an α-glucosidase-inhibitory peptide may have hypoglycemic efficacy confirmed by the molecular docking study of the synthesized DHPM.

Catalytic role in Biginelli reaction: Synthesis and biological property studies of 2-oxo/thioxo-1,2,3,4-tetrahydropyrimidines

The Biginelli reaction has received significant consideration in recent years due to its easily accessible aldehyde, urea/thiourea, and active methylene compounds. When it comes to pharmacological applications, the Biginelli reaction end-products, the 2-oxo-1,2,3,4-tetrahydropyrimidines, are vital in pharmacological applications. Due to the ease of carrying out the Biginelli reaction, it offers a number of exciting prospects in various fields. Catalysts, however, play an essential role in Biginelli's reaction. In the absence of a catalyst, it is difficult to form products with a good yield. Many catalysts have been used in search of efficientmethodologies, including biocatalysts, Brønsted/Lewis acids, heterogeneous catalysts, organocatalysts, and so on. Nanocatalysts are currently being applied in the Biginelli reaction to improve the environmental profile as well as speed up the reaction process. This review describes the catalytic role in the Biginelli reaction and pharmacological application of 2-oxo/thioxo-1,2,3,4-tetrahydropyrimidines. This study provides information that will facilitate the development of newer catalytic methods for the Biginelli reaction, by academics as well as industrialists. It also offers a broad scope for drug design strategies, which may enable the development of novel and highly effective bioactive molecules.

Design, Synthesis, Pharmacodynamic and In Silico Pharmacokinetic Evaluation of Some Novel Biginelli-Derived Pyrimidines and Fused Pyrimidines as Calcium Channel Blockers

Some new pyrimidine derivatives comprising arylsulfonylhydrazino, ethoxycarbonylhydrazino, thiocarbamoylhydrazino and substituted hydrazone and thiosemicarbazide functionalities were prepared from Biginelli-derived pyrimidine precursors. Heterocyclic ring systems such as pyrazole, pyrazolidinedione, thiazoline and thiazolidinone ring systems were also incorporated into the designed pyrimidine core. Furthermore, fused triazolopyrimidine and pyrimidotriazine ring systems were prepared. The synthesized compounds were evaluated for their calcium channel blocking activity as potential hypotensive agents. Compounds 2, 3a, 3b, 4, 11 and 13 showed the highest ex vivo calcium channel blocking activities compared with the reference drug nifedipine. Compounds 2 and 11 were selected for further biological evaluation. They revealed good hypotensive activities following intravenous administration in dogs. Furthermore, 2 and 11 displayed drug-like in silico ADME parameters. A ligand-based pharmacophore model was developed to provide adequate information about the binding mode of the newly synthesized active compounds 2, 3a, 3b, 4, 11 and 13. This may also serve as a reliable basis for designing new active pyrimidine-based calcium channel blockers.

Eco-friendly and Enantiospecific Biginelli Synthesis Using (+)-Myrtenal as the Substrate - An Impeccable and Unequivocal Analysis of the Product

BACKGROUND

We found in the literature, an excellent review of the Biginelli reaction that addresses the methodologies for obtaining enantiopure dihydropyrimidinones (DHPMs). In 1992, optically pure DHPMs were obtained by fractional crystallization of the diastereomeric ammonium salt derivative with (S)-(-) and (R)- (+)-α-methyl benzylamine and by other chiral resolution techniques, such as chiral high-performance liquid chromatography (HPLC). Asymmetric syntheses of these compounds are also explained in the literature. The main strategy is to use acid catalysts such as organophosphates, organometallic complexes, amines and diamines, nanocomposites, and chiral ionic liquids, e.g., L-prolinium sulfate (Pro2SO4).

OBJECTIVE

The objective was to study the Biginelli reaction with a chiral aldehyde.

METHODS

A mixture of ethyl acetoacetate (0.26 g, 3 mmol), urea (0.18 g, 3 mmol) and ethyl lactate (EL) (1 mL) was left under heating at 70°C and stirring for 1 h. Next, (-)-(1R)-myrtenal (0.45 g, 3 mmol) was added, and the medium was heated for 5 h more until the formation of a white solid. Ten millilitres of distilled water was added, and the product was extracted with CH2Cl2 (3 x 4 mL). The solvent was evaporated, and the product was recrystallized from ethanol-water.

RESULTS AND DISCUSSION

(+)-Myrtenal was used as a chiral substrate for a study that led to ethyl (R)-4-((1R,5S)- 6,6-dimethylbicyclo [3.1.1]hept-2-en-2-yl)-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate by the Biginelli synthesis using EL as a green solvent. The result is the first example of the enantiospecific Biginelli reaction. The product was exhaustively characterized by several physical analysis methods, i.e., 1H, 13C and 2D nuclear magnetic resonance (NMR) spectroscopies, infrared (IR) spectroscopy, mass spectrometry (MS), and high-resolution MS (HRMS), and its structure was unequivocally elucidated by X-ray crystallography.

CONCLUSION

Compound (4R)-4-(6,6-dimethylbicyclo[3.1.1]hept-2-en-2-yl)-6-methyl-2-oxo-1,2,3,4- tetrahydropyrimidine- 5-ethyl carboxylate is the first example of the enantiospecific Biginelli reaction. In addition, the process has the advantage of using EL as a green solvent. The product was characterized by 1H, 13C, and 2D NMR and IR spectroscopy, MS, HRMS, and X-ray crystallography.

Novel Quinolinyl-pyrrolo[3,4-d]pyrimidine-2,5-dione Derivatives Against Chloroquine-resistant Plasmodium falciparum

INTRODUCTION

In this work DHPMs were combined with the quinoline nucleus to obtain new quinolinyl-pyrrolo[3,4-d]pyrimidine-2,5-dione compounds with improved antiplasmodial activity as well as decreased cytotoxicity. Nineteen quinolinyl-pyrrolo[3,4-d]pyrimidine-2,5-dione derivatives connected by a linker group to quinolone ring moieties with different substituents were synthesized and assayed against P. falciparum.

MATERIALS AND METHODS

Nineteen quinolinyl-pyrrolo[3,4-d]pyrimidine-2,5-dione derivatives connected by a linker group to quinoline ring moieties with different substituents were synthesized and assayed against chloroquine-resistant Plasmodium falciparum, along with the reference drug chloroquine. Among these compounds, the derivatives with two methylene carbon spacers showed the best activity accompanied by low cytotoxicity.

RESULTS

The derivative without substituents on the aromatic ring (2a) and the derivative with a chlorine group at position 4 (2d) provided the best results, with IC50 = 1.15 µM and 1.5 µM, respectively.

CONCLUSION

Compared to the parent drugs, these compounds presented marked decreases in cytotoxicity, with MDL50 values over 1,000 µM and selectivity indexes of >869.5 and >666.6, respectively. The quinolinyl-pyrrolo[3,4-d]pyrimidine-2,5-dione framework appears to be promising for further studies as an antimalarial for overcoming the burden of resistance in P. falciparum.

Design, synthesis and evaluation of cytotoxic, antimicrobial, and anti-HIV-1 activities of new 1,2,3,4-tetrahydropyrimidine derivatives

A series of new 1,2,3,4-tetrahydropyrimidine (THPM) derivatives were designed and synthesized within a one-pot three component Biginelli reaction. The structures of compounds were characterized by FT-IR, 1HNMR, mass spectroscopy, and elemental analysis. All synthesized derivatives were screened for their cytotoxic, antimicrobial, and anti-HIV activities. Due to significant cytotoxic and antimicrobial effects of 1,2,3,4-THPM scaffold, in this study, cytotoxic and antimicrobial activities of synthesized derivatives were evaluated on two cell lines and four bacterial strains. Compounds 4e and 4k showed highest cytotoxic activity against HeLa and MCF-7 cell lines. In addition, 4c and 4d were most active against MCF-7 and HeLa cell lines, respectively. Among the compounds, 4e revealed high antimicrobial activity against four strains. According to the results, 4e possessing m-bromophenyl group at C-4 position of THPM exhibited the highest cytotoxic and antimicrobial effects. Also, all the newly synthesized compounds were evaluated for their anti-HIV-1 assay. Compounds 4l and 4a indicated remarkable anti-HIV-1 activity. It is concluded from cytotoxic, antimicrobial, and anti-HIV-1 activities that the 1,2,3,4-tertahydropyrimidines may serve as hit compounds for development of new anticancer small-molecules.

Dihydropyrimidinones and -thiones with improved activity against human polyomavirus family members

Human polyomaviruses are generally latent but can be reactivated in patients whose immune systems are suppressed. Unfortunately, current therapeutics for diseases associated with polyomaviruses are non-specific, have undefined mechanisms of action, or exacerbate the disease. We previously reported on a class of dihydropyrimidinones that specifically target a polyomavirus-encoded protein, T antigen, and/or inhibit a cellular chaperone, Hsp70, that is required for virus replication. To improve the antiviral activity of the existing class of compounds, we performed Biginelli and modified multi-component reactions to obtain new 3,4-dihydropyrimidin-2(1H)-ones and -thiones for biological evaluation. We also compared how substituents at the N-1 versus N-3 position in the pyrimidine affect activity. We discovered that AMT580-043, a N-3 alkylated dihydropyrimidin-2(1H)-thione, inhibits the replication of a disease-causing polyomavirus in cell culture more potently than an existing drug, cidofovir.

Identification of New Nonsteroidal RORα Ligands; Related Structure-Activity Relationships and Docking Studies

A high throughput screen was developed to identify novel, nonsteroidal RORα agonists. Among the validated hit compounds, the 4-(4-(benzyloxy)phenyl)-5-carbonyl-2-oxo-1,2,3,4-tetrahydropyrimidine scaffold was the most prominent. Among the numerous analogues tested, compounds 8 and 9 showed the highest activity. Key structure-activity relationships (SAR) were established, where benzyl and urea moieties were both identified as very important elements to maintain the activity. Most notably, the SAR were consistent with the binding mode of the compound 8 (S-isomer) in the RORα docking model that was developed in this program. As predicted by the model, the urea moiety is engaged in the formation of key hydrogen bonds with the backbone of Tyr380 and Asp382. The benzyl group is located in a wide hydrophobic pocket. The structural relationships reported in this letter will help in further optimization of this compound series and will provide novel synthetic probes helpful for elucidation of complex RORα physiopathology.