Quantitative structure activity relationship study of 2,4,6-trisubstituted-s-triazine derivatives as antimalarial inhibitors of Plasmodium falciparum dihydrofolate reductase

Pharmacokinetics and drug-likeness of antidiabetic flavonoids: Molecular docking and DFT study

Computer aided toxicity and pharmacokinetic prediction studies attracted the attention of pharmaceutical industries as an alternative means to predict potential drug candidates. In the present study, in-silico pharmacokinetic properties (ADME), drug-likeness, toxicity profiles of sixteen antidiabetic flavonoids that have ideal bidentate chelating sites for metal ion coordination were examined using SwissADME, Pro Tox II, vNN and ADMETlab web tools. Density functional theory (DFT) calculations were also employed to calculate quantum chemical descriptors of the compounds. Molecular docking studies against human alpha amylase were also conducted. The results were compared with the control drugs, metformin and acarbose. The drug-likeness prediction results showed that all flavonoids, except myricetin, were found to obey Lipinski's rule of five for their drug like molecular nature. Pharmacokinetically, chrysin, wogonin, genistein, baicalein, and apigenin showed best absorption profile with human intestinal absorption (HIA) value of ≥ 30%, compared to the other flavonoids. Baicalein, butein, ellagic acid, eriodyctiol, Fisetin and quercetin were predicted to show carcinogenicity. The flavonoid derivatives considered in this study are predicted to be suitable molecules for CYP3A probes, except eriodyctiol which interacts with P-glycoprotein (p-gp). The toxicological endpoints prediction analysis showed that the median lethal dose (LD50) values range from 159-3919 mg/Kg, of which baicalein and quercetin are found to be mutagenic whereas butein is found to be the only immunotoxin. Molecular docking studies showed that the significant interaction (-7.5 to -8.3 kcal/mol) of the studied molecules in the binding pocket of the α-amylase protein relative to the control metformin with the crucial amino acids Asp 197, Glu 233, Asp 197, Glu 233, Trp 59, Tyr 62, His 101, Leu 162, Arg 195, His 299 and Leu 165. Chrysin was predicted to be a ligand with high absorption and lipophilicity with 84.6% absorption compared to metformin (78.3%). Moreover, quantum chemical, ADMET, drug-likeness and molecular docking profiles predicted that chrysin is a good bidentate ligand.

Synthesis, Biological and In Silico Studies of a Tripodal Schiff Base Derived from 2,4,6-Triamino-1,3,5-triazine and Its Trinuclear Dy(III), Er(III), and Gd(III) Salen Capped Complexes

A tripodal Schiff base ligand, 2,4,6-Tris(4-carboxybenzimino)-1,3,5-triazine (MT) and its trinuclear Dy(III), Er(III), and Gd(III) complexes were synthesized. These were characterized using UV-visible, IR, ¹H, and ¹³C NMR spectroscopies, elemental analysis, and molar conductivity measurements. The spectral studies indicate that the ligand is hexadentate and coordinates to the Ln(III) ions through the oxygen atoms of the carboxylic group. The trinuclear complexes were characterized as being bridged by carboxylate anions to the Dy(III), Er(III), and Gd(III) salen centers and displaying a coordination number of six. Biological studies revealed that MT is more active against the test micro-organisms relative to the trinuclear complexes. Acute toxicity studies revealed that MT is safe and has a wide range of effective doses (ED₅₀). In vivo antimalarial studies indicate that MT could serve as an effective antimalarial agent since it has parasitemia inhibition of 84.02% at 50 mg/kg and 65.81% at 25 mg/kg, close to the value (87.22%) of the standard drug—Artesunate. Molecular docking simulation studies on the compounds against SARS-CoV-2 (6Y84) and E. coli DNA gyrase (5MMN) revealed effective binding interactions through multiple bonding modes. The binding energy calculated for Er(III)MT-6Y84 and Er(III)MT-5MMN complexes showed active molecules with the ability to inhibit SARS-CoV-2 and E. coli DNA gyrase.

2,4-Dimorpholino-4-yl-6-(4-nitrophenoxy)-[1,3,5]-triazine: Structural and spectroscopic study using experimental and DFT method

2,4-Dimorpholino-4-yl-6-(4-nitrophenoxy)-[1,3,5]-triazine (DMNT) was synthesized and the molecular structure and vibrational frequencies were studied by density functional theory (DFT) method. The functional used was Becke’s three parameter exchange functional combined with the Lee-Yang-Parr correlation (B3LYP) and the standard basis set was 6-31G(d) for all atoms. The Fourier Transform-Infra Red (FT-IR) and FT-Raman spectra of DMNT were recorded and complete assignments of the observed vibrational frequencies are done. The assignments were confirmed by isotopic labelling. The structural parameters, harmonic vibrational frequencies, IR intensities and Raman intensities of DMNT in the ground-state were also computed. Non-linear optical behaviour of DMNT was analysed by examining the properties like electric dipole moment, polarizability and hyperpolarizability. Molecular properties such as ionization potential, electro-negativity, chemical potential and chemical hardness were obtained from molecular orbital analysis. Hyper conjugative interaction and charge delocalization taking place in DMNT was confirmed by Natural bond analysis studies. UV-Vis spectrum of DMNT was also recorded to understand the electronic properties.

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Exploring isoxazoles and pyrrolidinones decorated with the 4,6-dimethoxy-1,3,5-triazine unit as human farnesyltransferase inhibitors

Unprecedented triazinyl-isoxazoles were afforded via an effective cycloaddition reaction between nitrile oxides and the scarcely described 2-ethynyl-4,6-dimethoxy-1,3,5-triazine as dipolarophile. The biological evaluation of the newly synthesized compounds showed that the inhibition of human farnesyltransferase by zinc complexation could be improved with triazine-isoxazole moieties. The replacement of the isoxazole unit by a pyrrolidin-2-one was detrimental to the inhibitory activity while the pyrrolidin-2-thione derivatives conserved the biological potential. The potential of selected compounds to disrupt protein farnesylation in Chinese hamster ovary (CHO) cells transfected with pEGFP-CAAX was also evaluated.

Design, synthesis and biological evaluation of antimalarial activity of new derivatives of 2,4,6-s-triazine

Dihydrofolate reductase (DHFR) is an important enzyme for de novo synthesis of nucleotides in Plasmodium falciparum and it is essential for cell proliferation. DHFR is a well known antimalarial target for drugs like cycloguanil and pyrimethamine which target its inhibition for their pharmacological actions. However, the clinical efficacies of these antimalarial drugs have been compromising due to multiple mutations occurring in DHFR that lead to drug resistance. In this background, we have designed 22 s -triazine compounds using the best five parameters based 3D-QSAR model built by using genetic function approximation. In-silico designed compounds were further filtered to 6 compounds based upon their ADME properties, docking studies and predicted minimum inhibitory concentrations (MIC). Out of 6 compounds, 3 compounds were synthesized in good yield over 95% and characterized using IR, ¹HNMR, ¹³CNMR and mass spectroscopic techniques. Parasitemia inhibition assay was used to evaluate the antimalarial activity of s -triazine compounds against 3D7 strain of P. falciparum. All the three compounds (7, 13 and 18) showed 30 times higher potency than cycloguanil (standard drug). It was observed that compound 18 was the most active while the compound 13 was the least active. On the closer inspection of physicochemical properties and SAR, it was observed that the presence of electron donating groups, number of hydrogen bond formation, lipophilicity of ligands and coulson charge of nitrogen atom present in the triazine ring enhances the DHFR inhibition significantly. This study will contribute to further endeavours of more potent DHFR inhibitors.

Molecular structure and vibrational spectra of 2-Ethoxymethyl-6-ethyl-2,3,4,5-tetrahydro-1,2,4-triazine-3,5-dione, a potential chemotherapeutic agent, by density functional methods

In this work, the vibrational spectral analysis was carried out using FT-IR and FT-Raman spectroscopy for 2-Ethoxymethyl-6-ethyl-2,3,4,5-tetrahydro-1,2,4-triazine-3,5-dione, which is a potential chemotherapeutic agent derivative. Theoretical calculations were performed by density functional methods. The complete vibrational assignments of the wavenumbers were made on the basis of potential energy distribution. The results of the calculations were applied to simulated spectra of the title compound, which show excellent agreement with the observed spectra. The frontier orbital energy gap and related properties of the molecule illustrates the high reactivity of the title compound. The first order hyperpolarizability, dipole moment and polarizability are also calculated. Stability of the molecule arising from hyper-conjugative interactions and charge delocalization has been analyzed using natural bond orbital analysis. Molecular electrostatic potential map is also constructed. The calculated geometrical parameters are in agreement with the XRD results.

Privileged s-triazines: structure and pharmacological applications

This review summarizes recent reports on s-triazine and its respective analogs from the medicinal chemistry angle. Due to its high reactivity and binding characteristic towards various enzymes, s-triazine has attracted attention. This is combined with facile synthesis and interesting pharmacology. The triazine class demonstrates wide biological applications - including antimicrobial, antituberculosis, anticancer, antiviral and antimalarial. In this article the library of s-triazine-based molecular designs has been collated with respective bioactivity. Compounds are further compared with other heterocyclic/nontriazine moieties to correlate the efficiency of privileged s-triazine. We hope this article may assist chemists in their drug design and discovery efforts.

Exploring QSAR for Antimalarial Activities and Drug Distribution within Blood of a Series of 4-Aminoquinoline Drugs Using Genetic-MLR

Malaria has been one of the most significant public health problems for centuries. QSAR modeling of the antimalarial activity and blood-to-plasma concentration ratio of Chloroquine and a new series of 4-aminoquinoline derivatives were developed using genetic algorithms with multiple linear regression (GA-MLR) method. We obtained two different models against Chloroquine-sensitive (3D7) and Chloroquine-resistant (W2) strains ofPlasmodium falciparumwith good adjustment levels. Drug distribution in blood, defined as drug blood-to-plasma concentration ratio (Rb), is related to molecular descriptors. Leave-many-out (LMO) andY-randomization methods confirmed the models' robustness.

Experimental and DFT studies on the vibrational and electronic spectra of 4,5-dihydro-6-methyl-4-[(E)-(3-pyridinylmethylene)amino]-1,2,4-triazin-3(2H)-one

Vibrational and electronic spectral measurements were made for 4,5-dihydro-6-methyl-4-[(E)-(3-pyridinylmethylene)amino]-1,2,4-triazin-3(2H)-one (pymetrozine). Optimized geometrical structure and harmonic vibrational frequencies were computed by ab initio RHF, B-based DFT methods (BLYP, BP86 and BPW91) and B3-based DFT methods (B3LYP, B3P86 and B3PW91) using 6-311++G(d,p) basis set. Complete assignments of the observed spectra were proposed. The absorption spectra of the compound were computed both in gas-phase and in C(2)H(5)OH solution using TD-B3LYP/6-311++G(d,p) and PCM-B3LYP/6-311++G(d,p) approaches, respectively, the calculated results provide a good description of positions of the bands maxima in the observed electronic spectrum. The MEP calculation indicates that the most possible site for electrophilic attack is H23 and the most possible sites for nucleophilic attack are N5 and O19.

Design, synthesis, and biological activities of arylmethylamine substituted chlorotriazine and methylthiotriazine compounds

Heterocyclic rings were introduced into the core structure of s-triazine to design and synthesize a series of novel triazines containing arylmethylamino moieties. These compounds were characterized by using spectroscopic methods and elemental analysis. Their herbicidal, insecticidal, fungicidal, and antitumor activities were evaluated. Most of these compounds exhibited good herbicidal activity, especially against the dicotyledonous weeds, and compound F8 was almost at the same level as the control compound atrazine. Their structure-activity relationships were discussed. At the same time, some triazines had interesting fungicidal and insecticidal activities, of which F4 exhibited 100% efficacy against Puccinia triticina even at 20 ppm, and F5 showed Lepidopteran-specific activity in both leaf-piece and artificial diet assays. Moreover, these compounds showed antitumor activities against leukemia HL-60 cell line and lung adenocarcinoma A-549 cell line.