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Plasmodium falciparum dihydrofolate reductase (PfDHFR) is a promising therapeutic target for antimalarial interventions. Diaminodihydrotriazine derivatives have demonstrated their efficacy as antimalarial agents by targeting PfDHFR inhibition. In this study, we used a multifaceted approach including 3D-QSAR, in silico pharmacokinetic/ADMET evaluation, molecular docking techniques, and molecular dynamics simulation to explore a series of diaminodihydrotriazine compounds, to identify new antimalarial drug candidates featuring the diaminodihydrotriazine scaffold. Using comparative molecular similarity indices analysis (CoMSIA), we built a robust 3D-QSAR model exhibiting favorable statistical parameters, with Q2 and R2 values of 0.553 and 0.981, respectively. External validation using a test set yielded an R2pre value of 0.787, confirming the model's predictive ability. In addition, we performed comprehensive ADMET and drug similarity profile analyses for potent designed compounds, yielding promising results. Molecular docking studies further complemented our investigation facilitating the elucidation of optimal interaction modes between these inhibitors and their target receptor. Additionally, molecular dynamics simulation was conducted for the promising compound 8a. This study not only provides valuable insights into the design of new antimalarial agents but also highlights the importance of computational methods for accelerating drug discovery processes, particularly in the context of infectious disease control.

The investigation of hydroxyxanthone derivatives has been conducted, including molecular docking, molecular dynamics simulation MM-PBSA binding energy calculation, and pharmacokinetics prediction of the potential plasmodium falciparum dihydrofolate reductase (pfDHFR) and plasmodium falciparum dihydroorotate dehydrogenase (pfDHODH) inhibitor. The Docking result showed that compound 1,3,6,7-tetrahydroxy-5,8-bis(3-methyl-2-buten-1-yl)-9H-xanthen-9-one (X16) was found to be the best ligand with good inhibitory action against pfDHFR. Meanwhile, the pfDHODH protein was compounded 1,3,6,7-tetrahydroxy-5,8-dinitro-9H-xanthen-9-one (X14). Additionally, the hydroxyxanthone X16 complex showed more excellent stability in the molecular dynamics simulation of the pfDHFR protein than the ligand WR99210 and chloroquine. The MM-PBSA calculation showed that compound X16 had lower binding energy than ligand WR99210. However, 1,3-dihydroxy-8-(3-methyl-2-buten-1-yl)-9H-xanthen-9-one (X4), 1,3,6,7-tetrahydroxy-8-nitro-9H-xanthen-9-one (X10), 1,3,6,7-tetrahydroxy-9-oxo-9H-xanthene-8-sulfonic acid (X11), and 1,3,6,7-tetrahydroxy-5,8-dinitro-9H-xanthen-9-one (X14) complexes were shown to be more stable than chloroquine and to have the same stability when compared to the native ligand A26, according to a molecular dynamics simulation conducted in pfDHODH protein. The MM-PBSA calculation showed that compound X14 had lower binding energy than ligand A26. The hydroxyxanthones X4, X10–11, X14, and X16 fulfill Lipinski's rule parameters in terms of physicochemical and ADMET qualities and parameters related to absorption, distribution, metabolism, excretion, and toxicity tests. To sum up, hydroxyxanthones X4, X10–11, X14, and X16 have the potential to be antimalarial medications, but more in vivo and in vitro testing is needed to confirm this.

Resistance of malaria parasites to antimalarial drugs is a huge public health concern. Partial resistance of Plasmodium falciparum to artemisinin has been reported in many malaria-endemic regions. Therefore, there is a need to develop new and potent treatments which possibly target multiple genes of the parasite simultaneously. This study aimed to identify compounds with potential inhibitory interaction with P. falciparum lactate dehydrogenase (PfLDH), dihydroorotate dehydrogenase (PfDHODH), and dihydrofolate reductase (PfDHFR). Anthocyanins, a class of flavonoids were engaged to elucidate their inhibitory potential on these targets. In silico screening was performed on the selected targets and phytoligands. Following that, an additional MM-GBSA technique was used to re-score the interactions and determine the binding free energy and spontaneity of the reactions. Five compounds with outstanding binding affinities were identified for each target. The compounds demonstrated excellent binding data in comparison to the co-crystallized ligand., yielding outstanding findings, delphinidin 3,5-O-diglucoside and cyanidin 3-O-diglucoside-5-O-glucoside with −15.253 and −13.430 docking score, respectively were the compounds with the highest score. Also, the induced fit docking result shows low standard deviations. Highest bindinf affinity was recorded in PfDHFR complexes (−80.76, −67.76, −69.21, −66.06, and −67.72 kcal/mol for delphinidin 3,5-O- glucosidel, cyaniding 3-O-diglucoside-5-O-glucoside, pelargonidin 3-O-rutinoside, cyanidin 3,5-O-diglucoside and cyaniding 3-O-(6″-caffeoyl-glucoside)). Additional pharmacokinetic testing anticipated moderate profiles. The findings in this study suggest that the reported compounds can be employed in combination therapy to develop good antimalarial drugs by targeting different genes of the parasite. Hence, further exploratory analyses are recommended to validate these findings.

Molecular surveillance of drug resistance markers through time provides crucial information on genomic adaptations, especially in parasite populations exposed to changing drug pressures. To assess temporal trends of established genotypes associated with tolerance to clinically important antimalarials used in Kenya over the last two decades, we sequenced a region of the pfcrt locus encompassing codons 72–76 of the Plasmodium falciparum chloroquine resistance transporter, full-length pfmdr1 – encoding multi-drug resistance protein, P-glycoprotein homolog (Pgh1) and pfdhfr encoding dihydrofolate reductase, in 485 archived Plasmodium falciparum positive blood samples collected in coastal Kenya at four different time points between 1995 and 2013. Microsatellite loci were also analyzed to compare the genetic backgrounds of parasite populations circulating before and after the withdrawal of chloroquine and sulfadoxine/pyrimethamine. Our results reveal a significant increase in the prevalence of the pfcrt K76 wild-type allele between 1995 and 2013 from 38% to 81.7% (p

Guanylthiourea (GTU) has been identified as an important antifolate antimalarial pharmacophore unit, whereas, 4-amino quinolones are already known for antimalarial activity. In the present work molecules carrying 4-aminoquinoline and GTU moiety have been designed using molecular docking analysis with PfDHFR enzyme and heme unit. The docking results indicated that the necessary interactions (Asp54 and Ile14) and docking score (-9.63 to -7.36 kcal/mmol) were comparable to WR99210 (-9.89 kcal/mol). From these results nine molecules were selected for synthesis. In vitro analysis of these synthesized compounds reveal that out of the nine molecules, eight show antimalarial activity in the range of 0.61-7.55 μM for PfD6 strain and 0.43-8.04 μM for PfW2 strain. Further, molecular dynamics simulations were performed on the most active molecule to establish comparative binding interactions of these compounds and reference ligand with Plasmodium falciparum dihydrofolate reductase (PfDHFR)., (Copyright © 2019 Elsevier Inc. All rights reserved.)