Physicochemical and Thermal Characterization of Dura Palm Kernel Powder as a Load for Polymers: Case of Polyvinyl Chloride

This work presents the physical and thermal characterization of the dura palm kernel powder of Cameroon for their use as fillers for polymers composites. The powders of palm kernel were obtained using a percussion grinder mill with an industrial microniser which allowed obtaining a powder less than 50 μm with an apparent density between 0,505 ≤ ρ ≤ 0,680 g/cm3 at 1.56 of relative humidity. The infrared of the powder of palm kernel shows the presence of phenols groups with a large band around 3341 cm-1, -C-H at 2917.02 cm-1 and -C-O at 1040 cm-1 as the main peaks. The polyvinyl chloride of infrared obtained shows the presence of -C-Cl, -CH2 and CH as the mains peaks. The infrared of 12.5% of palm kernel powder with polyvinyl chloride shows an increase of the CH2 and CH bonds and a decrease of the -OH bonds. Thermogravimetric analysis and differential scanning calorimetric analysis of powders, polyvinyl chloride and mixture showed that the mixing powders are intermediate between the polyvinyl chloride and palm kernel powder. The powder decreased the phase temperatures of the mixture from 98.58℃ to 95℃ for the glass transition temperature and from 515℃ to 459℃ for the crystallization temperature. The thermogravimetric curves of palm kernel powder and polyvinyl chloride have showed that these materials lose their different masses in three different phases, and the one of composite (mixture of polyvinyl chloride with 12.5% of palm kernel powder) in two different phases.

Computational Study of the Interactions between Antimalarial Chemotherapies with Folate Pathway Receptors and Telomerase Reverse Transcriptase

Malaria is a life-threatening disease responsible for half a million death annually, and with nearly half of the world’s population at risk. The rapid drop in observed cases of malaria in the last two decades has been due to a combination of preventive and therapeutic remedies. However, the absence of a vaccine, new antimalarial chemotherapies and increased parasitic resistance have led to a plateau of infections and renewed research interest in target human and Plasmodium (the malaria parasite) receptors and new drugs. In this study, the impact of mutation on the affinity on antimalarial drugs with the bifunctional enzyme complex, dihydrofolate reductase (DHFR) is explored. In addition, homology modeling is used to build the three-dimensional models of the enzymes Plasmodium telomerase reverse-transcriptase (pf-TERT) and Plasmodium dihydropteroate synthetase (pf-DHPS) to determine their affinity with antimalarial drugs. The interaction energies and stable complexes formed between these enzymes and antimalarial drugs (chloroquine, artemisinin, primaquine, pyrimethamine, sulfadoxine and pentamidine) were modelled using AutoDock vina. Our data indicate that pf-TERT and pf-DHPS form stable complexes with the antimalarial ligands with affinity ranging from −4.0 to −6.9 kcal/mol. The affinity with crystal structures of DHFR receptors was higher ranging from −6.0 to −10.0 kcal/mol. The affinity to DHFR also decreases with the mutation a confirmation of the source of resistance. The highest affinity interaction for all the receptors modeled is observed with Artemisinin a benchmark antimalarial drug. This can be attributed to the size, shape and dipolar surface of the ligand. The observed complexes are stabilized by strategic active site polar and non-polar contacts.