METHODS: The involved approaches build molecules from fragments that are either isosteric to GSH sub-moieties (ligand-based) or successfully docked to GSH binding sub-pockets (structure-based). Compared to reference GST inhibitor of S-hexyl GSH, ligands with improved rigidity, synthetic accessibility, and affinity to receptor were successfully designed. The method involves joining fragments to create ligands. The ligands were then explored using molecular docking, Cartesian coordinate's optimization, and simplified free energy determination as well as MD simulation and MMPBSA calculations. Several tools were used which include OPENEYE toolkit, Open Babel, Autodock Vina, Gromacs, and SwissParam server, and molecular mechanics force field of MMFF94 for optimization and CHARMM27 for MD simulation. In addition, in-house scripts written in Matlab were used to control fragments connection and automation of the tools.
MATERIALS AND METHODS: MTG and SRM was analyzed for their reducing power ability, ABTS radical inhibition and 1,1-diphenyl-2-picryl hydrazylfree radicals scavenging activities. Furthermore, the antiproliferation efficacy was evaluated using MTT assay on K 562 and HCT116 cancer cell lines versus NIH/3T3 and CCD18-Co normal cell lines respectively.
RESULTS: SRM and MTG demonstrate moderate antioxidant value with ABTS assay (Trolox equivalent antioxidant capacity (TEAC): 2.25±0.02 mmol trolox / mmol and 1.96±0.04 mmol trolox / mmol respectively) and DPPH (IC50=3.75±0.04 mg/mL and IC50=2.28±0.02 mg/mL respectively). Both MTG and SRM demonstrate equal potency (IC50=25.20±1.53 and IC50= 22.19±1.06 respectively) towards K 562 cell lines, comparable to control, betulinic acid (BA) (IC5024.40±1.26). Both compounds showed concentration-dependent cytototoxicity effects and exert profound antiproliferative efficacy at concentration > 100 μM towards HCT 116 and K 562 cancer cell lines, comparable to those of BA and 5-FU (5-Fluorouracil). Furthermore, both MTG and SRM exhibit high selectivity towards HCT 116 cell lines with selective indexes of 3.14 and 2.93 respectively compared to 5-FU (SI=0.60).
CONCLUSIONS: These findings revealed that the medicinal and nutitional values of mitragynine obtained from ketum leaves that growth in tropical forest of Southeast Asia and its analogues does not limited to analgesic properties but could be promising antioxidant and anticancer or chemopreventive compounds.
METHODS: Six healthy male Malaysian subjects were given a single oral dose of 200 mg artemether. Blood samples were collected to 72 h. Plasma concentrations of the two compounds were measured simultaneously by reversed-phase h.p.l.c. with electro-chemical detection in the reductive mode.
RESULTS: Mean (+/- s.d.) maximum concentrations of ARM, 310 +/- 153 micrograms l-1, were reached 1.88 +/- 0.21 h after drug intake. The mean elimination half-life was 2.00 +/- 0.59 h, and the mean AUC 671 +/- 271 micrograms l-1 h. The mean Cmax of DHA, 273 +/- 64 micrograms l-1 was observed at 1.92 +/- 0.13 h. The mean AUC of DHA was 753 +/- 233 micrograms h l-1'. ARM and DHA were stable at < or = -20 degrees C for at least 4 months in plasma samples.
CONCLUSIONS: The relatively short half-life of ARM may be one of the factors responsible for the poor radical cure rate of falciparum malaria with regimens employing daily dosing. In view of the rapid loss of DHA in plasma samples held at room temperature (26 degrees C) it is recommended to store them at a temperature of < or = -20 degrees C as early as possible after sample collection.
METHODS: Kinetic studies were used to investigate the interactions between the three GSTs and each of glutathione, 1-chloro-2,4-dinitrobenzene, cibacron blue, ethacrynic acid, S-hexyl glutathione, hemin and protoporphyrin IX. Since hemin displacement is intended for PfGST inhibitors, the interactions between hemin and other ligands at PfGST binding sites were studied kinetically. Computationally determined binding modes and energies were interlinked with the kinetic results to resolve enzymes-ligands interaction models at atomic level.
RESULTS: The results showed that hemin and cibacron blue have different binding modes in the three GSTs. Hemin has two binding sites (A and B) with two binding modes at site-A depending on presence of GSH. None of the ligands were able to compete hemin binding to PfGST except ethacrynic acid. Besides bind differently in GSTs, the isolated anthraquinone moiety of cibacron blue is not maintaining sufficient interactions with GSTs to be used as a lead. Similarly, the ethacrynic acid uses water bridges to mediate interactions with GSTs and at least the conjugated form of EA is the true hemin inhibitor, thus EA may not be a suitable lead.
CONCLUSIONS: Glutathione analogues with bulky substitution at thiol of cysteine moiety or at γ-amino group of γ-glutamine moiety may be the most suitable to provide GST inhibitors with hemin competition.
METHODS: Plasma concentrations of artesunic acid and dihydroartemisinin were determined simultaneously by HPLC with electrochemical detection. The test drug was well tolerated and no undesirable adverse effects were observed.
RESULTS: Comparison of pharmacokinetic parameters of artesunic acid after oral and rectal administration showed statistically significant differences in t(max) and AUC, with no changes for Cmax and t1/2. As for dihydroartemisinin, differences were observed for t(max) and Cmax but not for AUC.
CONCLUSION: There appear to be pharmacokinetic differences between oral and rectal modes of administration. The significance of these findings should be explored in malaria patients before appropriate therapeutic regimens are devised.
METHODS: Pharmacophore features were modelled using LigandScout 4.3 and validated through the area under curve (AUC), enrichment factor (EF) and Guner-Henry (GH) scores. Molecular docking was employed for virtual screening against modelled human 5HT1A homology receptor, molecular dynamics simulations and ADMET predictions.
RESULTS: The adopted pharmacophore possesses AUC, EF and GH scores of 0.7, 30.9 and 0.6 respectively, thus validated and used for molecular database screening. The modelled 5-HT1A homology receptor, validated using RCSB structure validation protocols, was employed for molecular docking and dynamics simulations. From the IBScreen database, the ligands, STOCK6S-36853, STOCK7S-36094, STOCK3S-94557, STOCK7S-28769 and STOCK5S-36248 interacted more strongly against the 5-HT1A receptor with docking scores of -8.735, -8.677, -8.140, -7.911 and -7.710 kcal/mol, and binding free energy of -29.72, -38.87, -29.85, -7.65 and -34.71 kcal/mol respectively, compared to fluoxetine and trazodone (positive controls) while albendazole and metformin (negative controls) scored least. They demonstrated good stability, satisfy the BDDCS RO5 and thus, are identified as potent SARIs.
CONCLUSION: The study represents a cost-effective, faster and environmentally friendly approach to the discovery of promising SARI antidepressants for further translational study.