New Synthetic Cannabinoids Metabolism and Strategies to Best Identify Optimal Marker Metabolites.

Synthetic cannabinoids (SCs) were initially developed as pharmacological tools to probe the endocannabinoid system and as novel pharmacotherapies, but are now highly abused. This is a serious public health and social problem throughout the world and it is highly challenging to identify which SC was consumed by the drug abusers, a necessary step to tie adverse health effects to the new drug\u27s toxicity. Two intrinsic properties complicate SC identification, their often rapid and extensive metabolism, and their generally high potency relative to the natural psychoactive Δ 9 -tetrahydrocannabinol in cannabis. Additional challenges are the lack of reference standards for the major urinary metabolites needed for forensic verification, and the sometimes differing illicit and licit status and, in some cases, identical metabolites produced by closely related SC pairs, i.e., JWH-018/AM-2201, THJ-018/THJ-2201, and BB-22/MDMB-CHMICA/ADB-CHMICA. We review current SC prevalence, establish the necessity for SC metabolism investigation and contrast the advantages and disadvantages of multiple metabolic approaches. The human hepatocyte incubation model for determining a new SC\u27s metabolism is highly recommended after comparison to human liver microsomes incubation, in silico prediction, rat in vivo, zebrafish, and fungus Cunninghamella elegans models. We evaluate SC metabolic patterns, and devise a practical strategy to select optimal urinary marker metabolites for SCs. New SCs are incubated first with human hepatocytes and major metabolites are then identified by high-resolution mass spectrometry. Although initially difficult to obtain, authentic human urine samples following the specified SC exposure are hydrolyzed and analyzed by high-resolution mass spectrometry to verify identified major metabolites. Since some SCs produce the same major urinary metabolites, documentation of the specific SC consumed may require identification of the SC parent itself in either blood or oral fluid. An encouraging trend is the recent reduction in the number of new SC introduced per year. With global collaboration and communication, we can improve education of the public about the toxicity of new SC and our response to their introduction

In silico pharmacodynamics, toxicity profile and biological activities of the Saharan medicinal plant Limoniastrum feei

In-silico study was performed to find the pharmacodynamics, toxicity profiles and biological activities of three phytochemicals isolated from Limoniastrum feei (Plumbagenaceae). Online pharmacokinetic tools were used to estimate the potential of Quercetin, kaempferol-3-O-β-D-glucopyranoside (astragalin) and quercitin-7-O-β-D-glucopyranoside as specific drugs. Then the prediction of potential targets of these compounds were investigated using PharmMapper. Auto-Dock 4.0 software was used to investigate the different interactions of these compounds with the targets predicted earlier. The permeability of quercetin was found within the range stated by Lipinski ׳s rule of five. Hematopoietic prostaglandin (PG) D synthase (HPGDS), farnesyl diphosphate synthetase (FPPS) and the deoxycytidine kinase (DCK) were potential targets for quercetin, astragalin and quercetin 7, respectively. Quercetin showed antiallergic and anti-inflammatory activity, while astragalin and quercetin 7 were predicted to have anticancer activities. The activity of Astragalin appeared to be mediated by FPPS inhibition. The inhibition of DCK was predicted as the anticancer mechanisms of quercetin 7. The compounds showed interesting interactions and satisfactory binding energies when docked into their targets. These compounds are proposed to have activities against a variety of human aliments such as allergy, tumors, muscular dystrophy, and diabetic cataracts

Skin metabolism established with the use of MetaSite for selected retinoids employed in topical and systemic treatment of various skin disorders and found in cosmeceuticals

Purpose. Besides being widely used in cosmetics, retinoids are potent therapeutic agents used topically and systemically as anti-acne agents. The aim of this study was to predict with the use of MetaSite the skin metabolism of selected retinoids employed in treatment of skin disorders and found in cosmeceuticals. The following compounds were studied: retinol, retinaldehyde, retinoic acid, retinyl acetate, retinyl palmitate, acitretin, etretinate, adapalene and bexarotene. Methods. MetaSite, Molecular Discovery Ltd. is a computational model that enables prediction of cytochrome P450-dependant metabolism. This software indicates atoms in the molecule structure that are mostly vulnerable to metabolic changes and predicts the metabolite structures. Results. MetaSite indicated that retinol and retinal metabolites were obtained through hydroxylation of the methyl group located in the position 3 of the aliphatic chain, whereas retinoic acid biotransformation would occur principally in the carbon atom situated in the position 4 in the cyclohexene ring. In acitretin molecule, carbon atom of the methoxy group attached to the benzene ring displayed the highest probability of biotransformation. In etretinate, metabolic reactions would occur principally on the carbon atom of the final ethyl group of the molecule. Conclusions. MetaSite metabolism predictions for retinoic acid, acitretin, etretinate, adapalene and bexarotene were in agreement with experimental findings. In case of compounds being converted by catalysts other than cytochrome P450 enzymes, the primary metabolites predicted by MetaSite differ from those reported previously. In conclusion, MetaSite is a useful tool that can aid identification of the major metabolites of compounds being administered topically

Investigating the chemical space and metabolic bioactivation of natural products and cross-reactivity of chemical inhibitors in CYP450 phenotyping

Includes bibliographical references.Natural products have been exploited by humans as the most consistently reliable source of medicines for hundreds of years. Owing to the great diversity in chemical scaffolds they encompass, these compounds provide an almost limitless starting point for the discovery and development of novel semi-synthetic or wholly synthetic drugs. In Africa, and many other parts of the world, natural products in the form of herbal remedies are still used as primary therapeutic interventions by populations far removed from conventional healthcare facilities. However, unlike conventional drugs that typically undergo extensive safety studies during development, traditional remedies are often not subjected to similar evaluation and could therefore harbour unforeseen risks alongside their established efficacy. A comparison of the ‘drug-like properties’ of 335 natural products from medicinal plants reported in the African Herbal Pharmacopoeia with those of 608 compounds from the British Pharmacopoeia 2009 was performed using in silico tools. The data obtained showed that the natural products differed significantly from conventional drugs with regard to molecular weight, rotatable bonds and H-bond donor distributions but not with regard to lipophilicity (cLogP) and H-bond acceptor distributions. In general, the natural products were found to exhibit a higher degree of deviation from Lipinski’s ‘Rule-of-Five’. Additionally, these compounds possessed a slightly greater number of structural alerts per molecule compared to conventional drugs, suggesting a higher likelihood of undergoing metabolic bioactivation

Exploring the effects of polymorphic variation on the stability and function of human cytochrome P450 enzymes in silico and in vitro

Includes bibliographical references.Cytochrome P450s are highly polymorphic enzymes responsible for the Phase I metabolism of over 80% of pharmaceutical drugs. Polymorphic variation can result in altered drug efficacy as well as adverse drug reactions so the lack of understanding of the effects of single amino acid substitutions on cytochrome P450 drug metabolism is a major problem for drug development. In order to begin to address this problem, this thesis describes an in silico analysis of over 300 nonsynonymous single nucleotide polymorphisms found across nine of the major human drug metabolising cytochrome P450 isoforms. Information from functional studies - in which regions of the cytochrome P450 structure important for substrate recognition, substrate and product access and egress and interaction with the cytochrome P450 reductase were delineated - was combined with in silico calculations on the effect of mutations on protein stability in order to establish the likely causes of altered drug metabolism observed for cytochrome P450 variants in functional assays carried out to date. This study revealed that 75% of all cytochrome P450 mutations showing altered activity in vitro are either predicted to be damaging to protein structure or are found within regions predicted to be important for catalytic activity. Furthermore, this study showed that 70% of the mutations that showed similar activity to the wild-type enzyme in in vitro studies lie outside of functional regions important for catalytic activity and are predicted to have no effect on protein stability. Based on these results, a cytochrome P450 polymorphic variant map was created that should find utility in predicting the functional effect of uncharacterised variants on drug metabolism. To further test the accuracy of the in silico predictions, in vitro assays were performed on a panel of CYP3A4 and CYP2C9 variants heterogeneously expressed in E.coli. All mutations predicted to alter protein function by stabilising or destabilising the apo-protein structure in silico were found to significantly alter the thermostability of the holo-protein in solution. Thermostability assays also suggest that other mutations may affect stability by disrupting haem binding, changing protein conformation or altering oligomer formation. The utility of a fluorescence-based functional P450 protein microarray platform, previously developed in our laboratory, for generating kinetic data for multiple CYP450 variants in parallel was also examined. Since the microarray platform in its current stage of development was found to be unsuitable for this purpose, kinetic data for the full panel of CYP3A4 and CYP2C9 variants was generated using solution phase assays, revealing several variants with altered catalytic turnover and/or binding affinity for fluorescent substrates

IN SILICO PHARMACOKINETICS AND MOLECULAR DOCKING OF THREE LEADS ISOLATED FROM TARCONANTHUS CAMPHORATUS L.

Objective: To investigate the pharmacokinetic and toxicity profiles and spectrum of biological activities of three phytochemicals isolated from Tarconanthus camphoratus L. Methods: Several integrated web based in silico pharmacokinetic tools were used to estimate the druggability of Hispidulin, Nepetin and Parthenolide. Afterward, the structural based virtual screening for the three compounds' potential targets was performed using PharmMapper online server. The molecular docking was conducted using Auto-Dock 4.0 software to study the binding interactions of these compounds with the targets predicted by PharmMapper server. Results: The permeability properties for all compounds were found within the limit range stated for Lipinski׳s rule of five. Only Parthenolide proved to be able to penetrate through blood brain barrier. Isopentenyl-diphosphate delta-isomerase (IPPI), uridine-cytidine kinase-2 (UCK-2) and the mitogen-activated protein kinase kinase-1 (MEK-1) were proposed as potential targets for Hispidulin, Nepetin and Parthenolide, respectively. Nepetin and Parthenolide were predicted to have anticancer activities. The activity of Nepetin appeared to be mediated through UCK-2 inhibition. On the other hand, inhibition of MEK-1 and enhancement of TP53 expression were predicted as the anticancer mechanisms of Parthenolide. The three compounds showed interesting interactions and satisfactory binding energies when docked into their relevant targets. Conclusion: The ADMET profiles and biological activity spectra of Hispidulin, Nepetin and Parthenolide have been addressed. These compounds are proposed to have activities against a variety of human aliments such as tumors, muscular dystrophy, and diabetic cataracts.Keywords: Tarconanthus camphoratus L., Hispidulin, Nepetin, Parthenolide, In silico pharmacokinetic, Molecular docking, PharmMapper server, and Auto-Dock 4.0 softwareÂ

Synthesis, Characterization and in Vitro Kinetic Study of Dopamine Prodrugs

Parkinson patients have insufficient dopamine in specific regions of the brain, so attempts have been made to replenish the deficiency in the dopamine. Dopamine itself doesn't cross blood brain barrier, but its precursor, levodopa (LD) is actively transported into the CNS and is converted to dopamine in the brain. The bioavailability of LD is less than 10% with only 1% of administered oral levodopa penetrates the brain. Large doses of levodopa are required because much of the drug is decarboxylated to dopamine in the periphery, resulting in side effects that include nausea, vomiting, cardiac arrhythmias, and hypotension. To minimize the conversion to dopamine (DA) outside the central nervous system (CNS), LD is usually co- administered with peripheral inhibitors of amino acid decarboxylase (carbidopa and benserazide). In spite of that, other central nervous side effects such as dyskinesia, on-off phenomenon and end-of-dose deterioration still remain.Based on DFT calculations a novel dopamine prodrugs for the treatment of Parkinson’s disease that can improve the overall biopharmaceutical profile of the current medications to enhance effectiveness and to ease the use of the medications were synthesized, characterized, in vitro intra-conversion to their parent drugs and in silico pharmacokinetics and toxicity prediction were also studied. The synthesized dopamine prodrugs have a carboxylic group as a hydrophilic moiety and a hydrocarbon skeleton as a lipophilic moiety, where the combination of both groups ensures a moderate hydrophilic lipophilc balance value. The potential prodrugs are expected to give better bioavailability than the parental drug owing to improved absorption. Furthermore, these prodrugs are believed to be more effective than L-dopa because the latter undergoes decarboxylation in the periphery before reaching the blood– brain barrier. Additionally, the synthesized prodrugs can be used in different dosage forms (I.V., S.C., tablets, and others) because of their potential solubility in organic and aqueous media. For dopamine ProD 1 the experimental t½ values in 0.1N HCl, buffer pH 2.2, buffer pH 5.5 and buffer pH 7.4 were 60.3 hours, 54.66 hours, 99.93 hours and 138.13 hours, respectively. Dopamine ProD 2 was readily converted in 0.1N HCl, buffer pH 2.2, pH 5.5 and pH 7.4 with half -life time (t½) of 48.34 hours, 54.22 hours, 131.98 hours and 193.42 hours, respectively. Finally, in silico predicting of physiochemical parameters, ADMET (Absorption, Distribution, Metabolism, Excretion and Toxicity) properties, oral bioavailability and BBB permeability for the synthesized prodrugs were studied. The results revealed that no prodrug had a high risk of toxicity, and all the prodrugs showed good pharmacokinetic properties. Moreover, all synthesized dopamine prodrugs were found to obey Lipinski’s rule of five

A Comprehensive Evaluation of Sdox, a Promising H2S-Releasing Doxorubicin for the Treatment of Chemoresistant Tumors

Sdox is a hydrogen sulfide (H2S)-releasing doxorubicin effective in P-glycoprotein-overexpressing/doxorubicin-resistant tumor models and not cytotoxic, as the parental drug, in H9c2 cardiomyocytes. The aim of this study was the assessment of Sdox drug-like features and its absorption, distribution, metabolism, and excretion (ADME)/toxicity properties, by a multi- and transdisciplinary in silico, in vitro, and in vivo approach. Doxorubicin was used as the reference compound. The in silico profiling suggested that Sdox possesses higher lipophilicity and lower solubility compared to doxorubicin, and the off-targets prediction revealed relevant differences between Dox and Sdox towards several cancer targets, suggesting different toxicological profiles. In vitro data showed that Sdox is a substrate with lower affinity for P-glycoprotein, less hepatotoxic, and causes less oxidative damage than doxorubicin. Both anthracyclines inhibited CYP3A4, but not hERG currents. Unlike doxorubicin, the percentage of zebrafish live embryos at 72 hpf was not affected by Sdox treatment. In conclusion, these findings demonstrate that Sdox displays a more favorable drug-like ADME/toxicity profile than doxorubicin, different selectivity towards cancer targets, along with a greater preclinical efficacy in resistant tumors. Therefore, Sdox represents a prototype of innovative anthracyclines, worthy of further investigations in clinical settings

In silico molecular docking of selected polyphenols against interleukin-17A target in gouty arthritis

The binding of Interleukin-17A (IL-17A) to its receptor causes the release of chemokine which have an implication in the pathogenesis of gouty arthritis. Though, some synthetic drugs have been proved worthy as IL-17A inhibitors in the management of gout but they have been associated with a number of side effects. Polyphenols have been documented for numerous therapeutic applications. In spite of this, there are scarce data on the mechanism of action and protective potentials of polyphenolic against gouty arthritis. This present in silico study aimed to assess the inhibitory potentials and ADMET properties of selected polyphenols against IL-17A using molecular docking tools. The crystal structure of IL-17A was retrieved from the protein database, while the structures of polyphenolic compounds were retrieved from Pubchem. Drug-likeness of the polyphenols was assessed using DruLiTo. A total of 22 out of 26 polyphenols investigated passed the Lipinski drug likeness rule of five which were then docked with the active site of IL-17A using docking software, and the docked complexes were analyzed using LigPlot and protein-ligand profiler web server. The results showed that all the investigated polyphenols have appreciable higher binding affinity when compared to the standard drug (allopurinol) with pelargondin and catechin having the highest binding affinity (-7.5 kcal/mol). Furthermore, ADMET screening were carried out on the five compounds with the best hits. Conclusively, this in silico study suggests that these investigated polyphenols could serve as better replacements for synthetic drugs such as allopurinol in the management of gouty arthritis. DOI: http://dx.doi.org/10.5281/zenodo.406423