In vitro safety signals for potential clinical development of the anti-inflammatory pregnane X receptor agonist FKK6.

Based on the mimicry of microbial metabolites, functionalized indoles were demonstrated as the ligands and agonists of the pregnane X receptor (PXR). The lead indole, FKK6, displayed PXR-dependent protective effects in DSS-induced colitis in mice and in vitro cytokine-treated intestinal organoid cultures. Here, we report on the initial in vitro pharmacological profiling of FKK6. FKK6-PXR interactions were characterized by hydrogen-deuterium exchange mass spectrometry. Screening FKK6 against potential cellular off-targets (G protein-coupled receptors, steroid and nuclear receptors, ion channels, and xenobiotic membrane transporters) revealed high PXR selectivity. FKK6 has poor aqueous solubility but was highly soluble in simulated gastric and intestinal fluids. A large fraction of FKK6 was bound to plasma proteins and chemically stable in plasma. The partition coefficient of FKK6 was 2.70, and FKK6 moderately partitioned into red blood cells. In Caco2 cells, FKK6 displayed high permeability (A-B: 22.8 × 10-6 cm.s-1) and no active efflux. These data are indicative of essentially complete in vivo absorption of FKK6. The data from human liver microsomes indicated that FKK6 is rapidly metabolized by cytochromes P450 (t1/2 5 min), notably by CYP3A4. Two oxidized FKK6 derivatives, including DC73 (N6-oxide) and DC97 (C19-phenol), were detected, and these metabolites had 5-7 × lower potency as PXR agonists than FKK6. This implies that despite high intestinal absorption, FKK6 is rapidly eliminated by the liver, and its PXR effects are predicted to be predominantly in the intestines. In conclusion, the PXR ligand and agonist FKK6 has a suitable pharmacological profile supporting its potential preclinical development.

Phytocannabinoid-rich galenic preparations for topical administration: extraction and stability testing.

Although medical cannabis was legalized in Czechia in 2013 and its use in topical treatments of skin disorders is now allowed, galenic formulations prepared from medical cannabis have not been widely implemented in the Czech healthcare system. One of the main reasons is the lack of a straightforward standardized protocol for their preparation. Cannabinoids, e.g., cannabidiol (CBD) and tetrahydrocannabinol (THC), have been shown to have therapeutic effects on various skin conditions, such as atopic dermatitis, psoriasis, scleroderma, acne and skin pigmentation. Recognizing the potential of dermatological treatment with medical cannabis, the present study aimed to evaluate the extraction capacity of various pharmaceutical bases for cannabinoids and the stability of prepared galenic formulations for dermatological applications with respect to cannabinoid content. The results showed that the stability of cannabinoids in formulations depended on the bases' physical and chemical properties. The highest THC decomposition was observed in cream bases and Vaseline, with estimated percentage loss of total content of up to 5.4% and 5.6% per week, respectively. In contrast, CBD was more stable than THC. Overall, the tested bases were comparably effective in extracting cannabinoids from plant material. However, olive oil and Synderman bases exhibited the highest cannabinoid extraction efficiencies (approximately 70%) and the best storage stabilities in terms of the content of monitored compounds. The proposed preparation protocol is fast and easily implementable in pharmacies and medical facilities.

Profiling of Health-Promoting and Taste-Relevant Compounds in Sixteen Radish (Raphanus sativus L.) Genotypes Grown under Controlled Conditions.

It is becoming increasingly challenging to maintain crop yields and quality as the global climate changes. The aim of this study was to determine whether and how the profile of health-promoting and taste-related compounds of radishes changes within a growing season. A total of 16 radish (Raphanus sativus L.) genotypes that are commercially available on the Czech market were assessed by means of chemical analysis. Radishes were cultivated in three independent growing cycles under controlled conditions, and the effects of the genotype and growing cycle, as well as their interactions, on the chemical traits were evaluated. Most of the variability in chemical composition was associated with the growing cycle, which accounted for 51.53% of total variance, followed by the genotype (26% of total variance). The interaction between the growing cycle and genotype explained 22.47% of total variance. The growing cycle had the strongest effect on amino acid profiles. More specifically, the amino acids that are known to contribute to overall taste (glycine, along with glutamic and aspartic acids) showed the highest degree of variation, while the amino acids related to glucosinolate biosynthesis (methionine, isoleucine, tryptophan, and phenylalanine) showed relatively low variability. On the other hand, indole glucosinolates were found to differ the most between genotypes.

Cannabis-derived products antagonize platinum drugs by altered cellular transport.

Cannabinoids, a class of compounds derived from Cannabis sativa L., have recently become more widely accessible for public consumption in the form of diverse cannabis products, in parallel with weakening the measures that so far restricted their availability. The US Food and Drug Administration has approved several cannabis-derived drugs for management of various diseases as well as chemotherapy-induced nausea and vomiting. Besides the attenuation of adverse effects of chemotherapy, numerous reports about cannabinoid-mediated anticancer effects further motivate cancer patients to support their therapy with such products. Here we present a set of preclinical data with human cell culture models, suggesting that cannabidiol and cannabis extracts may effectively counteract the anticancer effects of the clinically widely used standard-of-care platinum-based drugs. We show that even low concentrations of cannabinoids reduced the toxicity of cisplatin, oxaliplatin, and carboplatin, an effect which was accompanied by decreased platinum adduct formation and a set of commonly used molecular markers. Mechanistically, our results excluded the possibility that the observed enhanced survival of cancer cells was mediated transcriptionally. Instead, trace metal analyses strongly indicate an inhibitory impact of cannabinoids on intracellular platinum accumulation, thereby implicating changes in cellular transport and/or retention of these drugs as the likely cause of the observed biological effects. Our study raises the possibility that the desirable effect of counteracting adverse effects of chemotherapy might, at least for some cannabinoids, reflect impaired cellular availability, and consequently attenuation of the anticancer effects of platinum drugs. DATA AVAILABILITY: All data supporting the conclusions are available in the article and supplementary files. Raw data are available upon request from the corresponding author.

Acridine Based N-Acylhydrazone Derivatives as Potential Anticancer Agents: Synthesis, Characterization and ctDNA/HSA Spectroscopic Binding Properties.

A series of novel acridine N-acylhydrazone derivatives have been synthesized as potential topoisomerase I/II inhibitors, and their binding (calf thymus DNA­ctDNA and human serum albumin­HSA) and biological activities as potential anticancer agents on proliferation of A549 and CCD-18Co have been evaluated. The acridine-DNA complex 3b (-F) displayed the highest Kb value (Kb = 3.18 × 103 M−1). The HSA-derivatives interactions were studied by fluorescence quenching spectra. This method was used for the calculation of characteristic binding parameters. In the presence of warfarin, the binding constant values were found to decrease (KSV = 2.26 M−1, Kb = 2.54 M−1), suggesting that derivative 3a could bind to HSA at Sudlow site I. The effect of tested derivatives on metabolic activity of A549 cells evaluated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide or MTT assay decreased as follows 3b(-F) > 3a(-H) > 3c(-Cl) > 3d(-Br). The derivatives 3c and 3d in vitro act as potential dual inhibitors of hTopo I and II with a partial effect on the metabolic activity of cancer cells A594. The acridine-benzohydrazides 3a and 3c reduced the clonogenic ability of A549 cells by 72% or 74%, respectively. The general results of the study suggest that the novel compounds show potential for future development as anticancer agents.

Synthesis, characterization and antiproliferative activity of seco analogues of brassinosteroids.

Synthesis and structure-activity relationship analysis of a two groups of 2,3-seco analogues of brassinosteroids (BRs) were performed to examine their antiproliferative activities. Two steroid skeletons were chosen for the preparation of seco analogues - cholestane and stigmastane. The synthetic strategy consists of multistep reactions and detailed analysis of compounds prepared. We have discovered unpublished behaviour of 2,3-seco-2,3-dihydroxy-6-ketones leading to formation of intramolecular ketal with two new steroidal rings. Their reaction intermediates were also characterized in some cases. All compounds prepared were fully characterized with NMR and MS techniques. Most of compounds were tested for in vitro cytotoxicity on three cancer cell lines (CEM, MCF7, and HeLa) and normal human fibroblasts (BJ). It was discovered that some seco analogues caused apoptosis in cancer cells. The most promising seco derivative 28 proved to have high therapeutic index.

Intralaboratory comparison of analytical methods for quantification of major phytocannabinoids.

This study compares alternative approaches for analyzing phytocannabinoids in different plant materials. Three chromatographic analytical methods (ultra-high-performance liquid chromatography with tandem mass spectrometric detection and gas chromatography with mass spectrometric and flame ionization detection) were evaluated regarding selectivity, sensitivity, analytical accuracy, and precision. The performance of the methods was compared and all three methods were demonstrated to be appropriate tools for analyzing phytocannabinoids in cannabis. Gas chromatography coupled with mass spectrometric detection showed slightly better accuracy in determining phytocannabinoid acids, which are often difficult to quantify owing to their limited stability. Aspects of sample preparation, such as material homogenization and extraction, were also considered. A single ultrasonic-assisted ethanolic extraction of dried and powdered plant samples of cannabis was shown to be exhaustive for extracting the samples prior to analysis.

Quantitative Analysis of Ingenol in Euphorbia species via Validated Isotope Dilution Ultra-high Performance Liquid Chromatography Tandem Mass Spectrometry.

INTRODUCTION: Various species of the Euphorbia genus contain diterpene ingenol and ingenol mebutate (ingenol-3-angelate), a substance found in the sap of the plant Euphorbia peplus and an inducer of cell death. A gel formulation of the drug has been approved by the US Food and Drug Administration (FDA) and the European Medicines Agency (EMA) for the topical treatment of actinic keratosis. OBJECTIVE: To develop a rapid and reliable method for quantification of ingenol in various plant extracts. METHODOLOGY: Methanolic extracts of 38 species of the Euphorbia genus were analysed via ultra-high performance liquid chromatography with tandem mass spectrometry (UHPLC-MS/MS) after methanolysis and solid-phase extraction (SPE) purification. The 18 O-labelled ingenol analogue was prepared and used as an internal standard for ingenol content determination and method validation. RESULTS: The highest ingenol concentration (547 mg/kg of dry weight) was found in the lower leafless stems of E. myrsinites. The screening confirms a substantial amount of ingenol in species studied previously and furthermore, reveals some new promising candidates. CONCLUSION: The newly established UHPLC-MS/MS method shows to be an appropriate tool for screening of the Euphorbia genus for ingenol content and allows selection of species suitable for raw material production and/or in vitro culture initiation. Copyright © 2017 John Wiley & Sons, Ltd.

The natural cytokinin 2OH3MeOBAR induces cell death by a mechanism that is different from that of the "classical" cytokinin ribosides.

Cytokinin ribosides (N6-substituted adenosines) have demonstrated anticancer activity in various cultured cell lines, several xenografts and even a small clinical trial. Effects of kinetin riboside, N6-benzyladenosine (BAR) and N6-isopentenyladenosine on various parameters related to apoptosis have also been reported, but not directly compared with those of the highly active naturally occurring aromatic cytokinins oTR (ortho-topolin riboside) and 2OH3MeOBAR (N6-(2-hydroxy-3-methoxybenzyl)adenosine). Here we show that 2OH3MeOBAR is the most active cytokinin riboside studied to date (median, 1st quartile, 3rd quartile and range of GI50 in tests with the NCI60 cell panel: 0.19, 0.10, 0.43 and 0.02 to 15.7 µM, respectively) and it differs from other cytokinins by inducing cell death without causing pronounced ATP depletion. Analysis of NCI60 test data suggests that its activity is independent of p53 status. Further we demonstrate that its 5'-monophosphate, the dominant cancer cell metabolite, inhibits the candidate oncogene DNPH1. Synthesis, purification, HPLC-MS identification and HPLC-UV quantification of 2OH3MeOBAR metabolites are also reported.

Two New Isomers of Palmityl-4-hydroxycinnamate from Flowers of Taraxacum Species.

Two isomers, (Z)- and (E)-palmityl 4-hydroxycinnamate [hexadecyl(2Z)-3-(4-hydroxyphenyl)prop-2-enoate and hexadecyl(2E)-3-(4-hydroxyphenyl)prop-2-enoate] were isolated for the first time from ligulate flowers of Taraxacum linearisquameum Soest (sect. Taraxacum). The highest amount of these compounds was detected in pollen grains; 0.26 mg/100 mg DW of the (E)-isomer and 0.096 mg/100 mg DW of the (Z)-isomer. The structures of these compounds were elucidated by a combination of HPLC-ESI-Qtof-MS and 1D and 2D NMR spectroscopy. Their presence was confirmed in other species of Taraxacum, but they were not found in the male - sterile triploid agamospermous taxon T. parnassicum.

A novel series of highly potent 2,6,9-trisubstituted purine cyclin-dependent kinase inhibitors.

The inhibition of overactive CDKs during cancer remains an important strategy in cancer drug development. We synthesized and screened a novel series of 2-substituted-6-biarylmethylamino-9-cyclopentylpurine derivatives for improved CDK inhibitory activity and antiproliferative effects. One of the most potent compounds, 6b, exhibited strong cytotoxicity in the human melanoma cell line G361 that correlated with robust CDK1 and CDK2 inhibition and caspase activation. In silico modeling of 6b in the active site of CDK2 revealed a high interaction energy, which we believe is due to the 6-heterobiarylmethylamino substitution of the purine moiety.

Analysis of cytokinin nucleotides by capillary zone electrophoresis with diode array and mass spectrometric detection in a recombinant enzyme in vitro reaction.

A capillary zone electrophoresis (CZE) method for separation of adenosine and N(6)-isopentenyladenosine (cytokinin) nucleotides was developed, optimized and validated. Aqueous solutions of several amino acids were evaluated as the background electrolyte constituents. Separation of six nucleotides in less than 20 min with high theoretical plate number (up to 400000 for isopentenyladenosine triphosphate) was achieved using a 100 mM sarcosine/ammonia buffer at pH 10.0. The detection limits of the CZE-UV method are in the low micromolar range (0.69-1.27 µmol L(-1)). Good repeatability of migration times (within 1.3%), peak areas (within 1.8%) and linearity (R(2)>0.999) was achieved over the concentration range 5-1000 µmol L(-1). The method was used to assay the activity of the recombinant Arabidopsis thaliana isopentenyltransferase 1 (AtIPT1). Baseline separation of isopentenylated nucleotides by CE-ESI-MS using a volatile buffer (30 mM ammonium formate; pH 10.0) was accomplished. The identities of the reaction products - isopentenyladenosine di- and triphosphate were confirmed by HPLC-QqTOF-MS. Dephosphorylation of ATP was observed as a parallel reaction.

Tandem mass spectrometry identification and LC-MS quantification of intact cytokinin nucleotides in K-562 human leukemia cells.

We describe here a new reversed-phase high-performance liquid chromatography with mass spectrometry detection method for quantifying intact cytokinin nucleotides in human K-562 leukemia cells. Tandem mass spectrometry was used to identify the intracellular metabolites (cytokinin monophosphorylated, diphosphorylated, and triphosphorylated nucleotides) in riboside-treated cells. For the protein precipitation and sample preparation, a trichloroacetic acid extraction method is used. Samples are then back-extracted with diethyl ether, lyophilized, reconstituted, and injected into the LC system. Analytes were quantified in negative selected ion monitoring mode using a single quadrupole mass spectrometer. The method was validated in terms of retention time stabilities, limits of detection, linearity, recovery, and analytical accuracy. The developed method was linear in the range of 1-1,000 pmol for all studied compounds. The limits of detection for the analytes vary from 0.2 to 0.6 pmol.

Vacuolar and cytosolic cytokinin dehydrogenases of Arabidopsis thaliana: heterologous expression, purification and properties.

The catabolism of cytokinins is a vital component of hormonal regulation, contributing to the control of active forms of cytokinins and their cellular distribution. The enzyme catalyzing the irreversible cleavage of N(6)-side chains from cytokinins is a flavoprotein classified as cytokinin dehydrogenase (CKX, EC 1.5.99.12). CKXs also show low cytokinin oxidase activity, but molecular oxygen is a comparatively poor electron acceptor. The CKX gene family of Arabidopsis thaliana comprises seven members. Four code for proteins secreted to the apoplast, the remainder are not secreted. Two are targeted to the vacuoles and one is restricted to the cytosol. This study presents the purification and characterization of each of these non-secreted CKX enzymes and substrate specificities are discussed with respect to their compartmentation. Vacuolar enzymes AtCKX1 and AtCKX3 were produced in Pichia pastoris and cytosolic enzyme AtCKX7 was expressed in Escherichia coli. The recombinant proteins were purified by column chromatography. All enzymes preferred synthetic electron acceptors over oxygen, namely potassium ferricyanide and 2,3-dimetoxy-5-methyl-1,4-benzoquinone (Q(0)). In slightly acidic conditions (pH 5.0), N(6)-(2-isopentenyl)adenine 9-glucoside (iP9G) was the best substrate for AtCKX1 and AtCKX7, whereas AtCKX3 preferentially degraded N(6)-(2-isopentenyl)adenine 9-riboside-5'-monophosphate (iPMP). Moreover, vacuolar AtCKX enzymes in certain conditions degraded N(6)-(2-isopentenyl)adenine di- and triphosphates two to five times more effectively than its monophosphate.

Anticancer activity of natural cytokinins: a structure-activity relationship study.

Cytokinin ribosides (N(6)-substituted adenosine derivatives) have been shown to have anticancer activity both in vitro and in vivo. This study presents the first systematic analysis of the relationship between the chemical structure of cytokinins and their cytotoxic effects against a panel of human cancer cell lines with diverse histopathological origins. The results confirm the cytotoxic activity of N(6)-isopentenyladenosine, kinetin riboside, and N(6)-benzyladenosine and show that the spectrum of cell lines that are sensitive to these compounds and their tissues of origin are wider than previously reported. The first evidence that the hydroxylated aromatic cytokinins (ortho-, meta-, para-topolin riboside) and the isoprenoid cytokinin cis-zeatin riboside have cytotoxic activities is presented. Most cell lines in the panel showed greatest sensitivity to ortho-topolin riboside (IC(50)=0.5-11.6 microM). Cytokinin nucleotides, some synthesized for the first time in this study, were usually active in a similar concentration range to the corresponding ribosides. However, cytokinin free bases, 2-methylthio derivatives and both O- and N-glucosides showed little or no toxicity. Overall the study shows that structural requirements for cytotoxic activity of cytokinins against human cancer cell lines differ from the requirements for their activity in plant bioassays. The potent anticancer activity of ortho-topolin riboside (GI(50)=0.07-84.60 microM, 1st quartile=0.33 microM, median=0.65 microM, 3rd quartile=1.94 microM) was confirmed using NCI(60), a standard panel of 59 cell lines, originating from nine different tissues. Further, the activity pattern of oTR was distinctly different from those of standard anticancer drugs, suggesting that it has a unique mechanism of activity. In comparison with standard drugs, oTR showed exceptional cytotoxic activity against NCI(60) cell lines with a mutated p53 tumour suppressor gene. oTR also exhibited significant anticancer activity against several tumour models in in vivo hollow fibre assays.