Honeybees are prone to poisoning, also known as jujube flower disease, after collecting nectar from jujube flowers, resulting in the tumultuous demise of foragers. The prevalence of jujube flower disease has become one of the main factors affecting the development of the jujube and beekeeping industries in Northern China. However, the pathogenic mechanisms underlying jujube flower disease in honeybees are poorly understood. Herein, we first conducted morphological observations of the midgut using HE-staining and found that jujube flower disease-affected honeybees displayed midgut damage with peritrophic membrane detachment. Jujube flower disease was found to increase the activity of chitinase and carboxylesterase (CarE) and decrease the activity of superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), and the content of CYP450 in the honeybee midgut. Transcriptomic data identified 119 differentially expressed genes in the midgut of diseased and healthy honeybees, including CYP6a13, CYP6a17, CYP304a1, CYP6a14, AADC, and AGXT2, which are associated with oxidoreductase activity and vitamin binding. In summary, collecting jujube flower nectar could reduce antioxidant and detoxification capacities of the honeybee midgut and, in more severe cases, damage the intestinal structure, suggesting that intestinal damage might be the main cause of honeybee death due to jujube nectar. This study provides new insights into the pathogenesis of jujube flower disease in honeybees.

Pro-drugs, which ideally release their active compound only at the site of action, i.e., in a cancer cell, are a promising approach towards an increased specificity and hence reduced side effects in chemotherapy. A popular form of pro-drugs is esters, which are activated upon their hydrolysis. Since carboxylesterases that catalyse such a hydrolysis reaction are also abundant in normal tissue, it is of great interest whether a putative pro-drug is a probable substrate of such an enzyme and hence bears the danger of being activated not just in the target environment, i.e., in cancer cells. In this work, we study the binding mode of carboxylesters of the drug molecule camptothecin, which is an inhibitor of topoisomerase I, of varying size to human carboxylesterase 2 (HCE2) by molecular docking and molecular dynamics simulations. A comparison to irinotecan, known to be a substrate of HCE2, shows that all three pro-drugs analysed in this work can bind to the HCE2 protein, but not in a pose that is well suited for subsequent hydrolysis. Our data suggest, moreover, that for the irinotecan substrate, a reactant-competent pose is stabilised once the initial proton transfer from the putative nucleophile Ser202 to the His431 of the catalytic triad has already occurred. Our simulation work also shows that it is important to go beyond the static models obtained from molecular docking and include the flexibility of enzyme-ligand complexes in solvents and at a finite temperature. Under such conditions, the pro-drugs studied in this work are unlikely to be hydrolysed by the HCE2 enzyme, indicating a low risk of undesired drug release in normal tissue.

OBJECTIVE: Occurrence of hand-foot syndrome (HFS) during capecitabine treatment often results in treatment interruptions (26 %) or treatment discontinuation (17 %), and can severely decrease quality of life. In this study, we investigated whether single nucleotide polymorphisms (SNPs) in genes involved in capecitabine metabolism - other than DPYD - are associated with an increased risk for capecitabine-induced HFS.
METHODS: Patients treated with capecitabine according to standard of care were enrolled after providing written informed consent for genotyping purposes. Prospectively collected blood samples were used to extract genomic DNA, which was subsequently genotyped for SNPs in CES1, CES2 and CDA. SNPs and clinical baseline factors that were univariably associated with HFS with P ≤ 0.10, were tested in a multivariable model using logistic regression.
RESULTS: Of the 446 patients eligible for analysis, 146 (32.7 %) developed HFS, of whom 77 patients (17.3 %) experienced HFS ≥ grade 2. In the multivariable model, CES1 1165-33 C>A (rs2244613, minor allele frequency 19 %) and CDA 266 + 242 A>G (rs10916825, minor allele frequency 35 %) variant allele carriers were at higher risk of HFS ≥ grade 2 (OR 1.888; 95 %CI 1.075-3.315; P = 0.027 and OR 1.865; 95 %CI 1.087-3.200; P = 0.024, respectively).
CONCLUSIONS: We showed that CES1 1165-33 C>A and CDA 266 + 242 A>G are significantly associated with HFS grade 2 and grade 3 in patients treated with capecitabine. Prospective studies should assess whether this increased risk can be mitigated in carriers of these SNPs, when pre-emptive genotyping is being followed by dose adjustment or by alternative treatment by a fluoropyrimidine that is not substrate to CES1, such as S1.

Hepatic drug-metabolizing enzymes (DMEs) play critical roles in determining the pharmacokinetics and pharmacodynamics of numerous therapeutic agents. As such, noninvasive biomarkers capable of predicting DME expression in the liver have the potential to be used to personalize pharmacotherapy and improve drug treatment outcomes. In the present study, we quantified carboxylesterase 1 (CES1) protein concentrations in plasma samples collected during a methylphenidate pharmacokinetics study. CES1 is a prominent hepatic enzyme responsible for the metabolism of many medications containing small ester moieties, including methylphenidate. The results revealed a significant inverse correlation between plasma CES1 protein concentrations and the area under the concentration-time curves (AUCs) of plasma d-methylphenidate (P = 0.014, r = -0.617). In addition, when plasma CES1 protein levels were normalized to the plasma concentrations of 24 liver-enriched proteins to account for potential interindividual differences in hepatic protein release rate, the correlation was further improved (P = 0.003, r = -0.703), suggesting that plasma CES1 protein could explain ~ 50% of the variability in d-methylphenidate AUCs in the study participants. A physiologically-based pharmacokinetic modeling simulation revealed that the CES1-based individualized dosing strategy might significantly reduce d-methylphenidate exposure variability in pediatric patients relative to conventional trial and error fixed dosing regimens. This proof-of-concept study indicates that the plasma protein of a hepatic DME may serve as a biomarker for predicting its metabolic function and the pharmacokinetics of its substrate drugs.

Malathion organophosphates considered as the major constituent of herbicides, pesticides and insecticides. Extensively used in agricultural, horticultures and for numerous household applications contributes to precedence organic pollutants leading antagonistic effects on human health and environment. Therefore detoxification of malathion from contaminated site is of general interest. Simultaneously it is very emerging to isolated novel indigenous microbial strains from contaminated site with a record of pesticide application. In this study Escherichia coli IES-02 isolated from malathion contaminant effluent and the strain showed maximum efficiency in malathion degradation that utilized it as the sole source of carbon. Carboxylesterase (33.0, 30.0, 28.0 kDa) were purified (1685.71 U/mg) from Escherichia coli IES-02 showed significant results in malathion degradation approximately 81% within 20 min as compared with Escherichia coli IES-02 cells within 4 h (99.0 to 95.0%) into monocarboxylic acid and diacid derivatives. The generation time of Escherichia coli was also observed at 60 min with 0.1 ppm, 68 min with 0.5 ppm, 74.5 min with 2.0 ppm and 91.37 min with 50 ppm of malathion. The degradation rate and transformation metabolites were estimated by Gas Chromatography-Mass Spectrometry respectively. Malathion metabolites pathway proposed in this study which revealed the potential application against lethal environmental pollution.

Parabens are widely used as preservatives in personal care products, medicines and foods, resulting in substantial human exposures, even though some harmful effects, such as endocrine-disrupting activity, have been reported. Pregnane X receptor (PXR), constitutive androstane receptor (CAR) and peroxisome proliferator-activated receptor α (PPARα), which are members of the nuclear receptor superfamily, regulate the metabolism of endogenous substrates including hormones. Therefore, we hypothesized that parabens may alter hormone-metabolizing activities by acting on these receptors, and such changes could contribute to the endocrine-disrupting activity. To test this idea, we systematically examined the effects of 17 parabens on these receptors using reporter gene assays. Nine parabens significantly activated human and rat PXR. Parabens with C2-C5 (linear and branched) side chains were most active. Butylparaben and isobutylparaben also significantly activated rat CAR. We found that long-side-chain (C7-C12) parabens showed up to 2-fold activation of PPARα at 10 μM. Furthermore, pentylparaben and hexylparaben showed rat PXR antagonistic activity and rat CAR inverse agonistic activity. The activity of butylparaben towards PXR and CAR was lost after carboxylesterase-mediated metabolism. These findings confirm that parabens influence the activities of PXR, CAR and PPARα, and thus have the potential to contribute to endocrine disruption by altering hormone metabolism.

The hydrolysis activity and expression level of carboxylesterase (CES) in skin were compared with liver and intestine in the same individual of beagle dog and cynomolgus monkey, and their aging effects were studied. CES1 isozymes were mainly present in skin of both animals. The dermal hydrolysis activity was about 10 and 40% of hepatic activity in beagle dog and cynomolgus monkey, respectively. In beagle dog, the hydrolysis activity and the expression level of CES isozyme in liver and skin were nearly the same between 2- and 11-year-old individuals. On the other hand, the dermal hydrolase activity was lower in young individual than in old, in contrast to slight increase of hepatic and intestinal activity in old cynomolgus monkey. These differences by aging in cynomolgus monkey were related to the expression of CES1 proteins and their mRNA. Furthermore, mRNA level of human CES was investigated using total RNA of two individuals (63 and 85 years old). The two individuals showed approximately 2-fold higher expression of hCE2 than hCE1 in human skin.

The antifeedant and contact toxicity of Sphagneticola trilobata L. (Asterales: Asteraceae) extracts and isolated alkane compounds were investigated. Leaves of S. trilobata were sequentially extracted with hexane, dichloromethane, ethyl acetate, and methanol. Each extract and the compounds isolated were evaluated against the third instars of Spodoptera litura (F.) (Lepidoptera: Noctuidae), Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae), and Plutella xylostella L. (Lepidoptera: Yponomeutidae). Ethyl acetate extract and isolated alkanes were feeding deterrents as well as contact toxins against all the three species evaluated (FI50 ~ 0.27-2.34 mg/ml; LD50 ~ 0.88-4.2 µg/larvae for ethyl acetate extract, and FI50 ~ 0.06-4.35 mg/ml; LD50 ~ 0.72-3.54 Ethyl acetate extract for isolated alkane). Impact on detoxifying enzymes was variable. The ethyl acetate crude extract reduced carboxylesterase activity in S. litura and P. xylostella while in S. exigua the enzyme was induced. In contrast, glutathione-S-transferase activity was induced in S. exigua but no significant difference in P. xylostella and S.litura was observed. Our results suggest that the S. trilobata extracts have multiple biological activities that contribute to the toxicity in lepidopterans. Variable enzyme responses to the products evaluated in different lepidopteran species also confirm that some species-specific inductions do occur, suggesting the possibility of resistance development in the future, which cannot be summarily ignored. However, for this detailed biochemical studies are required. Multiple bioefficacies of S. trilobata makes it a potential botanical for further exploitation on larger scale so that field potential can be established in any integrated pest management (IPM) system.

Dasatinib, a new tyrosine kinase inhibitor, is used clinically to kill chronic myelogenous leukemia and acute lymphoblastic leukemia through apoptosis. Obviously, anemia is developed in many patients receiving dasatinib for treatment. Until now, the mechanism for the cytotoxic effects of dasatinib in human erythrocytes is not fully understood. As many tyrosine kinases are found in human erythrocytes, it is therefore logical to hypothesize that dasatinib is able to induce apoptosis (or eryptosis) in human erythrocytes. True to our expectation, dasatinib inhibited tyrosine kinase and induced eryptosis in human erythrocytes with early denature of esterase, cell shrinkage, loss of membrane integrity with inside-out phosphatidylserine, increase in the cytosolic Ca2+ ion concentration ([Ca2+]i), caspase-3 activation and change in cellular redox state. Mechanistically, the rise of [Ca2+]i seems to be a key mediator in the dasatinib-mediated eryptosis because depletion of external Ca2+ could suppress the eryptotic effects. Also, dasatinib was able to reduce membrane fluidity in human RBCs. For the direct action on membrane, dasatinib permeabilized RBC ghosts in a way similar to digitonin. Taken together, we report here for the first time that dasatinib inhibited tyrosine kinase and induced eryptosis in human erythrocytes through Ca2+ loading and membrane permeabilization.

To predict the impact of liver cirrhosis on hepatic drug clearance using physiologically based pharmacokinetic (PBPK) modeling, we compared the protein abundance of various phase 1 and phase 2 drug-metabolizing enzymes (DMEs) in S9 fractions of alcoholic (n = 27) or hepatitis C (HCV, n = 30) cirrhotic versus noncirrhotic (control) livers (n = 25). The S9 total protein content was significantly lower in alcoholic or HCV cirrhotic versus control livers (i.e., 38.3 ± 8.3, 32.3 ± 12.8, vs. 51.1 ± 20.7 mg/g liver, respectively). In general, alcoholic cirrhosis was associated with a larger decrease in the DME abundance than HCV cirrhosis; however, only the abundance of UGT1A4, alcohol dehydrogenase (ADH)1A, and ADH1B was significantly lower in alcoholic versus HCV cirrhotic livers. When normalized to per gram of tissue, the abundance of nine DMEs (UGT1A6, UGT1A4, CYP3A4, UGT2B7, CYP1A2, ADH1A, ADH1B, aldehyde oxidase (AOX)1, and carboxylesterase (CES)1) in alcoholic cirrhosis and five DMEs (UGT1A6, UGT1A4, CYP3A4, UGT2B7, and CYP1A2) in HCV cirrhosis was <25% of that in control livers. The abundance of most DMEs in cirrhotic livers was 25% to 50% of control livers. CES2 abundance was not affected by cirrhosis. Integration of UGT2B7 abundance in cirrhotic livers into the liver cirrhosis (Child Pugh C) model of Simcyp improved the prediction of zidovudine and morphine PK in subjects with Child Pugh C liver cirrhosis. These data demonstrate that protein abundance data, combined with PBPK modeling and simulation, can be a powerful tool to predict drug disposition in special populations.