Chemical analysis and acetylcholinesterase inhibitory effect of anthocyanin-rich red leaf tea (cv. Sunrouge)

BACKGROUND

The purpose of this study was to evaluate the effects of leaf order or crop season on anthocyanins and other chemicals in the anthocyanin-rich tea cultivar 'Sunrouge' (Camellia sinensis x C. taliensis) by using high-performance liquid chromatography, and to study the effect of 'Sunrouge' extract on acetylcholinesterase (AChE) activity in human neuroblastoma SK-N-SH cells.

RESULTS

The total anthocyanin content was higher in the third (3.09 mg g⁻¹) than in the second (2.24 mg g⁻¹) or first crop season (1.79 mg g⁻¹). The amount of anthocyanins contained in the stem was high (1.61 mg g⁻¹). In the third crop season, the concentrations of delphinidin-3-O-β-D-(6-(E)-p-coumaroyl)galactopyranoside (DCGa), cyanidin-3-O-β-D-(6-(E)-p-coumaroyl)galactopyranoside, delphinidin-3-O-β-D-galactopyranoside, delphinidin-3-O-β-D-(6-O-(Z)-p-coumaroyl)galactopyranoside, cyanidin-3-O-β-D-galactoside, and delphinidin-3-O-β-D-glucoside were 1.57 mg g⁻¹, 0.52 mg g⁻¹, 0.40 mg g⁻¹, 0.22 mg g⁻¹, 0.14 mg g⁻¹, and 0.11 mg g⁻¹, respectively. DCGa accounted for about 50% of the anthocyanins present. The suppressive effect of 'Sunrouge' water extract on AChE activity in human neuroblastoma SK-N-SH cells was the strongest among the three tea cultivars ('Sunrouge', 'Yabukita' and 'Benifuuki').

CONCLUSION

These results suggested that 'Sunrouge' might protect humans from humans from AChE-related diseases by suppressing AChE activity. To obtain sufficient amounts of anthocyanins, catechins and/or caffeine for a functional food material, 'Sunrouge' from the third crop season should be used.

New beverages of lemon juice enriched with the exotic berries maqui, açaı́, and blackthorn: bioactive components and in vitro biological properties

Following previous research on lemon juice enriched with berries, the aim of this work was to design new blends based on lemon juice mixed with different edible berries of exotic and national origin: maqui ( Aristotelia chilensis (Molina) Stuntz), açaı́ ( Euterpe oleracea Mart.), and blackthorn ( Prunus spinosa L.). The phytochemical characterization of controls and blends was performed by HPLC-DAD-ESI/MS(n). Their antioxidant capacity against DPPH, superoxide, and hydroxyl radicals and hypochlorous acid and their potential to inhibit cholinesterases were also assessed. The profiling of the red fruits and lemon revealed a wide range of bioactive phenolics. The novel beverage based on lemon juice and maqui berry (LM) was the most interesting blend in terms of antioxidant capacity. Berry control samples displayed reduced effects on acetylcholinesterase and butyrylcholinesterase, the lemon juice control being always the most active. This activity was also remarkable for lemon-blackthorn (LB) and lemon-açaı́ (LA) blends, the last being the most effective inhibitor of cholinesterases among all samples. The results suggested that lemon juice enriched with berries could be of potential interest in the design of new drinks with a nutritive related function on health for chronic diseases.

Multiple in vitro bioassay approach in sediment toxicity evaluation: Masan Bay, Korea

Extracts of 21 sediment samples from Masan Bay, Korea, used in an earlier chemical measurement, were screened for their ability to induce estrogen, - and dioxin - like gene expression using the E-Assay (+), DR-CALUX assay, respectively, and to inhibit acetylcholinesterase (AChE) activity using an in vitro AChE assay. Biological impact in the industry-rich inner bay is higher than outer bay. DDTs (0.65), coplanar PCBs (0.77), HCHs (0.64), PAHs (0.61) and APs (0.53) with good correlation to E-assay (+) are seen as environmental estrogens. The highest induction of DR-CALUX response was seen again at station M12 and 15 which received sewage effluents. PCDD/DFs gave the highest correlation (0.75). Interestingly, the M12 station at the sewage treatment outlet showed the highest activity. Among the targeted chemicals APs (0.66), PCBs (0.64), PAHs (0.61) and DDT (0.49) correlated well with the AChE bioassay. Spearman rank correlation on analytical and biochemical results affirmed the 'hot spots' and point sources (e.g., sewage treatment and industrial outfall) and suspected toxicants. Significant correlations between organo chlorine pesticides, PCBs, dioxins and alkylphenols and their biological effects were observed.

Screen-printed acetylcholinesterase-based biosensors for inhibitive determination of permethrin

An amperometric assay based on acetylcholinesterase (AChE) inactivation has been developed for the monitoring of permethrin using a screen-printed three-electrode system. The enzyme AChE catalyzes the hydrolysis of acetylthiocholine to thiocholine, which can be electrochemically oxidized. The presence of permethrin inhibits the AChE activity, resulting in a lower thiocholine production and thus, a decrease in the amperometric oxidation current. Immobilization of AChE was performed by cross-linking giving a capability of detection of 8.1±0.4 μM. Repeatability and reproducibility of the developed AChE biosensor were also calculated, yielding values of 9.6% (n=4) and 5.4% (n=5), respectively related to the slopes of the calibration curves performed in the range from 6.2 up to 41 μM. The method was successfully applied to the determination of permethrin content in a commercial lice gel.

Alkaloids from some amaryllidaceae species and their cholinesterase activity

Alkaloid extracts of four Amaryllidaceae species were studied with respect to their acetylcholinesterase and butyrylcholinesterase inhibitory activity and alkaloid patterns. Twenty-one alkaloids were determined by GC/MS, and seventeen of them identified from their mass spectra and retention times. The GC/MS analysis of the alkaloid extract of Nerine filamentosa is the first phytochemical investigation of this species. Promising erythrocytic acetylcholinesterase inhibitory activity was demonstrated by the alkaloid extracts of Narcissus poeticus var recurvus, Nerine filifolia and N. filamentosa (IC(50,HuAChE) = 6.0 +/- 0.1 microg/mL; IC(50,HuAChE) = 18.5 +/- 0.8 microg/mL, IC(50,HuAChE) = 21.6 +/- 1.1 microg/mL). The most potent inhibitory activity against serum butyrylcholinesterase was shown by extracts of Sternbergia lutea and Nerinefilamentosa (IC(50,HuBuChE) = 3.7 +/- 0.1 microg/mL; IC(50.HuBuChE) = 13.0 +/- 0.7 microg/mL).

[Expression and molecular evolution of recombinant acetylcholinesterase for detection of pesticide residues: a review]

Acetylcholinesterase (AChE) plays a key role in the pesticide determination. However, the extraction of AChE from natural materials has the disadvantages of low yield, complex purification and poor stability. Therefore, the preparation of recombinant AChE with high performance becomes the hot topic of researchers in recent years. In this article we summarize the progress in the expression of recombinant AChE and the improvement of its analytical characteristic. Finally, we point out that the directed evolution strategy combined with surface display technology is the future trend on improving recombinant AChE activity.

Reduction of diazinon and dimethoate in apple juice by pulsed electric field treatment

BACKGROUND

Organophosphorus pesticides (OPPs) are widely used in agricultural production in China, and residues of OPPs in agro-products and foods have become a public health concern. Chronic exposure to OPPs can result in potential immunosuppressive effects, cytotoxicity and mutagenicity. Pulsed electric fields (PEFs) have the potential to be used as an alternative to conventional techniques of food production. The aim of the present study was to investigate the influence of PEFs on the degradation of diazinon and dimethoate added to apple juice.

RESULTS

PEF treatment significantly promoted the degradation of both pesticides (P < 0.05). The extent of degradation was strongly influenced by the electric field strength and treatment time, and maximum degradation of both diazinon (47.6%) and dimethoate (34.7%) was achieved by treatment at 20 kV cm⁻¹ for 260 µs. The degradation behaviour of the pesticides was described by Weibull and Hülsheger models, both of which successfully fitted the degradation of diazinon and dimethoate. In addition, the decline in the toxicity of samples was observed with a photobacterium bioassay.

CONCLUSION

PEF treatment was effective in eliminating residues of diazinon and dimethoate spiked in apple juice and in mitigating sample toxicity.

Effect of Moringa oleifera flower extract on larval trypsin and acetylcholinesterase activities in Aedes aegypti

Aedes aegypti control is crucial to reducing dengue fever. Aedes aegypti larvae have developed resistance to organophosporous insecticides and the use of natural larvicides may help manage larval resistance by increasing elements in insecticide rotation programs. Here, we report on larvicidal activity of Moringa oleifera flower extract against A. aegypti L(1), L(2), L(3), and L(4) as well as the effect of flower extract on gut trypsin and whole-larval acetylcholinesterase from L(4.) In addition, the heated flower extract was investigated for larvicidal activity against L(4) and effect on larval gut trypsin. Moringa oleifera flower extract contains a proteinaceous trypsin inhibitor (M. oleifera flower trypsin inhibitor, MoFTI), triterpene (β-amyrin), sterol (β-sitosterol) as well as flavonoids (kaempferol and quercetin). Larvicidal activity was detected against L(2), L(3), and L(4) (LC(50) of 1.72%, 1.67%, and 0.92%, respectively). Flower extract inhibited L(4) gut trypsin (MoFTI K(i) = 0.6 nM) and did not affect acetylcholinesterase activity. In vivo assay showed that gut trypsin activity from L(4) treated with M. oleifera flower extract decreased over time (0-1,440 min) and was strongly inhibited (98.6%) after 310 min incubation; acetylcholinesterase activity was not affected. Thermal treatment resulted in a loss of trypsin inhibitor and larvicidal activities, supporting the hypothesis that flower extract contains a proteinaceous trypsin inhibitor that may be responsible for the deleterious effects on larval mortality.

High throughput enzyme inhibitor screening by functionalized magnetic carbonaceous microspheres and graphene oxide-based MALDI-TOF-MS

In this work, a high throughput methodology for screening enzyme inhibitors has been demonstrated by combining enzyme immobilized magnetic carbonaceous microspheres and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) with grapheme oxide as matrix. First, model enzyme acetylcholinesterase (AChE) was immobilized onto the 3-glycidoxypropyltrimethoxysilane (GLYMO)-modified magnetic carbonaceous (MC) microspheres, displaying a high enzyme activity and stability, and also facilitating the separation of enzyme from substrate and product. The efficiency of immobilized AChE was monitored by biochemical assay, which was carried out by mixing enzyme-immobilized MC microspheres with model substrate acetylcholine (ACh), and subsequent quantitative determination of substrate ACh and product choline using graphene oxide-based MALDI-TOF-MS with no background inference. The limit of detection (LOD) for ACh was 0.25 fmol/μL, and excellent linearity (R(2)=0.9998) was maintained over the range of 0.5 and 250 fmol/μL. Choline was quantified over the range of 0.05 and 15 pmol/μL, also with excellent linearity (R(2)=0.9994) and low LOD (0.15 fmol/μL). Good accuracy and precision were obtained for all concentrations within the range of the standard curves. All together, eight compounds (four known AChE inhibitors and four control chemical compounds with no AChE inhibit effect) were tested with our promoted methodology, and the obtained results demonstrated that our high throughput screening methodology could be a great help to the routine enzyme inhibitor screening.

Targeting acetylcholinesterase: identification of chemical leads by high throughput screening, structure determination and molecular modeling

Acetylcholinesterase (AChE) is an essential enzyme that terminates cholinergic transmission by rapid hydrolysis of the neurotransmitter acetylcholine. Compounds inhibiting this enzyme can be used (inter alia) to treat cholinergic deficiencies (e.g. in Alzheimer's disease), but may also act as dangerous toxins (e.g. nerve agents such as sarin). Treatment of nerve agent poisoning involves use of antidotes, small molecules capable of reactivating AChE. We have screened a collection of organic molecules to assess their ability to inhibit the enzymatic activity of AChE, aiming to find lead compounds for further optimization leading to drugs with increased efficacy and/or decreased side effects. 124 inhibitors were discovered, with considerable chemical diversity regarding size, polarity, flexibility and charge distribution. An extensive structure determination campaign resulted in a set of crystal structures of protein-ligand complexes. Overall, the ligands have substantial interactions with the peripheral anionic site of AChE, and the majority form additional interactions with the catalytic site (CAS). Reproduction of the bioactive conformation of six of the ligands using molecular docking simulations required modification of the default parameter settings of the docking software. The results show that docking-assisted structure-based design of AChE inhibitors is challenging and requires crystallographic support to obtain reliable results, at least with currently available software. The complex formed between C5685 and Mus musculus AChE (C5685•mAChE) is a representative structure for the general binding mode of the determined structures. The CAS binding part of C5685 could not be structurally determined due to a disordered electron density map and the developed docking protocol was used to predict the binding modes of this part of the molecule. We believe that chemical modifications of our discovered inhibitors, biochemical and biophysical characterization, crystallography and computational chemistry provide a route to novel AChE inhibitors and reactivators.

Repeated, intermittent exposures to diisopropylfluorophosphate in rats: protracted effects on cholinergic markers, nerve growth factor-related proteins, and cognitive function

Organophosphates (OPs) pose a constant threat to human health due to their widespread use as pesticides and their potential employment in military and terrorist attacks. The acute toxicity of OPs has been extensively studied; however, the consequences of prolonged or repeated exposure to levels of OPs that produce no overt signs of acute toxicity (i.e. subthreshold levels) are poorly understood. Further, there is clinical evidence that such repeated exposures to OPs lead to prolonged deficits in cognition, although the mechanism for this effect is unknown. In this study, the behavioral and neurochemical effects of repeated, intermittent, and subthreshold exposures to the alkyl OP, diisopropylfluorophosphate (DFP) were investigated. Rats were injected with DFP s.c. (dose range, 0.25-1.0 mg/kg) every other day over the course of 30 days, and then given a 2 week, DFP-free washout period. In behavioral experiments conducted at various times during the washout period, dose dependent decrements in a water maze hidden platform task and a spontaneous novel object recognition (NOR) procedure were observed, while prepulse inhibition of the acoustic startle response was unaffected. There were modest decreases in open field locomotor activity and grip strength (particularly during the DFP exposure period); however, rotarod performance and water maze swim speeds were not affected. After washout, DFP concentrations were minimal in plasma and brain, however, cholinesterase inhibition was still detectable in the brain. Moreover, the 1.0 mg/kg dose of DFP was associated with (brain region-dependent) alterations in nerve growth factor-related proteins and cholinergic markers. The results of this prospective animal study thus provide evidence to support two novel hypotheses: (1) that intermittent, subthreshold exposures to alkyl OPs can lead to protracted deficits in specific domains of cognition and (2) that such cognitive deficits may be related to persistent functional changes in brain neurotrophin and cholinergic pathways.

Response and recovery of acetylcholinesterase activity in freshwater shrimp, Paratya australiensis (Decapoda: Atyidae) exposed to selected anti-cholinesterase insecticides

The toxicity of carbaryl, chlorpyrifos, dimethoate and profenofos to the freshwater shrimp, Paratya australiensis was assessed by measuring acetylcholinesterase (AChE) inhibition after 96h exposures. Shrimp exposed to these pesticides exhibited significant AChE inhibition, with mortality in shrimp corresponding to 70-90% AChE inhibition. The sensitivity of P. australiensis to the four pesticides based on AChE inhibition can be given as chlorpyrifos > profenofos > carbaryl > dimethoate. Recovery of AChE activity was followed in shrimp after 96 h exposures to carbaryl, chlorpyrifos and dimethoate. Recovery after exposure to the carbamate pesticide carbaryl was more rapid than for the two organophosphorus pesticides, chlorpyrifos and dimethoate. The slow recovery of depressed AChE activity may mean that affected organisms in the natural system are unable to sustain physical activities such as searching for food or eluding predators. To investigate the ecological significance of AChE inhibition, chemotaxis behaviour was assessed in shrimp exposed to profenofos for 24h. Abnormal chemotaxis behaviour in the exposed shrimp was observed at concentrations representing 30-50% AChE inhibition. A clear relationship existed between the depression of AChE activity and observed chemotaxis responses, such as approaching and grasping the chemoattractant source. These results suggest that in vivo toxicity tests based on this specific biomarker are sensitive and present advantages over conventional acute tests based on mortality. Behavioural studies of test organisms conducted in conjunction with measurement of AChE inhibition will provide data to clarify the toxic effects caused by sublethal chemical concentrations of anti-cholinesterase compounds.

Detection of organophosphate pesticide using polyaniline and carbon nanotubes composite based on acetylcholinesterase inhibition

Acetylcholinesterase (AChE) activity may be useful biomarker for detecting of organophosphate pesticides (OP). Thus a sensitive biosensor for quantitative determination of OP based on AChE biomonitoring was developed. Multi-walled carbon nanotube (MWCNT)/polyaniline (PANI) composite film was prepared by electrochemical polymerization. The immobilized AChE catalyzed the hydrolysis of acetylthiocholine chloride to produce thiocholine, which engendered an irreversible oxidation peak. The enzyme activity was monitored by measuring the oxidation current of thiocholine and further detection of OP. The developed sensor provided a new promising tool for pesticide analysis and assay of enzyme activity.

Huperzine alkaloids from Australasian and southeast Asian Huperzia

CONTEXT

The pharmaceutical alkaloid huperzine A (HupA), currently used in herbal supplements and medicines worldwide, is predominantly sourced from the Chinese lycopod Huperzia serrata (Thunb. ex Murray) Trev. (Lycopodiaceae), which on average contains only 0.08 mg HupA g(-1) dry weight, and is experiencing a rapid decline in China due to over-harvesting.

OBJECTIVE

To find a high-yielding, natural source of HupA and/or the related huperzine B (HupB) that could potentially be used as the starting material in a commercial propagation program.

MATERIALS AND METHODS

We surveyed 17 Huperzia species (15 indigenous to Australia and southeast Asia) for their foliar HupA and HupB concentrations. We also studied intra-specific variation for the huperzines in four species that were available in sufficient numbers, and determined tissue-specific accumulation in larger specimens.

RESULTS

HupA was detected in 11 Australasian and southeast Asian species, with eight also containing HupB, albeit at much lower concentrations. A H. elmeri (Herter) Holub plant from the Philippines had one of the highest HupA concentrations recorded (1.01 mg g(-1) dry wt) and it also had the highest HupB content of all plants surveyed (0.34 mg g(-1) dry wt). Intra-specific HupA and HupB concentrations were extremely variable, and at the intra-plant level, reproductive strobili were found to accumulate the highest HupA concentrations.

DISCUSSION AND CONCLUSION

Select Huperzia species from Australia and southeast Asia have potential as the starting material for establishing commercial HupA plantations, but the high intra-specific variability observed suggests that detailed screening is needed to isolate high huperzine-yielding individuals.

Identification and characterization of new impurities in rivastigmine

Rivastigmine is a drug against Alzheimer's disease, and is a non-pharmacopoeial compound. During the preparation of rivastigmine in our laboratory, two impurities were detected and identified with a simple and sensitive reversed-phase liquid chromatography coupled with electrospray-mass spectrometry. The same impurities were also observed in commercial batches. These impurities were isolated by preparative HPLC and co-injected with rivastigmine sample to confirm the retention times in HPLC. These impurities were characterized as N,N-dimethyl-3-[1-dimethylaminoethyl]phenylcarboxylate (dimethyl-rivastigmine) and N,N-diethyl-3-[1-dimethylaminoethyl]phenylcarboxamide (diethyl-rivastigmine). Structural elucidation of these impurities by spectral data (1H NMR, 13C NMR and MS) is discussed.

Development of Au nanoparticles dispersed carbon nanotube-based biosensor for the detection of paraoxon

A disposable and sensitive biosensor has been fabricated for the detection of the organophosphorous (OP) compound paraoxon using an amperometric technique. For the measurements, gold nanoparticles dispersed on the outer surface of multiwalled carbon nanotubes (Au-MWNTs) has been used as the electrode material, as it possesses high electron transfer rates and provides large immobilization sites for the bioenzymes, which combines with the high electrocatalytic activity of MWNTs for thiocholine oxidation at low potential. Au-MWNTs have been synthesized by chemically reducing Au salt over functionalized MWNTs, and the same has been characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and high resolution transmission electron microscopic (HRTEM) techniques. The ability of the Au-MWNTs nanocomposite-based biosensor has been demonstrated to reliably measure the concentration of paraoxon in the nanomolar range.

Inhibition of cholinesterase activity by soil extracts and predicted environmental concentrations (PEC) to select relevant pesticides in polluted soils

The correlation of predicted environmental concentrations (PEC) with cholinesterase activity inhibition detected in soil extracts was determined. PEC was derived from organophosphate (OP) and carbamate (CA) compounds applied to a flower crop area. Samples of surface soil (0 - 30 cm in depth) and subsurface soil (30 to 60 cm in depth) were taken from a flower crop area in which OP pesticides such as acephate ((RS)-N-[methoxy(methylthio)phosphinoyl]acetamide), dimethoate (2-dimethoxyphosphinothioylthio-N-methylacetamide) and methyl parathion (O,O-dimethyl O-4-nitrophenyl phosphorothioate), and CA pesticides such as carbendazim (methyl benzimidazol-2-ylcarbamate), carbofuran (2,3-dihydro-2,2-dimethylbenzofuran-7-yl methylcarbamate) and methomyl (S-methyl (EZ)-N-(methylcarbamoyloxy) thioacetimidate) were applied for two years. Weekly loads of these pesticides were registered to estimate the annual load of each compound. Physicochemical analysis and relative inhibition of cholinesterasic activity were measured for each soil sample. PEC values were estimated with Pesticide Analytical Model (PESTAN), a leach model, for each pesticide using soil sample data obtained from physicochemical analysis. From all pesticides tested, only acephate and methomyl showed a significant correlation (p < 0.01) between PEC values and inhibition cholinesterase activity of soil extracts. These results suggest that inhibition of cholinesterase activity observed in soil extracts is produced mainly by these two pesticides. Further studies could be developed to measure acephate and methomyl concentrations to reduce their environmental impact.

Acetylcholinesterase enzyme inhibitory potential of standardized extract of Trigonella foenum graecum L and its constituents

Ethno pharmacological approach has provided several leads to identify potential new drugs from plant sources, including those for memory disorders. Acetylcholinesterase inhibitors (AChEI) give a symptomatic relief to some of the clinical manifestations of the disease. The main objective of this study is to standardize the extract of Trigonella foenum graecum L with trigonelline by HPTLC method and determine the in vitro AChE inhibitory activity of Trigonella foenum graecum L and its constituents using galanthamine as a reference. Different concentrations of hydro alcoholic extract of Trigonella foenum graecum and trigonelline were subjected to HPTLC analysis using the mobile phase n propanol, methanol and water (4:1:2, v/v). The R(f) of trigonelline was found to be 0.43, and the correlation coefficient of 0.99 was indicative of good linear dependence of peak area on concentration. The concentration of trigonelline was found to be 13mgg(-1)w/w in the hydro alcoholic extract of Trigonella foenum graecum. The AChE inhibitory activity of crude fenugreek seed extracts, fractions and trigonelline was evaluated using Ellman's method in 96-well micro plate's assay and TLC bioassay detection. The ethyl acetate fraction of the alcohol extract (IC50 53.00 +/- 17.33microg/ml), and total alkaloid fraction (IC50 9.23+/-6.08microg/ml) showed potential AChE inhibition. Trigonelline showed IC50 233+/-0.12microM. Galanthamine was used as standard and it showed inhibition of acetyl cholinesterase with an IC50 value of 1.27+/-0.21microM.

Membrane sensors for the selective determination of donepezil hydrochloride

The construction and electrochemical response characteristics of polyvinylchloride (PVC) membrane sensors for donepezil HCl (DP) are described. The sensing membranes incorporated ion-association complexes of DP cation and sodium tetraphenyl borate (sensor 1), phosphomolybdic acid (sensor 2), or phosphotungstic acid (sensor 3) as electroactive materials. The sensors displayed a fast, stable, and near-Nernstian response over a relatively wide DP concentration range (1 x 10(-2) to 1 x 10(-6) M), with cationic slopes of 53.0, 54.0, and 51.0 mV/ concentration decade over a pH range of 4.0 to 8.0. The sensors showed good discrimination of DP from several inorganic and organic compounds. The direct determination of 2.5-4000.0 microg/mL DP showed average recoveries of 99.0, 99.5, and 98.5%, and mean RSDs of 1.6, 1.5, and 1.7% at 100.0 microg/mL for sensors 1, 2, and 3, respectively. The proposed sensors have been applied for direct determination of DP in two pharmaceutical preparations. The results obtained for determination of DP in tablets using the proposed sensors compared favorably with those obtained using an HPLC method. The sensors have been used as indicator electrodes for potentiometric titration of DP.

Paraoxonase status and plasma butyrylcholinesterase activity in chlorpyrifos manufacturing workers

Chlorpyrifos is an organophosphorus (OP) anticholinesterase insecticide. Paraoxonase (PON1) is an enzyme found in liver and plasma that hydrolyzes a number of OP compounds. PON1 polymorphisms include a glutamine (Q)/arginine (R) substitution at position 192 (PON1(Q192R)) that affects hydrolysis of OP substrates, with the PON1(192Q) allotype hydrolyzing chlorpyrifos oxon less efficiently than the PON1(192R) allotype, a variation potentially important in determining susceptibility to chlorpyrifos. We studied 53 chlorpyrifos workers and 60 referents during 1 year and estimated chlorpyrifos exposure using industrial hygiene and employment records and excretion of the chlorpyrifos metabolite 3,5,6-trichloro-2-pyridinol (TCP). Plasma butyrylcholinesterase (BuChE) activity, which may by inhibited by chlorpyrifos exposure, was measured monthly. In addition, plasma samples were assayed for paraoxonase (PONase), diazoxonase (DZOase), and chlorpyrifosoxonase (CPOase) activity to determine PON1 status (inferred genotypes and their functional activity). Linear regression analyses modeled BuChE activity as a function of chlorpyrifos exposure and covariates. We postulated that the level of CPOase activity and the inferred PON1(192) genotype (together reflecting PON1 status) would differ between groups and that PON1 status would modify the models of chlorpyrifos exposure on BuChE activity. Chlorpyrifos workers and referents had a 100-fold difference in cumulative chlorpyrifos exposure. Contrary to our hypotheses, mean CPOase activity was similar in both groups (P=0.58) and PON1(192Q) showed a slight overrepresentation, not an underrepresentation, in the chlorpyrifos group compared with referents (PON1(192QQ), 51% chlorpyrifos, 40% referent; PON(192QR), 43% chlorpyrifos, 40% referent; PON(192RR), 6% chlorpyrifos, 20% referent, P=0.08). In our models, BuChE activity was significantly inversely associated with measures of interim chlorpyrifos exposure, but the biological effects of chlorpyrifos exposure on BuChE activity were not modified by PON1 inferred genotype or CPOase activity.

[The use of acetylcholinesterase inhibitors pesticides in eleven local health institutions, Colombia, 2002-2005]

INTRODUCTION

Due to the importance of acetylcholinesterase inhibiting chemicals as pesticides in developing countries, the Instituto Nacional de Salud in Colombia designed the organophosphate and carbamate epidemiological surveillance program for the period 2002-2005.

OBJECTIVE

The acetylcholinesterase activity was determined in study participants with a history of organophosphate and carbamate exposure and the most commonly used pesticides were identified in each study area.

MATERIALS AND METHODS

The information was compiled from reports sent to the Instituto Nacional de Salud organophosphate and carbamate epidemiological surveillance program from each of 11 provinces in Colombia. The analytical determination of the biomarker was performed by acetylcholinestare activity determined with the Lovibond field equipment.

RESULTS

A total of 28,303 people were designated as having risk of exposure to pesticides. Most were men (81.4%). Abnormal determinations averaged 9.3% (9.9% in men and 7.0% in women). The 18-25 year old age group showed the highest prevalence of abnormal results (12.3%), followed by the group of 0-5 year olds (10.7%). The highest prevalence of abnormal acetylcholinesterase activity was in farm workers (27.0%), followed by general outdoor activities (26.1%). In the province of Meta, 80% of participants showed abnormal values of enzyme activity. The most commonly used pesticides were organophosphates (39.7%) and carbamates (16.6%).

CONCLUSION

The increase in the prevalence of abnormal values of acetylcholinesterase activity and the risk of exposure to pesticides in children necessitates a lowering of use and commercialization of high risk pesticides, and a need for developing safer methods for pest management.

Membrane electrodes for the determination of pyridostigmine bromide

Two pyridostigmine bromide (PB) selective electrodes were investigated with 2-nitrophenyl octyl ether as a plasticizer in a polymeric matrix of carboxylated polyvinyl chloride (PVC-COOH), based on the interaction between the drug solution and the dissociated COOH groups in the PVC-COOH. One of the sensors was fabricated by using PVC-COOH only as anionic site without incorporation of an ionophore (sensor 1). The second sensor was constructed by using 2-hydroxy propyl beta-cyclodextrin as an ionophore (sensor 2). Linear responses of PB within a concentration range of 10(-3)-10(-2) and 10(-5)-10(-2) M, with slopes of 51.9 +/- 0.31 and 56.7 +/- 0.40 mV/decade over pH range of 5-10 were obtained using sensors 2 and 1, respectively. The proposed method displayed useful analytical characteristics for determination of PB in tablets with average recoveries of 100.22 +/- 0.62, and 100.15 +/- 0.72, and in plasma with average recoveries of 99.14 +/- 1.19 and 99.79 +/- 0.72, for sensors 2 and 1, respectively. The utility of 2-hydroxy propyl beta-cyclodextrin as an ionophore has a significant influence on increasing both membrane sensitivity and selectivity of sensor 2 in comparison with sensor 1. The methods were also used to determine the intact drug in the presence of its degradate, and thus could be used as stability-indicating methods. The results obtained by the proposed procedures were statistically analyzed and compared with those obtained by the U.S. Pharmacopeia method. No significant difference for either accuracy or precision was observed.

Metabolic and bioactivity insights into Brassica oleracea var. acephala

Seeds of Brassica oleracea var. acephala (kale) were analyzed by HPLC/UV-PAD/MSn-ESI. Several phenolic acids and flavonol derivatives were identified. The seeds of this B. oleracea variety exhibited more flavonol derivatives than those of tronchuda cabbage (Brassica oleracea var. costata), also characterized in this paper. Quercetin and isorhamnetin derivatives were found only in kale seeds. Oxalic, aconitic, citric, pyruvic, malic, quinic, shikimic, and fumaric acids were the organic acids present in these matrices, malic acid being predominant in kale and citric acid in tronchuda cabbage seeds. Acetylcholinesterase (AChE) inhibitory activity was determined in aqueous extracts from both seeds. Kale leaves and butterflies, larvae, and excrements of Pieris brassicae reared on kale were also evaluated. Kale seeds were the most effective AChE inhibitor, followed by tronchuda cabbage seeds and kale leaves. With regard to P. brassicae material, excrements exhibited stronger inhibitory capacity. These results may be explained by the presence of sinapine, an analogue of acetylcholine, only in seed materials. A strong concentration-dependent antioxidant capacity against DPPH, nitric oxide, and superoxide radicals was observed for kale seeds.

Development of a sensitive high-performance liquid chromatographic method with simple extraction for simultaneous determination of huperzine A and huperzine B in the species containing lycopodium alkaloids

A sensitive HPLC method with simple extraction was developed for simultaneous determination of huperzine A (HupA) and huperzine B (HupB) in Huperzia serrata, H. crispata, H. miyoshiana, and Lycopodiastrum casuarinoides. In order to avoid conventional multiple-step and time-consuming sample preparation methods, direct reflux extraction with alkaline chloroform was adopted. The quantitative determination was conducted by reversed-phase HPLC with a photodiode array detector set at 308 nm. Separation was performed on a Luna C18 column (250 x 4.6 mm id, 5 microm) with methanol-0.2% aqueous acetic acid (18 + 82, v/v) mobile phase. The method was validated for accuracy, reproducibility, precision, and limits of detection and quantification. Quantification of the two active compounds in the samples was performed by this newly developed method, and the content of HupA and HupB varied substantially among four different species. The satisfactory results indicated that the developed method can readily be utilized for quality control of the species of Huperziaceae and Lycopodiaceae containing the two compounds.

Electrophoretically mediated microanalysis technique as a tool for the rapid screening of novel acetylcholinesterase inhibitors

An electrophoretically mediated microanalysis technique was developed for the rapid screening of acetylcholinesterase inhibitors. Activity of four original compounds, N-benzylpiperidine, carbamoyloxyphenyl derivatives and reference inhibitor--tacrine was determined and compared with the data obtained from Ellman's assay. Percentage of enzyme inhibition detected at inhibitor concentration of 3.33.10(-4) M was between 0 and 78% and was the highest for tacrine. The comparison of data obtained from the EMMA assay and Ellman's test proved inhibitory activity of novel compounds.