Papers by Keyword: Acetylcholinesterase

Abstract: Pleurotus ostreatus, the worldwide edible mushroom, has a potent economic values and medicinal properties. In this study, nutritional properties, antioxidant, and anti-acetylcholinesterase activities of P. ostreatus were investigated. The extracts were prepared by maceration and soxhlet extraction with ethanol and decoction with distilled water. Nutritional analysis showed that P. ostreatus has high content of fibers (45.5%), proteins (20.8%) and carbohydrates (68.4%) with low content of lipids (0.56%). HPLC analysis revealed that P. ostreatus has high content of the potential health promoting of β-glucan (42.8%). Acetylcholinesterase (AChE) is a key enzyme in nervous system. Inhibition of this enzyme is used for the symptomatic treatment of Alzheimer’s disease (AD), the most common disease in aging population. Ellman colorimetric method was used to determine Acetylcholinesterase inhibitory (AChEI) activity. All extracts found containing high AChEI activity (IC50 = 1.75-5.91 mg/ml). Oxidative stress plays a major role in the pathogenesis of AD, thus antioxidant activity was also performed in this study. DPPH assay exhibited all P. ostreatus extracts had high antioxidant activity (IC50 = 0.59-5.47 mg/ml). The results suggested that P. ostreatus should be beneficial for AD treatment and the most efficient nutraceutical and functional foods.

Abstract: Huperzine A (HupA), an alkaloid isolated from the Chinese club moss, is a reversible inhibitor of cholinesterases which cross the blood-brain barrier and show high specificity for acetylcholinesterase (AChE). However, HupA induces unwanted side effects in an effective dose against nerve agent poisoning. In the present study, HupA–loaded poly (lactide-co-glycolide) nanoparticles (HupA-PLGA-NP) were prepared using the O/W emulsion solvent evaporation method. The results of SEM demonstrated that HupA-PLGA-NP had an spherical shape and a smooth surface without pores. It’s mean diameter and PDI were 208.5±3.6nm and 0.09±0.01 respectively. The Zeta potential was-35.3±1.8mV and the drug loading was 2.86±0.6%. In vitro drug release studies showed that HupA-PLGA-NP had a sustained-release behavior in phosphate buffer solution, The accumulated amount of HupA was about 72.1% at 48h with a low burst release within 30min. The LD₅₀ values of HupA and HupA-PLGA-NP were 1.40 and 4.85mg/kg respectively, showing that the toxicity of HupA was reduced by 3.5 times. We evaluated the protective efficacy for different doses of HupA or HupA-PLGA-NP against 1.0×LD₉₅(143.0μg/kg) soman toxicity. The results confirmed that HupA (0.3~0.5mg/kg) or HupA-PLGA-NP (0.5~1.5mg/kg) could ensure animals survive. However, about 10% of the animals injected with HupA (0.8mg/kg) died, while no animals died when injected with HupA-PLGA-NP (1.5mg/kg). Aim to 100% survival rate, the effective protective time (12h) of HupA-PLGA-NP (0.5mg/kg,iv) against 1.0×LD₉₅ soman toxicity in mice was significantly prolonged compared with that of HupA (4h). The study of AChE activity showed that whole-blood and supernatant of brain diluted by 80-fold and 10-fold respectively were optimum in this study. AChE inhibition after administration of HupA and HupA-PLGA-NP (0.5mg/kg,iv) was recorded and analyzed, The peak values of AChE inhibition in whole-blood and brain by HupA-PLGA-NP (17.6% and 21.8%) were lower than those by HupA (33.7% and 31.9%) and AChE inhibition time by HupA-PLGA-NP was longer than that by HupA. These data confirmed that HupA-PLGA-NP had less toxic and more longer time than HupA against 1.0×LD₉₅ soman poisoning and warrant further development as a potent medical countermeasure against chemical warfare nerve agents (CWNAs) poisoning.

Abstract: A sensitive amperometric acetylcholinesterase (AChE) biosensor based on platinum-palladium nanoparticles (Pt-Pd NPs)-single-walled carbon nanotubes (SWCNTs) and chitosan (CS) modified glassy carbon electrode (GCE) is developed. The Pt-PdNPs-SWCNTs-CS nanocomposites offer an excellent electron conductivity, catalysis and hydrophilic surface for biomolecule adhesion. CS is used as a cross-linker to immobilize the AChE on the surface of Pt-PdNPs-SWCNTs-CS and as a protective membrane of the AChE biosensor. The biosensor shows favorable affinity to acetylthiocholine chloride. It exhibits good sensitivity, stability, reproducibility and low cost, thus providing a promising tool for analysis of enzyme inhibitors. More importantly, this study could provide a universal platform for meeting the demand of the effective immobilization enzyme on the electrode surface.

Abstract: Multiple targets which closely related to Alzheimer's disease (AD) pathogenesis were selected for pharmacophore models generation and virtual screening in Chinese herbs. The targets comprised Acetylcholinesterase (AchE), muscarinic receptor 1 (M1), γ-secretase and glycogen synthase kinase 3β (GSK-3β). The pharmacophore models, which of AchE inhibitors, M1 agonists, γ-secretase inhibitors and GSK-3β inhibitors, were constructed by distance comparison method. Four testing databases for the evaluation of pharmacophore models were constructed with the active compounds with clearly marked activity on each target. The metric CAI (Comprehensive Appraisal Index) was then used to evaluate and obtain the best pharmacophore models of each target, which were then applied to screen the Traditional Chinese Medicine Database for potential active compounds in Chinese herbs. Four common used herbs were obtained, which contain the active compounds and can act on multiple targets, and were expected to have multiple activity of anti-AD disease.

Abstract: Monitoring of the organophosphorus pesticides dichlorvos at very low levels has been achieved with liposome-based nanobiosensors. The enzyme acetylcholinesterase was effectively stabilized within the internal nanoenvironment of the liposomes. Within the liposomes, the pH sensitive fluorescent indicator pyranine was also immobilized for the optical transduction of the enzymatic activity. Increasing amounts of pesticides lead to the decrease of the enzymatic activity for the hydrolysis of the acetylcholine and thus to a decrease in the fluorescent signal of the pH indicator. The decrease of the liposome biosensors signal is relative to the concentration of dichlorvos down to 10^-12 M levels. Also a colorimetric screening device for pesticide analysis has been evaluated.

Abstract: The staining effects of two staining methods of acetylcholinesterase isozymes were compared . One using acetylthiocholine iodide , K3[Fe(CN)6] and CuSO4 was named as AFCu method, and the other one using acetylthiocholine iodide , K3[Fe(CN)6] and FeCl3 was named as AFFe method. The staining effect of former was better.

Abstract: In order to study the toxicity mechanism of plant VOCs of four kinds of terpene monomers(α-terpineol,α-pinene,β-pinene,1,8-cineole), the activities of acetylcholinesterase in Zophobas morio larvae were treaded with spectrophotometer at different time (12h, 24h, 36h, 48h). The results showed that four kinds of terpene monomers (α-terpineol, β-pinene, α-pinene, 1,8-cineole) had high biological activity in Zophobas morio, which can inhibit the activity of acetylcholinesterase(AchE) effectively．

Abstract: We investigated the oxidative stress of methamidophos on Mytilus edulis. Sublethal concentrations of methamidophos (5.0, 10.0 and 15.0 μg L^-1) were administered to M. edulis for 5, 15 and 30 days respectively. The biochemical stress response of M. edulis was studied taking into account acetylcholinesterase (AChE), Na⁺-K⁺-adenosine triphosphatase (Na⁺-K⁺-ATPase) and some antioxidant enzyme activities. Protein contents in tissues was also measured. With the increase of methamidophos concentrations the activities of AChE and Na⁺-K⁺-ATPase in tissues decreased, whereas the activities of GPx, SOD and CAT increased. The protein content in tissues decreased after 5 days and then gradually increased until the 15th day of the experiment. On the 30th day, the protein level in organism was observed to have reached to that of the control group. It can be stated that methamidophos exerted its effect even at low concentration , its toxicity increased depending on its dosage and exposure time. This study revealed that M. edulis developed adaptive response to neutralize the oxidative stress following pesticide exposure.

Abstract: A novel photoelectrochemical biosensor incorporating nanosized ZnO semiconductor crystals with enzyme to enhance photochemical reaction has been investigated. In this work, the ZnO nanoparticles and acetylcholinesterase (AChE) were immobilized on Pt electrode by chitosan (CHI) via layer-by-layer technique (LbL) to fabricate a biological-inorganic hybrid system. Micrographs of (ZnO/CHI/AChE) films were obtained by scanning electron microscope, and photoelectrochemical properties of the resulting biosensors were measured by a three electrodes system and an ultraviolet lamp. Under ultraviolet light, the photo-effect of the ZnO nanoparticles showed enhancement of the biosensor to detect pesticide. Based on the inhibition of organophosphate pesticides on the AChE activity, using malathion as a model compound, the inhibition of dimethoate was proportional to its concentration ranging from 0.25 to 1.50 and from 1.75 to 10.00 μM, with a detection limit of 10 nM estimated at a signal-to-noise ratio of 3. The developed biosensor exhibited good reproducibility and acceptable stability, thus providing a new promising tool for analysis of enzyme inhibitors.

Abstract: We demonstrate a carbon nanotube based high-resolution biosensor for acetylcholine sensing. Carbon nanotubes are deposited on a silicon wafer in a repeated fashion with layer-by-layer nano self-assembly technique. With nano-assembled acetylcholinesterase molecules on the surface, the carbon nanotube biosensor is capable of detecting acetylcholine at an ultra-low concentration of 100 pM. The sensitivity of the acetylcholine sensor is measured as 7.2 µA/decade. The real-time measurement shows the response time of the biosensor is approximately 6 sec. Both the carbon nanotube film and the acetylcholinesterase film are crucial in the sensing process. Due to its high resolution, fast response, small size, and low cost, the carbon nanotube biosensor has tremendous potential for applications in medical research and clinical diagnosis.