Bioactivities of 7'­ethoxy­trans­feruloyltyramine from Portulaca oleracea L. and its metabolism in rats using ultra­high­performance liquid chromatography electrospray coupled with quadrupole time­of­flight mass spectrometry.

This research aims to study the antioxidation and anticholinesterase activities of 7'-ethoxy-trans-feruloyltyramine (ETFT), which was an alkaloid isolated from Portulaca oleracea for the first time. Furthermore, its main metabolites and metabolic pathways in rats were also explored. The antioxidation and anticholinesterase effects of ETFT were, respectively, examined using 1,1-diphenyl-2-picrylhydrazyl assay and modified Ellman's method. The results showed that ETFT exhibited both the good antioxidant and anticholinesterase effects. Its main metabolites in rats were implemented, and nine metabolites were finally found in the rat's plasma and urine, including the oxidation, reduction, hydrolysis, glucuronidation, sulfation, and glutathionylation process.

In vivo and in vitro metabolism and pharmacokinetics of cholinesterase inhibitor deoxyvasicine from aerial parts of Peganum harmala Linn in rats via UPLC-ESI-QTOF-MS and UPLC-ESI-MS/MS.

ETHNOPHARMACOLOGICAL RELEVANCE: Aerial parts of Peganum harmala Linn are a Uighur traditional medicinal herb in China used to treat amnesia, bronchial asthma, and cough. Deoxyvasicine (DVAS), a potent cholinesterase inhibitor exhibiting anti-senile dementia activity, is one of the chief active ingredients in aerial parts of P. harmala and plays a key role in mediating the pharmacological effects of P. harmala. However, the metabolic profiling and in vivo pharmacokinetic characteristics of DVAS still remain unknown. AIM OF THE STUDY: The aim of this present study was to investigate the metabolism and pharmacokinetic properties of DVAS in rats by using ultra-performance liquid chromatography combined with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (UPLC-ESI-QTOF-MS) and ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-ESI-MS/MS) method. MATERIALS AND METHODS: The metabolic profiling of DVAS was evaluated in vitro and in vivo by rat liver microsomes (RLMs) incubation and by rat bio-specimens, such as urine, feces, plasma, and bile, after the oral administration of 45 mg/kg DVAS. An efficient and sensitive UPLC-ESI-MS/MS method was developed and validated to simultaneously determine DVAS and its major four metabolites, namely, vasicine, deoxyvasicinone, vasicinone, and 1,2,3,9-tetrahydropyrrolo[2,1-b]quinazolin-3-ß-D-glucuronide in rat plasma. For pharmacokinetic studies, 32 Sprague-Dawley rats were randomly divided into four groups, namely, intravenous dosage group (2 mg/kg DVAS) and three oral dosage groups (5, 15, and 45 mg/kg DVAS). In addition, the activity of the components in plasma after intravenous administration of DVAS was evaluated by in vitro anti-butyrylcholinesterase (BChE) assays. RESULTS: A total of 23 metabolites were found in RLMs, plasma, urine, feces, and bile by UPLC-ESI-QTOF-MS. The metabolic pathway of DVAS in vivo and in vitro mainly involved hydroxylation, dehydrogenation, acetylation, methylation, glucuronidation, and O-sulphate conjugation, and the C-3 and C-9 sites were the main metabolic soft spots. All 23 metabolites were detected in the urine sample, and 13, 8, 22, and 6 metabolites were identified from rat feces, plasma, bile, and RLMs, respectively. The standard curves of DVAS and four metabolites in rat plasma showed good linearity in the concentration range of 0.82-524.00 ng/mL with acceptable selectivity, precision, accuracy, recovery, and stability. DVAS exhibited linear dose-proportional pharmacokinetics at doses of 5, 15, and 45 mg/kg after oral administration, and the average oral absolute bioavailability of DVAS was 47.46%. The in vitro anti-BChE assays implied that the inhibitive activities were mainly due to the different concentrations of prototype DVAS. CONCLUSIONS: DVAS can be rapidly absorbed and excreted by blood, and it is also extensively metabolized in vivo, and the anti-BChE activity in blood is mainly attributed to DVAS. These findings can lay a foundation for new drug development for DVAS.

Function of Plectranthus barbatus herbal tea as neuronal acetylcholinesterase inhibitor.

This study aims to determine the function of Plectranthus barbatus (Lamiaceae) herbal tea as inhibitor of the brain acetylcholinesterase (AChE) activity. To accomplish this objective the herbal tea as well as its main component, rosmarinic acid were administered to laboratory animals (rats) and the effect on the brain AChE activity was evaluated. The study of the herbal tea metabolites in the plasma and also in the brain was undertaken. The herbal water extract was administered intragastrically and also intraperitoneally. When the plant extract was intragastrically administered, vestigial amounts of metabolites from P. barbatus extract compounds were present in rat plasma, but none were found in brain, although inhibition of brain acetylcholinesterase activity was detected. However, when P. barbatus extract was administered intraperitoneally, all its compounds were found in plasma, and rosmarinic acid was found in brain. The highest concentrations of compounds/metabolites were found 30 min after administration. An inhibition of 29.0 ± 2.3% and 24.9 ± 3.7% in brain acetylcholinesterase activity was observed 30 and 60 min after intraperitoneal administration, respectively. These values were higher than those expected, taking into account the quantity of rosmarinic acid detected in the brain, which suggests that other active extract compounds or metabolites may be present in non-detectable amounts. These results prove that the administration of P. barbatus aqueous extract can reach the brain and act as AChE inhibitor.

A study of rivastigmine liposomes for delivery into the brain through intranasal route.

The present study is mainly aimed at delivering a drug into the brain via the intranasal route using a liposomal formulation. For this purpose, rivastigmine, which is used in the management of Alzheimer's disease, was selected as a model drug. Conventional liposomes were formulated by the lipid layer hydration method using cholesterol and soya lecithin as lipid components. The concentration of rivastigmine in brain and plasma after intranasal liposomes, free drug and per oral administration was studied in rat models. A significantly higher level of drug was found in the brain with intranasal liposomes of rivastigmine compared to the intranasal free drug and the oral route. Intranasal liposomes had a longer half-life in the brain than intranasally or orally administered free drug. Delivering rivastigmine liposomes through the intranasal route for the treatment of Alzheimer's disease might be a new approach to the management of this condition.

Distortion product otoacoustic emissions as non-invasive biomarkers and predictors of soman-induced central neurotoxicity: a preliminary study.

The organophosphorus nerve agent soman is an irreversible cholinesterase (ChE) inhibitor that can produce long-lasting seizures and brain damage in which the neurotransmitters acetylcholine and glutamate are involved. These same neurotransmitters play key-roles in the auditory function. It was then assumed that exploring the hearing function may provide markers of the central events triggered by soman intoxication. In the present study, distortion product otoacoustic emissions (DPOAEs), a non-invasive audiometric method, were used to monitor cochlear functionality in rats administered with a moderate dose of soman (45 microg/kg). DPOAEs were investigated either 4h or 24h post-challenge. In parallel, the effects of soman on whole blood and brain ChE activity and on brain histology were also studied. The first main result is that DPOAE intensities were significantly decreased 4h post-soman and returned to baseline at 24h. The amplitude changes were well related to the severity of symptoms, with the greatest change being recorded in the rats that survived long-lasting convulsions. The second main result is that baseline DPOAEs recorded 8 days before soman appear to predict the severity of symptoms produced by the intoxication. Indeed, the lowest baseline DPOAEs corresponded to the occurrence of long-lasting convulsions and brain damage and to the greatest inhibition in central ChE. These results thus suggest that DPOAEs represent a promising non-invasive tool to assess and predict the central consequences of nerve agent poisoning. Further investigations will be carried out to assess the potential applications and the limits of this non-invasive method.

New safe method for preparation of sarin-exposed human erythrocytes acetylcholinesterase using non-toxic and stable sarin analogue isopropyl p-nitrophenyl methylphosphonate and its application to evaluation of nerve agent antidotes.

INTRODUCTION: A non-toxic and stable sarin analogue, isopropyl p-nitrophenyl methylphosphonate (INMP), was synthesized for safe preparation of sarin-exposed acetylcholinesterase (AChE). RESULTS AND DISCUSSION: This agent was stable for years, able to be handled in an ordinary laboratory without special care, and its 50% inhibitory concentration (IC50) on 0.04 U/ml human erythrocytes AChE was 15 nM. This reagent was thought to be especially useful since it enables experiments that require sarin-inhibited AChE, such as the development of antidotes for sarin, in a usual laboratory. To demonstrate the usefulness of this method, 40 known and novel pyridinealdoxime methiodide (PAM)-type oxime antidotes were synthesized, and their reactivation activities to INMP-exposed AChE and structure-activities correlation were studied. CONCLUSION: Among the antidotes tested in this experiment except for 2-PAM, the compound found to have the highest reactivation activity, was the novel hydrophobic 2-PAM-type compound, 2-[(hydroxyimino)methyl]-1-[4-(tert-butyl)benzyl] pyridinium bromide.

Pharmacokinetics of huperzine A in dogs following single intravenous and oral administrations.

The pharmacokinetics of huperzine A in dogs after single intravenous and oral administrations was investigated. Concentrations of huperzine A were determined by a validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. Pharmacokinetic parameters were calculated by non-compartmental methods. After single intravenous administration, the Cmax, T1/2, AUC0-t, AUC0-infinity, CL, Vd and Vss were 5.55 +/- 1.61 microg/L, 5.02 +/- 0.31 h, 16.04 +/- 5.24, 16.49 +/- 5.29 microgh/L, 0.66 +/- 0.19 L/h/kg, 4.76 +/- 1.46, and 3.93 +/- 1.54 L/kg, respectively. After single oral administration, the Cmax, Tmax, T1/2, AUC0-t, AUC0-infinity and oral bioavailability were 2.60 +/- 0.60 microg/L, 1.25 +/- 0.50 h, 5.71 +/- 2.25 h, 12.90 +/- 3.19, 13.78 +/- 3.24 microgh/L, and 94.4 +/- 36.5%, respectively. In conclusion, huperzine A had a rapid and nearly complete oral absorption and was extensively distributed into tissues after drug administration in dogs.

The effects of Ginkgo biloba extracts on the pharmacokinetics and pharmacodynamics of donepezil.

The effects of ginkgo supplementation on the steady-state plasma concentration of donepezil and the activity of cholinesterase in red blood cells and cognitive function were examined. Fourteen inpatients with Alzheimer's disease received donepezil 5 mg/day, supplemented with extracts of Ginkgo biloba 90 mg/day for 30 days. Blood samples were collected before and during ginkgo supplementation and 30 days after its discontinuation, together with an assessment of cognitive function. Plasma drug concentration was measured using high-performance liquid chromatography (HPLC), and cholinesterase in red blood cells was measured using Ellman methods. Cognitive function was evaluated using the Mini-Mental Scale Examination (MMSE). Plasma concentration of donepezil during ginkgo supplementation (mean +/- SD [95% confidence interval]; 24.4 +/- 12.6 ng/mL [17.1-31.7 ng/mL]) was not significantly different from that before ginkgo supplementation (22.7 +/- 10.3 ng/mL [16.8-28.7 ng/mL]) or that 4 weeks after its discontinuation (25.0 +/- 12.9 ng/mL [17.6-32.4 ng/mL]). There was no significant difference between cholinesterase in red blood cells before ginkgo supplementation (1.75 +/- 0.21 U [1.63-1.87 U]), during ginkgo supplementation (1.91 +/- 0.27 U [1.76-2.07 U]), and 4 weeks after its discontinuation (1.83 +/- 0.29 U [1.66-2.00 U]). Ginkgo supplementation did not alter MMSE scores throughout the study. The present study shows that ginkgo supplementation does not have major impact on the pharmacokinetics and pharmacodynamics of donepezil.