Dehydroevodiamine attenuates beta-amyloid peptide-induced amnesia in mice

Major Indole Alkaloids in Evodia Rutaecarpa: The Latest Insights and Review of Their Impact on Gastrointestinal Diseases

Evodia rutaecarpa, the near-ripe fruit of Euodia rutaecarpa (Juss.) Benth, Euodia rutaecarpa (Juss.) Benth. var. officinalis (Dode) Huang, or Euodia rutaecarpa (Juss.) Benth. var. bodinieri (Dode) Huang, is a famous herbal medicine with several biological activities and therapeutic values, which has been applied for abdominalgia, abdominal distension, vomiting, and diarrhea as a complementary and alternative therapy in clinic. Indole alkaloids, particularly evodiamine (EVO), rutaecarpine (RUT), and dedhydroevodiamine (DHE), are received rising attention as the major bioactivity compounds in Evodia rutaecarpa. Therefore, this review summarizes the physicochemical properties, pharmacological activities, pharmacokinetics, and therapeutic effects on gastrointestinal diseases of these three indole alkaloids with original literature collected by PubMed, Web of Science Core Collection, and CNKI up to June 2023. Despite sharing the same parent nucleus, EVO, RUT, and DHE have different structural and chemical properties, which result in different advantages of biological effects. In their wide range of pharmacological activities, the anti-migratory activity of RUT is less effective than that of EVO, and the neuroprotection of DHE is significant. Additionally, although DHE has a higher bioavailability, EVO and RUT display better permeabilities within blood-brain barrier. These three indole alkaloids can alleviate gastrointestinal inflammatory in particular, and EVO also has outstanding anti-cancer effect, although clinical trials are still required to further support their therapeutic potential.

The attenuation effect of licorice on the hepatotoxicity of Euodiae Fructus by inhibiting the formation of protein conjugates and GSH depletion

ETHNOPHARMACOLOGICAL RELEVANCE

As a traditional Chinese medicine and food, Euodiae Fructus (EF) is widely used in clinics to relieve pain and prevent vomiting and for making tea for more than a thousand years. In recent years, hepatotoxic reactions to EF have been reported. The intermediates produced by evodiamine and rutaecarpine metabolism in vitro were captured by glutathione (GSH), suggesting that the toxicity of EF may be related to metabolic activation. Whether licorice can inhibit the metabolic activation of EF has not been reported, which needed an effective strategy to clarify the correlation between protein conjugates and hepatotoxicity and the attenuation mechanism of licorice processing.

AIM OF THE STUDY

This study aimed to explore the toxic components and mechanisms of EF based on metabolic activation and the detoxification of licorice.

MATERIALS AND METHODS

The content and toxicity index of protein conjugates in the liver were determined by orally administering mice and rats with EF. The attenuation mechanism of licorice was examined in cell and enzymology experiments.

RESULTS

The change in evodiamine-cysteinylglycine (EVO-Cys-Gly) and evodiamine-cysteine (EVO-Cys) levels was consistent with the change in hepatotoxicity. Licorice inhibited the formation of the protein conjugates of EF and increased the content of GSH in L02 cells.

CONCLUSION

EF mediated by P450 enzymes produced toxic intermediates, which combined with cysteine residues in animal liver and inactivate them, leading to hepatotoxicity. Interestingly, licorice can alleviate the GSH depletion caused by EF and inhibit the production of protein conjugates by inhibiting P450 enzymes.

The pharmacokinetics profiles, pharmacological properties, and toxicological risks of dehydroevodiamine: A review

Dehydroevodiamine (DHE) is a quinazoline alkaloid isolated from Evodiae Fructus (EF, Wuzhuyu in Chinese, Rutaceae family), a well-known traditional Chinese medicine (TCM) which is clinically applied to treat headache, abdominal pain, menstrual pain, abdominal distension, vomiting, acid regurgitation, etc. Modern research demonstrates that DHE is one of the main components of EF. In recent years, DHE has received extensive attention due to its various pharmacological activities. This review is the first to comprehensively summarize the current studies on pharmacokinetics profiles, pharmacological properties, and toxicological risks of DHE in diverse diseases. Pharmacokinetic studies have shown that DHE has a relatively good oral absorption effect in the mean concentration curves in rat plasma and high absorption in the gastrointestinal tract. In addition, distribution re-absorption and enterohepatic circulation may lead to multiple blood concentration peaks of DHE in rat plasma. DHE possesses a wide spectrum of pharmacological properties in the central nervous system, cardiovascular system, and digestive system. Moreover, DHE has anti-inflammatory effects via downregulating pro-inflammatory cytokines and inflammatory mediators. Given the favorable pharmacological activity, DHE is expected to be a potential drug candidate for the treatment of Alzheimer's disease, chronic stress, amnesia, chronic atrophic gastritis, gastric ulcers, and rheumatoid arthritis. In addition, toxicity studies have suggested that DHE has proarrhythmic effects and can impair bile acid homeostasis without causing hepatotoxicity. However, further rigorous and well-designed studies are needed to elucidate the pharmacokinetics, pharmacological effects, potential biological mechanisms, and toxicity of DHE.

Targeting Epstein-Barr virus dUTPase, an immunomodulatory protein using anti-viral, anti-inflammatory and neuroprotective phytochemicals

Although primary infection of Epstein-Barr virus is generally non-lethal, viral reactivation is often associated with fatal outcomes. Regardless, there is no FDA-approved treatment available for this viral infection. The current investigation targets viral maintenance and reactivation by inhibiting the functioning of viral deoxyuridine-triphosphatase (dUTPase) using phytochemicals. The EBV-dUTPase is essential for the maintenance of nucleotide balance and thus, plays a vital role in the viral replication cycle. Additionally, the protein has shown neuroinflammatory effects on the host. To selectively target the protein and possibly alter its activity, we utilized a virtual screening approach and screened 45 phytochemicals reported to have antiviral, anti-inflammatory, and neuroprotective properties. The analysis revealed several phytochemicals bound to the target protein with high affinity. In-silico ADMET and Lipinski's rule analysis predicted favorable druggability of Dehydroevodiamine (DHE) among all the phytochemicals. Further, we corroborated our findings by molecular dynamic simulation and binding affinity estimation. Our outcomes ascertained a stable binding of DHE to EBV-dUTPase primarily through electrostatic interactions. We identified that the protein-ligand binding involves the region around His71, previously reported as a potent drug target site. Conclusively, the phytochemical DHE showed a promising future as a drug development candidate against EBV-dUTPase.

Dehydroevodiamine ameliorates indomethacin-induced gastric injury via inhibition of ERK and p38 signaling pathway

BACKGROUND

Dehydroevodiamine (DHE), a pivotal quinazoline alkaloid isolated from Fructus Evodiae (Tetradium ruticarpum (A. Juss.) Hartley), has various pharmacological effects. However, the effect of DHE on gastric injury is still uncharted.

PURPOSE

To clarify the pharmacological effect and mechanism of DHE on gastric injury (GI) induced by indomethacin (IDO).

STUDY DESIGN

The gastric injury was induced in rat by oral administration of 5 mg/kg IDO for 7 days. Then the rats were treated with DHE (10, 20, 40 mg/kg, ig) for 7 days.

METHODS

The changes of food intake, body weight, gastric pH and general state observation were determined. And HE staining and AB-PAS staining was analyzed. Then, the inflammatory infiltration of gastric tissue was observed through MPO immunohistochemical approach, and the expression of TNF-α, IL-6 and IL-10 were measured. Furthermore, the levels of proteins ERK, p-ERK, P38, p-P38, JNK and p-JNK were determined to elucidate the molecular mechanism of DHE.

RESULTS

DHE alleviated food intake reduction, weight loss and gastric injury induced by IDO and made gastric pH and mucosal thickness return to normal. In addition, DHE could down regulate the expression of MPO, TNF-α and IL-6 and up regulate the expression of IL-10 to reduce the damage induced by inflammatory, and create a healing environment. Furthermore, DHE could significantly inhibit the phosphorylation of ERK and p38 not JNK.

CONCLUSION

DHE ameliorated dyspepsia, inflammatory infiltration and tissue damage induced by IDO through ERK and p38 signaling pathways rather than JNK pathway.

Processing and Polyherbal Formulation of Tetradium ruticarpum (A. Juss.) Hartley: Phytochemistry, Pharmacokinetics, and Toxicity

Herbal medicine is a major part of traditional Chinese medicine (TCM), which is evolved as a system of medical practice from ancient China. The use of herbal medicine is mainly based on practice and theories and concepts rooted in ancient philosophy. In the era of evidence-based medicine, it is essential to accurately evaluate herbal remedy with standard/modern medical practice approaches. Tetradium ruticarpum (A. Juss.) Hartley (TR), a medicinal plant with diversify bioactive components, has been broadly used to treat pain and gastrointestinal disorders in TCM. However, TR has also been reported to have potential toxicity by long-term use or excessive doses, though the associated compounds are yet to be identified. TR is usually processed, and/or combined with other herbs in TCM formulas in order to achieve a synergistic effect or reduce its toxicity. Since processing or polyherbal formulation of TR may lead to changes in its chemical composition and contents, quality, efficacy and toxicity, comparison of TR samples before and after processing, as well as its combination with other medicines, would provide useful knowledge of bioactive compounds, efficacy and toxicity of this valuable medicinal plant. Here we reviewed the recent studies about the phytochemistry, pharmacokinetic behaviors and toxicity of TR under various processing or polyherbal formulation conditions, which would expand our understanding of mechanisms of TR's efficacy and toxicity and be valuable for quality control in industrial manufacturing, future medicinal research, and safety and rational use of TR in TCM.

Pharmacokinetics Studies of 12 Alkaloids in Rat Plasma after Oral Administration of Zuojin and Fan-Zuojin Formulas

Zuojin formula (ZJ) is a traditional Chinese medicine (TCM) prescription consisted of Coptidis Rhizoma (CR) and Euodiae Fructus (EF), and has been used to treat gastrointestinal (GI) disease for more than 700 years. Fan-Zuojin formula (FZJ) is a related TCM prescription also consisted of CR and EF with the opposite proportion. In recent years, ZJ was getting more attention for its antitumor potential, but the indeterminate pharmacokinetic (PK) behavior restricted its clinical applications, and the PK differences between ZJ and FZJ were also largely unknown. Consequently it is necessary to carry out a full-scale PK study to demonstrate the physiological disposition of ZJ, as well as the comparative PK study between ZJ and FZJ to illustrate the compatibility dose effects. Therefore a liquid chromatographic–tandem mass spectrometry (LC–MS/MS) method was established and validated for the determinations of coptisine, epiberberine, palmatine, berberine, 8-oxocoptisine, 8-oxoepiberberine, noroxyhydrastinine, corydaldine, dehydroevodiamine, evodiamine, wuchuyuamide-I, and evocarpine in rat plasma. PK characteristics of 12 alkaloids after oral administration of ZJ and FZJ were compared, and the result was analyzed and discussed with the help of an in silico study. Then an integrated PK study was carried out with the AUC-based weighting method and the total drug concentration method. The established method has been successfully applied to reveal the PK profiles of the 12 alkaloids in rat plasma after oral administration of ZJ and FZJ. The results showed that: (1) double peaks were observed in the plasma concentration-time (C–T) curves of the alkaloids after ZJ administration; but the C–T curves approximately matched the two-compartment model after FZJ administration; (2) There were wide variations in the absorption levels of these alkaloids; and even for a certain alkaloid, the dose modified systemic exposure levels and elimination rate also varied significantly after administration of ZJ and FZJ extracts. The results could be interpreted as follows: firstly, inhibition effect on GI motility caused by the high content CR alkaloids (especially berberine) in ZJ could delay the T_max, and increase the absorption and systemic exposure levels of the other alkaloids, and also lead to the double peak phenomenon of these alkaloids. However, for quaternary protoberberine alkaloids (QPA), double peaks were primarily caused by the different Ka value in two intestinal absorption sites; Secondly, absorption was the major obstacle to the systemic exposure level of the alkaloids from CR and EF. In silico and PK studies suggested that the absorption of these alkaloids, except QPAs, mainly depended on their solubility rather than permeability; Thirdly, EF could promote the absorption and accelerate the elimination of QPAs, and had a greater influence on the former than the latter. At last the integrated PK analysis suggested that berberine and dehydroevodiamine could be regarded as the representative components to reflect the PK behaviors of CR and EF alkaloids after administration of ZJ and FZJ. In conclusion, the absorption, elimination and systemic exposure level of these alkaloids were mainly influenced by the proportion of EF and CR, the pharmacological effect on GI motility, and the physicochemical property of these alkaloids. These findings would be helpful for a better understanding of the activities and clinical applications of ZJ, FZJ and other related TCM prescriptions.

Selenofuranoside Ameliorates Memory Loss in Alzheimer-Like Sporadic Dementia: AChE Activity, Oxidative Stress, and Inflammation Involvement

Alzheimer's disease (AD) is becoming more common due to the increase in life expectancy. This study evaluated the effect of selenofuranoside (Se) in an Alzheimer-like sporadic dementia animal model. Male mice were divided into 4 groups: control, Aβ, Se, and Aβ + Se. Single administration of Aβ peptide (fragments 25-35; 3 nmol/3 μL) or distilled water was administered via intracerebroventricular (i.c.v.) injection. Selenofuranoside (5 mg/kg) or vehicle (canola oil) was administered orally 30 min before Aβ and for 7 subsequent days. Memory was tested through the Morris water maze (MWM) and step-down passive-avoidance (SDPA) tests. Antioxidant defenses along with reactive species (RS) were assessed. Inflammatory cytokines levels and AChE activity were measured. SOD activity was inhibited in the Aβ group whereas RS were increased. AChE activity, GSH, and IL-6 levels were increased in the Aβ group. These changes were reflected in impaired cognition and memory loss, observed in both behavioral tests. Se compound was able to protect against memory loss in mice in both behavioral tests. SOD and AChE activities as well as RS and IL-6 levels were also protected by Se administration. Therefore, Se is promising for further studies.

Virtual screening and biological evaluation of piperazine derivatives as human acetylcholinesterase inhibitors

The piperazine derivatives have been shown to inhibit human acetylcholinesterase. Virtual screening by molecular docking of piperazine derivatives 1-(1,4-benzodioxane-2-carbonyl) piperazine (K), 4-(4-methyl)-benzenesulfonyl-1-(1,4-benzodioxane-2-carbonyl) piperazine (S1), and 4-(4-chloro)-benzenesulfonyl-1-(1,4-benzodioxane-2-carbonyl) piperazine (S3) has been shown to bind at peripheral anionic site and catalytic sites, whereas 4-benzenesulfonyl-1-(1,4-benzodioxane-2-carbonyl) piperazine (S4) and 4-(2,5-dichloro)-benzenesulfonyl-1-(1,4-benzodioxane-2-carbonyl) piperazine (S7) do not bind either to peripheral anionic site or catalytic site with hydrogen bond. All the derivatives have differed in number of H-bonds and hydrophobic interactions. The peripheral anionic site interacting molecules have proven to be potential therapeutics in inhibiting amyloid peptides aggregation in Alzheimer's disease. All the piperazine derivatives follow Lipinski's rule of five. Among all the derivatives 1-(1,4-benzodioxane-2-carbonyl) piperazine (K) was found to have the lowest TPSA value.

Simultaneous determination of three alkaloids, four ginsenosides and limonin in the plasma of normal and headache rats after oral administration of Wu-Zhu-Yu decoction by a novel ultra fast liquid chromatography-tandem mass spectrometry method: application to a comparative pharmacokinetics and ethological study

A novel, sensitive and reliable ultra fast liquid chromatography-tandem mass spectrometry (UFLC-MS/MS) method has been developed and validated for simultaneous quantitation of eight main active ingredients (evodiamine, rutaecarpine, dehydroevodiamine, limonin, ginsenoside Rb1, Rd, Re and Rg1) in rat plasma after oral administration of Wu-Zhu-Yu (WZY) decoction, which is a celebrated and widely used Traditional Chinese Medicine formula for the treatment of headache. The analytes and internal standard (IS) were separated on a SHIM-PACK XR-ODS II column, and the detection was performed on a UFLC-MS/MS system with turbo ion spray source. The lower limits of quantification were 1.5, 0.5, 1.0, 2.0, 2.0, 1.0, 0.5 and 0.2 ng ml(-1) for evodiamine, rutaecarpine, dehydroevodiamine, limonin, gensenoside Rb1, Rd, Re and Rg1, respectively. Linearity, accuracy, precision and absolute recoveries of the eight analytes were all within satisfaction. The IS-normalized matrix factor was adopted for assessing the matrix effect and accompanied with a satisfactory result. The validated method has been successfully applied to compare pharmacokinetic profiles of the eight active ingredients in rat plasma between normal and headache rats after administration. Exact pharmaceutical effect of WZY decoction on headache was demonstrated by the ethological response of headache rats induced by nitric oxide donor after administration. The results indicated that the absorption of evodiamine, rutaecarpine, gensenoside Rb1, Re and Rg1 in headache group were significantly higher than those in normal group with similar concentration-time curves while no significant differences existed in limonin and ginsenoside Rd between the two groups.

Hippocampal extracellular signal-regulated kinase signaling has a role in passive avoidance memory retrieval induced by GABAA Receptor modulation in mice

Available evidence strongly suggests that the γ-aminobutyric acid type A (GABA(A)) receptor has a crucial role in memory retrieval. However, the signaling mechanisms underlying the role of GABA(A) receptor modulation in memory retrieval are unclear. We conducted one-trial passive avoidance task with pre-retention trial drug administration in the hippocampus to test the effects of GABA(A) receptor modulation on memory retrieval. We further tested the co-involvement of signaling molecules: extracellular signal-regulated kinase (ERK), Ca(2+)/calmodulin-dependent protein kinase II (CaMKII), and cAMP responsive element-binding protein (CREB). First, we observed that the phosphorylation of hippocampal ERK was required for memory retrieval during the task. Accordingly, to investigate whether GABA(A) receptor activation or inhibition induces ERK phosphorylation during memory retrieval, drugs that target the GABA(A) receptor were administered into the hippocampus before the retention trial. Muscimol, a GABA(A) receptor agonist, and diazepam, an agonist to benzodiazepine-binding site of GABA(A) receptor, blocked retention trial-induced ERK phosphorylation and impaired memory retrieval. Furthermore, co-treatment with sub-effective dose of U0126, a mitogen-activated protein kinase inhibitor, blocked the upregulation of ERK phosphorylation and impaired memory retrieval, and bicuculline methiodide (BMI), a GABA(A) receptor antagonist, increased ERK phosphorylation induced by the retention trial and facilitated memory retrieval. Finally, the effects of BMI were blocked by the co-application of a sub-effective dose of U0126. These results suggest that GABA(A) receptor-mediated memory retrieval is closely related to ERK activity.

Pharmacokinetics and urine metabolite identification of dehydroevodiamine in the rat

This study investigates the oral bioavailability and characterizes urine metabolites of dehydroevodiamine (DeHE), one of the bioactive alkaloids isolated from the fruit of Evodia rutaecarpa . A freely moving rat model coupled with an automated blood sample system was used to evaluate the pharmacokinetics of DeHE. High-performance liquid chromatography (HPLC), mass spectrometry (MS), and nuclear magnetic resonance (NMR) spectrometry were applied to determine DeHE and its metabolites. The averaged oral bioavailability of DeHE (100 and 500 mg/kg) in the freely moving rats was approximately 15.35%. Cumulative fecal and urinary excretions of unchanged DeHE were 6 and 0.5%, respectively, after a single oral dose (500 mg/kg) of DeHE. The protein binding of DeHE in rat plasma was 65.6 ± 6.5%. Six metabolites, including five DeHE-O-glucuronides and one DeHE-sulfate, were identified after oral administration. The structures of two glucuronide conjugates, DeHE-10-O-glucuronide (M3) and DeHE-11-O-glucuronide (M4), and one sulfate conjugate, DeHE-12-sulfate (M6), were assigned. The findings indicate that the oral bioavailability of DeHE was much higher than that of evodiamine, and hydroxylation and conjugative metabolism were essential for the urinary elimination of DeHE.

Anti-inflammatory and anti-infectious effects of Evodia rutaecarpa (Wuzhuyu) and its major bioactive components

This article reviews the anti-inflammatory relative and anti-infectious effects of Evodia rutaecarpa and its major bioactive components and the involvement of the nitric oxide synthases, cyclooxygenase, NADPH oxidase, nuclear factor kappa B, hypoxia-inducible factor 1 alpha, reactive oxygen species, prostaglandins, tumor necrosis factor, LIGHT, amyloid protein and orexigenic neuropeptides. Their potential applications for the treatment of endotoxaemia, obesity, diabetes, Alzheimer's disease and their uses as cardiovascular and gastrointestinal protective agents, analgesics, anti-oxidant, anti-atherosclerosis agents, dermatological agents and anti-infectious agents are highlighted. Stimulation of calcitonin gene-related peptide release may partially explain the analgesic, cardiovascular and gastrointestinal protective, anti-obese activities of Evodia rutaecarpa and its major bioactive components.

Inhibition of phosphodiesterase-4 reverses memory deficits produced by Aβ25-35 or Aβ1-40 peptide in rats

RATIONALE

Cyclic AMP signaling plays an important role in memory loss associated with Alzheimer's disease (AD). However, little is known about whether inhibition of phosphodiesterase-4 (PDE4), which increases intracellular cAMP, reverses β-amyloid peptide (Aβ)-induced memory deficits.

OBJECTIVE

Experiments were performed to demonstrate the effect of the PDE4 inhibitor rolipram on memory impairment produced by Aβ1-40 (Aβ40) or its core fragment Aβ25-35.

METHODS

We tested memory using Morris water-maze and passive avoidance tasks and examined expression of phosphorylated cAMP response-element binding protein (pCREB) in the hippocampus in rats treated with Aβ25-35 or Aβ40 into bilateral CA1 subregions, with or without rolipram administration.

RESULTS

Aβ25-35 (10 μg/side) increased escape latency during acquisition training and decreased swimming time and distance in the target quadrant in the water-maze probe trial; it also decreased 24-h retention in the passive avoidance paradigm. All these were reversed by chronic administration of rolipram (0.5 mg/kg). Similarly, Aβ40 (4 μg/side) produced memory impairment, as demonstrated by decreased retention in passive avoidance; this was also reversed by repeated treatment with rolipram. In addition, rolipram blocked extinction of memory during the 32-day testing period in the passive avoidance test. Further, Aβ40 decreased pCREB expression in the hippocampus, which was also reversed by rolipram; the changes in pCREB were highly correlated with those in memory.

CONCLUSIONS

These results suggest that the PDE4 inhibitor rolipram reverses cognitive deficits associated with AD most likely via increased cAMP/CREB signaling in the hippocampus; PDE4 could be a target for drugs that improve cognition in AD.

Swift and efficient synthesis of 4-phenylquinazolines: involvement of N-heterocyclic carbene in the key cyclization step

An original route to 2-alkyamino-4-phenylquinazolines in three steps from simple (hetero)aromatic amines is reported here. The key step involves the intramolecular cyclization of benzoyl arylguanidines performed in [OMIm]Cl ionic liquid. The basic (hetero)aromatic guanidines deprotonate the imidazolium-based ionic liquid, thus triggering the cascade process ultimately leading to the intramolecular cyclization. This reaction is the first example of a Friedel-Crafts-type reaction in which an N-heterocyclic carbene is involved in the formation of the electrophilic intermediate.

Two new acylgluconic acids from the nearly ripe fruits of Evodia rutaecarpa

Two new acylgluconic acids, trans-feruloylgluconic acid (1) and trans-caffeoylgluconic acid (2), together with three known compounds, myo-inositol (3), phthalic acid dibutyl ester (4), and wuzhuyuamide-I (5), were isolated from the water soluble part of the dried nearly ripe fruits of Evodia rutaecarpa (Juss.) Benth. Their structures were determined by spectroscopic methods, including IR, UV, ESITOFMS, HRSIMS, 1D and 2D NMR spectral analyses.

Dehydroevodiamine attenuates calyculin A-induced tau hyperphosphorylation in rat brain slices

AIM

This study was to investigate the effect of dehydroevodiamine (DHED) on Alzheimer's disease (AD)-like tau hyperphosphorylation induced by calyculin A (CA), an inhibitor of protein phosphatase (PP)-2A and PP-1, and the involvement of PP-2A in metabolically competent rat brain slices.

METHODS

Rat brain slices were pre-incubated at 33 degree centigrade in the presence (10, 100, and 200 micromol/L, respectively) or absence of DHED for 1 h. Then, CA 0.1 micromol/L was added and the slices were treated for another 2 h. Western blotting and/or immunohistochemistry were used to measure the phosphorylation level of tau and PP-2A.

RESULTS

CA treatment could remarkably increase the immunoreactivity of pS262 and decrease the staining of Tau-1, representing tau hyperphosphorylation at Ser262 (pS262) and Ser198/ 199/202 (Tau-1, as the antibody reacts with unphosphorylated tau, therefore, decreased staining represents increased phosphorylation). Pre-incubation of the brain slices with DHED could efficiently attenuate the CA-induced tau hyperphosphorylation at the above AD-related sites. Additionally, DHED also decreased the basal phosphorylation level of tau at Ser396, although CA failed to induce tau hyperphosphorylation at this site. Furthermore, CA treatment induced an increased level of Tyr307-phosphorylated PP-2A, which represents inactivation of the phosphatase, whereas DHED arrested the elevation of the inhibitory modification of PP-2A.

CONCLUSION

DHED can attenuate CA-induced tau hyperphosphorylation at multiple AD-related sites in metabolically active rat brain slices. The underlying mechanism may involve a decreased inhibitory phosphorylation of PP-2A at Tyr307.

Dehydroevodiamine attenuates tau hyperphosphorylation and spatial memory deficit induced by activation of glycogen synthase kinase-3 in rats

Tau hyperphosphorylation and memory deficit are characteristic alterations of Alzheimer's disease (AD), and glycogen synthase kinase-3 (GSK-3) plays a crucial role in these AD-like changes. We have reported that activation of GSK-3 through ventricular injection of wortmannin and GF-109203X (WT/GFX, 100 microM each) induces tau hyperphosphorylation and memory impairment of rats [Liu, S.J. et al., 2003. Overactivation of glycogen synthase kinase-3 by inhibition of phosphoinositol-3 kinase and protein kinase C leads to hyperphosphorylation of tau and impairment of spatial memory. J. Neurochem. 87, 1333-1344]. By using this model, we explored in the present study the effects of dehydroevodiamine (DHED), a quinazoline alkaloid isolated from Evodia rutaecarpa Bentham, on the memory retention, tau phosphorylation and the activity of GSK-3. We found that pre-administration of DHED through vena caudalis for 1 week efficiently improved the WT/GFX-induced spatial memory retention impairment of the rats; it also antagonized tau hyperphosphorylation at multiple AD sites and arrested the overactivation of GSK-3 induced by WT/GFX. Our study gave the first in vivo evidence that DHED could suppress the overactivation of GSK-3 and improve tau hyperphosphorylation and spatial memory deficit of the rats, suggesting that this chemical may be served as a candidate for arresting AD-like pathological and behavioral alterations.

The ameliorating effect of oroxylin A on scopolamine-induced memory impairment in mice

Oroxylin A is a flavonoid and was originally isolated from the root of Scutellaria baicalensis Georgi., one of the most important medicinal herbs in traditional Chinese medicine. The aim of this study was to investigate the ameliorating effects of oroxylin A on memory impairment using the passive avoidance test, the Y-maze test, and the Morris water maze test in mice. Drug-induced amnesia was induced by administering scopolamine (1 mg/kg, i.p.) or diazepam (1 mg/kg, i.p.). Oroxylin A (5 mg/kg) significantly reversed cognitive impairments in mice by passive avoidance and the Y-maze testing (P<.05). Oroxylin A also improved escape latencies in training trials and increased swimming times and distances within the target zone of the Morris water maze (P<.05). Moreover, the ameliorating effects of oroxylin A were antagonized by both muscimol and diazepam (0.25 mg/kg, i.p., respectively), which are GABA(A) receptor agonists. Furthermore, oroxylin A (100 microM) was found to inhibit GABA-induced inward Cl(-) current in a single cortical neuron. These results suggest that oroxylin A may be useful for the treatment of cognitive impairments induced by cholinergic dysfunction via the GABAergic nervous system.

Inhibition of lipopolysaccharide-induced iNOS and COX-2 expression by dehydroevodiamine through suppression of NF-κB activation in RAW 264.7 macrophages

Dehydroevodiamine is a major bioactive quinazoline alkaloid isolated from Evodiae Fructus. We investigated the anti-inflammatory properties of dehydroevodiamine in RAW 264.7 murine macrophages. The results indicated that dehydroevodiamine inhibited the expression of LPS-induced iNOS and COX-2 proteins and suppressed also their mRNAs from RT-PCR experiment on RAW 264.7 cells. Furthermore, this compound inhibited the level of LPS-stimulated prostaglandin E2 (PGE2) and LPS-induced nuclear factor-kappa B (NF-kappaB). Therefore, we suggested that the effect of dehydroevodiamine-mediated inhibition of the expression LPS-induced iNOS and COX-2 genes is due to under the suppression of NF-kappaB activation in the transcriptional level.

Studies of the Effects of Central Administration of β-Amyloid Peptide (25–35): Pathomorphological Changes in the Hippocampus and Impairment of Spatial Memory

The possible link between amnesia induced by central administration of beta-amyloid (25-35) (Abeta(25-35)) and neurodegenerative changes in the hippocampus was studied. Male Wistar rats received single intracerebroventricular injections of Abeta(25-35) at a dose of 15 nmoles and one month later were trained in an eight-arm radial maze. Training was followed by histological assessment of the state of the hippocampus on brain sections stained with hematoxylin and eosin. Abeta(25-35) induced impairments in long-term (reference) and working memory on testing in the maze. There was a moderate reduction in the number of neurons in hippocampal field CA1; there was no change in the number of cells in field CA3. The numbers of errors made by the animals on testing in the maze were found to correlate negatively with the numbers of nerve cells in hippocampal field CA1. Thus, this is the first demonstration that impairments of learning and memory induced by single doses of Abeta(25-35) are specifically associated with neurodegenerative changes in hippocampal field CA1 in rats.

Effect of a Nutritive-Tonic Drink on Scopolamine-Induced Memory Impairment in Mice

The effects of a liquid nutritive and tonic drug (NTD) selected from a modification of the "Kai-xin-shou-yu-shen-qi-wan" prescription, on scopolamine-induced amnesia in mice were investigated using the passive avoidance and water-maze tasks. A popular NTD in Japan that contains 17 crude (natural) drug extracts together with synthetic drugs such as taurine, caffeine, various vitamins and ethanol, and the natural drug extracts is based on a prescription of "Kampo" origin in Chinese medicine. Scopolamine (0.4 mg/kg, i.p.) reduces the step-through latency of the passive avoidance test and fear reaction behavior at 24 and 48 h after treatment. A single oral administration of the NTD (10 ml/kg) increased the step-through latency and the fear reaction behavior score in scopolamine-treated mice. Administration of the natural drug extracts found in the NTD tended to extend the step-through latency in the retention test at 48 h, but not 24 h after the initial scopolamine trial. However, administration of the synthetic drugs found in the NTD did not improve either the step-through latency or the behavioral score. The NTD and the natural drug extracts also improved the scopolamine-induced spatial memory impairment as assessed using the Morris water-maze test. In contrast, the synthetic drugs did not affect the escape latencies. Both NTD and the synthetic drugs increased the locomotor activity in scopolamine-treated mice, whereas the natural drug extracts did not. These results suggest that NTD improves scopolamine-induced amnesia, and that this action is attributable to the natural drug extracts in the NTD.

Effects of baicalein on β-amyloid peptide-(25–35)-induced amnesia in mice

Baicalein may act on the benzodiazepine binding sites to exert an anxiolytic-like effect in mice. Since many benzodiazepine drugs have amnesic side-effect and baicalein can protect cultured cortical neurons from beta-amyloid peptide-(25-35)-induced toxicity, this study examined the amnesic effect of baicalein and its effects on beta-amyloid peptide-(25-35) (3 nmol/mouse, i.c.v.)-induced amnesia in mice. Using the step-through passive avoidance test, the results showed that baicalein (10-100 mg/kg, i.p.), unlike the benzodiazepine drug chlordiazepoxide (10 mg/kg, i.p.), had no significant amnesic effect. Baicalein (10-50 mg/kg, i.p.) also had no facilitating effect on the learning and memory. However, one dosage pretreatment, but not post-treatment, of baicalein (5 or 10 mg/kg, i.p.) attenuated beta-amyloid peptide-(25-35)-induced amnesia. Interestingly, post-treatment for 7 or 13 days of baicalein (10-15 mg/kg/day, i.p.), like melatonin (10 mg/kg/day, i.p.), also attenuated beta-amyloid peptide-(25-35)-induced amnesia. Therefore, this study demonstrated that baicalein has protective effect on beta-amyloid peptide-(25-35)-induced amnesia.

Therapeutic effects of herbal extracts and constituents in animal models of psychiatric disorders

A search for novel pharmacotherapy from medicinal plants for psychiatric illnesses has progressed significantly in the past decade. This is reflected in the large number of herbal preparations for which psychotherapeutic potential has been evaluated in a variety of animal models. The objective of this review is to provide an overview of herbal extracts and constituents that have significant therapeutic effects in animal models of psychiatric illnesses. Eighty five individual herbs reviewed were classified as anxiolytic, antidepressant, neuroleptic, antidementia, or anti-substance abuse herbs. The full scientific name of each herb, herbal part used, active constituent, extract, dose range and route, animal model, possible mechanisms of action, and pertinent references are presented via synoptic tables. The herbal mixtures were also mentioned. A considerable number of herbal constituents whose behavioral effects and pharmacological actions have been well characterized may be good candidates for further investigations that may ultimately result in clinical use. The investigation of a large portion of the herbal extracts and herbal mixtures is in its infancy. Herbal remedies that have demonstrable psychotherapeutic activities have provided a potential to psychiatric pharmaceuticals and deserve increased attention in future studies.

Effects of dehydroevodiamine exposure on glutamate release and uptake in the cultured cerebellar cells

Dehydroevodiamine has been reported to have neuroprotective and antiamnesic effects. This study examined the effects of dehydroevodiamine on glutamate release and uptake in cultured cerebellar cells. Chronic dehydroevodiamine exposure decreased the viability of granule cells. The basal and N-methyl-D-aspartate (NMDA)-induced release of glutamate from granule cells were decreased (26 and 14%) by dehydroevodiamine. The NMDA-induced release of glutamate was concentration-dependently inhibited in the granule cells. The basal and NMDA-induced releases of glutamate in chronically dehydroevodiamine-preexposed granule cells were unaffected by dehydroevodiamine. Glutamate uptake in the glial cells incubated without and with cAMP was inhibited (31% and 8%, respectively) by dehydroevodiamine. In the chronically dehydroevodiamine-preexposed glial cells, glutamate uptake was increased (8%) in the cAMP-coexposed glial cells by dehydroevodiamine but was unaffected in the naive cells. In addition, dehydroevodiamine potentiated (from 20% to 34%) the inhibition of L-pyrollidine-2,4-dicarboxylic acid (PDC) on glutamate uptake in naive glial cells, but this inhibition was reduced (from 41% to 26%) in cAMP-coexposed glial cells. These results suggest that dehydroevodiamine inhibits glutamate uptake and release. Furthermore, the results suggest that the characteristics of glutamate release and uptake in granule and glial cells may be altered by chronic exposure to dehydroevodiamine.

Amyloid-β(25–35)-induced memory impairments correlate with cell loss in rat hippocampus

Amyloid beta-peptide (Abeta) plays an important role in the pathophysiology of Alzheimer's disease. The relationship between amnesia induced by central administration of aggregated Abeta(25-35) and neurodegeneration in the hippocampus was investigated. One month after a single intracerebroventricular injection of Abeta(25-35) (15 nmol), male Wistar rats were tested in an eight-arm radial maze. A quantitative evaluation of cell number in hippocampal regions was carried out on H&E-stained brain sections of rats used in the behavioral study. Indices of free radical-mediated processes in the hippocampus were evaluated in additional groups of animals 1, 3, 5, and 30 days after surgery. Abeta(25-35) induced impairments of working and reference memory (RM) as well as neurodegeneration in the CA1 but not in the CA3 field of the hippocampus. A significant correlation between both reference and working memory (WM) impairments and the neuronal cell loss in the hippocampal CA1 region was demonstrated. A gradually developing oxidative stress was evident in the hippocampus of rats treated with Abeta(25-35) as indicated by the increase in 2-thiobarbituric acid (TBARS) reactive substances and superoxide generation. These data suggest the involvement of oxidative stress in Abeta(25-35)-induced neurodegeneration and a relation between memory impairment and neurodegeneration in the CA1 subfield of the hippocampus.

Amnesia induced by β-amyloid fragments is counteracted by cannabinoid CB1 receptor blockade

Administration of drugs activating cannabinoid CB(1) receptors in the brain induces memory deficit in rodents, and blockade of these receptors may restore memory capacity in these animals. Central administration of beta-amyloid or beta-amyloid fragments may also lead to memory disturbances. This study was undertaken to study the involvement of cannabinoid CB(1) receptors in amnesia induced by beta-amyloid fragments in mice tested in a step-through passive avoidance paradigm. Pre-training intracerebroventricular (i.c.v.) injection of beta-amyloid fragments, beta-amyloid peptide-(25-35) (4, 8 or 16 nmol/mouse) or beta-amyloid peptide-(1-42) (200, 400, 800 pmol/mouse) 7 days prior to the learning trial reduced in a dose-dependent manner the retention of passive avoidance response. This effect was observed in two retention tests, 1 and 7 days after the learning trial. The two beta-amyloid fragments showed similar potency in reducing retention of passive avoidance behavior. This effect was counteracted by a single intraperitoneal (i.p.) injection of the cannabinoid CB(1) receptor antagonist, N-(piperidin-l-yl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide hydrochloride (SR141716A, 1 mg/kg), made 30 min prior to the second retention test. The injection of SR141716A per se did not affect memory capacity of mice. The i.c.v. administration of beta-amyloid peptide-(25-35) (8 nmol/mouse) or of beta-amyloid peptide-(1-42) (400 pmol/mouse) made 30 min prior to the learning trial failed to affect the retention capacity of mice as measured 1 and 7 days later. Also, the i.p. injection of SR 141716A (1 mg/kg) made 30 min prior to the learning trial did not influence the behavioral response of mice injected with beta-amyloid peptide-(25-35) (8 nmol/mouse) or of beta-amyloid peptide-(1-42) (400 pmol/mouse) 7 days prior to the learning trial. These results show that beta-amyloid fragments induce a dose-dependent memory deficit. Their effect on memory retention depends upon the time of administration and seems to involve cannabinoid CB(1) receptors in the brain.

Single intracerebroventricular administration of amyloid-beta (25-35) peptide induces impairment in short-term rather than long-term memory in rats

Ample experimental evidence indicates that intracerebral injection or infusion of amyloid-beta peptides (Abeta) to rodents induces learning and memory impairments as well as neurodegeneration in brain areas related to cognitive function. In the present study, we assessed the effects of a single intracerebroventricular (i.c.v.) injection of aggregated Abeta fragment (25-35) at a dose of 15nmol/rat on short-term and long-term memory in rats during the 6-month post-surgery period. The results demonstrate that Abeta(25-35)-induced memory impairments in spontaneous alternation behavior in a Y-maze at 17, 36, and 180 days after the surgery as well as in a social recognition task 110 days post-surgery. Abeta(25-35) also impaired spatial memory in an 8-arm radial maze, but did not influence performance of the step-down passive avoidance task. These results suggest that Abeta(25-35) preferably induces impairments of spatial and non-spatial short-term (working) memory rather than long-term memory in rats.

Anti-amnesic effect of dimemorfan in mice

(1) Dimemorfan, an antitussive for more than 25 years, has previously been reported to be a relative high-affinity ligand at sigma-1 (sigma(1)) receptor with the K(i) value of 151 nM. (2) To test whether dimemorfan has anti-amnesic effects similar to a sigma(1) receptor agonist, this study examined its effects on scopolamine- and beta-amyloid peptide-(25-35)-induced amnesia in mice. (3) Dimemorfan (10-40 mg kg(-1), i.p.) administered 30 min before the training trial, immediately after the training trial, or 30 min before the retention test significantly improved scopolamine (1 mg kg(-1), i.p.)- or beta-amyloid peptide-(25-35) (3 nmol mouse(-1), i.c.v.)-induced amnesia in a step-through passive avoidance test. Dimemorfan (5-40 mg kg(-1), i.p.) pretreatment also attenuated scopolamine (8 mg kg(-1), i.p.)-induced amnesia in a water-maze test. And, these anti-amnesic effects of dimemorfan, like the putative sigma(1) receptor agonist (+)-N-allylnormetazocine ((+)-SKF-10047), were antagonized by a sigma receptor antagonist haloperidol (0.25 mg kg(-1), i.p.). (4) These results indicated that dimemorfan has anti-amnesic effects and acts like a sigma(1) receptor agonist.