Neuroprotective effects of benzyloxy substituted small molecule monoamine oxidase B inhibitors in Parkinson's disease.

The benzyloxy substituted small molecules are well-known highly potent monoamine oxidase B inhibitors, but their therapeutic potential against Parkinson's disease have not been investigated in detail. In this paper, a series of representative benzyloxy substituted derivatives were synthesized and evaluated for MAO-A/B inhibition. In addition, their neuroprotective effects were investigated in 6-OHDA- and rotenone-treated PC12 cells. It was observed that most of the compounds exhibited a marked increase in survival of PC12 cells which treated with the neurotoxins. Among them, 13 exhibited remarkable and balanced neuroprotective potency. The protective effects of 13 against neurotoxins-induced apoptosis were confirmed with flow cytometry and staining methods. Furthermore, 13 also showed good BBB permeability and low toxicity according to in vitro BBB prediction and in vivo acute toxicity test. The results indicated that 13 is an effective and promising candidate to be further developed as disease-modifying drug for Parkinson's disease therapy.

Design, synthesis and evaluation of novel tacrine-rhein hybrids as multifunctional agents for the treatment of Alzheimer's disease.

A series of tacrine-rhein hybrid compounds have been designed and synthesized as novel multifunctional potent ChE inhibitors. Most of the compounds inhibited ChEs in the nanomolar range in vitro effectively. Compound 10b was one of the most potent inhibitors and was 5-fold more active than tacrine toward AChE, and it also showed a moderate BuChE inhibition with an IC50 value of 200 nM. Kinetic and molecular modeling studies of 10b also indicated that it was a mixed-type inhibitor binding simultaneously to the active and peripheral sites of AChE. In inhibition of the AChE-induced Aß aggregation assay, compound 10b (70.2% at 100 µM) showed the greatest inhibitory activity. In addition, 10b showed metal-chelating property and low hepatotoxicity. These results suggested that 10b might be an excellent multifunctional agent for AD treatment.

Multi-target tacrine-coumarin hybrids: cholinesterase and monoamine oxidase B inhibition properties against Alzheimer's disease.

A series of novel tacrine-coumarin hybrids were designed, synthesized and evaluated as multi-target agents against Alzheimer's disease. The biological assays indicated that most of compounds displayed potent inhibitory activity toward AChE and BuChE, and clearly selective inhibition for MAO-B. Among these compounds, 14c exhibited strong inhibitory activity for AChE (IC50 values of 33.63 nM for eeAChE and 16.11 nM for hAChE) and BuChE (IC50 values of 80.72 nM for eqBuChE and 112.72 nM for hBuChE), and the highest inhibitory activity against hMAO-B (IC50 value of 0.24 µM). Kinetic and molecular modeling studies revealed that 14c was a mixed-type inhibitor, binding simultaneously to catalytic, peripheral and mid-gorge sites of AChE. It was also a competitive inhibitor, which covered the substrate and entrance cavities of MAO-B. Moreover, 14c could penetrate the CNS and show low cell toxicity. Overall, these results suggested that 14c might be an excellent multi-target agent for AD treatment.

Multifunctional tacrine-trolox hybrids for the treatment of Alzheimer's disease with cholinergic, antioxidant, neuroprotective and hepatoprotective properties.

Combining tacrine with trolox in a single molecule, novel multifunctional hybrids have been designed and synthesized. All these hybrids showed ChE inhibitory activity in nanomolar range and strong antioxidant activity close to the parent compound trolox. Among them, compound 6d was the most potent inhibitor against AChE (IC50 value of 9.8 nM for eeAChE and 23.5 nM for hAChE), and it was also a strong inhibitor to BuChE (IC50 value of 22.2 nM for eqBuChE and 20.5 nM for hBuChE). Molecular modeling and kinetic studies suggested that 6d was a mixed-type inhibitor, binding simultaneously to CAS and PAS of AChE. In vivo hepatotoxicity assays indicated that 6d was much less toxic than tacrine. In addition, it showed neuroprotective effect and good ability to penetrate the BBB. Overall, all these results highlighted 6d a promising multifunctional agent for AD treatment.

Design, synthesis and evaluation of multifunctional salphen derivatives for the treatment of Alzheimer's disease.

A series of salphen derivatives (1-26) have been designed, synthesized, and evaluated as chemical reagents that target and modulate multiple facets of Alzheimer's disease. Most of the compounds exhibit a significant ability to inhibit self-induced and Cu(2+)-induced ß-amyloid (Aß1-42) aggregation, and to function as potential antioxidants and biometal chelators. In particular, the antioxidant activity of compound 2 is 2.6-fold of the trolox value by using the ABTS radical scavenging method, and it also shows a significant ability to inhibit self-induced and Cu(2+)-induced ß-amyloid (Aß1-42) aggregation (70.3%, 20 µM and 85.7%, 50 µM, respectively). Moreover, it is capable of decreasing reactive oxygen species (ROS) induced by Cu(2+)-Aß, shows a good neuroprotective effect in human SH-SY5Y neuroblastoma cells and can cross the blood-brain barrier. In addition, compound 2 retains the activities of antioxidant, anti Aß aggregation and neuroprotection after capturing the metal ions Cu(2+), Fe(3+) and Zn(2+) (its metal complexes 18, 22 and 23). Taken together, these results suggest that compound 2 might be a promising lead compound for AD treatment.

Analysis and pharmacokinetics studies of gastrodin and p-hydroxybenzyl alcohol in dogs using ultra fast liquid chromatography-tandem mass spectrometry method.

A simple, sensitive and reliable ultra fast liquid chromatography-electrospray ionization-tandem mass spectrometry (UFLC-ESI-MS/MS) method was developed for simultaneously quantifying gastrodin (p-hydroxy-methyl-phenol-ß-d-glucoside) and its metabolite p-hydroxybenzyl alcohol (HBA) in dog plasma. Separation was performed on an ultra fast liquid chromatography (UFLC) system. Detection was carried out on a tandem mass spectrometry (MS/MS) in multiple reaction monitoring (MRM) mode via an electrospray ionization (ESI) interface. MRM mode of precursor-product ion transitions was used for gastrodin, HBA and the internal standard (IS, bergeninum) at m/z 285.0→123.0, 123.0→105.0 and 326.9→192.2, respectively. The lower limits of quantification (LLOQ) of this method for both gastrodin and HBA were 1ng/mL, with their linear concentration ranging from 0.001 to 10µg/mL. The methods were validated for selectivity, calibration curves, accuracy and precision, extraction recoveries, matrix effects, carry-over, cross talk, dilution integrity, stability and incurred sample reanalysis (ISR). Using this validated method, pharmacokinetic behaviors of gastrodin and HBA after intragastric administration (ig) of gastrodin to dogs were studied for the first time.

H nuclear magnetic resonance-based metabolomics reveals sex-specific metabolic changes of gastrodin intervention in rats.

OBJECTIVES: To explore (1)H nuclear magnetic resonance-based metabolomics on sex-specific metabolic changes of gastrodin intervention in rats. METHODS: In this research, (1)H NMR-based metabolomics was used for the first time to investigate metabolic changes following chronic intervention with gastrodin in rats. RESULTS: 24 endogenous metabolites were identified. Body weight, daily diet and the total volume of urine in in each day of each rat were measured synchronously. Modifications in 12 metabolites were observed following gastrodin intervention, indicating gastrodin-induced alterations in carbohydrate and energy metabolism. Interestingly, these metabolic changes were not totally identical in female and male rats. Some metabolic changes arising from gastrodin intervention showed sexual dimorphism including LDL/VLDL and lactate which were on the decrease in the female but on the increase in the male, together with arginine/ornithine, creatine, and glycerol which were on the increase in the female but on the decrease in the male. While the decrease in pyruvate, succinate and glutamate was only shown in the male and the increase in valine, α-ketoglutarate, glycine and glucose was only in the female. CONCLUSIONS: This research shows the sex-specific metabolic response to GAS intervention, weather GAS is a healthy dietary supplement for the male merits further investigation.

Identification and analysis of gastrodin and its five metabolites using ultra fast liquid chromatography electrospray ionization tandem mass spectrometry to investigate influence of multiple-dose and food.

A reliable and highly sensitive ultra performance liquid chromatography electrospray ionization tandem mass spectrometry (UFLC-ESI-MS/MS) analytical method was developed for identification and quantification of gastrodin (GAS) and its metabolites in rat plasma. Five metabolites were identified: p-formylphenyl-ß-d-glucopyranoside (M1), p-hydroxybenzonic acid (M2), p-hydroxybenzyl alcohol (M3), p-formaldehydephenyl-ß-d-glucopyranoside (M4), p-hydroxybenzaldehyde (M5). The molecular structures of metabolites were proposed based on the characters of their precursor ions, product ions and chromatographic retention time. Four of them were reported firstly in rat plasma. This method involved the addition of bergeninum as the internal standard (IS), UFLC separation, and quantification by MS/MS system using negative electrospray ionization in the multiple reaction monitoring (MRM) mode. The lower limit of quantification of gastrodin and five metabolites were all 1ng/mL. The method was linear in the concentration range of 0.001-10µg/mL. The intra- and inter-day precisions (R.S.D %) were within 15.0% for all analytes. No interference was noted due to endogenous substances. All analytes were stable in rat plasma stored at room temperature and 4°C for at least 4h, -20°C combined with three freeze-thaw cycles for at least 1 month. By this method, the influence of multiple-dose and food on the pharmacokinetics behaviors of GAS and its metabolites were studied for the first time. We hope pharmacokinetic data of present study may inspire rational clinical usage of GAS.

Study on the anti-gout activity of chlorogenic acid: improvement on hyperuricemia and gouty inflammation.

Gout is a metabolic disorder associated with hyperuricemia resulting in the deposition of monosodium urate (MSU) crystals in joints and tissues. Lowering serum uric acid (Sur) levels and anti-inflammation are highly essential in treating gout. Chlorogenic acid (CA), as one of the most abundant polyphenols in the Chinese medicines, has been rarely reported to have an anti-gout effect. The model of potassium oxonate (PO)-induced hyperuricemia in mice and MSU crystal-induced inflammation in rats has been established in this study. The potential beneficial effects and mechanisms of CA on hyperuricemia and gouty arthritis were elucidated. The results demonstrated that CA significantly decreased the Sur level by inhibiting the xanthine oxidase (XOD) activity but not increasing the urinary uric acid (Uur) level. In addition, CA also exhibited the effect of suppressing paw swelling. Further investigation indicated that CA improved the symptoms of inflammation induced by MSU crystals by inhibiting the production of proinflammatory cytokines including interleukin-1ß (IL-1ß), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α). The present study suggests that CA may have a considerable potential for development as an anti-gouty arthritis agent for clinical application.

Multifunctional tacrine-flavonoid hybrids with cholinergic, ß-amyloid-reducing, and metal chelating properties for the treatment of Alzheimer's disease.

A new series of tacrine-flavonoid hybrids (13a-u) had been designed, synthesized, and evaluated as multifunctional cholinesterase (ChE) inhibitors against Alzheimer's disease (AD). In vitro studies showed that most of the molecules exhibited a significant ability to inhibit ChE and self-induced amyloid-ß (Aß1₋42) aggregation. Kinetic and molecular modeling studies also indicated compounds were mixed-type inhibitors, binding simultaneously to active, peripheral and mid-gorge sites of AChE. Particularly, compound 13k was found to be highly potent and showed a balanced inhibitory profile against ChE and self-induced Aß1₋42 aggregation. Moreover, it also showed excellent metal chelating property and low cell toxicity. These results suggested that 13k might be an excellent multifunctional agent for AD treatment.