Highly efficient synthesis and monoamine oxidase B inhibitory profile of demethyleneberberine, columbamine and palmatine.

The biosynthesis of berberine alkaloids is thought to begin with the demethylation of berberine followed by methylation reactions to generate other type berberine alkaloids. This seemingly expeditious way to access berberine alkaloids has been stagnated for over half a century due to certain vexing synthetic problems, such as low isolated yield, complex operations and toxic reagents. We further investigated this bioinspired semi-synthesis strategy and significantly improved the synthetic efficacy, by providing a practical synthetic process for demethyleneberberine (DMB), columbamine and palmatine. Furthermore, we found that DMB (IC50, 9.06 µM) inhibited the activity of monoamine oxidase B (MAO-B), an enzyme that deaminates dopamine and is particularly involved in the pathology of Parkinson's disease. Besides, columbamine was able to decrease MAO-B activity by approximately 40%. These findings provide perquisites for further in vivo investigation to confirm the therapeutic potentiality of berberine alkaloids, DMB in particular.

Molecular Targets of Bis (7)-Cognitin and Its Relevance in Neurological Disorders: A Systematic Review.

Background: The exact mechanisms involved in the pathogenesis of neurodegenerative conditions are not fully known. The design of drugs that act on multiple targets represents a promising approach that should be explored for more effective clinical options for neurodegenerative disorders. B7C is s synthetic drug that has been studied for over 20 years and represents a promising multi-target drug for the treatment of neurodegenerative disorders, such as AD. Aims: The present systematic review, thus, aims at examining existing studies on the effect of B7C on different molecular targets and at discussing the relevance of B7C in neurological disorders. Methods: A list of predefined search terms was used to retrieve relevant articles from the databases of Embase, Pubmed, Scopus, and Web of Science. The selection of articles was done by two independent authors, who were considering articles concerned primarily with the evaluation of the effect of B7C on neurological disorders. Only full-text articles written in English were included; whereas, systematic reviews, meta-analyses, book chapters, conference subtracts, and computational studies were excluded. Results: A total of 2,266 articles were retrieved out of which 41 articles were included in the present systematic review. The effect of B7C on molecular targets, including AChE, BChE, BACE-1, NMDA receptor, GABA receptor, NOS, and Kv4.2 potassium channels was evaluated. Moreover, the studies that were included assessed the effect of B7C on biological processes, such as apoptosis, neuritogenesis, and amyloid beta aggregation. The animal studies examined in the review focused on the effect of B7C on cognition and memory. Conclusions: The beneficial effects observed on different molecular targets and biological processes relevant to neurological conditions confirm that B7C is a promising multi-target drug with the potential to treat neurological disorders.

Discovery of Potent Succinate-Ubiquinone Oxidoreductase Inhibitors via Pharmacophore-linked Fragment Virtual Screening Approach.

Succinate-ubiquinone oxidoreductase (SQR) is an attractive target for fungicide discovery. Herein, we report the discovery of novel SQR inhibitors using a pharmacophore-linked fragment virtual screening approach, a new drug design method developed in our laboratory. Among newly designed compounds, compound 9s was identified as the most potent inhibitor with a Ki value of 34 nM against porcine SQR, displaying approximately 10-fold higher potency than that of the commercial control penthiopyrad. Further inhibitory kinetics studies revealed that compound 9s is a noncompetitive inhibitor with respect to the substrate cytochrome c and DCIP. Interestingly, compounds 8a, 9h, 9j, and 9k exhibited good in vivo preventive effects against Rhizoctonia solani. The results obtained from molecular modeling showed that the orientation of the R(2) group had a significant effect on binding with the protein.

Crystal structure of 1-benzyl-4-formyl-1H-pyrrole-3-carb-oxamide.

In the title compound, C13H12N2O2 (I), the mean planes of the pyrrole and benzyl rings are approximately perpendicular, forming a dihedral angle of 87.07 (4) °. There is an intra-molecular N-H⋯O hydrogen bond forming an S(7) ring motif. In the crystal, mol-ecules are linked via a pair of N-H⋯O hydrogen bonds forming inversion dimers. C-H⋯O hydrogen bonds link the dimers into chains along direction [10-1]. The chains are further linked by weak C-H⋯π inter-actions forming layers parallel to the ac plane.

Dimeric bis (heptyl)-Cognitin Blocks Alzheimer's ß-Amyloid Neurotoxicity Via the Inhibition of Aß Fibrils Formation and Disaggregation of Preformed Fibrils.

AIMS: Fibrillar aggregates of ß-amyloid protein (Aß) are the main constituent of senile plaques and considered to be one of the causative events in the pathogenesis of Alzheimer's disease (AD). Compounds that could inhibit Aß fibrils formation, disaggregate preformed Aß fibrils as well as reduce their associated neurotoxicity might have therapeutic values for treating AD. In this study, the inhibitory effects of bis (heptyl)-cognitin (B7C), a multifunctional dimer derived from tacrine, on aggregation and neurotoxicity of Aß1-40 were evaluated both in vitro and in vivo. METHODS: Thioflavin T fluorescence assay was carried out to evaluate Aß aggregation, MTT and Hoechst-staining assays were performed to investigate Aß-associated neurotoxicity. Fluorescent probe DCFH-DA was used to estimate the accumulation of intracellular reactive oxygen stress (ROS). Morris water maze was applied to determine learning and memory deficits induced by intracerebroventricular infusion of Aß in rats. RESULTS: B7C (0.1-10 µM), but not tacrine, effectively inhibited Aß fibrils formation and disaggregated preformed Aß fibrils following co-incubation of B7C and Aß monomers or preformed fibrils, respectively. In addition, B7C markedly reduced Aß fibrils-associated neurotoxicity in SH-SY5Y cell line, as evidenced by the increase in cell survival, the decrease in Hoechst-stained nuclei and in intracellular ROS. Most encouragingly, B7C (0.1 and 0.2 mg/kg), 10 times more potently than tacrine (1 and 2 mg/kg), inhibited memory impairments after intracerebroventricular infusion of Aß in rats, as evidenced by the decrease in escape latency and the increase in the spatial bias in Morris water maze test along with upregulation of choline acetyltransferase activity and downregulation of acetylcholinesterase activity. CONCLUSION: These findings provide not only novel molecular insight into the potential application of B7C in treating AD, but also an effective approach for screening anti-AD agents.

Robust Neuritogenesis-Promoting Activity by Bis(heptyl)-Cognitin Through the Activation of alpha7-Nicotinic Acetylcholine Receptor/ERK Pathway.

AIMS: Neurodegenerative disorders are caused by progressive neuronal loss in the brain, and hence, compounds that could promote neuritogenesis may have therapeutic values. In this study, the effects of bis(heptyl)-cognitin (B7C), a multifunctional dimer, on neurite outgrowth were investigated in both PC12 cells and primary cortical neurons. METHODS: Immunocytochemical staining was used to evaluate the proneuritogenesis effects, and Western blot and short hairpin RNA assays were applied to explore the underlying mechanisms. RESULTS: B7C (0.1-0.5 µM) induced robust neurite outgrowth in PC12 cells, as evidenced by the neurite-bearing morphology and upregulation of growth-associated protein-43 expression. In addition, B7C markedly promoted neurite outgrowth in primary cortical neurons as shown by the increase in the length of ß-III-tubulin-positive neurites. Furthermore, B7C rapidly increased ERK phosphorylation. Specific inhibitors of alpha7-nicotinic acetylcholine receptor (α7-nAChR) and MEK, but not those of p38 or JNK, blocked the neurite outgrowth as well as ERK phosphorylation induced by B7C. Most importantly, genetic depletion of α7-nAChR significantly abolished B7C-induced neurite outgrowth in PC12 cells. CONCLUSION: B7C promoted neurite outgrowth through the activation of α7-nAChR/ERK pathway, which offers novel insight into the potential application of B7C in the treatment of neurodegenerative disorders.

Brazilin inhibits amyloid ß-protein fibrillogenesis, remodels amyloid fibrils and reduces amyloid cytotoxicity.

Soluble amyloid ß-protein (Aß) oligomers, the main neurotoxic species, are predominantly formed from monomers through a fibril-catalyzed secondary nucleation. Herein, we virtually screened an in-house library of natural compounds and discovered brazilin as a dual functional compound in both Aß42 fibrillogenesis inhibition and mature fibril remodeling, leading to significant reduction in Aß42 cytotoxicity. The potent inhibitory effect of brazilin was proven by an IC50 of 1.5 ± 0.3 µM, which was smaller than that of (-)-epigallocatechin gallate in Phase III clinical trials and about one order of magnitude smaller than those of curcumin and resveratrol. Most importantly, it was found that brazilin redirected Aß42 monomers and its mature fibrils into unstructured Aß aggregates with some ß-sheet structures, which could prevent both the primary nucleation and the fibril-catalyzed secondary nucleation. Molecular simulations demonstrated that brazilin inhibited Aß42 fibrillogenesis by directly binding to Aß42 species via hydrophobic interactions and hydrogen bonding and remodeled mature fibrils by disrupting the intermolecular salt bridge Asp23-Lys28 via hydrogen bonding. Both experimental and computational studies revealed a different working mechanism of brazilin from that of known inhibitors. These findings indicate that brazilin is of great potential as a neuroprotective and therapeutic agent for Alzheimer's disease.

Sunitinib produces neuroprotective effect via inhibiting nitric oxide overproduction.

BACKGROUND: Sunitinib is an inhibitor of the multiple receptor tyrosine kinases (RTKs) for cancer therapy. Some sunitinib analogues could prevent neuronal death induced by various neurotoxins. However, the neuroprotective effects of sunitinib have not been reported. METHODS: Cerebellar granule neurons (CGNs) and SH-SY5Y cells were exposed to low-potassium and MPP(+) challenges, respectively. MTT assay, FDA/PI staining, Hoechst staining, DAF-FM, colorimetric nitric oxide synthase (NOS) activity assay, and Western blotting were applied to detect cell viability, NO production, NOS activity, and neuronal NOS (nNOS) expression. Short hairpin RNA was used to decrease nNOS expression. In vitro NOS enzyme activity assay was used to determine the direct inhibition of nNOS by sunitinib. RESULTS: Sunitinib prevented low-potassium-induced neuronal apoptosis in CGNs and MPP(+) -induced neuronal death in SH-SY5Y cells. However, PTK787, another RTK inhibitor, failed to decrease neurotoxicity in the same models. Sunitinib reversed the increase in NO levels, NOS activity, and nNOS expression induced by low potassium or MPP(+) . Knockdown of nNOS expression partially abolished the neuroprotective effects of sunitinib. Moreover, sunitinib directly inhibited nNOS enzyme activity. CONCLUSIONS: Sunitinib exerts its neuroprotective effects by inhibiting NO overproduction, possibly via the inhibition of nNOS activity and the decrease in nNOS expression.

Substantial neuroprotection against K+ deprivation-induced apoptosis in primary cerebellar granule neurons by novel dimer bis(propyl)-cognitin via the activation of VEGFR-2 signaling pathway.

BACKGROUND: Neuronal loss via apoptosis in CNS is the fundamental mechanism underlying various neurodegenerative diseases. Compounds with antiapoptotic property might have therapeutic effects for these diseases. In this study, bis(propyl)-cognitin (B3C), a novel dimer that possesses anti-AChE and anti-N-methyl-d-aspartate receptor activities, was investigated for its neuroprotective effect on K(+) deprivation-induced apoptosis in cerebellar granule neurons (CGNs). METHODS: Cerebellar granule neurons were switched to K(+) deprived medium with or without B3C. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium assay, fluorescein diacetate (FDA)/propidium iodide (PI) staining, Hoechst staining, and DNA laddering assays were applied to detect cytotoxicity and apoptosis. Additionally, the expression of p-VEGFR-2, p-Akt, p-glycogen synthase kinase 3ß (GSK3ß), and p-extracellular signal-regulated kinase (ERK) was examined in CGNs. RESULTS: Switching CGNs to K(+) deprived medium resulted in remarkable apoptosis, which could be substantially blocked by B3C treatment (IC50 , 0.37 µM). Moreover, a rapid decrease in p-Tyr1054-VEGFR-2 was observed after the switch. B3C significantly reversed the inhibition of p-Tyr1054-VEGFR-2 as well as Akt and ERK pathways. VEGFR-2 inhibitor PTK787/ZK222584, as well as PI3-K inhibitor LY294002 and MEK inhibitor PD98059, each abolished the neuroprotective effect of B3C. CONCLUSIONS: Our results demonstrate that B3C blocks K(+) deprivation-induced apoptosis in CGNs through regulating VEGFR-2/Akt/GSK3ß and VEGFR-2/ERK signaling pathways, providing a molecular insight into the therapeutic potential of B3C for the treatment of neurodegenerative diseases.

Reversal of scopolamine-induced spatial and recognition memory deficits in mice by novel multifunctional dimers bis-cognitins.

Our previous reports indicated that bis(propyl)-cognitin (B3C) and bis(heptyl)-cognitin (B7C), as novel dimers derived from tacrine, may be potential multifunctional drugs for treating Alzheimer's disease. There is little knowledge on the cognitive function of B3C while B7C appeared to reverse learning and memory impairments. In this study, for the first time, we evaluated the anti-amnesic effects of B3C and B7C on learning and memory deficits induced by scopolamine using both Morris water maze and novel object recognition tasks in mice. Under the same experimental condition, the anti-amnesic effect of tacrine was also compared. Briefly, in both tasks, scopolamine (0.1-0.6 mg/kg, ip) dose-dependently impaired learning and memory functions. B3C (1.5-2.5 µmol/kg), B7C (0.4-0.6 µmol/kg) or tacrine (8-12 µmol/kg), each administered ip, dose-dependently mitigated scopolamine-induced learning and memory impairments in both tasks. Our present results show, for the first time, that B3C and B7C reverse cognitive impairment resulted from scopolamine in both water maze and object recognition tasks; and under the same condition, the relative potency of B3C and B7C to improve cognitive capacity was 5-20 folds over that of tacrine. These novel in vivo findings further demonstrate that both B3C and B7C may potentially be developed as Alzheimer's therapeutic drugs for different severities of neurodegenerations.

[Neuroprotective effects of water extracts of American Ginseng on SH-SY5Y cells apoptosis induced by Abeta25-35].

OBJECTIVE: To study the neuroprotective effect of water extracts of American Ginseng (WEAG) on Abeta25-35-induced SH-SY5Y cells apoptosis in Alzheimer's Disease cellular model. METHODS: The optimal concentration and treating time of Abeta25-35 for Alzheimer's Disease cellular model as well as those of WEAG were measured by flow cytometer. In addition, the cell viability was measured by MTT test and the morphology of SH-SY5Y cells was observed by Hoechst 33258 staining. RESULTS: Treated by Abeta25-35 50 micromol/L 72 h later, SH-SY5Y cells turned rounder, aggregated and were positively stained with fluorochrome Hoechst 33258. Cells displayed a typical sub-diploid peak in flow cytometry, and the percentage of apoptosis reaches (37.30 +/- 0.69)% (P < 0.05 as compared with the control group) (1.56 +/- 0.80)%. When incubated with Abeta 50 micromol/L and different doses (0.5, 1, 5 mg/ml) of WEAG for 72h, the characteristics of apoptosis as measured by FCM dose-dependently declined to (16.71 +/- 1.08)%, (10.52 +/- 2.11)% and (3.39 +/- 1.65)%, respectively (P < 0.05 as compared with the model group). CONCLUSION: Water extracts of American Ginseng have markedly neuroprotective effects on SH-SY5Y cells apoptosis induced by Abeta25-35.