(?)-Clausenamide potentiates synaptic transmission in the dentate gyrus of rats

ALOX5 inhibition protects against dopaminergic neurons undergoing ferroptosis

Oxidative disruption of dopaminergic neurons is regarded as a crucial pathogenesis in Parkinson's disease (PD), eventually causing neurodegenerative progression. (-)-Clausenamide (Clau) is an alkaloid isolated from plant Clausena lansium (Lour.), which is well-known as a scavenger of lipid peroxide products and exhibiting neuroprotective activities both in vivo and in vitro, yet with the in-depth molecular mechanism unrevealed. In this study, we evaluated the protective effects and mechanisms of Clau on dopaminergic neuron. Our results showed that Clau directly interacted with the Ser663 of ALOX5, the PKCα-phosphorylation site, and thus prevented the nuclear translocation of ALOX5, which was essential for catalyzing the production of toxic lipids 5-HETE. LC-MS/MS-based phospholipidomics analysis demonstrated that the oxidized membrane lipids were involved in triggering ferroptotic death in dopaminergic neurons. Furthermore, the inhibition of ALOX5 was found to significantly improving behavioral defects in PD mouse model, which was confirmed associated with the effects of attenuating the accumulation of lipid peroxides and neuronal damages. Collectively, our findings provide an attractive strategy for PD therapy by targeting ALOX5 and preventing ferroptosis in dopaminergic neurons.

Physiological signature of a novel potentiator of AMPA receptor signalling

We have synthesized a novel small molecule based on the pyrrolidinone–containing core structure of clausenamide, which is a candidate anti–dementia drug. The synthetic route yielded multi–gram quantities of an isomeric racemate mixture in a short number of steps. When tested in hippocampal slices from young adult rats the compound enhanced AMPA receptor–mediated signalling at mossy fibre synapses, and potentiated inward currents evoked by local application of l–glutamate onto CA3 pyramidal neurons. It facilitated the induction of mossy fibre LTP, but the magnitude of potentiation was smaller than that observed in untreated slices. The racemic mixture was separated and it was shown that only the (−) enantiomer was active. Toxicity analysis indicated that cell lines tolerated the compound at concentrations well above those enhancing synaptic transmission. Our results unveil a small molecule whose physiological signature resembles that of a potent nootropic drug.

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A small molecule was developed using a novel approach towards the synthesis of clausenamide, which is thought to have anti–dementia properties.

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When tested in hippocampal slices the compound enhanced AMPA receptor signalling as well as glutamate–evoked currents in CA3 pyramidal neurons.

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It facilitated the induction of mossy fibre LTP.

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Cytotoxicity experiments revealed no deleterious effect to cells at sub–millimolar concentrations.

γ- and δ-Lactams from the Leaves of Clausena lansium

Eight new clausenamides, including three γ-lactams (1-3), four δ-lactams (4-7), and an amide (8), and seven known lactams, including compounds 9-11, which were purified from natural sources for the first time, were characterized from the leaves of Clausena lansium. Their structures were elucidated using spectroscopic methods, and the absolute configurations were determined using electronic circular dichroism and single-crystal X-ray diffraction analyses with Cu Kα radiation. Compound 2 (50 μM) protected 22.24% of cortical neurons against Aβ25-35-induced cell death.

Recent advances in the study of (-)clausenamide: chemistry, biological activities and mechanism of action

Clausenamide (clau) is one of seven novel compounds isolated from Clausena lansium (Lour) skeels. Clau is unusual in that it contains 4 chiral centers yielding 8 pairs of enantiomers. After identification of the configuration of these enantiomers, the synthesis of 16 enantiomers, including optically active clau and (+) and (–)clau was carried out. During this study, many stereochemical and synthetic difficulties were solved and the Baldwin principle was updated. Production scale is now sufficient to meet the needs of clinical practice. In a pharmacological study numerous models and indicators showed that (–)clau is the active enantiomer, while (+)clau is inactive and elicits greater toxicity than (–)clau. The principal pharmacological effects of (–)clau are to increase cognition, demonstrated in ten models of memory impairment, as well as to inhibit β-amyloid (Aβ) toxicity, blocking neurofibrillary tangle formation by inhibiting the phosphorylation of tau protein. This anti-dementia effect is characterized by increased synaptic plasticity both in efficacy and in structure and provides new support for the theory that synaptic loss is the main cause of dementia. (–)Clau is considered to be a promising drug candidate for treatment of Alzheimer׳s disease and other neurodegenerative disorders.

Activation of ERK1/2-CREB pathway during potentiating synaptic transmission of (-)clausenamide in rat dentate gyrus

To investigate the signal mechanism of (-)clausenamide ((-)-3-hydroxy-5-(hydroxy-phenyl-methyl)-1-methyl-4-phenyl-pyrrolidin-2-one, 1) and for understanding its effect on synaptic transmission, electrophysiological recording was done for basal synaptic transmission determination. Western blot analysis was employed to examine the phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2) and cAMP responsive element-binding protein (CREB). Immunohistochemistry and tissue in situ hybridization were applied to detect the expression of Zif268. The results showed that (-)clausenamide (1) increased the population spike of hippocampal dentate gyrus. The phosphorylation of ERK1/2 in hippocampus and cortex was increased and reached the maximum at 5 min and 30 min, respectively. (-)Clausenamide (1) promoted the phosphorylation of CREB, the downstream protein of ERK1/2. The expression of Zif268 protein and mRNA increased in both hippocampal dentate gyrus and cortex. Therefore, (-)clausenamide (1) activated the ERK1/2-CREB pathway, which may provide an explanation for its effect on potentiating synaptic transmission and improving learning and memory.

Retrospect and prospect of active principles from Chinese herbs in the treatment of dementia

With an ageing population, dementia has become one of the world's primary health challenges. However, existing remedies offer limited benefits with certain side effects, which has prompted researchers to seek complementary and alternative therapies. China has long been known for abundant usage of various herbs. Some of these herbal decoctions are effective in stimulating blood circulation, supplementing vital energy and resisting aging, the lack of which are believed to underlie dementia. These herbs are regarded as new and promising sources of potential anti-dementia drugs. With the rapid evolution of life science and technology, numerous active components have been identified that are highly potent and multi-targeted with low toxicity, and therefore meet the requirements for dementia therapy. This review updates the research progress of Chinese herbs in the treatment of dementia, focusing on their effective principles.