Taxifolin prevents ß-amyloid-induced impairments of synaptic formation and deficits of memory via the inhibition of cytosolic phospholipase A2/prostaglandin E2 content.

Taxifolin is a potent flavonoid with anti-inflammatory activity. Taxifolin has been reported to decrease the accumulation of ß-amyloid (Aß), and reduce Aß-induced neurotoxicity. However, the detail molecular mechanism of taxifolin against Aß-induced neurotoxicity is largely unknown. In this study, we revealed the protective effects and the underlying mechanisms of taxifolin on the impairments of cognitive function and synapse formation induced by soluble Aß oligomers. Our results showed that taxifolin prevented neuronal cell death in a concentration-dependent manner. The recognition memory in novel object recognition tasks and the spatial memory in Morris water maze tests are significantly lower in the Alzheimer's disease (AD) model mice induced by hippocampal injection of Aß42. Taxifolin treatment prevented the recognitive and spatial memory deficits of the AD mice. 10 mg/kg taxifolin treatment also significantly prevented the decreased expression levels of PSD 95 induced by Aß42. Live cell imaging study showed that 2 h pre-treatment of taxifolin prevented the decrease in the number of filopodium and spine induced by Aß42 oligomers. Aß42 oligomers significantly increased the production of cytosolic phospholipase A2 (cPLA2), a crucial enzyme of pro-inflammatory mediator, and prostaglandin E2 (PGE2), a neuroinflammatory molecule. Taxifolin significantly reduced the content of cPLA2 and PGE2 induced by Aß42 both in the primary hippocampal neurons and hippocampal tissues. These results indicated that taxifolin might prevent Aß42 oligomer-induced synapse and cognitive impairments through decreasing cPLA2 and PGE2. Our study provided novel insights into the cellular mechanisms for the protective effects of taxifolin on AD.

5-Hydroxycyclopenicillone Inhibits ß-Amyloid Oligomerization and Produces Anti-ß-Amyloid Neuroprotective Effects In Vitro.

The oligomer of ß-amyloid (Aß) is considered the main neurotoxin in Alzheimer's disease (AD). Therefore, the inhibition of the formation of Aß oligomer could be a target for AD therapy. In this study, with the help of the dot blotting assay and transmission electronic microscopy, it was have discovered that 5-hydroxycyclopenicillone, a cyclopentenone recently isolated from a sponge-associated fungus, effectively reduced the formation of Aß oligomer from Aß peptide in vitro. Molecular dynamics simulations suggested hydrophobic interactions between 5-hydroxycyclopenicillone and Aß peptide, which might prevent the conformational transition and oligomerization of Aß peptide. Moreover, Aß oligomer pre-incubated with 5-hydroxycyclopenicillone was less toxic when added to neuronal SH-SY5Y cells compared to the normal Aß oligomer. Although 5-hydroxycyclopenicillone is not bioavailable in the brain in its current form, further modification or encapsulation of this chemical might improve the penetration of 5-hydroxycyclopenicillone into the brain. Based on the current findings and the anti-oxidative stress properties of 5-hydroxycyclopenicillone, it is suggested that 5-hydroxycyclopenicillone may have potential therapeutic efficacy in treating AD.

Identification of homologous protein models via 3D comparisons using predicted structures.

Recent advances in protein structure prediction enable 3D homology alignment and domain annotation using tertiary structures. Here, we present a protocol to identify homologous structures and annotate protein domains through in silico comparisons using the AlphaFold database. We describe steps for downloading and installing PyMOL software, preparing the query structure, and conducting a 3D homology search. The example provided highlights the application of this protocol in reevaluating an mpox viral protein annotation. For complete details on the use and execution of this protocol, please refer to Pan et al. (2023).1.

Inhibition of acetylcholinesterase activity and ß-amyloid oligomer formation by 6-bromotryptamine A, a multi-target anti-Alzheimer's molecule.

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by learning and memory impairments. Recent studies have suggested that AD can be induced by multiple factors, such as cholinergic system dysfunction and ß-amyloid (Aß) neurotoxicity. It was reported that 6-bromo-N-propionyltryptamine could treat neurological diseases, including AD. In the present study, 6-bromotryptamine A, a derivative of 6-bromo-N-propionyltryptamine, was synthesized by the condensation of 2-(6-bromo-1H-indol-3-yl)ethan-1-amine and 2-(4-bromophenyl)acetic acid, and was used as a potential anti-AD molecule. Furthermore, scopolamine can induce impairments of learning and memory, and was widely used to establish AD animal models. The results demonstrated that 6-bromotryptamine A significantly prevented scopolamine-induced short-term cognitive impairments, as revealed by various behavioral tests in mice. Furthermore, an acetylcholinesterase (AChE) activity assay revealed that 6-bromotryptamine A directly inhibited AChE activity. Notably, it was observed that 6-bromotryptamine A blocked the formation of Aß oligomer, as evaluated by the dot blot assay. All these results suggested that 6-bromotryptamine A may be used to prevent impairments in short-term learning and memory ability possibly via the inhibition of AChE and the blockade of Aß oligomer formation.

Indirubin Derivative 7-Bromoindirubin-3-Oxime (7Bio) Attenuates Aß Oligomer-Induced Cognitive Impairments in Mice.

Indirubins are natural occurring alkaloids extracted from indigo dye-containing plants. Indirubins could inhibit various kinases, and might be used to treat chronic myelocytic leukemia, cancer and neurodegenerative disorders. 7-bromoindirubin-3-oxime (7Bio), an indirubin derivative derived from indirubin-3-oxime, possesses inhibitory effects against cyclin-dependent kinase-5 (CDK5) and glycogen synthase kinase-3ß (GSK3ß), two pharmacological targets of Alzheimer's disease (AD). In this study, we have discovered that 2.3-23.3 µg/kg 7Bio effectively prevented ß-amyloid (Aß) oligomer-induced impairments of spatial cognition and recognition without affecting bodyweight and motor functions in mice. Moreover, 7Bio potently inhibited Aß oligomer-induced expression of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α). Furthermore, 7Bio significantly prevented the decreased expression of synapsin-1 and PSD-95, biomarkers of pre-synaptic and post-synaptic proteins in Aß oligomer-treated mice. The mean optical density (OD) with hyper-phosphorylated tau (pTau), glial fibrillary acidic protein (GFAP) and CD45 positive staining in the hippocampus of 7Bio-treated mice were significantly decreased compared to those of Aß oligomer-treated mice. In addition, Western blotting analysis showed that 7Bio attenuated Aß oligomer-decreased expression of pSer9-GSK3ß. Those results suggested that 7Bio could potently inhibit Aß oligomer-induced neuroinflammation, synaptic impairments, tau hyper-phosphorylation, and activation of astrocytes and microglia, which may contribute to the neuroprotective effects of 7Bio. Based on these findings, we expected that 7Bio might be developed as a novel anti-AD lead compound.