Neuroprotective Effects of a Novel Single Compound 1-Methoxyoctadecan-1-ol Isolated from Uncaria sinensis in Primary Cortical Neurons and a Photothrombotic Ischemia Model

Abstract

We identified a novel neuroprotective compound, 1-methoxyoctadecan-1-ol, from Uncaria sinensis (Oliv.) Havil and investigated its effects and mechanisms in primary cortical neurons and in a photothrombotic ischemic model. In primary rat cortical neurons against glutamate-induced neurotoxicity, pretreatment with 1-methoxyoctadecan-1-ol resulted in significantly reduced neuronal death in a dose-dependent manner. In addition, treatment with 1-methoxyoctadecan-1-ol resulted in decreased neuronal apoptotic death, as assessed by nuclear morphological approaches. To clarify the neuroprotective mechanism of 1-methoxyoctadecan-1-ol, we explored the downstream signaling pathways of N-methyl-D-aspartate receptor (NMDAR) with calpain activation. Treatment with glutamate leads to early activation of NMDAR, which in turn leads to calpain-mediated cleavage of striatal-enriched protein tyrosine phosphatase (STEP) and subsequent activation of p38 mitogen activated protein kinase (MAPK). However, pretreatment with 1-methoxyoctadecan-1-ol resulted in significantly attenuated activation of GluN2B-NMDAR and a decrease in calpain-mediated STEP cleavage, leading to subsequent attenuation of p38 MAPK activation. We confirmed the critical role of p38 MAPK in neuroprotective effects of 1-methoxyoctadecan-1-ol using specific inhibitor SB203580. In the photothrombotic ischemic injury in mice, treatment with 1-methoxyoctadecan-1-ol resulted in significantly reduced infarct volume, edema size, and improved neurological function. 1-methoxyoctadecan-1-ol effectively prevents cerebral ischemic damage through down-regulation of calpain-mediated STEP cleavage and activation of p38 MAPK. These results suggest that 1-methoxyoctadecan-1-ol showed neuroprotective effects through down-regulation of calpain-mediated STEP cleavage with activation of GluN2B-NMDAR, and subsequent alleviation of p38 MAPK activation. In addition, 1-methoxyoctadecan-1-ol might be a useful therapeutic agent for brain disorder such as ischemic stroke.

Geniposide Attenuates Post-Ischaemic Neurovascular Damage via GluN2A/AKT/ ERK-Dependent Mechanism

“…Until now, however, the clinical application of NMDAR antagonists in human stroke participants has failed [9, 38] due to several reasons, as follows: (a) non-selective triggering of the broad intracellular cascades related to NMDARs, (b) the narrow time window for treatment within the acute phase of stroke, and (c) cognitive and emotional side effects. Importantly, growing evidence has shown that some of the positive effects of herbal extracts on cerebral ischaemia occur via natural stimulation of NMDARs; such extracts include resveratrol [39], 1-methoxyoctadecan-1-ol [40] and MQA [41]. Based on our results, geniposide seems to be a highly promising bioactive compound against ischaemic stroke in vivo .…”

A single fraction fromUncaria sinensisexerts neuroprotective effects against glutamate-induced neurotoxicity in primary cultured cortical neurons

“…The NMDAR and calpain-mediated STEP play a dominant role in mediating the toxic signal under glutamate exposure in our previous study [ 20 ]. Thus we attempted to determine whether JGH43IA could inhibit both activation of NMDAR and calpain and subsequent STEP cleavage caused by glutamate.…”

“…Especially, pretreatement of JGH43IA resulted in reduced ~145 kDa fodrin production of 30.2% compared with glutamate-treated cells at 360 minutes after glutamate exposure. And lower subsequent STEP 33 production, 28.4% compared with glutamate-treated cells, also observed at early phases after glutamate exposure in JGH43IA-treated cells [ 20 ]. Pretreatment with JGH43IA increased in the levels of phosphorylated CREB compared to glutamate alone treated cells ( Fig.…”

“…Furthermore, phosphorylation of the NMDAR GluN2B subunit at the 1303 site leads to ischemic neuronal death [ 29 ]. We simultaneously performed western assay of JGH43IA in glutamate-treated primary neuronal cells at same conditions with previous study to determine basic molecular mechanism of neuroprotection [ 20 ]. Our present western blot results showed that pretreatment with JGH43IA reduced phosphorylation of GluN2B-NMDAR at the same site suggesting GluN2B subunit could play a dominant role in arrest of neuronal death.…”

“…In the further screening for active constituents using a neuronal cells and ischemic animal model, we isolated two specific fraction 6 (JGH6-7) and 43 (JGH43IA) among 62 fractions of hexane extract that shows most prominent neuroprotective effects. We reported the structure and neuroprotective effects of fraction 6 as a novel neuroprotective compound, 1-methoxyoctadecan-1-ol [ 20 ], but JGH43IA have not been investigated with regard to the cell death and its related signaling pathway. In the present study, we investigated the molecular mechanism underlying neuroprotective effects of fraction, JGH43IA, against glutamate-induced toxicity focusing on NMDAR and endogenous protease calpain with related STEP in primary cultured rat cortical cells.…”