6′-O-caffeoylarbutin of Vaccinium dunalianum alleviated ischemic stroke through the PI3K/AKT/NF-κB pathway

Abstract

Background

Vaccinium dunalianum (“Que Zui Tea”) has been traditionally consumed as a tea substitute in Yunnan, China, for its health benefits, i.e., improving vascular health. 6′-O-caffeoylarbutin (CA) is its major bioactive compound (∼20 %). However, the potential of CA against ischemic stroke remains unknown.

Purpose

This study explores the protective properties of CA in ischemic stroke, providing empirical support for the folk use of the plant and further drug development.

Methods

An oxygen-glucose deprivation/reoxygenation (OGD/R)-induced BV2 cells were utilized to identify potential bioactive compounds. Moreover, the pathway and targets were predicted and further verified in OGD/R-induced microglia, nerve cells and in mice of middle cerebral artery occlusion.

Results

CA effectively reduced nitric oxide (NO) release and transcript-level expression of inflammatory factors in OGD/R-stimulated BV2 cells. NF-κB1, IL-6, AKT1, CASP3, and MMP9 were identified as key CA targets for ischemic stroke treatment. In silico predictions suggested that phosphatidylinositol 3-kinase (PI3K)/protein kinase B (PI3K/AKT), mitogen-activated protein kinase (MAPK), and tumor necrosis factor (TNF) were the relevant pathways. These predictions were supported in vitro by an observed decrease in NO, reactive oxygen species, lactate dehydrogenase, and inflammatory cytokines (IL-6, IL-1β, and TNF-α) levels following CA treatment. Western blotting confirmed the regulation of p-IκBα, P65, AKT, and apoptosis-related proteins (further confirmed by PI3K inhibitor LY294002 treatment). These findings were further supported in vivo, with CA ameliorating neurological functions and deficits in ischemic mice. This amelioration correlated with increased cerebral blood flow, and alleviated neuron wrinkling, necrosis, and cell shrinkage. CA also increased brain superoxide dismutase, catalase, and glutathione peroxidase levels.

Conclusion

CA exerts neuroprotective effects in ischemic stroke by inhibiting inflammation and oxidative stress through the PI3K/AKT/NF-κB pathway, suggesting its therapeutic potential for cerebral ischemia and supporting the traditional use of V. dunalianum.