Elsevier

Carbohydrate Polymers

Volume 98, Issue 2, 6 November 2013, Pages 1383-1388
Carbohydrate Polymers

Therapeutic effect of Ginkgo biloba polysaccharide in rats with focal cerebral ischemia/reperfusion (I/R) injury

https://doi.org/10.1016/j.carbpol.2013.07.045Get rights and content

Highlights

  • A polysaccharide (GBPw) was purified from the leaves of Ginkgo biloba.

  • GBPw has protective effects on cerebral ischemia/reperfusion (I/R) injury in rats.

  • Antioxidant and anti-inflammatory activities of GBPw play the central role.

Abstract

An araban type polysaccharide (GBPw) was purified from the leaves of Ginkgo biloba. The present study aimed to investigate the protective effects of GBPw on focal ischemia/reperfusion (I/R) injury in rat brain. The results of this study demonstrated that GBPw had a positive effect on the rat brain when administered 7 days before focal cerebral I/R injury. This effect was evident with the improvements in neurological deficits, reduction in infarct volume, MDA content and the levels of pro-inflammatory cytokines (TNF-α and IL-1β), and elevation in the SOD and MPO activities and the levels of anti-inflammatory cytokine (IL-10). Thus, the beneficial effects of GBPw on cerebral I/R injury may result from the reduction of oxidative stress and the inhibition of NO production and inflammation induced by I/R. The neuroprotective effects of GBPw supplement may have potential implication in the future for prevention/protection against cerebral ischemic stroke.

Introduction

Acute ischemic stroke is one of the leading causes of adult disability and death in the world, and the majority of ischemic strokes results from occlusion of the middle cerebral artery, which leads to a reduction of cerebral blood flow in a specific region. Reperfusion of the tissue is associated with inflammation, increased reactive oxygen species, necrosis and apoptosis. Hence, damage to the brain will continue even after the blood flow is restored. Reperfusion after ischemia leads to profound cerebral microcirculatory disturbance and even death of neurons (Aronowski, Strong, & Grotta, 1997), thus protecting the brain from reperfusion injury after ischemia is an alternative for therapy of stroke. Although numerous interventions have been investigated, few neuroprotective agents have been successfully translated from basic research into clinical applications (Linares & Mayer, 2009). Thrombolytic therapy and intravascular techniques are recommended to restore blood flow to the brain in acute ischemic stroke but carries with the risk of hemorrhage and aggravates cerebral damage caused by reperfusion (Aronowski et al., 1997).

Over the past decade, intense interest has focused on discovering effective agents from medicinal plants, especially traditional Chinese herbal medicines (CHM), for the prevention and treatment of ischemic stroke, since many CHMs are reported to possess cardioprotective or neuroprotective activities (He et al., 2012, Huang et al., 2012, Sun et al., 2010). Therefore, a search for safe and effective agents from CHMs for management of ischemic brain injury is urgently needed.

The extract of Ginkgo biloba L. (Ginkgoaceae) has been extensively used in a variety of cardiovascular and cerebrovascular diseases such as ischemia, dementia, and depression (Ahlemeyer and Krieglstein, 2003, Gertz and Kiefer, 2004, Nishida and Satoh, 2004, Saleem et al., 2008, Sierpina et al., 2003). Although highly neuroprotective effects of G. biloba extract against ischemia/reperfusion (I/R) injury has been well proven (Krieglstein et al., 1995, Wang et al., 1998), the mechanism and mode underlying the therapeutic effects is still under investigation. It has been revealed that neuroprotection action of G. biloba extract during cerebral I/R injury might be related to two major groups, namely flavonols and lactones (Cho et al., 2009, Dubber and Kanfer, 2004), while nothing is known about the neuroprotective effect of purified water-soluble G. biloba polysaccharide on I/R-induced cerebral injury. Therefore the present study was undertaken to purify the polysaccharide from this plant and investigate its neuroprotective potential and mechanism in the middle cerebral artery occlusion (MCAO)-induced focal cerebral I/R model in rats.

Section snippets

Materials and chemicals

The leaves of G. biloba L were purchased from Hebei Anguo Medicinal Materials Market, China, and identified by Dr. Weiqi Zhong at Northeast Agricultural University. Sephadex G-200 and DEAE-52 cellulose were from Pharmacia (Sweden). Standard dextran was from Sigma. All other reagents were of the highest available quality in China.

Isolation and purification of polysaccharide GBPw

The dried leaves (700 g) of G. biloba were soaked with 95% EtOH for 6 h to remove lipids and pigment, followed by filtration. The residue was dried in air and then

Isolation and characterization of GBPw

The water-soluble crude polysaccharides (CGBP) with a yield of 10.85% (w/w) of starting material were obtained from the leaves of G. biloba by defatting with ethanol, hot water extraction, ethanol precipitation, deprotein by Sevag method, dialysis against water and drying in freeze dryer. Then CGBP was subjected to a DEAE–cellulose chromatography and eluted with distilled water, followed by 0.1, 0.2, 0.4 and 1.0 M NaCl at a flow rate of 1.0 mL/min. A 0.2 mL sample from each collected fraction (8 

Conclusions

The MCAO model established by thread insertion is by far the most commonly used stroke model, the pathophysiology presented in which closely matches that in stroke patients suffered from focal cerebral arterial thrombosis (Longa et al., 1989). Using this model, pretreatment with GBPw was found to provide significant protection against the neuronal damage induced by cerebral I/R in rats. Our results showed clearly that a significant dose-dependent reduction of infracted volume, one most vigorous

Acknowledgement

We gratefully acknowledge the excellent technical assistance from Dr. Qilin Zhong at Northeast Agricultural University.

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