원문정보
초록
영어
Alzheimer’s disease (AD) is a major public health problem, and there is currently no clinically accepted treatment to cure or stop its progression. Fibrillar aggregates of the β-amyloid peptide (Aβ) are the major constituents of the senile plaques found in the brains of AD patients and have been related to AD neurotoxicity. A formation from amyloid precursor protein (APP) is caused mainly byβ-secretase. Phellinus linteus (PL) has been recognized as a major source of natural antioxidants that could decrease reactive oxygen species (ROS). However, its role in protection of Aβ-induced cytotoxicity and apoptosis in neuronal cells remains unclear. The present study aims to investigate such an effect of PL extracts on neuroprotection by evaluating the inhibition of β-secretase activity. From the hot-water extract (PL-WE) of PL fruiting body, a high-molecular weight fraction (Et-P) and a low-molecular weight fraction (Et-S) were obtained by 75% ethanol (EtOH) precipitation. The latter was further extracted with ethyl acetate (EA). Three major water-soluble polysaccharides (Et-P1, Et-P2, Et-P3) were purified from the Et-P fraction by DEAE-cellulose column chromatography. Molecular masses were estimated to be ~1,629, 1,294, and 21kDa, respectively, by size-exclusion chromatography (SEC). These polysaccharides were shown to be composed of glucose, galactose, and mannose as the major monosaccharides and fucose, xylose as minor ones. The FT-IR analysis suggested that they are typical polysaccharides having at least partially -linkages and possibly existing as complex with phenolic compounds. Laminarinase digestion and HPLC analysis suggested that these polysaccharides are a variant of β-(1,3)-glucan. Theses polysaccharides significantly inhibited the β-secreatase activity, suggesting that they may inhibit the formation of Aβ. Further characterizations of this extract may lead to identification of a potent therapeutic compounds for the prevention and/or decreasing the severity of AD.