Hericium erinaceus (HE) is a well-known mushroom that is consumed as food and used in traditional Chinese medicine. These mushrooms contain physiologically significant components, such as ?-glucan polysaccharides and other biomaterials, which have demonstrated anticancer, immunomodulatory, hypolipidemic, antioxidant and neuroprotective properties [1–6]. As an anticancer agent, the polysaccharides from HE have more significant anti-artificial pulmonary metastatic tumor effects and immunomodulatory activity than those of Hericium laciniatum [1]. HE and Lentinus edodes have been compared with regard to their antitumor activities and immunoregulatory effects on mice with sarcoma 180 [7]. Additionally, HE extracts (HTJ5 and HTJ5A) have been found to be more effective and less toxic than clinically used anticancer drugs such as 5-fluorouracil against liver cancer HepG2 and Huh-7, colon cancer HT-29 and gastric cancer NCI-87 cells in vitro and in tumor xenografts in vivo [8].
Macrophages are activated by HE polysaccharides to produce nitric oxide and express cytokines (IL-1beta and TNF-beta), which lead to effective antitumor activity and immunomodulation [9]. Previously, we demonstrated that HE extracts can induce the activation of dendritic cells and increase the secretion of IL-12 to modulate a TH1 immune response [2]. The hypolipidemic effects proportionally increased with oral administration of an HE exo-biopolymer in a dose-dependent manner in animal studies [3]. The HE biomaterials reduced levels of low-density lipoprotein cholesterol while maintaining relatively high levels of high-density lipoprotein cholesterol and reduced the risk of atherosclerosis.
It was previously reported that HE extracts have neuroprotective effects, promote normal development of cultivated cerebellar cells and have regulatory effects on the development of myelin genesis processes in vitro [10]. The ethanol extract of HE has been shown to induce nerve growth factor expression and to prevent A?25–35-induced impairment of memory functions in animal experiments [11, 12]. Oxidative stress has been shown to be involved in the initiation and progression of various disorders caused by oxygen radicals, which damages lipids, proteins and nucleic acids [13, 14]. The hot water extract of HE has been reported to improve this free radical scavenging activity and inhibit lipid peroxidation [15]. HE polysaccharide extracts have been reported to decrease lipid peroxidation levels, increase antioxidant enzyme activity and increase radical scavenging activity [4, 16, 17].
In this study, we purified HEPS, which consists of two high molecular weight polysaccharides and exhibits antioxidant activity, from fruiting bodies. HEPS-treated cells showed an increase in the rate of free radical scavenging, a reduction in the production of ROS, a recovery in mitochondrial function, maintenance in morphology changes, and a reduction in cell apoptosis of PC12 cells upon A? treatment. Finally, we demonstrated that HEPS has neuroprotective properties for neurons.