Extraction, purification, characterization and antitumor activity of polysaccharides from Ganoderma lucidum

Abstract

Ultrasonic-aid extraction (UAE) was applied to the extraction of polysaccharides from Ganoderma lucidum and then the crude polysaccharides were purified by filtration, DEAE cellulose-52 chromatography and Sephadex G-100 size-exclusion chromatography in that order. Two main fractions, GP-1 and GP-2, were obtained through the extraction and purification steps. The characterizations, such as molecular weight, monosaccharides composition, ultraviolet spectrum and infrared spectrum of the two fractions were analyzed in this study. Furthermore, the influence of G. lucidum polysaccharides fractions upon activation of macrophage cell (RAW 264.7) and antitumor activities to the human breast cancer cell (MDA-MB-231) in vitro were evaluated by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay. The results indicated that GP-1 and GP-2 can increase the proliferation and pinocytic activity of macrophage significantly and play an inhibited effect on the cancer cell, moreover, the antitumor activity of the GP-1 and GP-2 increased with the participation of the antitumor factors induced from macrophage by polysaccharides fractions.

Introduction

For thousands of years, mushrooms have been known as a source of medicine. Ganoderma lucidum, which belongs to the family of Ganodermataceae of Polyporales, is known as ‘Lingzhi’. In East Asia, the fruiting body of G. lucidum has been used for centuries and it is also called ‘marvelous herb’. It has been reported that G. lucidum polysaccharides have strong antioxidant activities (Chen et al., 2009, Jia et al., 2009, Xu et al., 2009), immuno-modulating activities (Lin et al., 2006, Shao et al., 2004), and antitumor activities (Li et al., 2007, Paterson, 2006, Yuen and Gohel, 2008, Zhang et al., 2007), etc.

Extraction is widely used for the separation of these biologically functional components from various plant, bacteria, or animal sources. The processes of conventional liquid extraction such as stirring extraction and Soxhlet extraction for solid and semisolid materials are generally time-consuming and laborious. Ultrasound-assisted extraction (UAE) is an environmentally friendly technique with increased productivity. It uses high-frequency (typically higher than 16 kHz) sound to disrupt the target compound from cells (Raso & Barbosa-Canovas, 2003). To date, there have been several reports on the application of UAE in the separation of various biologically active compounds such as the anti-cancer drug camptothecin from Nothapodytes foetida (Fulzele & Satdive, 2005), isoflavones from freeze-dried ground soybean (Rostagno, Palma, & Barroso, 2003), phenolic compounds from alperujo (Priego-Capote, Ruiz-Jimenez, & de Castro, 2004), and astaxanthin from microorganisms (Han, Lee, Jung, & Choi, 2002). But there is hardly any report that UAE is applied to separate the polysaccharides from G. lucidum.

In this study, we isolated polysaccharides from G. lucidum by UAE, filtration, DEAE cellulose-52 chromatography and size-exclusion chromatography in order, analyzed the elementary characterization of the polysaccharides fractions, and evaluated the influence of G. lucidum polysaccharides fractions upon activation to macrophage cell (RAW 264.7) and antitumor activities to the human breast cancer cell (MDA-MB-231) in vitro.