C: Food Chemistry Microwave-Assisted Extraction, Chemical Structures, and Chain Conformation of Polysaccharides from a Novel Cordyceps Sinensis Fungus UM01 Kit-Leong Cheong, Lan-Ying Wang, Ding-Tao Wu, De-Jun Hu, Jing Zhao, and Shao-Ping Li Abstract: Cordyceps sinensis is a well-known tonic food with broad medicinal properties. The aim of the present study was to investigate the optimization of microwave-assisted extraction (MAE) and characterize chemical structures and chain conformation of polysaccharides from a novel C. sinensis fungus UM01. Ion-exchange and gel filtration chromatography were used to purify the polysaccharides. The chemical structure of purified polysaccharide was determined through gas chromatography-mass spectrometry. Moreover, high performance size exclusion chromatography combined with refractive index detector and multiangle laser light scattering were conducted to analyze the molecular weight (M w ) and chain conformation of purified polysaccharide. Based on the orthogonal design L 9 , optimal MAE conditions could be obtained through 1300 W of microwave power, with a 5-min irradiation time at a solid to water ratio of 1:60, generating the highest extraction yield of 6.20%. Subsequently, the polysaccharide UM01-S1 was purified. The UM01-S1 is a glucan-type polysaccharide with a (1→4)-β -d-glucosyl backbone and branching points located at O-3 of Glcp with a terminal-d-Glcp. The M w , radius of gyration (R g ) and hydrodynamic radius (R h ) of UM01-S1 were determined as 5.442 × 10 6 Da, 21.8 and 20.2 nm, respectively. Using the polymer solution theory, the exponent (ν ) value of the power law function was calculated as 0.38, and the shape factor (ρ = R g /R h ) was 1.079, indicating that UM01-S1 has a sphere-like conformation with a branched structure in an aqueous solution. These results provide fundamen- tal information for the future application of polysaccharides from cultured C. sinensis in health and functional food area. Keywords: chain conformation, Cordyceps sinensis, microwave-assisted extraction, polysaccharide Practical Application: Polysaccharide is extracted from mycelium of a novel Cordyceps sinensis fungus UM01 using microwave assisted extraction (MAE). MAE method is a reasonably easy task to obtain sufficient amounts of polysaccharide for further research. A basic understanding of the structure of polysaccharides is essential for the successful interpretation of the correlation between the structure and function of these molecules and the future application of these polysaccharides in functional foods. C. sinensis fungus UM01 is promising useful substitute for the naturally rate C. sinensis, and used as a nutraceutical product for preparation of functional foods. Introduction Cordyceps sinensis, called “Dong Chong Xia Cao” in China, which means “winter worm summer grass,” has been used exten- sively as folk tonic food in East Asia. It is usually supplied to people in soup who have weak constitution and help them to restore the self-regulatory ability of the body (Li and others 2006a). C. sinensis has a wide and varied range of functions in the human body, such as effects on immune function, disease resistance, and the prevention of kidney, liver, and heart disease (Zhou and others 2009; Zhao and others 2014). Natural Cordyceps requires a specific host and a strictly conditioned environment for growth. Hence, the sources of natural Cordyceps are limited and insufficient to meet the de- mand (Li and others 2006a). In this case, the mycelia fermentation of Cordyceps easily resolves this problem (Das and others 2010), MS 20160322 Submitted 2/28/2016, Accepted 7/1/2016. Authors are with State Key Laboratory of Quality Research in Chinese Medicine, Inst. of Chinese Medical Sciences, Univ. of Macau, Macao, China. Direct inquiries to author Zhao (E-mail: zhaojing.cpu@163.com). as a number of mycelial strains have been isolated from natural Cordyceps, which exhibit the large-scale production of mycelium through fermentation as an alternative choice (Li and others 2006a). These fungi have similar pharmacological efficacies with natural Cordyceps (Li and others 2001). Indeed, polysaccharides are one of the most abundant components of these fungi, often associ- ated with the biological activities of cultured Cordyceps (Li and oth- ers 2003; Yan and others 2014). There is a growing interest in the use of these polysaccharides as pharmaceuticals, as these molecules have been demonstrated by many interesting biological activities (Nie and others 2013), such as antioxidation (Li and others 2001; Li and others 2003), antitumor (Yan and others 2011), immunomod- ulation (Cheung and others 2009), and hypoglycemic activities (Li and others 2006b). Unfortunately, little attention has been given to the optimal extraction of polysaccharides from cultured C. sinensis, resulting in low yields and high costs of polysaccharide production, thereby hindering the further exploitation and utilization of these compounds. The extraction of polysaccharides from C. sinensis mycelia is a significant process for the application of these molecules in C  2016 Institute of Food Technologists R  doi: 10.1111/1750-3841.13407 Vol. 00, Nr. 0, 2016  Journal of Food Science C1 Further reproduction without permission is prohibited