Study on the structure of exopolysaccharide of ophiocordyceps sinensis and their cosmetic applications

Abstract

Exopolysaccharide (EPS) extracted from O. sinensis and supplied by Institute of Research and Hi-tech Application in Agriculture of Dalat University had firstly treated by deproteination and acetylation before being analyzed by gas chromatography (GC) to determine the sugar composition. The sulfation with sulfur trioxide pyridine complex (SO3.Py) was then applied to increase the bioactivity and solubility of EPS. The sign of successful reaction was determined by Fouriertransform infrared (FTIR) spectroscopy assay. The sulfated exopolysaccharide (SEPS) were then tested for the hygroscopic and moisture retention activities and compared to exopolysaccharide, chitin and hyaluronic acid (HA) for positioning. The hygroscopic activity was examined following the method of placing the samples in closed system with saturated calcium chloride (CaCl2). The purposes are to set the similar condition for all samples, maintain the same humidity and measuring the changes in weight per certain time. The moisture retention activity was tested by humidifying the samples and then dehydrating by placing them in the closed system with silica gel and measuring the percentage of water losing per certain time. The bioactivities such as collagenase inhibitory activity and cytotoxicity against fibroblast cell line of EPS and SEPS were tested. Afterward, SEPS and EPS were applied in developing moisturizer gel cream. The results indicate that EPS contains mainly three kinds of monosaccharide such as glucose, mannose and galactose with the ratio of 1.8 : 2.3 : 1. The SEPS was synthesized by the sulfation with SO3.Py. Its IR spectrum showed the absorption band at 1253 cm-1 related to a >S=O stretching vibration of the sulphate group (Lloyd et al., 1961). The collagenase inhibitory activity of SEPS was more potent than that of EPS, with the inhibition percentage (I%) of 35.66 ± 1.014 (%) and 31.77 ± 1.123 (%), respectively, at the concentration of 2000 µg/ml. Based on the final results, the cytotoxicity against fibroblast cell line of EPS and SEPS were -2.08 ± 5.99 (%) and -1.28 ± 6.85 (%), respectively, showing their cell proliferation abilities. In addition, the hygroscopic and moisture retention activities of EPS were proved to be better than SEPS.