A new polysaccharide isolated from Dendrobium offcinale, stimulates aquaporin-3 expression in human keratinocytes

Polysaccharides are the major components of the water extract from Dendrobium officinale, which have been thoroughly studied and found to have favorable moisturizing properties on mammalian skin. However, the structures of polysaccharides on skin moisturizing properties remains unknown. The aim of this study was to extract and characterize D. officinale polysaccharides, which have anti-oxidant activity and the role of promoting effects of aquaporin-3 (AQP3). Two crude polysaccharide fractions were extracted using water and biological fermentation, respectively. The crude polysaccharides were further purified by graded alcohol precipitation, and finally purified polysaccharides DOP-S and DOP-F were obtained by Sephacryl S-300 column chromatography. The average molecular weights of DOP-S and DOP-F were 3.604 x 10(5) and 1.027 x 10(5) Da, respectively. Monosaccharide units and structures of DOP-S and DOP-F were further elucidated by gas chromatography-mass spectrometry (GC-MS) and Fourier Transform infrared spectroscopy (FTIR). At the same time, DOP-S and DOP-F induced aquaporin-3 (AQP3) expression was evaluated by immuno-fluorescence analysis. The antioxidant activities of the polysaccharides were evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and ethylbenzothiazoline-6-sulfonic acid (ABTS) radical scavenging capacities, and ferric reducing antioxidant power (FRAP). The results showed that biological fermentation effectively achieved the hydrolysis of the polysaccharides and stimulated antioxidant activity and AQP3 expression.