Structure identification of an arabinogalacturonan in Citrus reticulata Blanco 'Chachiensis' peel

Unlike common orange fruit, Citrus reticulata Blanco 'Chachiensis' (CRB) is usually served as traditional herbal medicine and function food. It is an abundant source of bioactive polysaccharides which contribute to the health benefits of CRB. However, the structure information of polysaccharides still remains unknown. In this work, the leading polysaccharide (CRBP) was purified from CRB peel. The structure was identified by nuclear magnetic resonnance spectroscopy. The backbone was (1 -> 4)-alpha-D-galacturonan, while the branch was alpha-L-Araf-(1 -> 5)-alpha-L-Araf-(1 ->. The molecular weight was calculated to be 55.4 kDa. The proposed structure was drawed as below. The cell assays indicated that CRBP was not toxic to macrophage cells, and could promote the NO production significantly in a dose-dependent manner. These results demonstrated that CRBP was a good candidate for functional food development.