1. The First Affiliated Hospital of Anhui University of Chinese Medicine, Hefei 230031, P. R. China
2. Key Laboratory of Precision and Intelligent Chemistry, Department of Chemistry, University of Science and Technology of China, Hefei 230026, P. R. China
3. Department of Gastroenterology, the First Affiliated Hospital of USTC, Division of Life Science and Medicine, University of Science and Technology of China, Hefei 230001, P. R. China