**2. Materials and Methods**

## *2.1. Materials*

Dencichine was provided from Chengdu Plant standard pure Biotechnology Co., Ltd. (Chengdu, China). 4-ethylpyridine and 2,2 -azobisisobutyronitrile (AIBN) were provided from Shanghai Aladdin Biochemical Technology Co., Ltd. (Shanghai, China). N, N methylenebis (acrylamide) and acetic acid were provided from Shanghai Maclin Biochemical Technology Co., Ltd. (Shanghai, China). Methyl alcohol was obtained from Chengdu Cologne Chemicals Co., Ltd. (Chengdu, China). Glycine-DL-leucine (GL) and glycyl-Lphenylalanine (GP) were provided from Aladdin Chemistry Co. Ltd. (Shanghai, China). HPLC-grade acetonitrile and methanol were provided from Agilent Technologies (Shanghai, China) Co., Ltd. Ethylene glycol maleic rosinate acrylate (EGMRA) was purchased by Wuzhou Sun Shine Forestry & Chemicals Co., Ltd. (Wuzhou, China) [17].
