Extraction and HPLC analysis of resveratrol and polydatin in peanut waste materials

Large amount of plant waste materials (root, stem, leaf and fruit shell) are produced in peanut (Arachis hypogaea) cultivation and processing. We investigated the extraction, identification and contents of resveratrol and polydatin in different organ wastes of four varieties of peanut (Arachis hypogaea), Pearl Red 14, Guangdong Oil 114, Santou Oil 523 and Zhanjian Oil 75. The optimal extraction is that dried material was crushed and sieved through a 40 mesh sieve, ultrasonic-extracted with 60% ethanol for 3 times. Contents of the bioactive substances were analyzed by HPLC. Both resverstrol and polydatin were identified in all root, stem, leaf and fruit shell of the four varieties of peanut. The contents of the two compounds varied greatly in different peanut varieties and organs, with the highest contents for both compounds in Pearl Red 14, and the lowest in Cham oil 75. The root of all varieties contained much higher resveratrol and polyatin than other organs. Resveratrol contents were 148.7, 33.3, 23.1 and 9.4 g/g, and polyatin contents were 133.7, 37.7, 27.7 and 11.5 g /g in Pearl Red 14 roots, stems, leaves and shell, respectively. The contents of both resveratrol and polydatin in Pearl Red 14 root are much higher than in grapes, mulberries and other plant materials. The work provides useful information for comprehensive utilization of peanut wastes.