Detection of Cyanidin in Different-colored Peanut Testae and Identification of Peanut Cyanidin 3-sambubioside

Abstract

Peanut testae are potent sources of polyphenols. When the water extracts and acid hydrolysates of five different-colored testae were analyzed by HPLC, chromatograms monitored at 280 nm varied remarkably, whereas two major peaks in the chromatograms monitored at 530 nm were detected only in kernels having completely or partially black color. After acid hydrolysis of the extracts, cyanidin was detected in each of the hydrolysates. By respectively subjecting the black testae of raw and roasted (175 degrees C for 20 min) kernels of a black colored cultivar to water extraction and HPLC analysis, a prominent peak was detected in both extracts. The structure of the substance under those peaks was identified by mass and NMR spectrometry as cyanidin 3-sambubioside in peanut testae for the first time. Subjection of cyanidin 3-sambubioside to antioxidation and anti-inflammation assessments revealed that it was a potent antioxidant and inhibitor of nitric oxide production.