Structures and Bioactivities Characterization of Peanut Testa Anthocyanins

• Main Authors: Jung-Chu Cheng, 鄭炯柱
• Other Authors: Y.-Y. Chiou, Ph.D.
• Format: Others
• Language: zh-TW
• Online Access: http://ndltd.ncl.edu.tw/handle/77329611605218051947

碩士 === 國立嘉義大學 === 食品科學系研究所 === 96 === Peanut testa contains rich polyphenolic compounds and is regarded as waste byproduct after de-skinning of peanut kernels. The polyphenolic compounds of peanut testae are of worth further investigations. In this study, structures and bioactivities of the peanut testa anthocyanins were conducted. Sound peanut kernels of three peanut cultivars, namely, Tainan 11, Tainan 14 and Black Kingkong, were subjected to testa collection. When the peanut kernel testa samples were soaked with water, squeezed to separate solid and liquid, and the extracts were lyophilized. The extracted yields were 154.8, 175.5 and 162.2 mg/g, respectively. Total contents of the phenolic compounds of the extracts were 52.0, 50.0, 35.4 mg/g (expressed by gallic acid) and contents of the flavonoid compounds were 0.2, 1.4 and 21.3 mg/g (expressed by quercetin), respectively. When the water-extracts were tested at 25 μg/ml of concentration, their DPPH (α,α-diphenyl-β-picryl hydrazyl) scavenging activities were equivalent to 83.0, 69.9 and 32.6 μg/ml of BHT, respectively. As tested at 100 μg/ml of concentration, their antioxidative potencies (AOP) were equivalent to 1.1, 2.9 and 0.6 μg/ml of BHT and their corresponding reducing powers were equivalent to 56.7, 50.4 and 33.1 μg/ml of Vitamin C, respectively. The extracts of Black Kinkong were further purified by HPLC and subjected to identification with 1H and 13C NMR. A major anthocyanin was elucidated as Cyanidin-3-Glucose-Xylose (C3GX). DPPH scavenging activity of 25 μg/ml C3GX is equivalent to 27.5 μg/ml of BHT. AOP and reducing power were of 100 μg/ml C3GX equivalent to 2.0 μg/ml of BHT and 50 μg/ml of Vitamin C, respectively. The result from in vitro study showed that water extracts of Black Kingkong at 0, 62.5, 125, 250 and 500 μg/ml, and mediated with lipopolysaccharide (LPS) at 1 μg/ml, all test doses did not result in significant cytotoxicity. As affected by the introduced concentration of the testa extracts, 14, 15, 22 and 31 % of NO biosynthesis were inhibited, correspondingly. As tested with C3GX at 0, 22, 43, 86 and 172 μM, no obvious cytotoxicity was observed. At 86 and 172 μM, C3GX inhibited decreased NO synthesis 10 and 45 % respecting. Both WEBK and C3GX at the concentration, as high as 500 μg/ml and 172 μM did not exhihit cytotoxic effect on RAW 264.7 cells. In conclusion, the water-extracts of peanut testae of three peanut cultivars contain rich phenolic compounds and bear potent antioxidative activities. The major anthocyanin of Black Kinkong peanut testae was purified and identified as Cyanidin-3-Glucose-Xylose (C3GX, Mw 581). The C3GX exhibited potent antioxidative activities and suppressed NO production of the RAW 264.7 cells induced with LPS. Based on these observed bioactivities, water extracts of the peanut tastae and C3GX deserve further research interests and related product developments.