Nakagawa Kouichi, Yooin Wipawadee, Saenjum Chalermpong
Division of Regional Innovation, Graduate School of Health Sciences, Hirosaki University.
Department of Pharmaceutical Sciences, Faculty of Pharmacy, Chiang Mai University.
J Oleo Sci. 2018;67(10):1347-1353. doi: 10.5650/jos.ess18093.
We investigated the pigments in Thai purple rice using electron paramagnetic resonance (EPR), X-band (9 GHz) EPR imaging (EPRI), and HPLC. The location and spatial distribution of the paramagnetic species in purple and white rice were determined by EPR and EPRI. EPR primarily detected three paramagnetic species in purple rice, which were identified as stable radicals, Mn, and Fe based on the gvalues and hyperfine components of the EPR signals. Subsequent noninvasive two-dimensional (2D) EPRI revealed that these stable radicals are primarily located in the pigmented region of purple rice, while very few radicals were observed in the interior of the rice. HPLC revealed that the major compounds were cyanidin-3-O-glucoside and peonidin-3-O-glucoside. Scavenging activities, EPR, and EPR imaging results indicate that the stable radicals contain the radical state of anthocyanins and are mostly found within the pigmented embryo region of purple rice. They could be either associated with scavenging activities or could be one of the products of their oxidative decomposition.
我们使用电子顺磁共振（EPR）、X波段（9吉赫兹）电子顺磁共振成像（EPRI）和高效液相色谱法（HPLC）对泰国紫米中的色素进行了研究。通过EPR和EPRI确定了紫米和白米中顺磁物质的位置和空间分布。EPR主要在紫米中检测到三种顺磁物质，根据EPR信号的g值和超精细成分，它们被鉴定为稳定自由基、锰和铁。随后的非侵入性二维（2D）EPRI显示，这些稳定自由基主要位于紫米的色素区域，而在米粒内部观察到的自由基很少。HPLC显示主要化合物为矢车菊素-3-O-葡萄糖苷和芍药素-3-O-葡萄糖苷。清除活性、EPR和EPR成像结果表明，稳定自由基含有花青素的自由基状态，主要存在于紫米的色素胚区域内。它们可能与清除活性有关，也可能是其氧化分解产物之一。
