Core Research Program 1515, Key Laboratory for Food Science and Biotechnology of Hunan Province, College of Food Science and Technology, Hunan Agricultural University, Changsha, China.
Hunan Agricultural Product Processing Institute, Hunan Academy of Agricultural Sciences, Changsha, China.
Acta Biochim Biophys Sin (Shanghai). 2019 Jan 1;51(1):31-40. doi: 10.1093/abbs/gmy148.
Lotus seed is well known as traditional food and medicine, but its skin is usually discarded. Recent studies have shown that lotus seed skin contains a high concentration of proanthocyanidins that have multi-functions, such as antioxidation, anti-inflammation, and anti-cancer effects. In the present study, we aimed to isolate and purify the proanthocyanidins from lotus seed skin by acetone extraction and rotary evaporation, identify their chemical structures by HPLC-MS-MS and NMR, and further investigate the antioxidant properties of the extract purified by macroporous resin (PMR) from lotus seed skin both in vitro and in vivo. The results showed that PMR mainly contained oligomeric proanthocyanidins, especially dimeric procyanidin B1 (PB1), procyanidin B2 and procyanidin B4. Although it had limited ability to directly scavenge radicals in vitro, PMR could significantly enhance the expressions of antioxidant proteins via activation of nuclear factor-E2-related factor 2 (Nrf2)-antioxidant response element (ARE) pathway in HepG2 cells. Molecular data revealed that PB1, a major component in PMR, stabilized Nrf2 by inhibiting the ubiquitination of Nrf2, which led to subsequent activation of the Nrf2-ARE pathway, including the enhancements of Nrf2 nuclear translocation, Nrf2-ARE binding and ARE transcriptional activity. Moreover, the in vivo results in high fat diet-induced mice further verified the powerful antioxidant property of PMR. These results revealed that lotus seed skin is a promising resource for functional food development.
莲子是众所周知的传统食品和药材，但它的皮通常被丢弃。最近的研究表明，莲子皮含有高浓度的原花青素，具有多种功能，如抗氧化、抗炎和抗癌作用。在本研究中，我们旨在通过丙酮提取和旋转蒸发从莲子皮中分离和纯化原花青素，通过高效液相色谱-串联质谱（HPLC-MS-MS）和核磁共振（NMR）鉴定其化学结构，进一步研究莲子皮大孔树脂（PMR）纯化提取物的抗氧化性能，包括体外和体内研究。结果表明，PMR 主要含有低聚原花青素，特别是二聚原花青素 B1（PB1）、原花青素 B2 和原花青素 B4。尽管 PMR 体外直接清除自由基的能力有限，但通过激活 HepG2 细胞中的核因子 E2 相关因子 2（Nrf2）-抗氧化反应元件（ARE）通路，PMR 可以显著增强抗氧化蛋白的表达。分子数据显示，PMR 中的主要成分 PB1 通过抑制 Nrf2 的泛素化稳定 Nrf2，从而导致随后激活 Nrf2-ARE 通路，包括 Nrf2 核易位、Nrf2-ARE 结合和 ARE 转录活性的增强。此外，高脂肪饮食诱导的小鼠体内结果进一步验证了 PMR 强大的抗氧化特性。这些结果表明，莲子皮是功能性食品开发的有前途的资源。
