Thepthanee Chorpaka, Liu Chan-Chiung, Yu Hsu-Sheng, Huang Ho-Shin, Yen Chia-Hung, Li Yen-Hsien, Lee Maw-Rong, Liaw Ean-Tun
Department of Food Science, National Pingtung University of Science and Technology, Pingtung 91201, Taiwan.
R&D Center, King Herb BioMed, Tainan 71201, Taiwan.
Foods. 2021 Dec 3;10(12):2987. doi: 10.3390/foods10122987.
Black rice leaves ( L.) are a major part of rice straw left in open fields after rice harvest as agricultural waste. In this study, crude ethanolic extract (CEE) and various solvent fractions (hexane (Hex), ethyl acetate (EtOAc), -butanol (-BuOH), and aqueous fractions) of black rice leaves were investigated for their bioactive compound contents as well as antioxidant, anti-inflammatory, and anticancer activities. The results demonstrated that among all the fractions, the -BuOH fraction presented the greatest contents of total phenolics and flavonoids, while anthocyanins were found to be abundant in the -BuOH and aqueous fractions, which also exhibited powerful antioxidant abilities according to DPPH and ABTS radical-scavenging assays and a reducing power assay. Regarding anti-inflammatory activity, CEE and EtOAc reduced the production of NO and cytokine secretion (PGE, IL-6, and IL-1β) but displayed less effect on tumor necrosis factor α (TNF-α) release in lipopolysaccharide (LPS)-induced RAW 264.7 cells. They also significantly decreased iNOS and COX-2 protein expression. Additionally, the phenolics-rich ethyl acetate fraction showed the greatest activity against HepG2 liver carcinoma cells, inhibited cell growth, increased the Sub-G1 population, and induced apoptosis via mitochondrion-dependent mechanisms. In conclusion, black rice leaves, a byproduct of rice, exhibited strong antioxidant, anti-inflammatory, and anticancer capacities and might be useful for application in functional foods and the pharmaceutical industry.
黑米叶（L.）是水稻收获后留在露天田地作为农业废弃物的稻草的主要部分。在本研究中，对黑米叶的粗乙醇提取物（CEE）和各种溶剂萃取物（己烷（Hex）、乙酸乙酯（EtOAc）、正丁醇（-BuOH）和水相萃取物）的生物活性化合物含量以及抗氧化、抗炎和抗癌活性进行了研究。结果表明，在所有萃取物中，正丁醇萃取物的总酚类和黄酮类含量最高，而花青素在正丁醇和水相萃取物中含量丰富，根据DPPH和ABTS自由基清除试验以及还原能力试验，它们也表现出强大的抗氧化能力。关于抗炎活性，CEE和EtOAc可降低一氧化氮（NO）的产生和细胞因子分泌（前列腺素E、白细胞介素-6和白细胞介素-1β），但对脂多糖（LPS）诱导的RAW 264.7细胞中肿瘤坏死因子α（TNF-α）的释放影响较小。它们还显著降低诱导型一氧化氮合酶（iNOS）和环氧化酶-2（COX-2）蛋白表达。此外，富含酚类的乙酸乙酯萃取物对肝癌HepG2细胞表现出最大活性，抑制细胞生长，增加亚G1期细胞群体，并通过线粒体依赖性机制诱导细胞凋亡。总之，作为水稻副产品的黑米叶具有强大的抗氧化、抗炎和抗癌能力，可能在功能性食品和制药工业中具有应用价值。
