B Gowda Siddabasave Gowda, Fuda Hirotoshi, Tsukui Takayuki, Chiba Hitoshi, Hui Shu-Ping
Faculty of Health Sciences, Hokkaido University, Kita-12, Nishi-5, Kita-Ku, Sapporo 060-0812, Japan.
Department of Nutrition, Sapporo University of Health Sciences, Nakanuma Nishi-4-3-1-15, Higashi-Ku, Sapporo 007-0894, Japan.
Antioxidants (Basel). 2020 May 8;9(5):397. doi: 10.3390/antiox9050397.
Branched fatty acid esters of hydroxy fatty acids (FAHFAs) are a recently discovered class of biologically active lipids with anti-inflammatory and anti-diabetic properties. Despite the possible link between endogenous FAHFA levels and nuclear factor erythroid 2-related factor 2 (Nrf2), their possible function as antioxidants and the mechanisms involved in this are unknown. Here, we investigate FAHFAs' plausible antioxidant potential with reference to their effect on the Nrf2 levels, oxidative stress, and lipid droplet oxidation in human hepatocytes (C3A). Six authentic FAHFAs were chemically synthesized and performed activity-based screening by reporter gene assay. Among them, eicosapentaenoic acid (EPA) esterified 12-hydroxy stearic acid (12-HSA) and 12-hydroxy oleic acid (12-HOA) FAHFAs showed less cytotoxicity compared to their free fatty acids and potent activators of Nrf2. To define their mode of action, relative levels of nuclear Nrf2 were determined, which found a higher amount of Nrf2 in nucleus of cells treated with 12-EPAHSA compared to the control. Furthermore, 12-EPAHSA increased the expression of Nrf2-dependent antioxidant enzyme genes (, , , , and ). Fluorescence imaging analysis of linoleic-acid-induced lipid droplets (LDs) in C3A cells treated with 12-EPAHSA revealed the strong inhibition of small-size LD oxidation. These results suggest that EPA-derived FAHFAs as a new class of lipids with less cytotoxicity, and strong Nrf2 activators with plausible antioxidant effects via the induction of cytoprotective proteins against oxidative stress, induced cellular damage.
羟基脂肪酸的支链脂肪酸酯（FAHFAs）是最近发现的一类具有抗炎和抗糖尿病特性的生物活性脂质。尽管内源性FAHFA水平与核因子红细胞2相关因子2（Nrf2）之间可能存在联系，但其作为抗氧化剂的可能功能及其相关机制尚不清楚。在此，我们参照FAHFAs对人肝细胞（C3A）中Nrf2水平、氧化应激和脂滴氧化的影响，研究其可能的抗氧化潜力。化学合成了六种纯正的FAHFAs，并通过报告基因检测进行基于活性的筛选。其中，二十碳五烯酸（EPA）酯化的12-羟基硬脂酸（12-HSA）和12-羟基油酸（12-HOA）FAHFAs与其游离脂肪酸相比细胞毒性较小，且是Nrf2的强效激活剂。为确定其作用模式，测定了核Nrf2的相对水平，发现与对照组相比，用12-EPAHSA处理的细胞细胞核中Nrf2含量更高。此外，12-EPAHSA增加了Nrf2依赖性抗氧化酶基因（、、、和）的表达。对用12-EPAHSA处理的C3A细胞中亚油酸诱导的脂滴（LDs）进行荧光成像分析，结果显示对小尺寸LD氧化有强烈抑制作用。这些结果表明，EPA衍生的FAHFAs作为一类新的脂质，细胞毒性较小，是强效的Nrf2激活剂，通过诱导细胞保护蛋白抵抗氧化应激，对氧化应激诱导的细胞损伤具有合理的抗氧化作用。
