Panighel Giovanni, Ferrarese Irene, Lupo Maria Giovanna, Sut Stefania, Dall'Acqua Stefano, Ferri Nicola
Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Via Marzolo 5, 35121 Padova, Italy.
Department of Medicine, Via Giustiniani 2, 35128 Padova, Italy.
Food Chem (Oxf). 2022 Jul 25;5:100126. doi: 10.1016/j.fochms.2022.100126. eCollection 2022 Dec 30.
Okra () have been introduced as food relatively recently in Europe. It is native to India and one of the most important vegetables in Nigeria. The leaves can be consumed but also the fruit is rich in nutrients and bioactive compounds (i.e., dietary fiber, vitamins, oils, polysaccharides, polyphenols) and several health promoting actions have been ascribed, including a lipid-lowering properties. In this work the effects of fruit and leaf extracts on expression of key mediators of cholesterol metabolism, i.e. the low-density lipoprotein receptor (LDLR) and proprotein convertase subtilisin/kexin type 9 (PCSK9), were investigated in human hepatoma cell line Huh7. Furthermore, effects on proinflammatory cytokines (IL-1β, IL-6 and TNF-α) expressed by THP1-derived macrophages were studied to assess potential anti-inflammatory actions. Okra fruit extract significantly induced the mRNA and protein levels of the LDLR by 1.4 ± 0.3 and 4.8 ± 1.5-fold, respectively without any significant modification of PCSK9 expression. In addition, fruit extract showed a significant sequestering ability of cholic acid. Leaf butanol extract exerted similar action by inducing the expression of both the LDLR (+3.1 ± 1.6-fold vs control) and PCSK9 (+1.3 ± 0.4-fold vs control). The evaluation of the potential anti-inflammatory effect revealed a significant action of leaf butanol extract with reduced mRNA levels of IL-1β (-28 ± 8 % vs control), IL-6 (-11 ± 1 % vs control) and TNF-α (-43 ± 8 % vs control), while fruit extract did not show any anti-inflammatory activity. Finally, leaf ethyl acetate extract showed a significant antioxidant capacity comparable to ascorbic acid. Taken together, we provided evidence that leaf butanol extract and, more effectively, fruit extract induced the LDLR expression, effect that may explain the previously reported hypocholesterolemic action of okra. In addition, okra's extracts reduced the expression of pro-inflammatory cytokines from THP1-derived macrophages, an effect that may suggest a vascular protective action of okra.
秋葵在欧洲作为食物被引入的时间相对较近。它原产于印度，是尼日利亚最重要的蔬菜之一。秋葵的叶子可以食用，其果实富含营养和生物活性化合物（如膳食纤维、维生素、油脂、多糖、多酚），并且具有多种促进健康的作用，包括降血脂特性。在这项研究中，我们在人肝癌细胞系Huh7中研究了秋葵果实和叶子提取物对胆固醇代谢关键调节因子，即低密度脂蛋白受体（LDLR）和前蛋白转化酶枯草溶菌素/kexin 9型（PCSK9）表达的影响。此外，我们还研究了其对THP1衍生巨噬细胞表达的促炎细胞因子（IL-1β、IL-6和TNF-α）的影响，以评估其潜在的抗炎作用。秋葵果实提取物显著诱导LDLR的mRNA和蛋白水平分别提高了1.4±0.3倍和4.8±1.5倍，而PCSK9的表达没有任何显著变化。此外，果实提取物显示出显著的胆酸螯合能力。叶子的丁醇提取物通过诱导LDLR（相对于对照组增加3.1±1.6倍）和PCSK9（相对于对照组增加1.3±0.4倍）的表达发挥了类似作用。对潜在抗炎作用的评估显示，叶子丁醇提取物具有显著作用，可使IL-1β（相对于对照组降低28±8%）、IL-6（相对于对照组降低11±1%）和TNF-α（相对于对照组降低43±8%）的mRNA水平降低，而果实提取物未显示出任何抗炎活性。最后，叶子的乙酸乙酯提取物显示出与抗坏血酸相当的显著抗氧化能力。综上所述，我们提供的证据表明，叶子丁醇提取物，更有效的是果实提取物，可诱导LDLR表达，这一作用可能解释了先前报道的秋葵的降胆固醇作用。此外，秋葵提取物降低了THP1衍生巨噬细胞中促炎细胞因子的表达，这一作用可能表明秋葵具有血管保护作用。
