Cyclo(-Phe-Phe) is a cyclic dipeptide formed by the cyclization of two phenylalanine molecules via a peptide bond[1]. This compound can activate the Nrf2 signaling pathway, thereby enhancing cellular antioxidant defense capacity and exerting a protective effect against chemical-induced liver injury[2].
In vitro cell experiments, HepG2 cells were pretreated with Cyclo(-Phe-Phe) at concentrations of 0.06–6μmol/L for 2 hours, followed by co-treatment with the oxidative stress inducer AAPH (60–100mmol/L) for 1–24 hours. Cyclo(-Phe-Phe) significantly suppressed intracellular reactive oxygen species (ROS) accumulation and mitochondrial membrane potential depolarization. Cyclo(-Phe-Phe) activated the Nrf2 pathway, upregulating the expression of the antioxidant genes heme oxygenase-1 (HO-1) and NAD(P)H quinone oxidoreductase 1 (NQO1)[2].
In vivo embryo models, fertilized chick embryos were administered Cyclo(-Phe-Phe) via air chamber injection at doses of 0.1–1nmol per egg every three days until the 17th day of embryonic development. Cyclo(-Phe-Phe) significantly reduced AAPH-induced embryonic mortality, improved liver development parameters (including liver weight and volume), and effectively attenuated liver tissue fibrosis and cellular apoptosis[2].
References:
[1] Sheinblatt M. NMR studies on the conformation of cyclodipeptides with two identical L-aromatic amino acid residues in solutions--cyclo[L-5(OH)Trp-L-5(OH)Trp] and cyclo[-L-Phe-L-Phe]. Int J Pept Protein Res. 1991 Jul;38(1):8-14.
[2] Zhang QY, Han SC, Huang RP, et al. Cyclo(-Phe-Phe) alleviates chick embryo liver injury via activating the Nrf2 pathway. Food Funct. 2022 Jul 4;13(13):6962-6974.
Cyclo(-Phe-Phe) 是一种由两个苯丙氨酸分子形成的环二肽[1]。Cyclo(-Phe-Phe)还能够通过激活Nrf2通路来增强细胞抗氧化能力，从而对肝损伤产生保护作用[2]。
在体外，环二肽Cyclo(-Phe-Phe)以0.06–6μmol/L的浓度预处理HepG2细胞2小时后，联合使用AAPH（60–100mmol/L）刺激1–24小时，Cyclo(-Phe-Phe)可显著抑制细胞内活性氧（ROS）的积累和线粒体膜电位去极化，同时通过激活Nrf2通路增强抗氧化基因HO-1和NQO1的表达[2]。
在体内，Cyclo(-Phe-Phe) (0.1-1nmol per egg) 每隔三天通过气室注射一次，用于处理受精鸡胚胎直至第17天。Cyclo(-Phe-Phe)显著减轻了AAPH诱导的胚胎死亡和肝损伤，包括改善肝重量和体积，并减少肝纤维化及细胞凋亡[2]。