Ac2-26 is an N-terminal-derived peptide of annexin-A1 (ANX-A1), a glucocorticoid-regulated anti-inflammatory protein belonging to the annexin superfamily. This peptide shares biological properties with the full-length ANX-A1 protein, including the capacity to inhibit neutrophil adhesion and infiltration. Ac2-26 binds to the formyl peptide receptor (FPR) family of G-protein coupled receptors, particularly FPR2, which is considered the primary mediator of its anti-inflammatory effects. The peptide is known to modulate immune responses by influencing leukocyte activation and migration.

In experimental models, Ac2-26 demonstrates direct protective actions on cardiomyocytes, preserving cell viability under conditions of stress such as hypoxia-reoxygenation. It reduces markers of cellular injury, including lactate dehydrogenase and cardiac troponin release. The peptide also influences gene expression in cardiac cells, upregulating FPR subtypes and attenuating pro-inflammatory and pro-fibrotic pathways. These actions highlight its role in mitigating cellular damage and modulating inflammatory processes within the myocardium.

• Perretti and Gavins (2003) Annexin 1: an endogenous anti-inflammatory protein. News Physiol.Sci. 18 60 PMID: 12644621
• Leoni et al (2015) Annexin A1-containing extracellular vesicles and polymeric nanoparticles promote epithelial wound repair. J.Clin.Invest. 125 1215 PMID: 25664854
• Possebon et al (2018) Mimetic peptide AC2-26 of annexin A1 as a potential therapeutic agent to treat COPD, International Immunopharmacology, 63 270 PMID: 30121452

三氟乙酸（Trifluoroacetic acid，简称 TFA）是高效液相色谱（简称 HPLC）纯化过程中常用的反离子。TFA 的存在可能会对肽的净重量、外观及溶解度产生影响，具体如下：

对净重量的影响：TFA 盐会增加产物的总质量。在大多数情况下，肽的含量占总重量的 80% 以上，剩余部分则为 TFA。

对溶解度的影响：TFA 盐通常能提高肽在水溶液中的溶解度。

在生物检测中的影响：对于大多数标准的体外检测，残留的 TFA 水平一般不会造成干扰。但需注意，在高灵敏度的细胞研究或生化研究中，需关注其存在可能带来的影响。

干品多肽的重量中不仅仅包含多肽，还包含有一些非肽的组份，如水、被吸收的溶剂、配位离子和盐等。肽的净含量是指肽在其中的重量百分比，这个百分比的数值范围很大，可能从50%到90%，取决于纯度、序列以及合成和纯化的方法，不要将肽的净含量和肽的纯度混为一谈，他们是两个完全不同的概念。纯度通常是通过HPLC测定的。纯度定义的是多肽样品中含正确序列的组分的百分比，而肽的净含量是指样品中肽类物质相对于总物质所占的百分比，肽的净含量通常是氨基酸组分分析或紫外分光法测定的，这个信息主要是在一些对肽的浓度很敏感的实验中，对计算肽的浓度是很重要的。