The discovery of branched fatty acid esters of hydroxy fatty acids (FAHFAs) in humans draw attention of many researches to their biological effects. Although FAHFAs were originally discovered in insects and plants, their introduction into the mammalian realm opened new horizons in bioactive lipid research. Hundreds of isomers from different families have been identified so far and their role in (patho) physiological processes is currently being explored.

The family of palmitic acid esters of hydroxy stearic acids (PAHSAs), especially 5-PAHSA and 9-PAHSA regioisomers, stands out in the crowd of other FAHFAs for their anti-inflammatory and anti-diabetic effects. Beneficial effects of PAHSAs have been linked to metabolic disorders such as type 1 and type 2 diabetes, colitis, and chronic inflammation. Besides PAHSAs, a growing family of polyunsaturated FAHFAs exerts mainly immunomodulatory effects and biological roles of many other FAHFAs remain currently unknown. Therefore, FAHFAs represent unique lipid messengers capable of affecting many immunometabolic processes.

The objective of this review is to summarize the knowledge concerning the diversity of FAHFAs, nomenclature, and their analysis and detection. Special attention is paid to the total syntheses of FAHFAs, optimal strategies, and to the formation of the stereocenter required for optically active molecules. Biosynthetic pathways of saturated and polyunsaturated FAHFAs in mammals and plants are reviewed together with their metabolism and degradation. Moreover, an overview of biological effects of branched FAHFAs is provided and many unanswered questions regarding FAHFAs are discussed.

人体中羟基脂肪酸支链脂肪酸酯（FAHFA）的发现吸引了许多研究对其生物学效应的关注。尽管FAHFA最初是在昆虫和植物中发现的，但将它们引入哺乳动物领域为生物活性脂质研究开辟了新的视野。迄今为止，已经鉴定了来自不同家族的数百种异构体，目前正在探索它们在（病理）生理过程中的作用。

羟基硬脂酸（PAHSA）的棕榈酸酯家族，尤其是5-PAHSA和9-PAHSA区域异构体，因其抗炎和抗糖尿病作用而在其他FAHFA人群中脱颖而出。PAHSA的有益作用与代谢性疾病（例如1型和2型糖尿病，结肠炎和慢性炎症）有关。除PAHSA以外，一个不断增长的多不饱和FAHFA家族主要发挥免疫调节作用，许多其他FAHFA的生物学作用目前仍未知。因此，FAHFA代表独特的脂质信使，能够影响许多免疫代谢过程。

这篇综述的目的是总结关于FAHFA的多样性，命名法及其分析和检测的知识。特别注意FAHFA的总合成，最佳策略以及旋光分子所需的立体中心的形成。综述了哺乳动物和植物中饱和和多不饱和FAHFAs的生物合成途径及其代谢和降解。此外，提供了分支FAHFA的生物学效应的概述，并讨论了有关FAHFA的许多未解决的问题。