Nucleotide-binding oligomerization domain 2 (NOD2) is a receptor of the innate immune system that is capable of perceiving bacterial and viral infections. Muramyl dipeptide (MDP, -acetyl muramyl L-alanyl--isoglutamine), identified as the minimal immunologically active component of bacterial cell wall peptidoglycan (PGN) is recognized by NOD2. In terms of biological activities, MDP demonstrated vaccine adjuvant activity and stimulated non-specific protection against bacterial, viral, and parasitic infections and cancer. However, MDP has certain drawbacks including pyrogenicity, rapid elimination, and lack of oral bioavailability. Several detailed structure-activity relationship (SAR) studies around MDP scaffolds are being carried out to identify better NOD2 ligands. The present review elaborates a comprehensive SAR summarizing structural aspects of MDP derivatives in relation to NOD2 agonistic activity.

中文翻译：

---

NOD2 激动性胞壁酰二肽的构效关系


核苷酸结合寡聚结构域 2 (NOD2) 是先天免疫系统的受体，能够感知细菌和病毒感染。胞壁酰二肽（MDP，-乙酰胞壁酰 L-丙氨酰-异谷氨酰胺）被确定为细菌细胞壁肽聚糖 (PGN) 的最小免疫活性成分，可被 NOD2 识别。在生物活性方面，MDP 表现出疫苗佐剂活性，并刺激针对细菌、病毒、寄生虫感染和癌症的非特异性保护。然而，MDP 具有某些缺点，包括热原性、快速消除和缺乏口服生物利用度。围绕 MDP 支架进行了几项详细的构效关系 (SAR) 研究，以确定更好的 NOD2 配体。本综述阐述了全面的 SAR，总结了与 NOD2 激动活性相关的 MDP 衍生物的结构方面。