二甲基巯基丙酸（，缩写DMSP）是一种化学式为(CH)SCHCHCOO的有机化合物，常以内盐形式存在于海洋浮游植物、海藻以及某些陆生及水生维管植物中。It functions as an osmolyte as well as several other physiological and environmental roles have also been identified. DMSP was first identified in the marine red alga "Polysiphonia