Pristimerin is a potent and reversible monoacylglycerol lipase (MGL) inhibitor with an IC₅₀ of 93 nM. IC50 & Target: IC50: 93 nM (MGL)^[1] In Vitro: Pristimerin inhibits the activity of purified MGL with an IC₅₀ of 93±8 nM and that of non-purified MGL (cell lysates of MGL-transfected HeLa cells) with an IC₅₀ of 398±68 nM. Pristimerin inhibits MGL through a mechanism that is rapid, reversible and non-competitive. The binding of pristimerin to MGL might be strengthened by formation of a polar interaction with a regulatory cysteine, possibly Cys^208[1]. Pristimerin inhibits HFLS-RA and HUVEC cell viability in a dose- and time-dependent manner. Pristimerin decreases VEGF-induced autophosphorylation of VEGFR2 and attenuates the activation of the VEGF-induced VEGFR2-mediated signaling pathway ^[2]. In Vivo: Pristimerin inhibits inflammation and tumor angiogenesis. Pristimerin significantly reduces vessel density in synovial membrane tissues of inflamed joints and reduces the expression of pro-angiogenic factors in sera, including TNF-α, Ang-1, and MMP-9^[2].