Effect of 3-caffeoyl, 4-dihydrocaffeoylquinic acid from Salicornia herbacea on endothelial nitric oxide synthase activation via calcium signaling pathway.

3-Caffeoyl-4-dicaffeoylquinic acid (CDCQ) is a natural chlorogenic acid isolated from Salicornia herbacea that protects against oxidative stress, inflammation, and cancer. Nitric oxide (NO) plays a physiologically beneficial role in the cardiovascular system, including vasodilation, protection of endothelial cell function, and anti-inflammation. However, the effect of CDCQ on NO production and eNOS phosphorylation in endothelial cells is unclear. We investigated the effect of CDCQ on eNOS phosphorylation and NO production in human endothelial cells, and the underlying signaling pathway. CDCQ significantly increased NO production and the phosphorylation of eNOS at Ser1177. Additionally, CDCQ induced phosphorylation of PKA, CaMKII, CaMKKβ, and AMPK. Interestingly, CDCQ increased the intracellular Ca²⁺ level, and L-type Ca²⁺ channel (LTCC) blockade significantly attenuated CDCQ-induced eNOS activity and NO production by inhibiting PKA, CaMKII, CaMKKβ, and AMPK phosphorylation. These results suggest that CDCQ increased eNOS phosphorylation and NO production by Ca²⁺-dependent phosphorylation of PKA, CaMKII, CaMKKβ, and AMPK. Our findings provide evidence that CDCQ plays a pivotal role in the activity of eNOS and NO production, which is involved in the protection of endothelial dysfunction.