Oh Eok Kwon

Manassantin a and b isolated fromSaururus chinensis inhibit TNF-α-induced Cell adhesion molecule expression of human umbilical vein endothelial cells

Leukocyte adhesion to the vascular endothelium is a critical initiating step in inflammation and atherosclerosis. We have herein studied the effect of manassantin A (1) and B (2), dineolignans, on interaction of THP-1 monocytic cells and human umbilical vein endothelial cells (HUVEC) and expression of intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and E-selectin in HUVEC. When HUVEC were pretreated with1 and2 followed by stimulation with TNF-α, adhesion of THP-1 cells to HUVEC decreased in dose-dependent manner with IC50 values of 5 ng/mL and 7 ng/mL, respectively, without cytotoxicity. Also,1 and2 inhibited TNF-α-induced up-regulation of ICAM-1, VCAM-1 and E-selectin. The present findings suggest that1 and2 prevent monocyte adhesion to HUVEC through the inhibition of ICAM-1, VCAM-1 and E-selectin expression stimulated by TNF-α, and may imply their usefulness for the prevention of atherosclerosis relevant to endothelial activation.

Pheophorbide a-methyl ester, acyl-coa: cholesterol acyltransferase inhibitor fromDiospyros kaki

In the course of our search for Acyl-CoA: cholesterol acyltransferase (ACAT) inhibitors from natural sources, a new type of ACAT inhibitor was isolated from a methanol extract ofDiospyros kaki. On the basis of spectral and structural evidence, the compound was identified as pheophorbide A-methyl ester. Pheophorbide A-methyl ester inhibited ACAT activity in a dose dependent manner with an IC50 value of 1.85 μg/mL.