Inhibitory effects of acylated kaempferol glycosides from the leaves of Cinnamomum kotoense on the proliferation of human peripheral blood mononuclear cells

A new chemical entity, namely kaempferol 3-O-alpha-L-[2-(Z)-p-coumaroyl-4-(E)-p-coumaroyl]rhamnopyranoside (1), and the known kaempferol 3-O-alpha-L-[2,4-di-(E)-p-coumaroyl]rhamnopyranoside (2) have been isolated from the methanolic extract of leaves of Cinnamomum kotoense. Structural elucidation of compounds 1 and 2 were achieved on the basis of spectroscopic analysis. The effects of compounds 1 and 2 on phytohemagglutinin (PHA) stimulated cell proliferation were studied towards human peripheral blood mononuclear cells (PBMC). The results indicated that compounds 1 and 2 suppressed PBMC proliferation induced by PHA with an IC50 value of 5.0 +/- 1.3 and 6.0 +/- 1.5 MM, respectively. Interleukin-2 production in activated PBMC inhibited by compounds 1 and 2 were in a concentration-dependent manner. Therefore, we suggested that compounds 1 and 2 in C. kotoense were likely the growth modulators for PBMC.