Novel Glycolipoproteins from Ginseng

Abstract

Ginseng has been used as a general tonic agent to invigorate human body. In the present study, we isolated novel glycolipoproteins from ginseng that activate Ca²?-activated Cl- channel (CaCC) in Xenopus oocytes and transiently increase intracellular free Ca²? concentration ([Ca²?]i) in mouse Ehrlich ascites tumor cells. We named the active ingredients as gintonin. Gintonin exists in at least six different forms. The native molecular weight of gintonin is about 67 kDa but its apparent molecular weight is about 13 kDa, indicating that gintonin might be a pentamer. Gintonin is rich in hydrophobic amino acids. Its main carbohydrates are glucose and glucosamine. Its lipid components are linoleic, palmitic, oleic, and stearic acids. Gintonin actions were blocked by U73122, a phospholipase C inhibitor, 2-aminoethxydiphenyl borate, an inositol 1,4,5-trisphosphate receptor antagonist, or bis (o-aminophenoxy) ethane-N,N,N0,N0-tetracetic acid acetoxymethyl ester, a membrane permeable Ca²? chelator. In the present study, we for the fi rst time isolated novel gintonin and showed the signaling pathways on gintonin-mediated CaCC activations and transient increase of [Ca²?]i. Since [Ca²?]i as a second messenger plays a pivotal role in the regulation of diverse Ca²?-dependent intracellular signal pathways, gintonin-mediated regulations of [Ca²?]i might contribute to biological actions of ginseng.