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 Ca 2+ -activated Cl -channel (CaCC) in Xenopus oocytes and transiently increase intracellular free Ca 2+ concentration ([Ca 2+ ] 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 Ca 2+ 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 [Ca 2+ ] i . Since [Ca 2+ ] i as a second messenger plays a pivotal role in the regulation of diverse Ca 2+ -dependent intracellular signal pathways, gintonin-mediated regulations of [Ca 2+ ] i might contribute to biological actions of ginseng.

Gintonin, a Ginseng-Derived Lysophosphatidic Acid Receptor Ligand, Potentiates ATP-Gated P2X1 Receptor Channel Currents

“…Gintonin was applied between the third and fourth ATP applications. Gintonin elicited an endogenous Ca 2+ -activated Cl -channel (CaCC) current (Pyo et al, 2011). Gintonin also significantly potentiated the amplitude of subsequent I ATP responses by 2-3-fold, as compared with the third I ATP (Fig.…”

“…We previously demonstrated that gintonin evoked a [Ca 2+ ] i transient and activated endogenous CaCC in Xenopus oocytes via LPA receptor activation (Hwang et al, 2012;Pyo et al, 2011). Thus, the main action of gintonin is to induce a transient elevation of Ca 2+ from the endoplasmic reticulum, and the re- leased Ca 2+ can subsequently influence diverse Ca 2+ -dependent ion channel and receptor activities (Hwang et al, 2012;Pyo et al, 2011).…”

“…Thus, the main action of gintonin is to induce a transient elevation of Ca 2+ from the endoplasmic reticulum, and the re- leased Ca 2+ can subsequently influence diverse Ca 2+ -dependent ion channel and receptor activities (Hwang et al, 2012;Pyo et al, 2011). However, in the present study, although we observed that gintonin-mediated Ca 2+ release is coupled to endogenous CaCC activation, we found that gintonin-mediated Ca 2+ release did not mediate I ATP potentiation because the membrane-permeable Ca 2+ chelator, BAPTA-AM, had no effect on the gintonin-mediated I ATP potentiation.…”

“…Gintonin devoid of ginseng saponins was prepared from Panax ginseng according to method of Pyo et al (2011). Gintonin used in this study was dissolved in dimethyl sulfoxide (DMSO) and then diluted with bath medium before use.…”

“…However, the active ingredients and the underlying molecular mechanism by which ginseng exerts its diverse effects are not fully understood. Recently, we isolated a novel ligand of the ginseng-derived G protein-coupled lysophosphatidic acid (LPA) receptor, gintonin (Hwang et al, 2012;Pyo et al, 2011). We demonstrated that gintonin activates LPA receptors with high affinities in cells expressing LPA receptors endogenously or heterologously (Hwang et al, 2012).…”