去氫梔子甘(geniposide)是梔子 (Gardenia jasminoides Ellis)中的主要成份，其結構為一iridoid型之配醣體。對於去氫梔子甘在肝細胞處於氧化壓力時的保護特性是北研究中第一次被提出。當我門利用巴拉割(paraquat)在濃度5mM與黃嘌呤/黃嘌呤氧化酵素(xanthine/xanthine oxidase)在濃度5μM/0.01μ/ml處理之下能產生活性氧系(reactive oxygen species;ROS)進而造成初代培養之肝細胞(primary culture hepatocyte)的傷害。利用巴拉割與黃嘌呤/黃嘌呤氧化酵素這兩種系統皆可以顯著的提高肝細胞的乳酸去氫酵素(lactate dehydrogenase;LDH)、丙氨酸轉氨酵素(alanine transaminas;ALT)以及脂肪酸過氧化的產物丙二醛酸(malondialdehyde;MDA)而造成肝細胞的毒性，但是可以有效的被去氫梔子甘(0.1mM)所抑制。另外巴拉割與黃嘌呤/黃嘌呤氧化酵素這兩種系統產生的含氧自由基(oxyradical)所造成的DNA損傷則是以UDS(unscheduled DNA synthesis)方法來測肝細胞DNA修補的量，發現加入去氫梔子甘(0.02-0.1mM)能夠降低這二種系統引起之基因毒性。研究中也發現去氫梔子甘並不能抑制藉由黃嘌呤/黃嘌呤氧化酵素所產生的超氧陰離子(superoxide anion),但能捕捉部分DPPH(1,1-diphenyl-2-picryhydrazyl)自由基。對於抗氧化酵素方面，去氫梔子甘可以提高glutathione peroxidase(GSH-Px)與catalase的活性。總結而論，去氫梔子甘可能藉由捕捉部分的自由機和提升一些抗氧化酵素(GSH-Px和catalase)的活性來降低肝細胞在遭遇氧化壓力時的傷害。 Geniposide is an iridoid glycoside in the fruit of Gardenia jasminoides Ellis.Its properties of properties of protecting hepatocyte subjected to oxidative stress were first investigated. Paraquat(PQ:5mM)and xanthine/xanthine oxidase system (X/XO:5μM/0.01μ/ml)can generate reactive oxygen species(ROS)which will induce oxidative damage to primary hepatocyte.PQ or X/XO system increased the leakage of lactate dehydrogenase (LDH)and alanine transaminase (ALT) and the formation of malondialdehyde (MDA) but the hepatotoxicity was significantly suppressed by the pretreatment of generation by PQ or X/XO system caused DNA damage was evaluated with unscheduled DNA synthesis (UDS) in the rat primary hepatocyte. Addition of geniposide (0.02~0.1mM) decreased genotoxicity evaluated by UDS in both system. Geniposide did not inhibit the generation of superoxide anion in X/XO system but qenotoxicity the free radical of 1,1-diphenyl-2-picryhydrazy(DPPH). Geniposide elevated the activities of catalase and glutathione peroxidase (GSH-Px) in time course studies. It is concluded that the protective action of geniposide subjected to oxidative stress were via quenching free radical and/or elevating defending enzymes(catalase and GSH-Px).
