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Inhibitory Effects of Epigallocatechin Gallate on Apoptosis in Human Vascular Endothelial Cells

혈관내피세포의 세포사멸작용에 대한 (-)Epigallocatechin Gallate의 억제효과

  • 최연정 (한림대학교 생명과학부 식품영양학 전공) ;
  • 최정숙 (한림대학교 생명과학부 식품영양학 전공) ;
  • 이세희 (한림대학교 생명과학부 식품영양학 전공) ;
  • 이용진 (한림대학교 생명과학부 식품영양학 전공) ;
  • 강정숙 (제주대학교 식품영양학과) ;
  • 강영희 (한림대학교 생명과학부 식품영양학 전공)
  • Published : 2002.08.01

Abstract

Oxidative stress contributes to cellular injury following clinical and experimental ischemia/reperfusion scenarios. Oxidative injury can induce cellular and nuclear damages that result in apoptotic cell death. We tested the hypothesis that the catechin flavonoid of (-)epigallocatechin gallate, a green tea polyphenol, inhibits hydrogen peroxide ($H_2O$$_2$)-induced apoptosis in human umbilical vein endothelial cells. The effect of apigenin, a flavone found in citrus fruits, on apoptosis parameters was also examined. A 30 min pulse treatment with 0.25 mM $H_2O$$_2$ decreased endothelial cell viability within 24 hrs by > 30% ; this was associated with nuclear condensation and biochemical DNA damage consistent with programmed cell death. In the 0.25 mM $H_2O$$_2$apoptosis model, 50${\mu}{\textrm}{m}$ (-)epigallocatechin gallate markedly increased cell viability with a reduction in the nuclear condensation and DNA fragmentation. In contrast, equimicromolar apigenin increased cell loss with intense DNA laddering, positive nick-end labeling and Hoechst 33258 staining. Thus, polyphenolic (-)epigallocatechin gallate, but not apigenin flavone, qualify as an antioxidant in apoptosis models caused by oxidative stress. Further work is necessary for elucidating the anti-apoptotic mechanisms of polyphenolic catechins.

본 연구에서는 free radicals의 산화적인 손상에 의한 세포사멸에 있어서 녹차성분의 하나인 (-)epigallocatechin gallate의 억제효과를 규명하였다. 우선 radicals 소거작용에 있어서 (-)epigallocatechin gallate는 탁월한 항산화력을 발휘하였다. 혈관손상과 직결되는 혈관내피세포를 이용하여 hydroxyl radical의 $H_2O$$_2$에 의한 산화적인 손상을 유발시켜 세포생존율을 조사하였는데, (-)epigallocatechin gallate는 100 $\mu\textrm{m}$ 이하의 농도에서는 그 자체 독성이 없었고 $H_2O$$_2$의 산화적 독성효과를 경감시키는 것으로 나타났다. 그러나 flavone인 apigenin은 고농도에서 독성을 가지며 radical 소거활성이 미약하고 $H_2O$$_2$의 산화독성은 경감시키지 못하였다. 다양한 세포사멸 검출법을 이용하여 세포 및 세포핵의 형태학적 양상을 조사한 결과, 0.25mM $H_2O$$_2$에 의한 24시간 이내의 세포죽음은 세포사멸현상에 의하여 초래되었다. 그러나 이러한 세포사멸과정을 겪고 있는 혈관내피세포에 50 $\mu\textrm{m}$ (-)epigallocatechin gallate를 처리한 경우에 세포핵의 응축이나 DNA fragmentation은 사라지고 세포사멸작용을 억제시키는 효과를 보여주었다. 예상한 바와 같이 apigenin의 flavone은 세포사멸 억제효과를 나타내지 못하였다. (-)Epigallocatechin gallate는 녹차에 함유된 catechins의 하나로서 free radicals의 산화적 손상에 의한 세포사멸에 있어서 탁월한 방어적 인 세포생리학적인 기능을 지니고 있으며, 혈관노화 및 혈관손상과 함께 유발되는 세포사멸성 심혈관질환의 예방과 치료에 기능성 식품 신소재로서 활용될 수 있으리라 본다.

Keywords

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