Abstract
To examine antitumor activity of the edible plant Zanthoxylum schinifolium, the cytotoxic effect of various organic solvent extracts of its stems on human acute leukemia Jurkat T cells was investigated. Among these extracts such as methanol extract (SS-7), methylene chloride extract (SS-8), ethyl acetate extract (SS-9), n-butanol extract (SS-10), and residual fraction (SL-11), SS-8 exhibited the most cytotoxic activity against Jurkat T cells. The methylene chloride extract (SS-8) possessed the apoptogenic activity capable of inducing sub-G1 peak along with apoptotic DNA fragmentation in Jurkat T cells. Western blot analysis revealed that SS-8 induced apoptosis via mitochondrial cytochrome c release into cytoplasm, subsequent activation of caspase-9 and caspase-3, and cleavage of PARP, which could be blocked by overexpression of Bcl-xL. Jurkat T cell clone I2.1 $FADD^{-/-}$) and Jurkat T cell clone I9.2 (caspase-$8^{-/-}$ were as sensitive as was the wild-type Jurkat T cell clone A3 to the cytotoxic effect of SS-8, suggesting no contribution of Fas/FasL system to the SS-8-mediated apoptosis. The GC-MS analysis of SS-8 showed that it was composed of 16 ingredients including 9,12-octadecanoic acid (18.62%), 2,4-dihydro-5-methyl-4- (1-methylethylidene)- 2-(4-nitrophenyl)-3H- pyrazol-3-one (14.97%), hexadecanoic acid (14.23%), (z,z)-6,9-pentadecadien- 1-ol (13.73%), 5,6-dimethoxy-2-methyl benzofuran (10.95%), and 4-methoxy-2-methylcinnamic acid (5.38%). These results demonstrate that the methylene chloride extract of the stems of Z. schinifolium can induce apoptotic cell death in Jurkat T cells via intrinsic mitochondria-dependent caspase cascade regulated by Bcl-xL without involvement of the Fas/FasL system.
식용 및 약용으로 이용되는 산초(Zanthoxylum schinifolium)의 줄기로부터 항암활성 성분을 분리하기 위하여, 산초 줄기를 유기용매로 추출하고 각 추출물의 인체 급성백혈병 암세포에 대한 독성 및 세포자살 유도 활성을 조사하였다. Methanol (SS-7), methylene chloride (SS-8), ethyl acetate (SS-9), n-butanol (SS-10)로 추출한 각 시료와 유기용매 추출 후 잔여분획 (SL-14)의 세포 독성을 인체 급성백혈병 Jurkat T 세포주를 대상으로 조사한 결과, 암세포에 대한 세포독성이 주로 methylene chloride 추출분획인 (SS-8)에서 확인되었다. Methylene chloride 추출물 (SS-8)의 Jurkat T 세포주에 대한 세포독성의 기전은 mitochondria로부터cytochrome c 방출, caspase-9 및 caspase-3의 활성화, PARP 분해, internucleosomal DNA fragmentation 등의 일련의 생화학적 반응을 수반하며, 항 세포자살단백질인 Bcl-xL단백질의 과발현에 의해 억제되는 세포자살 기전임을 확인하였다. FADD가 disruption된 Jurkat T cell clone I2.1 ($FADD^{-/-}$) 및 caspase-8가 결핍된 Jurkat T cell clone I9.2 (caspase-$8^{-/-}$)와 함께 the wild-type Jurkat T cell clone A3에 미치는 SS-8의 세포독성작용을 비교 분석한 결과, wild-type Jurkat A3, FADD-deficient Jurkat clone I2.1및 caspase-8-deficient Jurkat clone I9.2 모두는 SS-8의 세포독성에 대해 유사한 정도의 감수성을 나타내었다. 이는 SS-8에 의해 유도되는 apoptosis에 있어서, Fas/FasL system이 관계되지 않음을 시사한다. 한편, SS-8를 GC-MS 분석하여, 9,12-octadecanoic acid (18.62%), 2,4-dihydro-5-methyl-4-(1-methylethylidene)-2-(4-nitrophenyl)- 3H-pyrazol-3-one (14.97%), hexadecanoic acid (14.23%), (z,z)-6,9-pentadecadien-1-ol (13.73%), 5,6-dimethoxy- 2-methyl benzofuran (10.95%), 그리고 4-methoxy-2-methylcinnamic acid (5.38%) 등을 포함한 16가지의 구성 성분과 그 조성비를 확인하였다. 이상의 연구결과는 산초 줄기에 함유된 항암 활성에 대한 규명과 이해를 증진시킨다.