클로로필을 제거한 영하구기엽 에탄올 추출물의 항산화 활성

Purpose: The aim of this study was to estimate the antioxidant activities of 50%, 70%, and 100% ethanol extracts of Lycium barbarum leaf and chlorophyll removal extract. Methods: The antioxidant activities were estimated by measuring total polyphenol content and by assays of 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfate) (ABTS) radical scavenging activities and ferric reducing antioxidant power (FRAP). In addition, reactive oxygen species (ROS) production, DNA fragmentation, and antioxidant enzyme (superoxide dismutase and catalase) activities of the extracts were measured in hydrogen peroxide ($H_2O_2$)-stressed HepG2 cells. Results: The total polyphenol content, DPPH and ABTS radical scavenging activities, and FRAP value of the extracts increased in an ethanol concentration-dependent manner. The antioxidant activities of the chlorophyll-removal extracts were much higher than those of the chlorophyll-containing extracts. Cytotoxicity was not observed in HepG2 cells with extracts up to $1,000{\mu}g/mL$. All extracts inhibited ROS production in a concentration-dependent manner from $31.3{\mu}g/mL$ and inhibited DNA damage at $250{\mu}g/mL$. The SOD and catalase activities of cell lines treated with the extracts and $H_2O_2$ were similar to those of normal cells, indicating a strong protective effect. Conclusion: Lycium barbarum leaf extracts had high antioxidant activities and protected $H_2O_2$-stressed HepG2 cells. Since the chlorophyll-removal extract exhibited higher antioxidant activities than the chlorophyll-containing ones and the cytoprotective effect was similar, chlorophyll removal extract of Lycium barbarum leaf could be developed as ingredients of functional food and cosmetics. 본 연구에서는 구기엽의 항산화 활성을 확인하고자 50%, 70%, 100% 에탄올 추출물과 100% 에탄올 추출물에서 클로로필을 제거한 시료를 포함하여 총 4종 시료의 항산화 활성을 비교하였다. 항산화능을 측정하기 위하여 총 폴리페놀 함량, DPPH와 ABTS radicals 소거능, FRAP assay를 통해 시료의 항산화능을 평가하였다. 또한 $H_2O_2$처리로 산화적 스트레스를 유발한 HepG2세포주에서 추출물 들이 세포보호 효과를 나타낼 수 있는지 알아보고자 ROS 생성, DNA fragmention, 세포의 항산화효소활성 (SOD와 catalase)을 측정하였다. 연구결과, 총 폴리페놀 함량, DPPH와 ABTS radicals 소거능, 그리고 FRAP value에서 모두 추출용매의 알코올 농도가 높을수록 증가하였고 클로로필 제거 시료가 제거 전 시료에 비하여 월등히 높았다(p < 0.05). HepG2세포에서 세포독성을 확인한 결과 모든 시료에서 $1,000{\mu}g/mL$까지 세포독성을 유발하지 않았다. 모든 추출물들은 $31.3{\mu}g/mL$ 농도부터 $H_2O_2$에 의해 증가한 ROS생성량을 농도 의존적으로 감소시키는 효과를 보였다 (p < 0.05). 모든 추출물은 $250{\mu}g/mL$의 농도로 배양액에 처리하였을 때 세포의 DNA 손상을 억제하는 효과를 보여주었다 (p < 0.05). 또한 $H_2O_2$처리한 세포에 비하여 추출물들을 함께 처리한 세포군의 SOD와