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 (H2O2)-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 μg/mL. All extracts inhibited ROS production in a concentration-dependent manner from 31.3 μg/mL and inhibited DNA damage at 250 μg/mL. The SOD and catalase activities of cell lines treated with the extracts and H2O2 were similar to those of normal cells, indicating a strong protective effect. Conclusion: Lycium barbarum leaf extracts had high antioxidant activities and protected H2O2-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. (http://creativecommons. org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 서 론 구기자 (Lycii fructus)는 가지과 (Solanceae)에 속한 구 기자 나무의 성숙한 과실을 건조한 것으로 우리나라를 비롯한 중국, 대만, 일반 등지에서 자생하거나 재배되고 있는 생약재로 한방에서는 인삼 등과 함께 독성이 없는 120종의 상약 (上藥)군으로 취급하고 있다 [1]. 구기자나 무의 종류는 상당히 많으나 그 열매를 식용으로 사용하는 나무 중 잘 알려진 것으로 한국의 청양 등에서 주로 재배 되는 Lycium chinense Miller와 중국, 티벳, 몽고 등에서 재배되는 Lycium barbarum Linne (영하구기자)로 볼 수 있다 [2]. 구기자에는 carotinoid, choline, zeaxanthin, physalin (dipalmity-zeaxanthin), vitamin B1과 meliscic acid 등의 불 포화지방산과 같은 영양성분이 다량 함유되어 있고, 또한 phytochemical로서 β-sitosterol, betaine과 rutin과 같은 기 능성 성분이 함유되어 있다. 이에 따라 구기자의 항암 [3], 면역증진 [4], 간 기능 개선효과 [5], 혈중 지질 저하 [6] 등 의 효능에 대한 연구가 진행되었다. 구기엽의 성분으로는
