Effect of Phenolic Extract of Dry Leaves of Lespedeza cuneata G. Don on Antioxidant Capacity and Tyrosinase Inhibition

야관문 잎 페놀 추출물의 항산화능 및 미백 효과

  • Cho, Eun-Jung (Department of Food Science and Technology, Kyung Hee University) ;
  • Ju, Hyun-Mi (Department of Food Science and Technology, Kyung Hee University) ;
  • Jeong, Chang-Ho (Department of Food Science and Technology, Kyung Hee University) ;
  • Eom, Seok-Hyun (Department of Horticultural Biotechnology, Kyung Hee University) ;
  • Heo, Ho-Jin (Department of Food Science and Technology, Institute of Agriculture and Life Science, Gyeongsang National University) ;
  • Kim, Dae-Ok (Department of Food Science and Technology, Kyung Hee University)
  • 조은정 (경희대학교 식품공학과) ;
  • 주현미 (경희대학교 식품공학과) ;
  • 정창호 (경희대학교 식품공학과) ;
  • 엄석현 (경희대학교 원예생명공학과) ;
  • 허호진 (경상대학교 식품공학과) ;
  • 김대옥 (경희대학교 식품공학과)
  • Received : 2011.01.24
  • Accepted : 2011.05.24
  • Published : 2011.08.30

Abstract

Lespedeza cuneata G. Don is a plant commonly grown in Asian countries, which has been widely used as an oriental medicinal herb to treat diabetes, diarrhea and various other inflammatory diseases. The phenolics of dry leaves of L. cuneata G. Don were extracted by using 80% (v/v) aqueous methanol in assistance with homogenization and sonification. The phenolic extract and its five different fractions (n-hexane, chloroform, ethyl acetate, n-butanol, and water) were used to evaluate the levels of total phenolics, total flavonoids, and antioxidant capacity as well as the inhibitory effect of tyrosinase activity. Ethyl acetate fraction (1 g) had the highest levels of total phenolics at 240.8 mg gallic acid equivalents (GAE), total flavonoids as 90.4 mg catechin equivalents (CE) as well as antioxidant capacity at 523.4 mg vitamin C equivalents (VCE) on ABTS assay and 329.5 mg VCE on DPPH assay among fractions. One g of water fraction contained total phenolics at 133.1 mg GAE, total flavonoids at 34.5 mg CE, and antioxidant capacity at 333.4 mg VCE for ABTS assay and 313.2 mg VCE for DPPH assay. Inhibition of tyrosinase activity of water fraction at 300 ${\mu}g{\cdot}mL^{-1}$ was at 47.2% and 21.1% for L-tyrosine and L-DOPA as its substrate, respectively. On the other hand, ethyl acetate fraction at 300 ${\mu}g{\cdot}mL^{-1}$ showed tyrosinase inhibition of 10.2% for L-tyrosine and 11.9% for L-DOPA. These results suggested that the phenolics from dry leaves of L. cuneata G. Don may be utilized as a potent source of antioxidants and skin whitening agents.

야관문은 당뇨병, 설사, 여러 염증성 질병의 치료에 널리 이용되어진 약초로서 아시아 지역에서 흔히 자라는 식물이다. 야관문의 총페놀 함량, 총플라보노이드 함량, 항산화능과 tyrosinase 활성 저해능 평가를 통한 미백효능을 연구하고자 80%(v/v) 수용성 메탄올을 이용한 페놀 추출물과 이 추출물로부터 극성이 서로 다른 5개 분획층(n-hexane, chloroform, ethyl acetate, n-butanol, 물)의 기능성을 평가하고자 총페놀 함량과 총플라보노이드 함량을 측정하였고, 아울러 항산화능을 ABTS와 DPPH radical 소거능을 이용하여 정량 평가하였다. 건조 야관문 잎 1g의 추출물은 총페놀 함량이 199.4mg GAE, 총플라보노이드 함량이 60.4mg CE, 항산화능은 416.6mg VCE(ABTS 분석)와 366.8mg VCE(DPPH 분석)을 보였다. 극성이 서로 다른 5개의 분획층에서 ethyl acetate 분획층이 총페놀 함량(240.8mg GAE), 총플라보노이드 함량(90.4mg CE), 그리고 항산화능(523.4mg VCE(ABTS 분석), 329.5mg VCE(DPPH 분석))에서 유의적으로 가장 높은 수준을 가졌다. 멜라닌 생성 초기 단계에서 가역적 산화반응에 관여하는 tyrosinase 활성 억제능을 평가하는 미백 실험에서는 야관문 페놀 추출물과 chloroform 분획층이 tyrosinase를 효과적으로 억제하였다. 본 연구는 야관문에 생리활성을 부여하는 페놀성 화합물의 항산화능 및 미백효과에 관한 기본적인 정보를 제공함과 아울러 기능성 소재로서 활용 가능성을 제시하였다는데 큰 의미가 있겠다.

Keywords

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