Antioxidant Activity of Extract from Walnut Uuglans sinensis Dode) and Its Protective Effect on Cell Injury and Lipid Peroxidation in Renal Cortical Slices

To investigate the antioxidant activity of extract from the raw walnut, Juglans sinensis Dode, we prepared five fractions (methanol (MeOH), dichloromethane $(CH_2Cl_2)$, ethyl acetate (EtOAc), n-buthanol (n-BuOH) and dehydrogen monooxide $(H_2O)$ fractions) and examined. The effect of walnut extract on the oxidative stress was investigated in vitro. The DPPH (2,2-Di (4-tert-octylphenyl)-1-picrylhydrazyl) free radical scavenging activity of extract from raw walnut was shown in the following order: $EtOAc\;fraction was observed in EtOAc fraction, whereas n-BuOH fraction, MeOH fraction, $CH_2O_2$ fraction and $H_2O$ layer of $IC_{50}$ were $2.34{\mu}g//ml,\;3.88{\mu}g/ml,\;8.06{\mu}g/ml,\;and\;8.19{\mu}g/ml$, respectively. The radical scavenging activity assay of each fraction showed that the antioxidative activity was observed in the following order: EtOAc fraction $(74.27\pm1.56\%)>MeOH\;fraction\;(60.76\pm3.4\%)>n-BuOH\;fraction\;(59.32\pm0.88\%)>H_2O\;layer\;(41.69\pm2.06\%)$. These results revealed that all fractions, except for $CH_2Cl_2$ fraction, showed high antioxidative activity. Furthermore, the peroxynitrite $(ONOO^-)$ scavenging activity was assayed in each fraction. The result showed that the $ONOO^-$ scavenging activity of EtOAc fraction, MeOH fraction and n-BuOH fraction from raw walnut was $95.14\pm0.36\%,\; 90.02\pm1.19\%\;and\;89.41\pm0.81\%$, respectively. The tert-butylhydroperoxide (t-BHP) treatment in vitro increased lactate dehydrogenase release and lipid peroxidation in renal cortical slices. Such changes were completely prevented by addition of MeOH fraction, EtOAc fraction and n-BuOH fraction of walnut. These results indicate that the walnut extract exerts the benedicial effect against t-BHP-induced cell injury and its effect may be due to antioxidant action. In addition, it is suggested that walnut extract might be developed as the effective scavenger for the prevention of oxidative stress.

호두 추출물의 항산화 활성과 신피질에서 세포 손상과 지질과산화 방지효과

본 연구에서는 호두박 분획층의 항산화 활성을 검색하기 위해 MeOH, $CH_2Cl_2$, EtOAc, BuOH 그리고 $H_2O$ 분획으로 추출하여 수행하였고, 각 분획층의 산화적 세포손상과 지질 과산화의 방지 효과를 in vitro에서 확인하였다. 그 결과 호두박의 free radical (DPP보 radical) 소거 활성은 EtOAc층에서 가장높게 나타났고, 활성산소종 억제율과 peroxynitrite $(ONOO^-)$ 소거 활성은 $CH_2Cl_2$층을 제외한 모든 분획층에서 높게 나타났다. 신피질 절편에 t-BHP의 처리 시 LDH의 방출과 지질과 산화를 증가시켰고 이러한 변화는 호두의 MeOH, EtOAc, n-BuOH 분획에 의해서 완전하게 방지되었다. 이러한 결과는 호두 추출물이 t-BHP에 의한 신장 세포 손상에 효과적이고 이러한 효과는 항산화력에 의한 것으로 추측된다. 또한 이러한 결과는 호두 추출물에서 많은 질병의 원인이 되고 있는 산화적 스트레스를 방지할 수 있는 효과적인 약물 개발의 가능성을 시사한다