Abstract
Lipid-soluble fractions extracted with methylene chloride and ethyl acetate as well as 70% ethanolic extract were made from 5 cultivars of the pigmented rice brans (DZ 78, Elwee, LK1A-2-12-1-1, LK1-3-6-12-1-1 and Killimhukmi) to determine their antioxidative activities and to measure the contents of phenolic compounds, phytic acid, together with unsaponificated compounds such as retinol, tocopherol and stigmasterol. We also attempted to characterize candidate components in charge of antioxidation and measure their relative contents in each methylene chloride and ethyl acetate fraction by using GC-MS techniques. As the results, we found a 30% higher antioxidative activity with 26-fold greater phenolic compound content of the pigmented rices as compared to those of the normal rice. Especially, in Killimhukmi, the contents of the unsaponificated compounds such as retinol, tocopherol and stigmasterol were also found to be more than 2.3-fold greater than those of normal rice. However, we could not find the overall correlations between antioxidativity of rices and their color values, or unsaponificated compounds contents. Methylene chloride fraction from Killimhukmi and LK1A-2-12-1-1, both showing strong antioxidativity, contained relatively high contents of (Z)-9-hexadecenyl ester-9-octadecanoic acid and 2-Hydroxyl-1-1(hydroxymethyl) ethyl-9-octadecanoic acid, respectively. In ethyl acetate fractions, on the contrary, 1H indene, methyl ester-tetradecanoic acid and methyl ester-hexadecanoic acid were detected as the commonly-occurring substances in the 5 cultivars of pigmented rices, implying a possible role in antioxidative action.
5품종의 유색미(DZ 78, Elwee, LK1A-2-12-1-1, LK1-3-6-12-1-1, 길림흑미) 겨 70% 에탄올 추출물 및 염화메틸렌 및 에틸아세트로 추출한 지용성 분획들의 DPPH radical 소거활성을 측정하고 페놀성화합물 및 피틴산, 그리고 불검화물로서 retinol, tocopherol과 stigmasterol의 함량을 정량하였다. 또한 GC-MS를 사용하여 염화메틸렌 및 에틸아세트 분획이 함유한 구성분을 동정하고 상대적 함량을 측정함으로써 항산화 활성의 발현에 필요할 것으로 보이는 성분들을 조사하고자 하였다. 그 결과, 유색미의 항산화성은 일반미보다 약 30%정도 더 높았고, 페놀성화합물의 함량은 일반미보다 26배까지 더 많았다. 특히 길림흑미는 retinol이나 tocopherol, stigmasterol 같은 불검화물의 함량이 일반미보다 2.3배 이상 더 많았다. 그러나 항산화성과 색도 및 불검화물의 함량과는 전반적인 상관성은 없었다. 항산화성이 강한 길림흑미 및 LK1A-2-12-1-1의 염화메틸렌 분획은 각각 (Z)-9-Hexadecenyl ester-9-octadecanoic acid 및 2-Hydroxyl-1-1(hydroxymethyl)ethyl-9-octadecanoic acid의 상대적 함량이 높았다. 반면, 에틸아세트 분획에서는 1H Indene과 Methyl ester-tetradecanoic acid 및 Methyl ester-hexadecanoic acid가 5품종 유색미에서 공통적으로 검출되어, 이들 화합물이 항산화성에 관여할 가능성을 시사하였다.
