고구마 페놀화합물의 항산화 활성

Phenolic Compounds in Sweet Potatoes and Their Antioxidative Activity

식용유지에 대한 고구마 추출물의 항산화능을 검토하기 위하여 linoleic acid와 돈지에 70% methanol 고구마 추출물을 가하여 $60^{\circ}C$에서 저장하면서 POV를 측정하여 항산화능을 비교하였으며, 고구마 항산화 성분을 추출하여 HPLC를 이용하여 정성, 정량하여 다음과 같은 결과를 얻었다. 70% methanol 고구마 추출물의 항산화능은 목포18이 율미보다, 껍질부위가 속부위보다 강한 항산화활성을 나타내었다. 고구마 페놀화합물 3개 분획 중 가장 강한 항산화능을 보인 것은 free phenolic acids(fraction-I)층 분획이었다. 껍질부위의 free phenolic acids 항산화능은 속부위보다 강하였고 율미가 목포18보다 항산화능이 높았다. 고구마 항산화 성분인 페놀화합물을 HPLC로 분석한 결과 caffeic acid와 chlorogenic acid이었고, 함량은 caffeic acid는 율미껍질에 68.4mg%, 율미속에 2.8mg%, 목포18껍질에 47.2mg%, 목포18속에 4.6mg% 함유되어 있었으며, chlorogenic acid는 각각 67.4mg%, 1mg%, 92.6mg%, 1.2mg% 이었다. Linoleic acid-emulsion에 대한 항산화능은 caffeic acid가 chlorogenic acid보다 높게 나타났다.

The phenolic compounds of Korean sweet potatoes, Mokpo 18 and Yulmi, were extracted by using 70%-methanol and the extracts(ME) were fractionated and obtained three fractions such as free phenolic acid(FPAF), soluble phenolic acid ester(SPAF) and insoluble bound phenolic acid(BPAF) fractions. The antioxidative activities(AA) was represented as the peroxide values(POVs). The POVs were calculated by measuring the oxidation of linoleic acid and lard emulsions at $60^{\circ}C$. AA of FPAF has shown the most effective. AA of FPAF were more effective than those of ME in both Yulmi and Mokpo 18. AA of the ME of Mokpo 18 were more effective than those of Yulmi, however, those of FPAF in Ulmi were more effective than in Mokpo 18. The POVs of ME and FPAF of the peel part in both sweet potatoes were more effective than those of peeled part. The qualitative and quantitative analysis of the phenolic compounds in both sweet-potatoes were performed by using high performance liquid chromatography(HPLC) and the major phenolic compounds were identified as chlorogenic acid and caffeic acid. The contents of caffeic acid were 0.684mg/g in the peel part and 0.028mg/g in the peeled part of Yulmi and 0.472mg/g in the peel part and 0.046mg/g in the peeled part of Mokpo 18 and those of chlorogenic acid was 0.674mg/g, 0.926mg/g, and 0.012mg/g, respectively. In comparative test of antioxidative activities between a standard chlorogenic acid and caffeic acid, AA of caffeic acid were more effective than those of chlorogenic acid.