Abstract
Doenjang (Korean fermented soybean paste) is a unique fermented food in Korea. It has been traditionally manufactured from soybeans, by Jang Yang process. We focused on the newly formed compound in highly aged Doenjang and its biological activity. One new o-dihydroxyisoflavone, 7,3',4'-trihydroxyisoflavone and two known o-dihydroxyisoflavone derivatives were isolated from 5-year-old Doenjang and evaluated as potent antioxidant and whitening effect by comparing with other known isoflavone. 7,8,4'-Trihydroxyisoflavone (compound 1), 7,3',4'-trihydroxyisoflavone (compound 2) and 6,7,4'-trihydroxyisoflavone (compound 3) inhibited DPPH (diphenyl-1-picrylhydrazyl) formation by 50 % at a concentration of $21.5{\pm}0.2$, $28.7{\pm}0.4$ and $32.6{\pm}0.6$ ($IC_{50}$) respectively, whereas daidzein showed weak DPPH radical scavenging activity. In superoxide scavenging effect were measured in one assay. Compound 1 ($IC_{50}=18.10{\pm}0.2{\mu}M$) and 2 ($IC_{50}=10.54{\pm}0.4{\mu}M$) show significant inhibitory activity and greater effect than L-ascorbic acid. But compound 3 and daidzein showed lower inhibition activity. Also, o-dihydroxyisoflavone derivatives evaluated as potent inhibitors on tyrosinase activity and melanin formation in melan-a cells. Compound 1 ($IC_{50}=11.21{\pm}0.2{\mu}M$), compound 2 ($IC_{50}=5.23{\pm}0.6{\mu}M$) exhibited significant inhibitory effect on tyrosinase activity. Furthermore, those compounds are significantly suppressed the cellular melanin formation by 50 % at a concentration of $12.23{\pm}0.7{\mu}M$ (1) and $7.83{\pm}0.7{\mu}M$ (2). This result suggests that 7,3',4'-trihydroxyisoflavone from highly aged Doenjang could be used as an active ingredient for cosmetics.
된장은 한국의 독특한 발효 식품이며 장양이라 불리는 전통적인 제조 방법에 의해 제조된다. 이에 본 연구에서는 고숙성 된장에서 새롭게 생성된 성분과 그것의 생리활성을 측정하였다. 5년 숙성된 된장으로부터 새로운 o-dihydroxyisoflavone인 7,3',4'-trihydroxyisoflavone과 기존에 알려진 두 가지의 o-dihydroxyisoflavone을 각각 분리하여 다른 isoflavone과의 항산화 효과 및 미백효과를 비교 측정하였다. Diphenyl-1-picrylhydrazyl (DPPH) 활성 저해 효과는 7,8,4'-trihydroxyisoflavone (compound 1), 7,3',4'-trihydroxyisoflavone (compound 2) 그리고 6,7,4'-trihydroxyisoflavone (compopund 3)은 각각 $21.5{\pm}0.2$, $28.7{\pm}0.4$ 그리고 $32.6{\pm}0.6$ ($IC_{50}$)을 나타낸 반면 daidzein은 이들에 비해 약한 DPPH 활성 저해 효과를 나타냈다. Superoxide 소거 효과는 L-ascorbic acid에 비해 compound 1 ($IC_{50}=18.10{\pm}0.2{\mu}M$)과 2 ($IC_{50}=10.54{\pm}0.4{\mu}M$)가 보다 효과적인 반면 compound 3과 daidzein은 이들에 비해 낮은 활성을 나타냈다. 또한 melan-a cells에서 o-dihydroxyisoflavone 유도체들의 티로시나제 활성과 멜라닌 생성을 비교 측정하였다. 특히 Compound 1 ($IC_{50}=11.21{\pm}0.2{\mu}M$), 2 ($IC_{50}=5.23{\pm}0.6{\mu}M$)의 경우 compound 3과 daidzein에 비해 티로시나제 활성을 억제하는데 효과가 있었으며 또한 멜라닌 생성을 50 % 억제할 때의 결과에서 이들 화합물은 각각 $12.23{\pm}0.7{\mu}M$ (1), $7.83{\pm}0.7{\mu}M$ (2)과 같이 멜라닌 생성 억제 효능을 나타내었다. 따라서 고숙성 된장에서 유래한 7,3',4'-trihydroxyisoflavone은 항산화 및 미백효과를 가지는 화장품 소재로써 사용 가능하리라 판단된다.
