대황으로부터 추출한 rhapontin을 산업용 효소로 가수분해하여 rhapontigenin을 제조하고 kojic acid, hydroquinone 및 ascorbic acid를 비교물질로 한 tyrosinase 활성저해 실험과 S. bikiniensis를 이용한 멜라닌 생성 억제효과 실험을 통해 미백효과에 대한 가능성을 확인하였다. Rhapontin과 rhapontigenin의 결과를 비교해 보면 rhapontigenin의 경우 tyrosinase활성저해 및 멜라닌 생성 억제능이 증가하는 것으로 나타났다. 따라서 rhapontin을 효소 가수분해하여 생성된 rhapontigenin은 미백능이 월등히 증가된 천연 미백화장품소재로 개발될 수 있을 것으로 기대된다.
Rhapontin is the glycosylated stilbene compound, and comprising major component of rhubarb root extract. Rhapontin has been used as a raw material of skin-whitening cosmetics in Korea. Rhapontigenin, the aglycone of rhapontin, has been suggested to be more active than its glycosylated form. Therefore, the rhubarb root extract was treated with commercial enzyme, Pectinex to remove glycosylated moiety of rhapontin and rhapontigenin was prepared. The resulting material was analysed and identified as rhapontigenin by proton NMR and MALDI-Mass. Rhapontigenin exhibited tyrosinase inhibitory activity with an $IC_{50}$ of $126.72{mu}g/mL$. The tyrosinase inhibitory activity of rhapontigenin was six times higher than that of rhapontin. In melanin biosynthesis inhibition assay using Streptomyces bikiniensis, rhapontigenin showed wider inhibition zone than that of rhapontin. From these results, we expect that rhapontigenin has stronger skin whitening effect than rhapontin and has advantages in cosmetic industry.
