본 연구는 메조-디하이드로구아레틱산(MDGA, 1)과 합성 유도체(2와 3)의 일산화질소(NO)억제 효능 에 대한 내용이다. MDGA는 토후박(Machilus thunbergii Sieb. et Zucc.)껍질에서 분리된 리그난 화합물이다. 본 연구자들은 디메틸로 치환된 화합물(2)과 디아세틸로 치환된 화합물(3)을 합성하였고, 이 두 화합물의 일산 화질소 억제 효능을 MDGA (1)와 비교하여 측정하였다. MDGA (1)와 화합물(3)은 LPS에 의해서 유도된 일산 화질소 억제 효능을 나타내었다. RT-PCR 분석을 통해 MDGA (1)와 화합물(3)의 일산화질소 억제 효능은 iNOS의 mRNA 발현의 감소에 기인함을 확인하였다. 이러한 실험 결과로부터 디아세틸로 치환된 화합물(3)은 MDGA의 프로드럭으로 사용될 수 있음을 확인하였다.

Background : Kenaf (Hibiscus cannabinus L.) is a member of the malvaceae family and has been prescribed in traditional folk medicine in Africa and India. It showed broad biologicas activities such as hepatoprotective activity, antioxidative activity and haematinic activity, Recently, immunomodulatory effect of kenaf extract has been elucidated. However, depigmenting activity from kenaf extract has not been evaluated. In the present study, the tyrosinase inhibitory effect of kenaf leaf extract was investigated before and after subjecting the extract to together with infrared(FIR) irradiation. Methods and Results :　FIR irradiation involves electromagnetic waves with wavelengths ranging from 4 to 15 μM. It has been hypothesized that FIR treatment during extraction of polyphenols from plant cells stimulates exudation of chemical components in cells without destroying the cells by radiant heat and breaks covalent bonds of polymerized polyphenols resulting in the release of active, natural antioxidants with a low molecular weight. The purpose of this study was to evaluate not only the changes in antityrosinase activity but also the chemical transformation of kenaf extract exposed to FIR(Scheme 1). Conclusion: The tyrosinase inhibitory activity of kenaf xtract was evaluated after far-infrared (FIR) irradiation. The ethanol extract of kenaf was prepared and its main component was analyzed as a kaempferitrin (kaempferol-3,7-O-a-dirhamnoside). Inhibitory activity of kenaf extract was not detected in tyrosinase assay. However, tyrosinase inhibitory activity was observed in kenaf extract treated with FIR irradiation. After 60 min of FIR irradiation onto kenaf extract at 60oC, a ethanolic extract was prepared and it showed significant tyrosinase inhibitory activity (IC50=3500ppm). According to HPLC analysis, kaempferol, afzelin and minor product were detected(. The inhibitory activity may be due to the existence of kaemperol, afzelin and minor product. This study showed that FIR irradiation method can be used as a convenient tool for deglycosylation of flavonoid glycoside.