거대배아미 에탄올 추출물의 항산화활성을 지질과산화 억제활성 및 활성산소종의 소거활성을 중심으로 일반미와 대조하여 검토하였다. 연구 결과, 발아처리는 전반적으로 환원력 및 지질과산화 억제활성, superoxide radical 및 hydroxyl radical 소거활성을 상승시켰으며, 발아처리에 의한 항산화 활성의 증가현상이 화청거대배아미에서 가장 뚜렷하였다. Superoxide radical 소거작용에 있어서는 남풍거대배아미가 전체적인 소거활성은 높았으나, 발아처리에 의한 활성의 상승률은 역시 화청거대배아미가 가장 높았고, 그 작용기작은 시료에 의한 직접적인 radical 소거에 있는 것으로 나타났다. 생체 독성이 가장 큰 hydroxyl radical 소거활성을 조사한 결과, 화청거대배아미가 전체적인 소거활성 뿐 아니라, 발아처리에 의한 소거활성의 증가율도 가장 높았으며, 그 작용기작도 $Fe^{2+}$의 포족이 아닌 직접적인 라디칼 소거임이 밝혀졌다. 이와 같은 in vitro에서 관찰된 시료의 ROS 소거활성은 TPA하여 유도된 HL-60 세포의 ROS 생산을 억제하는데 유효하게 작용하였다.
Antioxidant activity of ethanolic extract of two giant embryonic rices, Nampung giant embryonic rice and Hwachung giant embryonic rice, were investigated mainly focusing on their ability to inhibit lipid peroxidation and scavenge reactive oxygen species in comparison with those of general rice. The results showed that germination process increased reducing power, inhibitory activity on lipid peroxidation and scavenging ability either on superoxide or hydroxyl radicals. Among the cultivars tested, increase in antioxidative action was found to be most prominent for Hwachung giant embryonic rice cultivar. For scavenging of superoxide radicals, the extract from Nampung giant embryonic rice has the most potent activity, however, increasing rate of scavenging activity by germination process was also found to be the greatest for Hwachung giant embryonic rice. We found that the scavenging mechanism for superoxide radicals was attributed to the direct scavenging of the radicals. The scavenging of hydroxyl radicals, the most toxic oxygen radical to biological system, by the rice extracts were also examined, and the results showed that either overall activity or the increasing rate of the activity to scavenge hydroxyl radicals by germination process was the greatest for Hwachung giant embryonic rice. Moreover, the results suggested that the scavenging action to hydroxyl radicals might be mediated by direct quenching of the radicals, not by chelating $Fe^{2+}$. Further studies showed that the antioxidant action of the rice extracts tested in vitro was also operative for suppressing ROS production induced in TPA-stimulated HL-60 cells.
