Morales Noppawan Phumala, Sirijaroonwong Srisuporn, Yamanont Paveena, Phisalaphong Chada
Department of Pharmacology, Faculty of Science, Mahidol University.
Biol Pharm Bull. 2015;38(10):1478-83. doi: 10.1248/bpb.b15-00209.
The quantitative free radical scavenging capacity of curcumin and its demethoxy derivatives (demethoxycurcumin (Dmc) and bisdemethoxycurcumin (Bdmc)) and hydrogenated derivatives (tetrahydrocurcumin (THC), hexahydrocurcumin (HHC) and octahydrocurcumin (OHC)) towards 1,1-diphenyl-2-picryl hydrazyl (DPPH), nitric oxide radical (NO), hydroxyl radical (HO(·)) and superoxide anion radical (O2(·)) were investigated by electron paramagnetic resonance (EPR) spectroscopy. One mole of the hydrogenated derivatives scavenged about 4 mol of the DPPH radical, while curcumin and Dmc scavenged about 3 mol of the DPPH radical. Curcumin and THC showed moderate scavenging activity towards NO, yielding 200 mmol of NO scavenged per 1 mol of the scavenger. In contrast, curcumin and its derivatives showed very low scavenging activity towards HO(·) and O2(·), yielding approximately only 3-12 mmol scavenged per 1 mol of the tested compounds. Our results suggest that curcumin and its derivatives principally act as chain breaking antioxidants rather than as direct free radical scavengers. Furthermore, we showed that the ortho-methoxyphenolic group and the heptadione linkage of these molecules greatly contributed to their DPPH and NO scavenging activity.
通过电子顺磁共振（EPR）光谱研究了姜黄素及其去甲氧基衍生物（去甲氧基姜黄素（Dmc）和双去甲氧基姜黄素（Bdmc））以及氢化衍生物（四氢姜黄素（THC）、六氢姜黄素（HHC）和八氢姜黄素（OHC））对1,1-二苯基-2-苦基肼（DPPH）、一氧化氮自由基（NO）、羟基自由基（HO(·)）和超氧阴离子自由基（O2(·)）的定量自由基清除能力。1摩尔氢化衍生物可清除约4摩尔DPPH自由基，而姜黄素和Dmc可清除约3摩尔DPPH自由基。姜黄素和THC对NO表现出中等清除活性，每1摩尔清除剂可清除200毫摩尔NO。相比之下，姜黄素及其衍生物对HO(·)和O2(·)的清除活性非常低，每1摩尔测试化合物仅能清除约3 - 12毫摩尔。我们的结果表明，姜黄素及其衍生物主要作为链断裂抗氧化剂而非直接的自由基清除剂起作用。此外，我们还表明这些分子的邻甲氧基酚基团和庚二酮键对其DPPH和NO清除活性有很大贡献。
