- 作者： 曾德賜; 陳瑞祥; 李敏惠
- 作者服務機構： 國立中興大學植物病理學系
- 中文摘要：
甲硫胺酸與核黃素混合物（以下簡稱MR）在光照下對多種微生物具有強烈的殺生作用，此一毒性之造成已知主要
為光反應中各種氧自由基形成之影響。本研究旨在進一步利用電子順磁共振光譜儀(ESR)檢測此一光化反應中氧自由基
之生成作用。以DMPO為自由基捕捉劑，測試結果顯示在pH 4.0之MR中，光照處理15分鐘即可明顯地偵測到一組
1:2:2:1之quartet共振訊號（DMPO-OH?與DMPO-OOH?）及一組1:1:1:1:1:1之sextet共振訊號(DMPO-CH3?)的形成。
添加乙醇於此反應中，可使所測得DMPO-OH?之quartet訊號強度大為減弱，而伴隨之則為DMPO-CH3?sextet訊號之明
顯增強，顯示所偵測到之quartet訊號主要為源自OH?之 DMPO-OH?及源自O2 之 DMPO-OOH?之混合圖譜。至於在
pH 8.0之MR中，同法則僅偵測得quartet訊號，且其在進一步以乙醇添加測試後證實主要為源自02 ? 之 DMPO-OOH?。
另外以2, 2, 6, 6-tetramethyl-4-piperidone為捕捉劑測試則發現，於pH大於8.0之MR中可以很明顯偵測得單重氧(sin-
glet oxygen, O2)之典型1:1:1 triplet共振訊號圖譜，唯此一捕捉劑之作用性在pH小於8.0時很明顯呈一不穩定狀態。進
一步以光電光譜儀利用RNO褪色法測定單重氧之生成則證實，隨著pH之降低，單重氧之生成量有明顯增加之趨勢。
由低pH狀況下明顯測得較高量之OH?與 02之形成作用，再次印證此類激活態氧分子確為MR微生物毒性之關鍵因子。
s - 英文摘要： Upon photolysis, aqueous solution of methionine riboflavin mixture (MR) is strongly biocidal to awide spectrum of microorganisms; MR toxigenicity is caused by producing of various oxygen radicals. Inthis work, we thoroughly examined the generation of oxygen radicals in the photochemical reaction of MRby electron spin resonance（ESR）spectroscopy. At pH 4.0 with 5, 5-dimethyl-1-pyrroline-N-oxide（DMPO)as a spin trap, a prominent quartet signal of DMPO-OH and a sextet signal of DMPO-CH3 appeared 15min after MR illumination. Adding ethanol to this reaction mixture caused DMPO-OH to significantlyreduce and DMPO-CH3 to concomitantly increase. This occurrence suggests that DMPO-OH detected isa combination of OH -derived DMPO-OH and O2 一derived DMPO-OOH . For MR at pH 8.0, DMPO-OOH was the only ESR signal detected. In addition, using 2,2,6,6-tetramethyl-4-piperidone as spin trapallowed a characteristic triplet signal of singlet oxygen from MR to be detected at pH > 8.0. The subse-quent spin adduct was unstable particularly at pH < 8.0. In MR at pH 4.0-8.0, N, N-dimethyl-p-nitrosoaniline(RNO)-bleaching assay revealed that the rate of singlet oxygen production was a function of decreasingpH. Detection of higher yields of hydroxyl radical and singlet oxygen from MR at low pH range furtherconfirms that these oxygen species are the prominent factors in MR microbial toxicity.
- 中文關鍵字： ESR spectrosocopy; hydroxyl radical; methionine riboflavin mixture; singlet oxygen.
- 英文關鍵字： --
