不同取代度马来酰κ-卡拉胶的抗氧化活性研究

Antioxidant activity of maleoyl κ-carrageenans with different substituting degrees

摘要:

对κ-卡拉胶进行酸降解，经过透析得到2种低聚糖。进而分别马来酰化得到2种κ-卡拉胶马来酰衍生物（MA和MB）。对产物进行红外表征，采用GPC方法测定2种衍生物的分子量分别为4 350和4 540，比色法测定其取代度分别为0.61和0.44，并考察了2种衍生物对超氧阴离子自由基O₂^-、DPPH自由基、过氧化氢的清除活性以及还原能力。结果表明：MA与MB对超氧阴离子自由基O₂^-的半抑制浓度IC₅₀分别为0.441 mmol/L和0.489 mmol/L；清除DPPH自由基的IC₅₀分别为0.101 mmol/L和0.273 mmol/L；MA清除过氧化氢的IC₅₀为0.052 mmol/L，而MB在测试浓度范围内对过氧化氢未能达到半抑制；当浓度为0.5 mmol/L时，MA和MB的吸光度分别是0.894和0.487。可见，MA的抗氧化能力优于MB，即随着取代度的升高，抗氧化能力增强，这可能与马来酰基的吸电子性质有关。揭示了取代度对抗氧化活性的影响规律，为κ-卡拉胶及其衍生物生物活性的深入研究相关依据和思路。

Abstract:

Two κ-carrageenan oligosaccharides were prepared by acidic degradation. Then the maleyol derivatives (MA，MB) were synthesized with maleyol anhydride, respectively. The products were characterized by FTIR, the molecular weights (4 350, 4 540) were measured by gel permeation chromatography (GPC) method, and the substituting degrees (0.61, 0.44) were determined by colorimetry method. Their antioxidant activities were evaluated by the scavenging of superoxide anion, 1,1diphenyl2picrylhrazyl radicals (DPPH), H²O² and reducing power. The 50% inhibition concentrations (IC₅₀s) against superoxide anion of MA and MB were 0.441 and 0.489 mmol/L, respectively. As for DPPH radical scavenging, the IC₅₀s of MA and MB were 0.101 and 0.273 mmol/L, respectively. The IC₅₀against H²O² of MA was 0.052 mmol/L, MB failed to achieve halfinhibition in the test concentration. At a concentration of 0.5 mmol/L, and the absorbance of MA and MB was 0.894 and 0.487, respectively. The results indicated that MA showed better antioxidant activities than MB. The maleyol derivatives with higher substituting degrees have better antioxidant activity. It may be related to the nature of substituting group. In this paper, the relationship between the substituting degrees of the acylated κ-carrageenan oligosaccharides and their antioxidant activities was first reported. This research will be helpful to expand their applications in biomedicine.