Azabou Samia, Najjar Wahiba, Ghorbel Abdelhamid, Sayadi Sami
Laboratoire des BioProcédés, Centre de Biotechnologie de Sfax, BP K, Tunisia.
J Agric Food Chem. 2007 Jun 13;55(12):4877-82. doi: 10.1021/jf070081j. Epub 2007 May 12.
Hydroxytyrosol, a naturally occurred orthodiphenolic antioxidant molecule found in olive oil and olive mill wastewaters, was obtained from the wet hydrogen peroxide photocatalytic oxidation of its monophenolic precursor tyrosol. The liquid-phase oxidation of tyrosol to hydroxytyrosol was performed by use of an iron-containing heterogeneous catalyst (Al-Fe)PILC with the assistance of UV irradiation at 254 nm and at room temperature. The spectroscopic and HPLC data of the synthesized compound proved to coincide fully with those of a pure sample obtained by continuous countercurrent extraction. This reaction was found to be light-induced. The hydroxytyrosol synthesis reaction reached its maximum yield of 64.36% under the optimized operating conditions of 3.6 mM tyrosol, 0.5 g L(-1) catalyst, and 10(-2) M H2O2 with the assistance of UV light. Increasing the initial hydrogen peroxide concentration more than 10(-2) M has a diminishing return on the reaction efficiency. Catalyst can be recuperated by means of filtration and then reused in a next run after regeneration since its activity did not significantly decrease (<10%). The reaction synthesis is operationally simple and could find application for industrial purposes.
羟基酪醇是一种存在于橄榄油和橄榄果渣废水中的天然邻二酚类抗氧化分子，它是通过其单酚前体酪氨酸在湿过氧化氢光催化氧化反应中制得的。在254 nm紫外光照射和室温条件下，使用含铁的非均相催化剂（Al-Fe）层柱黏土对酪氨酸进行液相氧化反应，从而制得羟基酪醇。合成化合物的光谱和高效液相色谱数据被证明与通过连续逆流萃取得到的纯样品的数据完全一致。该反应被发现是光诱导的。在3.6 mM酪氨酸、0.5 g L⁻¹催化剂和10⁻² M过氧化氢，并在紫外光辅助的优化操作条件下，羟基酪醇合成反应达到了64.36%的最大产率。将初始过氧化氢浓度提高到超过10⁻² M时，反应效率的回报会逐渐减少。催化剂可以通过过滤回收，然后在再生后用于下一次运行，因为其活性没有显著下降（<10%）。该反应合成操作简单，可用于工业生产。
