Kadoma Yoshinori, Ito Shigeru, Atsumi Toshiko, Fujisawa Seiichiro
Department of Applied Function Molecules, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-Surugadai, Chiyoda-Ku, 101-0062 Tokyo, Japan.
Chemosphere. 2009 Feb;74(5):626-32. doi: 10.1016/j.chemosphere.2008.10.039. Epub 2008 Dec 11.
To clarify the mechanism of phenol toxicity, the radical-scavenging activity of 2- or 2,6-di-tert-butyl- and 2-methoxy-substituted phenols was investigated by combining two distinct approaches: first, the induction period method for methacrylate polymerization initiated by benzoyl peroxide or 2,2'-azobisisobutyronitrile; and secondly, 1,1'-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging test. The homolytic bond dissociation enthalpy (BDE) and ionization potential (IP(koopman)) were calculated by the DFT/B3LYP method. The cytotoxicity was investigated using tumor cells (human submandibular gland carcinoma cells, HSG; human promyelocytic leukemia cells, HL-60) and primary cells (human gingival fibroblasts, HGF; human periodontal ligament fibroblasts, HPLF; human pulp fibroblasts, HPF) derived from oral tissues. The cytotoxicity between tumor and primary cells was similar, except for eugenol dimer showing less toxicity for primary cells. The DPPH assay was not useful for tert-butylphenols due to their steric hindrance. For both HSG and HGF cells, a linear relationship was found between 50% cytotoxic concentration (CC(50)) and inhibition rate constant (k(inh)), but not BDE, IP, or logP. The acceptable quantitative structure-activity relationships (QSAR) obtained for cytotoxicity vs. k(inh) suggested that the cytotoxicity of phenols may be dependent on radical reactions. The cytotoxicity of vanillin and 3,5-di-tert-butyl-4-hydroxy-benzaldehyde with large k(inh) values, weak antioxidants was markedly less than that of 2,6-di-tert-butyl-4-methylphenol, 2,4,6-tri-tert-butylphenol and curcumin with small k(inh) values, potent antioxidants.
为阐明苯酚毒性的机制，通过结合两种不同方法研究了2-或2,6-二叔丁基-和2-甲氧基取代苯酚的自由基清除活性：第一，用过氧化苯甲酰或2,2'-偶氮二异丁腈引发甲基丙烯酸酯聚合的诱导期方法；第二，1,1'-二苯基-2-苦基肼（DPPH）自由基清除试验。采用密度泛函理论/B3LYP方法计算均裂键解离焓（BDE）和电离势（IP(koopman)）。使用源自口腔组织的肿瘤细胞（人下颌下腺癌细胞，HSG；人早幼粒细胞白血病细胞，HL-60）和原代细胞（人牙龈成纤维细胞，HGF；人牙周膜成纤维细胞，HPLF；人牙髓成纤维细胞，HPF）研究细胞毒性。除丁香酚二聚体对原代细胞毒性较小外，肿瘤细胞和原代细胞之间的细胞毒性相似。由于空间位阻，DPPH试验对叔丁基苯酚无效。对于HSG和HGF细胞，在50%细胞毒性浓度（CC(50)）与抑制速率常数（k(inh)）之间发现线性关系，但与BDE、IP或logP无关。针对细胞毒性与k(inh)获得的可接受定量构效关系（QSAR）表明，酚类的细胞毒性可能取决于自由基反应。香草醛和3,5-二叔丁基-4-羟基苯甲醛的k(inh)值大、抗氧化剂弱，其细胞毒性明显小于k(inh)值小、抗氧化剂强的2,6-二叔丁基-4-甲基苯酚、2,4,6-三叔丁基苯酚和姜黄素。
