Zaidi R, Hadi S M
Department of Biochemistry, Faculty of Life Sciences, Aligarh Muslim University, India.
J Biochem Toxicol. 1992 Winter;7(4):213-7. doi: 10.1002/jbt.2570070404.
Gossypol, a polyphenolic binaphthyl dialdehyde found in cotton seeds, is a dietary mutagen and a potential male contraceptive. In the presence of Cu(II), gossypol caused breakage of supercoiled plasmid pBR322 DNA. The products were relaxed circles or a mixture of these and linear molecules. Other metal ions tested [Ni(II), Co(II), Mn(II), and Fe(II)] were ineffective or less effective in the DNA breakage reaction. In the case of gossypol-Cu(II) mediated cleavage, Cu(I) was shown to be an essential intermediate by using the Cu(I) sequestering reagent bathocuproine. By using job plots, it was established that in the absence of DNA, eight Cu(II) ions can be reduced by one gossypol molecule. The involvement of active oxygen species, such as singlet oxygen and H2O2, was established by the inhibition of DNA breakage by catalase and by sodium azide. It was further shown that gossypol is capable of directly producing H2O2.
棉酚是一种存在于棉籽中的多酚联萘二醛，是一种膳食诱变剂和潜在的男性避孕药。在铜（II）存在的情况下，棉酚会导致超螺旋质粒pBR322 DNA断裂。产物是松弛环或这些与线性分子的混合物。测试的其他金属离子[镍（II）、钴（II）、锰（II）和铁（II）]在DNA断裂反应中无效或效果较差。在棉酚-铜（II）介导的切割中，通过使用铜（I）螯合试剂bathocuproine表明铜（I）是必需的中间体。通过绘制工作曲线确定，在没有DNA的情况下，一个棉酚分子可以还原八个铜（II）离子。通过过氧化氢酶和叠氮化钠对DNA断裂的抑制作用，确定了活性氧物种如单线态氧和过氧化氢的参与。进一步表明棉酚能够直接产生过氧化氢。
