Sasmal Pijus K, Patra Ashis K, Chakravarty Akhil R
Department of Inorganic and Physical Chemistry, Indian Institute of Science, Sir C.V. Raman Avenue, Bangalore 560 012, India.
J Inorg Biochem. 2008 Jul;102(7):1463-72. doi: 10.1016/j.jinorgbio.2007.12.031. Epub 2008 Jan 8.
Ternary oxovanadium(IV) complexes [VO(salmdtc)(B)] (1-3), where salmdtc is dianionic N-salicylidene-S-methyldithiocarbazate and B is N,N-donor phenanthroline bases like 1,10-phenanthroline (phen, 1), dipyrido[3,2-d:2',3'-f]quinoxaline (dpq, 2) and dipyrido[3,2-a:2',3'-c]phenazine (dppz, 3), are prepared, characterized and their DNA binding and DNA cleavage activity studied. Complex 3 is structurally characterized by single-crystal X-ray crystallography. The molecular structure shows the presence of a vanadyl group in six-coordinate VN(3)O(2)S coordination geometry. The S-methyldithiocarbazate Schiff base acts as a tridentate NSO-donor ligand in a meridional binding mode. The N,N-donor heterocyclic base displays a chelating mode of binding with an N-donor site trans to the vanadyl oxo-group. The complexes show a d-d band in the range of 675-707 nm in DMF. They exhibit an irreversible oxidative cyclic voltammetric response near 0.9 V due to the V(V)/V(IV) couple and a quasi-reversible reductive V(IV)/V(III) redox couple near -1.0 V vs. SCE in DMF-0.1M TBAP. The complexes show good binding propensity to calf thymus DNA giving binding constant values in the range of 7.4 x 10(4)-2.3 x 10(5)M(-1). The thermal denaturation and viscosity binding data suggest DNA surface and/or groove binding nature of the complexes. The complexes show poor chemical nuclease activity in dark in the presence of 3-mercaptopropionic acid (MPA) or hydrogen peroxide. The dpq and dppz complexes show efficient DNA cleavage activity in UV-A light of 365 nm via a type-II mechanistic pathway involving formation of singlet oxygen ((1)O(2)) as the reactive species.
制备了三元氧钒（IV）配合物[VO(salmdtc)(B)]（1 - 3），其中salmdtc是二阴离子N - 水杨基亚甲基 - S - 甲基二硫代氨基甲酸盐，B是N，N供体菲咯啉碱，如1,10 - 菲咯啉（phen，1）、二吡啶并[3,2 - d:2',3' - f]喹喔啉（dpq，2）和二吡啶并[3,2 - a:2',3' - c]吩嗪（dppz，3），对其进行了表征，并研究了它们与DNA的结合及DNA切割活性。配合物3通过单晶X射线晶体学进行了结构表征。分子结构显示在六配位VN(3)O(2)S配位几何结构中存在一个氧钒基团。S - 甲基二硫代氨基甲酸盐席夫碱以子午结合模式作为三齿NSO供体配体。N，N供体杂环碱以螯合模式与一个N供体位点结合，该位点与氧钒氧基团呈反式。这些配合物在DMF中在675 - 707 nm范围内显示出d - d带。由于V(V)/V(IV)电对，它们在0.9 V附近表现出不可逆的氧化循环伏安响应，并且在DMF - 0.1M TBAP中相对于SCE在 - 1.0 V附近表现出准可逆的还原V(IV)/V(III)氧化还原电对。这些配合物对小牛胸腺DNA显示出良好的结合倾向，结合常数在7.4×10(4) - 2.3×10(5)M(-1)范围内。热变性和粘度结合数据表明这些配合物具有DNA表面和/或沟槽结合性质。在3 - 巯基丙酸（MPA）或过氧化氢存在下，这些配合物在黑暗中显示出较差的化学核酸酶活性。dpq和dppz配合物在365 nm的UV - A光下通过涉及单线态氧((1)O(2))作为反应物种形成的II型机制途径显示出有效的DNA切割活性。
