Acta Phys. -Chim. Sin. ›› 2011, Vol. 27 ›› Issue (11): 2682-2690.doi: 10.3866/PKU.WHXB20111132

• PHOTOCHEMISTRY AND RADIATION CHEMISTRY • Previous Articles     Next Articles

Photophysical and Photobiological Properties of Coordination Polymers of Hypocrellin B Complexes Containing Magnesium and Zinc

GUO Chuang-Long, OU Zhi-Ze, GAO Yun-Yan, WANG Zhong-Li, JIN He-Lin, LI Hai-Xia   

  1. Key Laboratory of Space, Applied Physics and Chemistry, Ministry of Education, School of Science, Northwestern Polytechnical University, Xi'an 710072
  • Received:2011-07-19 Revised:2011-08-31 Published:2011-10-27
  • Contact: OU Zhi-Ze, GAO Yun-Yan;
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (21073143),“Chunhui Project ”of the Ministry of Education of China (Z2009-1-71002, Z2009-1-71006) and Northwestern Polytechnical University Foundation for Fundamental Research, China (JC200822, JC20100239).

Abstract: Hypocrellin B (HB) can chelate with Mg2+ and Zn2+ ions to form the coordination complexes Mg2+-HB and Zn2+-HB, which consist of 5-22 repeat units. The structures of these two complexes are characterized by ultraviolet-visible (UV-Vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and 1H nuclear magnetic resonance (1H NMR). The relative quantum yields of singlet oxygen (1O2) for Mg2+-HB and Zn2+-HB are 1.2 and 0.42 times as high as that of HB, respectively. Transient absorption spectra results indicate that O2 is able to quench the triplet excited state of Mg2+-HB and Zn2+-HB with an efficiency higher than 96% . The intersystem crossing efficiency (ΦT) and the fraction of triplet states quenched by O2 that yield 1O2 (fΔT) are considered to be essential for the singlet oxygen quantum yields of HB and its complexes. Electron paramagnetic resonance (EPR) results suggest that Mg2+-HB and Zn2+-HB have a weak ability to generate a semiquinone anion radical, which reduces the generation of the superoxide anion radical (O2·-) by Mg2+-HB and Zn2+-HB. The results of the UV-Vis spectra and the deoxyribonucleic acid (DNA) melting temperature experiments indicate that Mg2+-HB and Zn2+-HB bind with calf thymus (CT) DNA in an electrostatic interaction mode. Under aerobic conditions, the efficiencies of photoinduced damage to CT DNA by Mg2+-HB, HB, and Zn2+-HB are found to be 32%, 25%, and 22%, respectively. The reactive oxygen quencher experiments indicate that singlet oxygen is the main component generated by Mg2+-HB that damages CT DNA.

Key words: Hypocrellin B, Coordination polymer, Singlet oxygen, Superoxide anion radical, DNA photodamage