Abstract
The effects of the complexes of the type M(L)2(nia)2 (M = Cd or Zn; L = acetate (ac) or NCS−; nia = nicotinamida) on reduction of chlorophyll content in suspensions of Chlorella vulgaris and inhibition of photosynthetic electron transport in spinach chloroplasts were investigated. The inhibitory effects of the studied compounds depended on the central metal atom as well as on the structure of L ligands. In general, the toxicity of M(NCS)2(nia)2 was higher than that of M(ac)2(nia)2 and the compounds containing cadmium were more toxic than those with Zn.
Dry mass of plants cultivated in the presence of the studied complexes (c = 100 µmol dm−3) showed a decrease related to control plants. The uptaken metal (Cd or Zn) was accumulated mainly in the roots. In general, application of M(ac)2(nia)2 compounds led to higher accumulated metal content in dry mass of plant organs (in mg g−1) related to M(NCS)2(nia)2 administration. In plants treated with Zn(NCS)2(nia)2 lower content of essential metals Mn and Cu was found than in those treated with Zn(ac)2(nia)2.
Toxic effects of the studied M(L)2(nia)2 compounds could be caused by exchange of their ligands with potential “biotic S-, O-, and N-donor ligands” occurring in the plant cells.