Synthesis, characterization, and biological activity studies of copper(II) mixed compound with histamine and nalidixic acid
Authors: Sylvain Bernès
Mercedes G López
Mario Pedraza-Reyes
Egla Yareth Bivián-Castro
Guillermo Mendoza-Díaz
Journal: Bioinorganic Chemistry and Applications (2009)
Discipline: CHEMISTRY
Keywords: copper complex; nalidixic acid; histamine; crystal structure; bacterial DNA
Affiliations: Departamento de Química, División de Ciencias Naturales y Exactas, Universidad de Guanajuato, Noria Alta s/n, 36050 Guanajuato, GTO, Mexico, Departamento de Biotecnología y Bioquímica, Cinvestav-IPN Unidad Irapuato, Km.9.6 Libramiento Norte, Carr. Irapuato-León, 36500 Irapuato, GTO, Mexico, Departamento de Biología, División de Ciencias Naturales y Exactas, Universidad de Guanajuato, Noria Alta s/n, 36050 Guanajuato, GTO, Mexico, DEP Facultad de Ciencias Químicas, UANL, Guerrero y Progreso s/n, Col. Treviño, 64570 Monterrey, NL, Mexico

Abstract:  A mixed copper complex with deprotonated nalidixic acid (nal) and histamine (hsm) was synthesized and characterized by FTIR, UV-Vis, elemental analysis, and conductivity. The crystal structure of [Cu(hsm)(nal)H(2)O]Cl.3H(2)O (chn) showed a pentacoordinated cooper(II) in a square pyramidal geometry surrounded by two N atoms from hsm, two O atoms from the quinolone, and one apical water oxygen. Alteration of bacterial DNA structure and/or associated functions in vivo by [Cu(hsm)(nal)H(2)O]Cl.3H(2)O was demonstrated by the induction of a recA-lacZ fusion integrated at the amyE locus of a recombinant Bacillus subtilis strain. Results from circular dichroism and denaturation of calf thymus DNA (CT-DNA) suggested that increased amounts of copper complex were able to stabilize the double helix of DNA in vitro mainly by formation of hydrogen bonds between chn and the sugars of DNA minor groove. In vivo and in vitro biological activities of the chn complex were compared with the chemical nuclease [Cu(phen)(nal)H(2)O]NO(3) . 3H(2)O (cpn) where phen is phenanthroline. 

Retracted: No

PubPeer comments:
 Figure 4. ![file] Upon enhancing the brightness, several repetitive features are observed (marked with boxes of colours white and yellow). Surprisingly, the band in the last lane (No. 6) appears to be cropped out spliced out (marked with a faint blue box). ![file] , 
 #1 I ve just forwarded your comment to the co-authors of this article for feedback. SB , 
 The 1st author provided the original image. The original file (jpg, 96 ppp, 24 bits) can be downloaded [here] (dropbox) or [here] (imgur). Note that only lanes 1-6 were retained for the publication, while lanes 7-8 were discarded. ![file] I also prepared an image with enhanced contrast: ![file] The sentence related to lane 6 in the article states that  as previously reported the **cpn** complex behaved as a thiol-dependent chemical nuclease with a complete degradation of DNA at this concentration (Figure 4, Lane 6) [27] . The third co-author, who is the head of the lab where the electrophoresis was carried out, mentions the following: it turns out that a very short DNA fragment (197 kb) was synthesized by PCR and used as substrate. In order to separate the reaction products, a buffer was used, which contained bromophenol blue, and a 2% agarose gel including ethidium bromide was used for the electrophoresis. Which such a concentrated gel, it is possible that the massively degraded DNA migrated in the same position as the dye, producing the observed darkened lane. Regarding the pattern observed in lane 1, I was unable to notice it in the original image. All co-authors are in agreement with these comments. Cheers. ,