DNA TARGETING AS A MOLECULAR MECHANISM UNDERLYING
ENDOGENOUS INDOLES BIOLOGICAL EFFECTS
CRISTINA MANUELA DRĂGOI 1, ALINA CRENGUŢA NICOLAE 1*, ION-BOGDAN DUMITRESCU 2, DANIELA ELENA POPA 3, MIRELA RITIVOIU 4, ANDREEA LETIŢIA ARSENE 5
1Department of Biochemistry, Faculty of Pharmacy, “Carol Davila” University of Medicine and Pharmacy, Bucharest, Romania
2Department of Physics and Informatics, Faculty of Pharmacy, “Carol Davila” University of Medicine and Pharmacy,
Bucharest, Romania
3Department of Drug Control, Faculty of Pharmacy, “Carol Davila” University of Medicine and Pharmacy, Bucharest, Romania
4Department of Paediatrics, Faculty of Medicine, “Alessandrescu-Rusescu” INSMC, “Carol Davila” University of Medicine
and Pharmacy, Bucharest, Romania,
5Department of Microbiology, Faculty of Pharmacy, “Carol Davila” University of Medicine and Pharmacy, Bucharest, Romania
*corresponding author: alina.nicolae@umfcd.ro
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Abstract:
The present study aimed to investigate the potential intra-nuclear signalling mechanism of the endogenous bioindoles:
melatonin, serotonin and tryptophan, through their direct interaction with the DNA. The DNA-indoles interaction has been
studied in vitro by using a spectrofluorometric method, determining the intensity of the fluorescent signal issued by the
indole molecules, natively fluorescent, in the presence of the DNA, molecule which lacks fluorescence. The experimental
results highlighted a decrease of the fluorescent signal of the indoles under analysis, in the presence of DNA, proving an in
vitro direct interaction the double-stranded DNA quenching the fluorescent signal of the studied endogenous molecules. This
masking effect could be due to their intercalation in the double helix DNA structure. The results were significantly higher in
the case of DNA-melatonin interaction compared to serotonin (p < 0.0001) and tryptophan (p < 0.0001), respectively. The
quenching of the florescent signals of DNA-indole systems were evaluated through the Stern-Volmer constants (KSV).
Further on, the type of DNA-indoles bonds has been assessed by means of ethidium bromide (EB) studies and UV
spectroscopy was used in order to calculate the binding constants.






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