NANO-DIFFERENTIAL SCANNING FLUORIMETRY FOR STUDYING THE EFFECT OF POLYPHENOLS IN THE PRESENCE OF HP & beta;CD ON HUMAN SERUM ALBUMIN DENATURATION IN AQUEOUS-DIMETHYL SULFOXIDE SOLUTIONS

In this work, we studied the effect of additions of curcumin, rutin, quercetin and their com-plexes with hydroxypropyl-& beta;-cyclodextrin on the structure and denaturation temperature of human serum albumin in aqueous dimethyl sulfoxide solutions containing 3.4% and 8 vol% dimethyl sul-foxide, in phosphate buffer at pH=7.0. The study was carried out using the NanoTemper Tycho NT.6 for rapid protein quality analysis system. The principle Tycho NT.6 is based on the nano -differential scanning fluorimetry, which makes it possible to detect the conformational and colloi-dal stability of proteins. Changes in the protein structure were monitored by the temperature cor-responding to the "inflection" points of the thermal dependence of the fluorescence intensity. When flavonoids are added to human serum albumin, an increase in the inflection temperature is ob-served. The percentage of coincidence of the thermal profile curve with the reference sample is evenly reduced. The interaction of quercetin, curcumin and rutin with human serum albumin leads to a change in the structural integrity of the protein in the presence of hydroxypropyl-& beta;-cyclodex-trin. It was found that in the absence of hydroxypropyl-& beta;-cyclodextrin, the intensity of human se-rum albumin fluorescence decreases with increasing concentrations of curcumin, rutin, quercetin. In the presence of complexes of flavonoids with hydroxypropyl-& beta;-cyclodextrin, the intensity of hu-man serum albumin fluorescence is almost independent of the concentration of curcumin, rutin and quercetin. It has been suggested that molecular complexes of flavonoids change the structure of human serum albumin less than flavonoids in their free states. The fluorescence intensity of human serum albumin without flavonoids is comparable to the fluorescence intensity of human serum albumin in the presence of hydroxypropyl-& beta;-cyclodextrin. This result may indirectly confirm the absence of interaction between cyclodextrin and human serum albumin under the conditions under consideration, which is consistent with previous results.