In vitro antioxidative and binding properties of phenolics in traditional, citrus and exotic fruits

• Polyphenol content and distribution varied among investigated fruits.
• The highest quercetin content is in strawberry and citrus fruits.
• Correlation between polyphenols, antioxidant and binding capacities
• Fluorometry and IR indicate the binding properties of polyphenols.

Many polyphenols bind proteins, therefore our research was focused on the potential of protein binding to polyphenols of investigated fruits and their health-related effects. The contents of polyphenols and related antioxidant activities of traditional, citrus and exotic fruits were compared. The presence of polyphenols (flavonoids and phenolic acids) in the investigated samples and their interaction with human serum albumin (HSA) was studied by HPLC, Fourier Transform Infrared (FT-IR) and three dimensional fluorescence spectroscopy (3D-FL). The highest levels of polyphenols, antioxidant and binding capacities were found in red and blond grapefruits (citrus group), followed by strawberries and apples (traditional group) and mangosteen and kiwi fruit (exotic fruit), which also contained the highest levels of protocatechuic, p-coumaric, ferulic acids and quercetin. In conclusion, for the first time, the interaction of the polyphenols with human serum albumin was evaluated by fluorometry/FTIR. The obtained binding profiles allowed the comparison of three different groups of fruits. A mixture of these fruits can be recommended for consumption.

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