SYNTHETIC HYDROXYLATED DIMER OF RHODODENDROL, RASPBERRY KETONE AND TYROSOL, AS POTENTIAL BIOANTIOXIDANTS FROM NATURAL SOURCE

4-(4-hydroxyphenyl)-2-butanol, 4-(4-hydroxyphenyl)-2-butanone, 2-(4-hydroxyphenyl)ethanol, commonly known respectively as rhododendrol 1, raspberry ketone 2 and tyrosol 3 are natural phenols which displayed remarkable variety of biological activities. Rhododendrol, mostly present in Acer nikoense1a, was developed as a tyrosinase inhibitor for lightening/whitening cosmetics. Raspberry ketone, occuring on a variety of fruits, sometimes used in cosmetics, was proved to restrain oxidative stress and the lipid peroxidation reaction, and to prevent damage in liver cells1b. Tyrosol is a natural phenolic antioxidant present in a variety of natural sources. It is one of the main natural phenols found in olive oil. As antioxidant, tyrosol can protect cells against injury due to oxidation1c. In our laboratory we are actively engaged in the synthesis and biological evaluation of hydroxylated natural-like biphenyls2. Hydroxylated biphenyl unit is embedded in many structures of bioactive natural products and some of them are present in compounds of high biological relevance. It is previously reported by us that generally dimers manifested higher antioxidant efficiency than those of the corresponding monomers3.