Biotransformation of phlorizin by human intestinal flora and inhibition of biotransformation products on tyrosinase activity

► Five biotransformation products of phlorizin were produced by human intestinal flora. ► Phloretin has better inhibition on tyrosinase activity than parent compound phlorizin. ► Method of determination of phlorizin and its biotransformation products was developed. ► The results provided a firm basis for evaluating the bioactivities of phlorizin. ► The above-mentioned results were reported for the first time.