Physicochemical and biopharmaceutical characterization of new sulfonamide derivatives of gallic acid

Gallic acid (GA) is known for its antioxidant activitywhichis restricted due to its low oral permeability. In this project the carboxylic group of (GA) was substitutedwith sulfonamide group and hydroxyl groups were methylated which resulted insignificantly (p<0.01) increased permeability of 3,4,5-trimethoxybenzenesulfonamide (TMBS) and 3,4,5-trihydroxybenzenesulfonamide (THBS) over GA, inParallel Artificial Membrane Permeability Assay studies with simulatedgastrointestinal fluids and Human intestinal epithelial cells HIEC-6 cells.Biochemical studies confirmed TMBS was O-demethylated by CYP2D6. THBS and GAhad increased antioxidant activity with increased concentration in DPPH assaywhile TMBS indicated lower activity at all tested concentration. Theantioxidant activity of TMBS was greater than GA in HIEC-6 cells which mainlyrelated to its O-demethylation by CYP2D6.