A thermodynamically radical scavenging activity (RSA) of vitamin B niacin (NCN), niacin amide (NMD) and
vitamin C ascorbic acid (AA) using 1,1-diphenyl-2-picrylhydrazyl (DPPH•) through spectrophotometric and
physicochemical methods at T = (298.15, 303.15 and 308.15) K has been studied. New experimental data on
density, sound velocity, isentropic and apparent molal compressibility of vitamin+DPPH• solutions are reported
as a function of temperature and concentration. The results are discussedwith regards to their structure–activity
relationship (SAR) principles and relative deviations in RSAs with the structural potentials of the vitamins have
been analyzed by comparing both the spectrophotometric and physicochemical results.