Reactive oxygen species (ROS) and free radicals induce membrane damages, DNA strand breaks, and protein alterations. Oxidative stress, induced by oxygen radicals, is believed to be a primary factor in various degenerative diseases as well as in the normal process of aging. The ROS are involved in the course of aging, cancer, cardiovascular disease, diabetes, neurodegenerative disease, osteoporosis, etc. 1,2) Among the various reactive species, superoxide radical ( · O 2 Ϫ ), hydroxyl radical ( · OH), hydrogen peroxide (H 2 O 2 ), and hypochlorous acid (HOCl) play important roles in the pathophysiologies as mentioned above, which make them potential targets for the chemotherapy of inflammatory diseases.
3)Neohesperidin dihydrochalcone (NHDC) is an intense sweetener which is produced by hydrogenation of neohesperidin first prepared by Horowitz and Gentili in 1963. 4) Citrus fruits are rich sources of neohesperidin; the peels of oranges, lemons, and grapefruit contain bitter taste of neohesperidin. [5][6][7][8][9] Dihydrochalcones are a family of the bicyclic flavonoids, defined by the presence of two benzenoid rings joined by a three-carbon bridge. NHDC, the most familiar among these compounds, is permitted for commercial use as a food additive in Europe on the basis of its safety assessed by the EU Scientific Committee for Food. 10) In recent studies, there were several reports about improve the solubility and stability in aqueous solution and another research group evaluated neohesperidin-rich plant to get a source of NHDC. 8,11) Some dihydrochalcones including phloridzin and myrigalone B have been found to occur naturally 12,13) and to possess an antioxidant activity.14,15) Several chalcones inhibit various enzymes involved in the generation of reactive oxygen species and many of their pharmacological properties are supposed to be related to their antioxidant effect.16) Recently, 2Ј,5Ј-dihydroxychalcones have been reported as potent anti-inflammatory chemicals. 17,18) Although a large number of antioxidants, including most types of flavonoids, have been reported in the literature, there are few systematic studies of dihydrochalcones on biological activities such as an antioxidant effect. In recent studies, NHDC can inhibit DPPH stable radical, lipid peroxidation, and xanthine oxidase activity. 19,20) However, there are few reports to evaluate NHDC as an antioxidant or specific radical scavenger.In this study, to evaluate NHDC as a novel antioxidant material for a pharmaceutical agent or a food additive, its stable radical scavenging activity and inhibitory effect on the major inflammation-related ROS including · O 2 Ϫ , H 2 O 2 , · OH, and HOCl were elaborated. Also, the inhibitory effect of NHDC on protein degradation, DNA strand cleavage, and cellular damage from HOCl attack were determined to verify the specific ROS scavenging function. In addition, the ROS scavenging effect of the structurally related compounds including neohesperidin and phloridzin was also estimated to explore the structure-activity rel...