Phytomedicine, Vol. 5(6), pp. 469-4 73 © Gusta v Fischer Verlag 1998 _ In vitro scavenger and antioxidant properties of hesperidin and neohesperidin dihydrochalcone J. Suarez, M. D. Herrera, and E. Marhuenda Laboratorio de Farmacodinamia. Departamento de Farmacia y Tecnologia Farmaceutica, Facultad de Farmacia , Universidad de Sevilla, Spain Summary We have assesed the actions as free radical scavengers and inhibitors on peroxidation of hesperidin and neohesperidin dihydrochalcone, two flavonoids, flavanone and dihydrochalcone respectively, as some of the pharmacological properties of flavonoids group have been related with these activities. Hesperidin just at 10-4 and 5 . 10-4M is able to show a low inhibitory activity in the superoxide anion radicals (02) genesis (8.66 ± 1.40 and 11.69 ± 2.36% respectively), and on the non-enzymatic lipid per- oxidation at to- 3 M dose (9.78 ± 0.35%), without affecting the hydroxyl radical ('OH) formation, gen- erated by the ascorbic acid-Fe 3+-EDTA system. In the other hand, neohesperidin dihydrochalcone is an authentic antioxidant drug as tested at all doses. It showed a great scavenger activity and/or inhibition of formation on 02" radicals (31.53 - 84.62%) and a significant scavenging effect on OH radicals (6.00- 23.49%), as well as an important inhibitory action on non-enzymatic lipid peroxidation (15.43- 95.33%). Key words: Hesperidin, neohesperidin dihydrochalcone, radical scavengers, antioxidant activity. Introduction At cellular level, the reactive oxygen species (ROS) pro- duce alterations, which can induce the cellular death. The basic cellular constituents as nucleic acid, proteins and lipids are attacked by ROS with extreme reactivity. So in membrane lipids they induce lipid peroxida- tion, giving rise to the formation of several toxic com- pounds for the cell like epoxide , aldehydes and new free radical s (Pryor, 1976, 1984) . Hesperidin (HESP) and neohesperidin dihydrochal- cone (NHOC) are two flavonoids, flavanone and dihy- drochalcone respectively, which prevent gastric muco- sal lesion produced by various experimental ulcer in- duced methods (Suarez et a!., 1996). The ROS are directly implicated in the pathogenesis of the mucosal lesion (Salim, 1990), so our research pretends to determine the possible antioxidant and rad- ical scavenging properties of both substances. We have carried out two studies on two different free radicals, because the scavenging activity mostly depends on the nature of the radical (Pincemail, 1985). We also deter- rninated the effect of HESP and NHOC on non-enzy- matic lipid peroxidation of rat liver microsomes. Materials and Methods Drugs and dosage The following drugs and dosages were used: Superox- ide dismuta se (SOD) from bovine erythrocytes 2S U/ml, allopurinol lO r'M, mannitol (MN) S·lO-2M, and butylated hydroxytoluene (BHT) 10-4M used as refer- ence substances, were obtained from Sigma; and hes- peridin and neohesperidin dihydrochalcone (10-4M- 5.10- 3 M) from Extrasynthese. The tested doses have been selected on the basis of their solubilities in the different vehicles used for each experiment, so that they produced the minimum inter- ferences in the reaction.