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J. Cosmet. Sci., 67, 71–92 (March/April 2016) 71 Free radical scavenging capacity and protective effect of natural substances in peloids from the thermal spring pool Bagnaccio (Viterbo, Italy) RAFFAELE SALADINO, UGO CHIOCCHINI, GIORGIA BOTTA, MICHELA DELFINO, ROBERTO CONIGLIARO, and PASQUALE MOSESSO, Department of Ecology and Biology, Tuscia University, Largo dell’Università (R.S., G.B., M.D., P.M.), Department for Agriculture, Forestry, Nature and Energy, Tuscia University, Largo dell’Università (U.C.), and Terme dei Papi Spa (R.C.), 01100 Viterbo VT, Italy. Accepted for publication April 10, 2016. Synopsis Natural peloids from sulfurous thermal springs are largely used in cosmetic and pelotherapy for the treatment of different dermatological conditions, including skin aging, dermatitis, and other eczemas. The benefi cial effects are correlated to mineralogical and other thermal properties, as well as to the presence of natural substances with specifi c antioxidant activity. Few data are available for the comparison between natural peloids and synthetic (i.e., artifi cially maturated) muds. In this context, the natural substances and antioxidant activity of natural white mud (WM) and dark mud (DM) peloids from the sulfurous thermal spring pool Bagnaccio (Viterbo, Italy) have been studied in detail to evaluate possible relationships between physico- chemical properties and therapeutic effect. A large panel of natural substances in WM and DM were characterized for the fi rst time by 31 P-nuclear magnetic resonance and gas chromatography associated to mass spectrometry analysis. Polar fractions of WM and DM peloids were characterized by the presence of several bioactive natural compounds, showing high antioxidant activity and DNA protective effect, as evaluated by 2,2-diphenyl-1-picrylhydrazyl assay, and hydrogen peroxide–induced DNA breakage in the alkaline comet assay. The antioxidant activity and DNA protective effect could be attributed to radical scavenging rather than a modulatory effect on the induced DNA repair, and are of order of intensity higher than that reported for synthetic muds. INTRODUCTION Peloids are thermal muds characterized by an inorganic matrix embedded with natural bioactive compounds, which are synthesized during the metabolism of growing microor- ganisms (1). The therapeutic use of peloids is called pelotherapy (2,3), and represents a typical procedure in cosmetic and medical hydrology for the treatment of different Address all correspondence to Raffaele Saladino at saladino@unitus.it.