CONICET | Buscador de Institutos y Recursos Humanos

The consumption of antioxidant supplements in well-nourished populations have been increasing because they are associated to the prevention of cardiovascular diseases, cancer and aging processes [1]. Packaged Facts (Consultant of market information for top industry decision makers) estimates that antioxidant featuring foods, beverages, supplements, and personal care/cosmetics totaled $65 billion in U.S. retail sales in 2014 and up 9% over 2016. By 2018, the market is projected to approach $86 billion [2]. In past decades, several researches have documented the efficient activity of antioxidants, although recent studies suggest that antioxidants in addition to scavenging free radicals, may have the opposite effect and promote or even accelerate the development of tumors [3,4]. Singlet oxygen (1O2) can be generated by photochemical reactions type II, and its detection is possible by either spectroscopic technics [5]. However, due the increasingly contradictory reports about the pro-oxidant effects of these and other antioxidants, the aim of this research was to evaluate the ability of the flavonoid ?jaceidin? obtained from Zinnia peruviana to photosensitize the generation of 1O2 using the photo-oxidation of L-tryptophan (Trp) as an indirect detection method. Steady state photolysis of Trp was studied following the decrease of the fluorescence intensity and the observed rate constant (kobs) were obtained by a linear least-squares fit of the semilogarithmic plot of Ln F0/F vs time. Photo-oxidation of Trp was used to determine 1O2 production by pro-oxidant activity of ?jaceidin?, using bengal rose as positive control. The solution was irradiated under continuous oxygen flow, and a 150W lamp was used as source of illumination (380?780 nm). Riboflavin (Rf) has a triene structure and many double bonds be able to react with 1O2; at the same time Rf its photo-degradated for his own production of this excited oxygen species [6]. This ambiguous behavior allows us to determinate the antioxidant effects of ?jaceidin? against to 1O2. Under irradiation riboflavin content decreased considerably depending of the illumination time. The negative control sample containing only riboflavin. The presence of ?jaceidin? in riboflavin solutions reduced photo-degradation of riboflavin, and the rate of degradation was slower than negative control. To estimate the capacity of ?jaceidin? to protect riboflavin facing of photo-degradation, we used ascorbic acid due to great capacity as scavenger of reactive oxygen species. About Trp photolysis, we demonstrated that ?jaceidin? shows a barely detectable pro-oxidant activity. This research allows us to propose a new approach in the classification of natural antioxidants scavenger?s free radicals. Therefore, it?s necessary to evaluate a large number of antioxidants, already used in food industry, beverages, supplements, and personal care/cosmetics, or find new ones in order to use real antioxidants compounds.