THE ACTIVITY OF PROPOLIS IN THE PROMOTION AND SCAVENGING OF VITAMIN B2-PHOTOGENERATED ROS

MARIELA GONZÁLEZ; MARIA L. TERESCHUK; SUSANA CRIADO; EUGENIA REYNOSO; CECILIA CHALLIER; MARIA BELÉN AGÜERO; LORENA LUNA; GABRIELA FERRARI; MARIA P. MONTAÑA; NORMAN A. GARCÍA

REDOX REPORT

MANEY PUBLISHING

Lugar: London; Año: 2015 vol. 20 p. 246 - 253

1351-0002

Objectives: The study was focused on the activity of propolis from Amaicha del Valle, Argentina (ProAV) as a promoter and scavenger of Riboflavin (Rf) photogenerated reactive oxygen species (ROS). Methods: Through a kinetic and mechanistic study, employing stationary and time-resolved photochemical and electrochemical techniques, the protecting activity of ProAV was investigated. Results: In the absence of light and Rf, ProAV exerted a relatively efficient inhibitory effect on 1,1-diphenyl-2-picrylhydrazyl radicals and acts as a protector of artificially promoted linoleic acid oxidation. Under aerobic visible-light-irradiation conditions, in the presence of Rf as the only light-absorber species, a complex picture of competitive processes takes place, starting with the quenching of singlet and triplet electronically excited states of Rf by ProAV. The species O2(1∆g), O2●-−, H2O2, and OH● are generated and interact with ProAV. Discussion: ProAV behaves as an efficient ROS scavenger. It is scarcely photo-oxidized by interaction with the mentioned ROS. Quantitative results indicate that ProAV is even more resistant to photo-oxidation than the recognized antioxidant trolox. Two dihydroxychalcones, mostly present in the ProAV composition, are responsible for the protecting activity of the propolis.