Pro-oxidant activity of Monascus purpureus pigments, a fungus used in food supplements to reduce cholesterol levels

Monascus food supplements are marketed because of the presence of hypocholesterolemic compounds and some species of the genus Monascus are characterized by their ability to biosynthesize industrially important azaphilone-type dyes. Although some colored compounds can photosensitize the singlet oxygen ( 1 O 2 ) generation, which is associated with chronodegenerative diseases, information on the photosensitizing capacity of Monascus dyes and Monascus based-products is lacking. Therefore, in this study, the photosensitizing capacity to generate 1 O 2 of Monascus purpureus extracts together with the main compound isolated, monascin, was evaluated through the photo-oxidation of ergosterol method (CFL-T4-GE 20W, λ> 380 nm, 19625± 129 lux, 2 h). In addition, the photosensitizing capacity of a Monascus food supplements was also evaluated. Subsequently, a thermodynamic theoretical analysis of the six most frequently reported azaphilones from M. purpureus was performed utilizing the time-dependent density functional theory (TD-DFT) to compare Gibbs free energies in relation to their potential as photosensitizers. Thus, the photo-oxidation of ergosterol using M. purpureus extracts, monascin and the Monascus food supplement extract as photosensitizers, combined with the computational study of the azaphilones from this fungal species, demonstrated that the metabolites of this species can transfer energy to molecular oxygen ( 3 O 2 ) through photosensitization processes to generate 1 O 2 . Therefore, this study opens the door to further in vitro and in vivo research on 1 O 2 generation by Monascus pigments to assess the potential health risks associated with frequent use of Monascus food supplements and, if necessary, to introduce appropriate regulatory measures for the marketing of Monascus food supplements based on their ability to generate 1 O 2 . • Monascin is an effective photosensitizer • Azaphilones isolated from Monascus are photosensitizing colorants • The Monascus food supplements produce singlet oxygen in the presence of light • The Monascus food supplements can act as prooxidants in the presence of light