Peridinin as the Major Biological Carotenoid Quencher of Singlet Oxygen in Marine Algae Gonyaulax polyedra

Abstract

Carotenoids in light-harvesting proteins and reaction centers increase the overall efficiency of photosynthesis by transferring absorbed light energy to chlorophylls. Peridinin and β-carotene were isolated from Gonyaulax polyedra in a one-step purification protocol using the preparative circular chromatography (Chromatotron), performed on silica gel under N2 atmosphere and n-hexane/acetone 8:2 as mobile phase and characterized by extensive 1H NMR, infrared, and electrospray ionization mass spectrometry analyses. The quenching of singlet molecular oxygen [O2 (1Δg)] was evaluated by NIR-emission assays using singlet oxygen generated by sensitization of either perinaphthenone or methylene blue. The NIR-emission assay showed that peridinin quench as singlet oxygen (kq = 9.5 × 108 M−1 s−1) 5-fold less efficiently than β-carotene (52 × 108 M−1 s−1). A method, based on the use of high-performance liquid chromatography with UV–VIS detection, was then developed for the sensitive quantification of peridinin (55% of total carotenoids) and β-carotene (4.1% of total carotenoids). Thus, since peridinin is 10-fold more abundant than β-carotene, it is expected to be the major protector against the deleterious effects of O2 (1Δg) in Gonyaulax polyedra.