Photosensitized Oxidative Reaction of 2,5-Dimethyl-4-hydroxy-3(2H)-furanone

2,5-Dimethyl-4-hydroxy-3(2 H )-furanone (DMHF) in absolute alcohol containing chlorophyll was exposed to light while being bubbled with oxygen. The photooxidation products, including ethyl pyruvate, ethyl lactate, acetic acid, ethyl 2-acetoxypropionate, acetoxyacetone, 1,2-ethanediol, acetoxy-2,3-butanedione, 2-oxopropyl 2-acetoxypropionate, lactic acid, and 2-acetoxypropionic acid were identified using gas chromatography (GC) and gas chromatography−mass spectrometry (GC-MS). Possible formation mechanisms for these products are postulated. The antiphotooxidative effect of capsanthin and lutein on DMHF in absolute alcohol containing chlorophyll was studied under light exposure while bubbling with oxygen. Both capsanthin and lutein showed the antiphotooxidative effect on DMHF, and their antiphotooxidative activity increased with increasing concentration. The activity of capsanthin, which contains 11 conjugated double bonds, a conjugated keto group, and one cyclopentane ring, was higher than that of lutein, which contains 10 conjugated double bonds but neither a conjugated keto group nor a cyclopentane ring.