Elucidation of an α-glucosidase inhibitor from the peel of Allium cepa by principal component analysis.

We conducted liquid chromatography-mass spectrometry measurements on hot-water extracts of peel from different varieties of Allium cepa. Some quercetin glycosides were identified as potential α-glucosidase inhibitors by principal component analysis of the liquid chromatography-mass spectrometry data. α-Glucosidase inhibitory activity assays identified quercetin-4'-O-glucoside as an α-glucosidase inhibitor.

Isomerization of feruloylputrescine in orange juice by light exposure.

Exposure to light may adversely affect the quality of foods. This investigation of how light exposure affects citrus (orange and mandarin blend) juice in polyethylene terephthalate (PET) bottles demonstrated that the isomeric form of a compound in the juice changed during storage. This compound was identified as feruloylputrescine (FP; CAS: 501-13-3; CHNO) using LC/MS (Q-TOF).