title: Identification of bioactive metabolites dihydrocanadensolide, Kojic acid, and vanillic acid in soy sauce using GC-MS, NMR spectroscopy, and single-crystal X-ray diffraction.
abstract: Microbial transformations of intrinsic substrates offer immense potential for generating new bioactive compounds in fermented food products. The aim of this work was to characterize the secondary metabolites in soy sauce, one of the oldest fermented condiments. Ethyl acetate extract (EAE) of soy sauce was separated using flash column chromatography, crystallized, and analyzed by nuclear magnetic resonance (NMR), single-crystal X-ray diffraction (SC-XRD), and mass spectroscopy. Dihydrocanadensolide (DHC), an antiulcer agent, was identified in a food for the first time. The natural stereostructure of DHC, which remained controversial for several decades, was determined as (3S,3aS,6R,6aR)-6-butyl-3-methyltetrahydrofuro[3,4-b]furan-2,4-dione using SC-XRD analysis. Kojic acid (KA) and vanillic acid (VA) were also identified from EAE as bioactive metabolic products of fungi and yeasts. Moreover, a new polymorphic form of KA was determined by SC-XRD.
authors.affiliation: Department of Nutrition and Food Science, University of Maryland , College Park, Maryland 20742, United States.
authors.forename: Ying
authors.initials: Y
authors.lastname: Li
authors.forename: Zi
authors.initials: Z
authors.lastname: Teng
authors.forename: Kirk L
authors.initials: KL
authors.lastname: Parkin
authors.forename: Qin
authors.initials: Q
authors.lastname: Wang
authors.forename: Qingli
authors.initials: Q
authors.lastname: Zhang
authors.forename: Wei
authors.initials: W
authors.lastname: Luo
authors.forename: Deyun
authors.initials: D
authors.lastname: Ma
authors.forename: Mouming
authors.initials: M
authors.lastname: Zhao
mesh_terms: D008401:Gas Chromatography-Mass Spectrometry; D007783:Lactones / Q000737:chemistry* / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D011753:Pyrones / Q000737:chemistry* / Q000378:metabolism; D045730:Soy Foods / Q000032:analysis*; D014641:Vanillic Acid / Q000737:chemistry* / Q000378:metabolism; D014961:X-Ray Diffraction
chemical_list: D007783:Lactones; D011753:Pyrones; C434312:canadensolide; C011890:kojic acid; D014641:Vanillic Acid
keywords: GC-MS; NMR; bioactive metabolites; dihydrocanadensolide (DHC); kojic acid; polymorphism; single-crystal X-ray diffraction (SC-XRD); soy sauce