New lactones in liquorice (Glycyrrhiza glabra L.)

The lactonic fraction of a commercial liquorice root extract (licorice, Glycyrrhiza glabra L., family Fabaceae), exhibiting a pleasant sweet, woody, dried fruit-like odour, contains mainly fatty acids (C2–C16) and phenols (phenol, guaiacol), together with common saturated linear γ-lactones (C6–C14) and, in trace amounts, a series of new 4-methyl-γ-lactones and 4-ethyl-γ-lactones. Their structures have been confirmed by synthesis. Spectral data and organoleptic descriptors are given. Some 5-methyl-δ-lactones, which can easily be confused with the 4-ethyl-γ-lactones, are also discussed.