Fig. 4

Identification of compound 1. a GC chromatograms of mannose, galactose, glucose, fructose, and sugar from compound 1. A major peak of each sugar was indicated. Fructose and sugar from compound 1 co-eluted. b GC–MS spectrum of fructose. c GC–MS spectrum of the sugar from compound 1. d NMR spectrum of compound 1. 1D proton spectrum (top); HSQC spectrum (middle); HMBC spectrum (bottom). e Structure of 3,4-disinapoyl-fructopyranose