Disclosed herein is the gentiobiose glycoside of methyl syringate, a biologically active ingredient of manuka honey. Specifically, the present description discloses a compound represented by formula I where the substituents are as defined herein, for example the compound methyl-4-O-[&bgr；-D-glucopyranosyl-(1&rarr；6)-&bgr；-D-glucopyranosyl]-3,5-dimethoxybenzoate (MGGD). Also disclosed are methods for the isolation of the compound and its use as a honey evaluation marker with reference to the inhibition of myeloperoxidase activity.
