Diethyl succinate

Levoglucosenone was graciously provided by the Circa Group. Potassium carbonate 99% (Acros), hydrogen peroxide 30% (Fischer), diethyl succinate 98% (Alpha Aesar), malonyl chloride 97% (Sigma Aldrich), succinyl chloride 95% (Sigma Aldrich), adipoyl chloride 98% (Sigma Aldrich), glutaryl chloride 97% (Sigma Aldrich), terephthaloyl chloride >99% flakes (Sigma Aldrich) were used without further purification unless mentioned. NMR solvents including deuterated chloroform, deuterated methanol, and deuterated dimethyl sulfoxide were purchased from Cambridge Isotopes Laboratories.

Commercial standards of delphinidin 3-O-sambubioside (DS), cyanidin 3-O-sambubioside (CS) and quercetin, were purchased from Extrasynthese, Genay, (France), while trifluoroacetic acid, LC-MS grade formic acid, gallic acid, caffeic acid, Folin-Ciocalteu's reagent and ethanol were from Sigma Aldrich, St Louis, Missouri, (USA). 2-phenylethanol, isoamyl alcohol, ethyl acetate, ethyl hexanoate, ethyl decanoate, ethyl lactate, isoamyl acetate, methyl butyrate, intestinal acetone powder from rat, glucose assay reagent, maltose and sodium mono and dibasic phosphate were from Sigma-Aldrich, Dorset, (UK); while 1hexanol, eugenol, diethyl succinate and ethyl octanoate were from Alfa Aesar, Lancashire, (UK). Sodium carbonate was from Fisher scientific, Loughborough (UK) and the solid phase extraction Oasis MAX cartridge 3 mL (60 mg) was purchased from Waters Corporation Ltd., Massachusetts (USA). All other standards used in the study were either analytical grade, HPLC or GC grade.