Available comparable reference phenolics were caffeine, theobromine, theophylline, (±)-catechin, (-)-epigallocatechin gallate, (-)-epicatechin, (-)-epicatechin gallate, (-)-epigallocatechin, caffeic acid, p-coumaric acid, vanillic acid, rosmarinic acid, quercetin, naringenin, luteolin, kaempferol, ursolic acid, pinocembrin, carnosic acid, apigenin, ferulic acid, cyanidin-3-rutinosede, pelargonidin-3-glucoside, cyanidin, pelargonidin, quercetin 3-glucoside, and kaempferol 3-glucoside from Sigma Aldrich (St. Louis, MO, USA) [20 (link)].
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