SUMMARY: The anthocyanin pigments present in the skins of Tinto cão grapes were extracted with 0.1% HCI in methanol. The pigments were purified by Dowex 50 W‐X4 cation exchange resin, and separated into individual pigments by two‐dimensional paper chromatography with n‐butanol‐acetic acid‐water (4:1:5, v/v) and acetic acid‐water‐HCI (15:82:3, v/v) as solvent systems. Partial acid hydrolysis revealed the number of sugar molecules in each pigment. Acyl components and sugar moieties were identified through acid hydrolysis and spectral measurement. The R f measurement of the pigments and their hydrolysis products, together with the alkaline degradation of the aglycone, confirmed the chemical structures of the anthocyanins as malvidin 3‐monoglucoside, peonidin 3‐monoglucoside, cyanidin 3‐monoglucoside, petunidin 3‐monoglucoside, petunidin 3‐monoglucoside acylated with caffeic acid, malvidin 3‐monoglucoside acylated with caffeic acid, malvidin 3‐monoglucoside acylated with p‐coumaric acid, peonidin 3‐monoglucoside acylated with p‐coumaric acid, and cyanidin 3‐monoglucoside acylated with caffeic acid. Malvidin and peonidin were not present in the original sample. They were formed during the extraction and purification procedures. Malvidin 3‐monogfucoside and malvidin 3‐monoglucoside acylated with p‐coumaric acid were the dominant anthocyanins present in Tinto‐cao grapes.
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Liao et al. (1970) studied this question.