Monocaffeoylquinic acid

AMOUNTS OF MONOCAFFEOYLQUINIC ACIDS (MNOCQA), DICAFFEOYLQUINIC ACIDS (DICQA), AND FLAVONIDES (FLAV) IN DRIED ARTICHOKE EXTRACTS. RESULTS ARE EXPRESSED AS PER CENT (%) SD ALL SAMPLES WERE INJECTED IN TRIPLICATE... 

Peak 1 and 2 can be assigned to the nucleosides Guanin (1) and Adenosin (2), identified with reference compound). Peak 3 is chlorogenic acid as the only monocaffeoylquinic acid. The peak numbers 4-6 with the characteristic double maxima at 257 and 348 nm can be assigned to flavonoids. The peak 7-9 possess a very similar UV-spectrum as peak 3 (chlorogenic acid) and can be identified as dicaffeoylquinic acids (see also TLC-Fig. 2). 

The ethyl acetate fraction of Art. campestris was purified to give 3,4-dicafeoylquinic acid (10), 3,S-dicafeoyIquinic acid (11) and 4,5-dicaffeoylquinic acid (12), methyl 3,5-dicaffeoylquinate (13) together with monocaffeoylquinic acid isomers and flavonoids. Figure 3 shows the DPPH radical scavenging activity of caffeoylquinic acid derivatives. Monocaffeoylquinic acids showed the activity comparable to a-tocopherol and ascorbic acid. On the other hand,... 

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