Quali-Quantitative Determination of Chlorogenic Acid in Artichoke Heads by Means of RP-HPLC and GC-MS

Chlorogenic acid (trans-5-O-caffeoyl-D-quinic acid) is the quantitatively predominant hydroxycinnamate contained in artichoke (Cynara scolymus L.) tissues, and is directly involved in many of its well-documented hepatoprotective effects. The research has concerned: (a) the quali-quantitative determination of chlorogenic acid in the edible parts (inner bracts or ‘hearts’) of the main head at harvest time in 4 early artichoke cultivars from South Italy (“Violetto di Provenza”, ”Violetto di Sicilia”, “Locale di Mola”, “Thema”) and 2 late cultivars from Central Italy (“Grato 1” and “Terom”); (b) the determination of the chlorogenic acid content during the development of the main head (cv. ”Terom” and cv. “Grato 1”); (c) the evaluation of the effect of thermal treatment on the chlorogenic acid content in the edible parts of artichoke heads (cv.”Grato1”). The analysis of the methanolic extracts were carried out by means of RP-HPLC and GC/MS using chlorogenic acid methylester as internal standard. The results of cultivar comparison shows a more limited variability (ranging from 1.003 mg/g of FW in “Thema” to 2.464 mg/g of FW in “Grato 1”) than previously reported in literature, mainly due to the analytical under/overestimation of the true chlorogenic acid content without using an internal standard. The chlorogenic acid concentration decreases during the development of the main heads (i.e. for “Grato 1” a reduction of 38 % in the chlorogenic acid content has been found, going from 26 days before harvest to harvest stage). Finally, after boiling the inner bracts in water for 20 minutes, a loss of 44% in the chlorogenic acid content has been observed.