Cynaropicrin, total caffeoylquinic acids and flavonoids in leaves of Cynara cardunculus (cardoon) forms

Cynara cardunculus leaves contain several polyphenols such as phenolic acids, flavonoids and cynaropicrin, which are highly desirable in diet, because of their beneficial effects on human health, and in food and no-food applications for their antioxidant, antibacterial and allelopathic activity. The qualitative and quantitative profile of these compounds is affected by several factors such as genotype, part of the plant, postharvest storage, industrial processing and agronomic factors. Among these, the harvest time appears to be very important due to the different weather conditions experienced during the harvest period, as well as the leaf growth stage. Considering that additional investigation of these compounds is still required in order to promote the use of agricultural material as source of bioactive compounds, the purpose of the present work was to assess the content of individual phenolics, by HPLC analysis on leaves of cultivated cardoon, in relation to the harvest time and the leaf growth stage. The dry matter content was also evaluated. A field experiment was conducted on the Catania Plain (Sicily). Our results showed the chlorogenic acid was not affected by harvest time, but it was influenced by the leaf growth stage. In particular, the branch leaves registered a higher level than new caulicle ones (2.65 vs. 2.29 g 100 g‑1 dry matter), with the maximum peak in winter time. The total caffeoylquinic acids, and cynaropicrin content were highest in spring time (3.93 and 3.64 g 100 g‑1 dry matter, respectively). A similar trend was observed for the dry matter content. Definitely, this research underlined the factors under study have an important impact on the amount of these compounds and, therefore, they should be taken into account in terms of industrial costs and benefits.