## 3 Results and Discussion
### Chemical Investigation
#### 3.3.1 Characterization and Quantification of Phenolic Compounds by HPLC-DAD
As previously discussed, the observed differences could be attributed to several factors, including, among others, the different genotypes, and the various environmental conditions in which they were grown (Sardinia and Sicily for the two cultivars and Central Italy for the three genotypes analyzed in this study). These factors could exert a significant impact on polyphenol biosynthesis and accumulation. According to our findings in the secondary flower heads, 5-O-caffeoylquinic acid (chlorogenic acid) and 3,5- and 1,5-di-O-caffeoylquinic acids were the most abundant phenolic compounds in both cultivars, representing more than 90% of the total polyphenols [? ]. In contrast, the flavonoid content, represented only by apigenin and apigenin 7-O-glucose, was very low (approximately 1% of the total identified polyphenols) [? ]. Despite the considerable variability reported in the literature regarding the phenolic content and composition of different artichoke plant parts, the total phenolic compounds identified in the stems and secondary flower heads of two representative genotypes of the \"_Carciofo Ortano_\" landrace in this study highlight their potential as cost-effective and valuable sources of bioactive compounds, primarily 5-O-caffeoylquinic acid (chlorogenic acid) and 3,5- and 1,5-di-O-caffeoylquinic acids, which, regardless of genotype or plant part, accounted for more than 90% of the total identified polyphenols. These compounds are well-recognized for their potential health benefits, including antioxidant, anti-inflammatory, hepatoprotective, and anticancer properties [??? ]. Notably, the highest concentration of these compounds was observed in the stem, a plant part typically discarded as waste. Consequently, stems could serve as an underutilized source of natural antioxidants, with their industrial recovery offering additional economic value for local producers. In contrast to polyphenols, limited data are currently available on the concentration of the sesquiterpene cynaporicrin in various parts of the artichoke plant. [PERSON] et al. [? ] reported a cynaporicrin concentration of 2.7 g/kg DW in the stem of the \"Tondo di Paestum\" variety, which was comparable to the levels of this sesquiterpene lactone found in the same tissue of the two \"Carciofo Ortano\" genotypes analyzed in this study. Conversely, a significantly lower concentration of cynaporicrin (0.014 g/kg DW) was detected in the primary heads of the same variety compared to the levels found in the secondary heads of the two \"Carciofo Ortano\" genotypes (0.284-0.977 g/kg DW) in the present study. Considering that the highest concentration of this sesquiterpene lactone among the various artichoke plant parts has been reported in the leaves, ranging from 4 to 20 g/kg DW [?? ], the two main by-products of artichoke cultivation (stems and leaves) could serve as valuable sources of this important bioactive compound. Several studies have demonstrated that cynaporicrin, which is primarily responsible for the characteristic bitter taste of artichoke, exhibits various biological activities, including anti-hyperlipidemic, anti-inflammatory, and anti-photoaging effects [?? ]. Furthermore, it has been reported that cynaporicrin, even at very low concentrations, can activate the human bitter taste receptor hTAS2R46 in vitro [? ]. This property may contribute to the metabolic benefits primarily associated with the consumption of artichoke polyphenols. Indeed, emerging evidence indicates that bitter compounds influence neurohormonal pathways involved in regulating gastrointestinal motility, glucose homeostasis, and appetite control by activating bitter taste receptors distributed throughout the gastrointestinal tract.