## 2 Results and Discussion
### Targeted Multivariate Statistical Analysis of Secondary Metabolites
(2021) have demonstrated that the different medicinal properties of the _Croton_ genus might be related to the high content of bicyclogermacrene (Sesq22), which has been detected among the dominant constituent of the VOCs fingerprint of the different species [26]. The skins of the Faustrime CV are differentiated by the higher presence of hydrocarbon monoterepenes \(\alpha\)-pinene, \(\alpha\)-phellandrene, \(\beta\)-myrcene, and p-cymene, (MH1, MH7, MH8, and MH15, respectively), along with the oxygenated monoterepenes linalool and \(\beta\)-citronellol (MO3 and MO7, respectively), and the sesquiterpenes \(\alpha\)-bergamotene, \(\alpha\)-caryophilene, and \(\beta\)-bisabolene, (Sesq8, Sesq16, and Sesq23, respectively). The hydrocarbon monoterepne fraction (MH1, MH7, MH8, and MH15), all described by a terpenic, citrus, slightly green flavor, and the two oxygenase monoterepenes (MO3 and MO7), both with citrus and floral odor, have been often found in moderate concentrations in lime species [1; 9; 12]. Moreover, these terpen have been reported to extend different biological activities [1; 12; 23]. In particular, [PERSON] et al. (2017) have demonstrated that mastic oil, which contains about 67.7% \(\alpha\)-pinene and 18.8% myrce, is able to induce a statistically significant anti-tumor effect on colon cancer in mice, but not \(\alpha\)-pinene, myrce, or a combination thereof, providing evidence that the interaction of different monoterepenes in a plant matrix can produce a remarkable synergistic or additive effect which seems to enhance the biological properties [27]. Regarding the three sesquiterpenes, Sesq8, Sesq16, and Sesq23 are typically detected in lime species and are responsible for the woody lime character perceived in the fresh peel of this fruit [1; 9]. Additionally, \(\alpha\)-caryophilene (Sesq16) and \(\alpha\)-bergamotene (Sesq8), among the major components in the bergamotene oil, have been found to possess marked anti-inflammatory actions, while a combination of \(\alpha\)-bergamotene (Sesq8), \(\beta\)-bisabolene (Sesq23), and \(\alpha\) and \(\beta\)-seline, the four major components of _Copifera reticulata_, have been reported to have good activity against oral pathogens [28]. Data related to the juice of all three CVs and the peel of the Pink Pearl CV form a single cluster of the PCA model (Figure 3A). These samples are directly correlated to limonene and \(\beta\)-phellandrene (MH10 and MH11, respectively), which occurred in higher content in their VOCs profiles (Table 1, Figure 3B). All the other identified compounds lay in proximity to the origin, so they can not represent characteristic markers of discrimination. Limonene, which greatly contributes to the fruity scent owing to its low odor threshold, has been reported to possess several healthy properties [11]. Specifically, various in vitro assays have demonstrated that limonene extends a concentration-dependent decrease in free radical formation and, when evaluated together with other terpenoids, it has resulted to be among the most powerful scavengers of the free radical DPPH [10]. [PERSON] et al. (2010) have observed that the antifungal, antiaflatoxicenic, and antioxidant activities of the essential oils of _Citrus maxima_ and citrus sinensis are almost due to limonene, the major component in both oils. Moreover, authors reported that limonene showed an even better antiflatoxicigenic efficacy at half of the concentration (250 ppm) that requested for both essential oils and their 1:1 combination to have the same effect [29]. Consequently, _Citrus_ spp. essential oils and/or limonene alone could be recommended as a plant-based antimicrobial, as well as useful additives for food preservation to prolong shelf life and improve the quality of stored food commodities, without modifying their organoleptic properties [29]. On the other hand, limonene has been revealed to exhibit other potential biological activities, including hypocholesterolic and anticarcinogenic properties [30]. The essential oil of _Stachys lavandulifolia_ Vahl. subsp.