## 3 Results and Discussion
### Polyphenic Composition  
The HPLC-UV qualitative and quantitative analysis results of the extracts are presented in Table 3.  
Eight phenolic acids, (i.e., gallic acid, \(p\)-OH-benzoic acid, chlorogenic acid, vanillic acid, caffeic acid, syringe acid, ferulic acid, and rosmarinic acid), one phenolic monoterpene (carvacrol) and two flavonoids (i.e., luteolin and apigenin) were identified in thyme. Rosmarinic acid was the compound with the highest concentration in all extracts. Rosmarinic acid is known as one of the main constituents of thyme and it has been recognized for antioxidant, antiviral, anti-inflammatory, antibacterial, and immunostimulant activities [49; 50]. UAE and M extracts were significantly poorer of polyphenols, except for the highest UAE luteolin content; however, they were the only extracts containing some phenolic acids (i.e., vanillic and caffeic acids in UAE, syringe acid in M). RSLDE exhibited improved extraction of \(p\)-OH-benzoic and chlorogenic acids. A non-univocal effect of the increase of the extraction time was observed, as some components have increased and others decreased. In line with our findings, the decrease in content of rosmarinic acid and luteolin at prolonged extraction time has been reported by other authors [51; 52]. Besides the extraction operative conditions like solvent, temperature, and time, the stability of natural products in certain conditions is a variable that may influence the chemical composition of the extract. The bioactive compound, during the extraction procedure, are exposed to chemical reactions with solvent and/or other components in the solution that rearrange chemical structures. Chemical alterations occur also after the extraction process, due to manipulation (e.g., solvent removal) and/or conservation conditions (e.g., compounds breakdown by oxidation or light) [53; 54]. Figure 4: Dendrogram obtained from the cluster analysis based on terpenes classes data for thyme extracts. Three phenolic acids (i.e., gallic acid, \(p\)-OH-benzoic acid, and rosmarinic acid) and two flavonoids (i.e., luteolin and apigenin) were mainly found in hemp. The most abundant component was luteolin, a flavonoid with antioxidant [55], anti-inflammatory and antiallergic [56] activity. Among the few literature studies on the identification of polyphenols in hemp extracts, the presence in hemp essential oil of gallic acid and \(p\)-OH benzoic acid has been already reported [57]. Considering the different extraction techniques, N2h was the extract richest in the three main compounds: rosmarinic acid, luteolin, and apigenin. N6h indicated that the increase in extraction time allowed the recovery of gallic acid, \(p\)-OH-benzoic acid, and ferulic acid, with a loss in the main components. Indeed, the increase in Soxhlet extraction time from 2 h to 6 h led to an increase in the concentration of gallic acid and of the two flavonoids luteolin and apigenin, accompanied by the decrease of \(p\)-OH-benzoic acid and rosmarinic acid. M was the poorest extract compared to other techniques. Similarly to thyme, eight phenolic acids (i.e., gallic acid, \(p\)-OH-benzoic acid, chlorogenic acid, vanillic acid, caffe acid, syringic acid, ferulic acid, and rosmarinic acid) and two flavonoids (i.e., luteolin and apigenin) were detected in coriander seeds. [PERSON] and collaborators [58] reported a similar profile in the analysis of polyphenols of coriander seeds. However, gallic acid, luteolin, and apigenin were not detected. [PERSON] and collaborators [59] described a similar composition, with a higher number of flavonoids components (quercetin, rutin, luteolin, apigenin, and kaempfer). Among the different extraction techniques, RSLDE extracts were richer in gallic, \(p\)-OH-benzoic, and rosmarinic phenolic acids and in luteolin and apigenin, with a positive effect of longer extraction time on their concentration, except for \(p\)-OH-benzoic acid and luteolin.