## 4 Discussion  
Initial optimization of floral fragrance pattern in different flowering stages of _Aster yomena_ showed that the floral scent characteristics varied based on the development of the flowering stage. Since the RAI was highest in the full flowering stage, further flower fragrance analysis by E-nose in the nine _Aster_ species was performed in the full flowering  
Figure 8: DPPH (**a**) and ABTS (**b**) radical scavenging capacity of the flowers of _Aster_ species. Different letters in columns indicate significance from [PERSON] post hoc test (A value of \(p\) < 0.05 was considered significant). Error bars indicate standard error of the mean. stage. Further, floral scent patterns of nine _Aster_ species were analyzed in the fully opened flowering stage through multivariate statistical analysis such as PCA and DFA of E-nose sensor data (Figure 3). The PCA and DFA plots of E-nose floral scent of nine _Aster_ species showed that all the samples were located separately based on species, which indicates that the scent pattern was species specific. E-nose sensors PA/2, P40/1, P10/2, and T30/1 showed stronger signals. Earlier reports indicated that E-nose sensors including PA/2, P40/1, P10/2, and T30/1 exhibit an affinity for organic solvents, fluoride/chloride, and non-polar volatile substances [30]. Volatile compounds that respond to the mentioned sensors could be candidate compounds that contribute to identifying _Aster_ species. Earlier studies reported that monoterenes and sesquiterpenes were the main volatile compounds in _Aster scaber_ essential oil, and myrcene, limonene, and germanene D were the main volatile compounds [12]. \(\beta\)-myrcene is spicy, woody volatile, and is used as a starting material for commercially important fragrances such as geraniol, linalool, and menthol [35]. It has various therapeutic effects such as antioxidant, anti-inflammatory, and analgesic effects [36; 37; 38]. D-limonene and trans-\(\beta\)-ocimene were identified in eight species except for AKS. Limonene is a terpene and has a citrus aroma and taste. It is found in citrus oils such as lemon, orange, and grapefruit [39]. It has low toxicity and has been reported to have potential physiological activities including antitumor, antioxidant, and anti-inflammatory effects [40; 41]. Trans-\(\beta\)-ocimene has a sweet herbal scent and is one of the wide range of floral volatile organic compounds. It acts as an attractive compound for pollinating species [42; 43]. \(\alpha\)-pinene is present in seven species except AYN and AKS with higher contents in APN (16.7%) and ADG (17.6%). \(\alpha\)-pinene has pine tree aroma and it is also found in high concentrations in _Juniperus oxycedrus_ berry and wood oils from cedar of Lebanon. Its flavor is an important starting material for the fragrance industry and it is reported to have antioxidant and hypoglycemic activities [44; 45]. Caryophyllene is found in the eight species except ADG, with higher concentration in AKS (24.5%). Caryophyllene is a common, widely present, sesquiterpene anti-inflammatory and has anti-carcinogenic properties [46]. The volatility profile also consisted of key compounds such as \(\beta\)-bisabolene and \(\alpha\)-curcumene. These compounds were reported to possess potential anti-cancer properties [47; 48]. In addition, terpinene which is abundant in AAR, is used as a flavoring and synthetic flavoring agent and is also found to have antioriginal and antioxidant properties that can prevent LDL oxidation [49; 50]. HCA dendrograms based on E-nose and GC-MS data divided the nine _Aster_ species into two major clusters (Figure 7a,b). Hence, all the nine _Aster_ species could be discriminated according to their scent patterns and volatile components. Previous reports also showed that the cultivars of _Alpinia officinarum_ and Chinese _Cybidium_ were discriminated based on the differences in volatile components and their characteristics [51; 52]. The present study represents the qualitative evaluation of floral volatiles by HS-SPME-GC-MS.