## 3 Discussion  
Saudi Arabia has a distinct climate and geographical location, with many mountains, a desert, and plains resulting in diverse plant biodiversity. According to the literature review, 309 genera with 471 species in 89 families are used in ethnomedicine and to treat various modern diseases [15]. _Ruta_ species are well-known aromatic plants, and their isolated oils provide significant aromaticity. Essential oils are a complex mixture of different constituent classes such as aliphatic alcohols, monoterpenes, sesquiterpenes, ketones, aldehydes, and acids [8]. The current study shows the isolation of pale-yellow essential oil with a strong and penetrating odor. The identification of the chemical constituents of isolated oils using the GC/MS chromatographic method revealed 68 volatile organic constituents, and they accounted for 97.70% of their essence (Table 1). Long-chain aliphatic ketones accounted for 63.80% of the constituents, with 2-undecanone being the most  
Figure 2: The 2D and 3D interactions of (**A**) “\(\alpha\)-Selinene”, (**B**) “Bergapten”, (**C**) “\(\delta\)-Cadinene”, (**D**) “(E)-\(\alpha\)-bisabolene”, (**E**) “Psoralen”, (**F**) “Germacre D”, and (**G**) “\(\beta\)-Eudesmol with the receptor NADPH oxidase. abundant (37.30%) and 2-nonanone accounting for the remaining 20.00%. Monoterpenes cyclic and hydrocarbons were found in reasonable amounts in the air-dried aerial part of the selected plant growing in Saudi Arabia, with camphor (2.70%), limonene (2.60%), and carvone (1.30%) as major constituents. This chemical class of volatile matter is responsible for many biological activities and as the fragrances and odor sensations of many plants [16]. In addition to monoterpenes, the sesquiterpene was present in a volatile fraction at 3.50%, with (_E_)-\(\beta\)-caryophyllene (0.70%) predominating followed by 0.3% of \(\alpha\)-curcurvinn and \(\beta\)-sesquiphellandrene. Diterpene was present in trace amounts and was dominated by moskachane D. Other chemical constituents represented 20.40% of the oil content, including fatty acids, alcohols, and phenolic compounds (see Table 1). Previous studies revealed that the main composition of the oil produced by the _R. chalepensis_ species growing in Argentina, Turkey, Iran, and India was 2-undecanone (38.1, 66.5, 52.5, and 41.3-67.8, respectively). In contrast, 2-nonanone was a significant constituent in Turkish, Italian, Iranian, and Indian oils (16.2, 49.9, 24.1, and 5.2-33.6%, respectively). The major components of the Saudi oil isolated from plants were 2-undecanone, 2-tridecanone, elemol, and \(\beta\)-eudesmol (16.2, 49.9, 24.1, and 5.2-33.6%, respectively) [8]. The key components of the Greek oil were 2-methyl octyl acetate (44.0%) and \(\beta\)-phellandrine (10.7%). These variations in phytochemical components may be due to the different geographical locations, climates, and weather conditions under which the plant was collected [17]. 2-Undecanone is the main constituent of the oils extracted from _Ruta_ species; therefore, it has been proposed as a suitable chemotaxonomic marker for the genus \(Ruta\). However, 2-nonanone could be another marker compound for the chemotaxonomic study of this genus [8]. Hydrodistillation, steam distillation, supercritical fluid extraction, and headspace solid-phase microextraction (HS-SPME) are all methods for extracting essential oil. HS-SPME is a relatively new advanced technique for the isolation of volatile constituents. It extracts organic compounds from its matrix using a fine quartz fiber with a polymeric coating. Then, it directly transfers them into the injector of a gas chromatograph for thermal desorption and analysis. It was designed to extract volatile compounds with a wide range of boiling points without forming artifacts. Additionally, it is a rapid method that does not require solvents or a huge number of instruments. Further, it shields the oil constituents and provides more components than other volatile extraction techniques.