## 4 Conclusions  
The chemical, antioxidative, and antibacterial properties of leaf and stem oils were studied. The GC/MS method revealed 73 different constituents, 47 of which were found in the leaf and 40 were found in the stem; of these, only 13 common compounds were found in both the leaf and stem oils, with a content of 21.7% and 55.6%, respectively. The main constituents in the leaf oil included alcohols (34.1%), hydrocarbons (24.1%), terpenoids (16.2%), benzenes (7.5%), and fatty acids (4.9%). In the stem oil, the constituents were chiefly benzenes (18.8%), ketones (13.9%), terpenoids (17.0%), fatty acids (8.8%), phenolics (8.7%), steroids (8.6%), hydrocarbons (8.0%), and esters (5.7%). The representative compounds in the leaf oil were (_E_)-3-hexen-1-ol (13.7%), (_Z_)-3-hexen-1-ol (14.0%), tetraetracontane (4.7%),heneicosane (4.4%), and 1,2,3,4,5,6,7,8-octahydro-9,10-dimethyl-anthracene (4.2%), whereas the stem oil mainly contained 2-(1-cyclopent-1-enyl-1-methylethyl)cyclopentanone (11.7%), 1,2,3,4,5,6,7,8-octahydro- 9,10-dimethyl-anthracene (8.4%), 5-heptylrescorinol (6.5%), \(\alpha\)-sitosterol (5.2%), 1,3-dimethyl-benzene (4.4%), and 1,1'-bicyclohexyl (4.0%). This depicted a vast difference in the leaf and stem compositions.  
Additionally, the stem oil presented apparent antioxidant and antibacterial capacities. This was likely linked to its high accumulation of benzenes, phenolics, and terpenoids, especially monoterenes. Monoterpenes, as representative constituents with antioxidative and antibacterial capacities, demonstrated a different distribution or accumulation in the leaf and stem volatiles. This was possibly based on the stem advantages in terms of regulating the enzymes responsible for generating volatiles, namely, HMGR, PMK, and MK in the MVA pathway or enzymes DXS and DXR in the MEP pathway as well as their relative highly expressed genes. The findings also exhibited strong inhibition for G\({}^{+}\) microbes (MSSA and MRSA) as well as weak inhibition for G\({}^{-}\) microbes (_P. aeruginosa_, _E. coli_, _P._ spp., and _K. pneumoniae_). This could be related to the inhibition properties of volatiles and may be worthy of further study and exploitation.  
In this work, constituent type, chemical compounds, relative content, and antioxidant and antibacterial capacities in _F. japonicum_ leaf and stem oils were studied. This revealed a large difference in both plant organs. SFE-CO\({}_{2}\) extraction revealed a high accumulation of monoterenes and this could play a special role in these findings. This may provide could provide a direction for more extensive research in the future.  
Conceptualization and methodology, Y.-H.Z.; writing--review and editing, Q.W. All authors have read and agreed to the published version of the manuscript. This research was funded by Natural Science Fund of Education Department of Anhui Province (grant number: KJ2020A0791) and Key Subject of Anhui Xinhua University (grant number: zdxk202104).  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** Not applicable.  
**Conflicts of Interest:** The authors declare no conflict of interest.  
**Sample Availability:** Samples of the compounds are not available from the authors.