**4. Conclusions**

This study reports the chemical profiles of the essential oils from the roots of *P. pabularia* containing 5-pentylcyclohexa-1,3-diene, menthone, 1-tridecyne, and osthole as major compounds. The high coumarin (osthole) content of the essential oil is particularly interesting in regard to the biological activities of the plant. Our investigations clarified the use of essential oil from the roots of *P. pabularia* for the development of formulations based on enzyme inhibition of PTP-1B. Based on molecular docking, we conclude that secondary volatile metabolites (especially osthole) are likely responsible for the inhibition of PTP-1B. Furthermore, the experimental data are also in agreemen<sup>t</sup> with the computational investigation. The anti-diabetic activity of essential oil is related to the dominant volatile compounds, which may be acting synergistically. Further confirmation of anti-diabetic activity of the essential oil from *P. pabularia* needs more research e fforts (especially *in vivo* antihyperglycemic activity), which may be applied in food, agriculture, and medicinal industries as a source of anti-diabetic agent.

**Author Contributions:** S.N., F.S.S., A.M., S.A. performed the phytochemical investigation, designed, and wrote the manuscript; W.N.S., F.S.S., S.N., A.S., M.B. analyzed data; W.N.S., S.N., M.S., M.H. studied the bio-pharmacological activities; H.A.A., W.N.S., made a critical revision of the manuscript.

**Funding:** The authors are grateful for financial support to the Chinese Academy of Sciences President's International Fellowship Initiative (Grant No. 2019PB0043), Central Asian Drug Discovery & Development Center of Chinese Academy of Sciences (Grant No. CAM 201808), Foreign young scholar (Grant No. 2018FYB0004) and CAS "Light of West China" Program 2018-YDYLTD-001.

**Acknowledgments:** W.N.S. participated in this project as part of the activities of the Aromatic Plant Research Center (APRC, https://aromaticplant.org/).

**Conflicts of Interest:** The authors declare no conflict of interest.
