Chemical composition of thyme (Thymus vulgaris) extracts and potential inhibition of SARS-CoV-2 spike protein-ACE2 binding and ACE-2 expression, and radical scavenging capacity

Authors: YAO, YUANHANG - University Of Maryland; LI, YANFANG - University Of Maryland; Pehrsson, Pamela; Sun, Jianghao; Chen, Pei; HUANG, DEJIAN - National University Hospital Singapore; YU, LIANGLI (LUCY) - University Of Maryland; Whent, Monica; Wu, Xianli

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/17/2023
Publication Date: 12/1/2023
Citation: Yao, Y., Li, Y., Whent, M.M., Pehrsson, P.R., Sun, J., Chen, P., Wu, X., Huang, D., Yu, L. 2023. Chemical composition of thyme (Thymus vulgaris) extracts and potential inhibition of SARS-CoV-2 spike protein-ACE2 binding and ACE-2 expression, and radical scavenging capacity. Journal of Agricultural and Food Chemistry. 71(49):19523-19530. https://doi.org/10.1021/acs.jafc.3c05432.
DOI: https://doi.org/10.1021/acs.jafc.3c05432

Interpretive Summary: Thyme is an herb used in cooking and has medicinal properties. In this study water and ethanol extracts of dried thyme were analyzed for chemical composition, inhibition of SARS-CoV-2 spike protein-ACE2 interaction, inhibition of ACE2 expression, and free radical scavenging capacity. Thirty-two compounds were identified in water extract (WE) and 27 were identified in ethanol extract (EE) of thyme. The WE (33.3 mg/mL) and EE (3.3 mg/mL) of thyme inhibited the spike protein-ACE2 interaction by 82.6% and 86.4%, respectively. Thyme WE at 5 mg/mL inhibited ACE-2 activity by 99% and EE at 5 mg/mL inhibited ACE-2 by 65.8%. Total phenolic compounds were measured as 38.9 and 8.8 GAE/g in WE and EE. Both WE and EE displayed free radical scavenging activities. Hydroxyl radical scavenging capacity was 1121.1 and 284.4 µmol TE/g in WE and EE, respectively. Relative DPPH• scavenging capacity was 126.3 µmol TE/g for WE and 28.2 µmol TE/g in EE. The ABTS•+ scavenging capacity was 267.1 µmol TE/g for WE and 96.7 µmol TE/g in EE. The results suggested that thyme extract could be potentially used to prevent SARS-CoV-2 infection.

Technical Abstract: Water and ethanol extracts of dried thyme (Thymus vulgaris) were analyzed for chemical composition, inhibition of SARS-CoV-2 spike protein-ACE2 interaction, inhibition of ACE2 expression, and free radical scavenging capacity. Thirty-two compounds were identified in water extract (WE) and 27 were identified in ethanol extract (EE) of thyme through LC-MS. The WE (33.3 mg/mL) and EE (3.3 mg/mL) of thyme inhibited the spike protein-ACE2 interaction by 82.6% and 86.4%, respectively. Thyme WE at 5 mg/mL inhibited ACE-2 activity by 99% and EE at 5 mg/mL inhibited ACE-2 by 65.8%. Total phenolics were 38.9 and 8.8 GAE/g in WE and EE. Hydroxyl radical scavenging capacity (HOSC) was 1121.1 and 284.4 µmol TE/g in WE and EE, respectively. Relative DPPH• scavenging capacity (RDSC) was 126.3 µmol TE/g for WE and 28.2 µmol TE/g in EE. The ABTS•+ scavenging capacity was 267.1 µmol TE/g for WE and 96.7 µmol TE/g in EE. The results suggested that thyme extract could be potentially used to prevent SARS-CoV-2 infection.