Chemical compositions of clove (Syzygium aromaticum (L.) Merr. & L.) extracts and their potentials in suppressing SARS-CoV-2 spike protein-ACE2 binding, inhibiting ACE2, and scavenging free radicals

Authors: LI, YANFANG - University Of Maryland; LIU, ZHIHAO - University Of Maryland; ZENG, MELODY - University Of Maryland; EL KADIRI, ALEM - University Of Maryland; HUANG, JHONGYAN - University Of Maryland; KIM, ASHLEY - University Of Maryland; He, Xiaohua; Sun, Jianghao; Chen, Pei; Wang, Thomas - Tom; ZHANG, YAQIONG - Shanghai Jiaotong University; GAO, BOYAN - Shanghai Jiaotong University; XIE, ZHUOHONG - University Of Maryland; YU, LIANGLI - University Of Maryland

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/17/2022
Publication Date: 11/1/2022
Citation: Li, Y., Liu, Z., Zeng, M., El Kadiri, A., Huang, J., Kim, A., He, X., Sun, J., Chen, P., Wang, T.T., Zhang, Y., Gao, B., Xie, Z., Yu, L. 2022. Chemical compositions of clove (Syzygium aromaticum (L.) Merr. & L.) extracts and their potentials in suppressing SARS-CoV-2 spike protein-ACE2 binding, inhibiting ACE2, and scavenging free radicals. Journal of Agricultural and Food Chemistry. 70(45):14403-14413. https://doi.org/10.1021/acs.jafc.2c06300.
DOI: https://doi.org/10.1021/acs.jafc.2c06300

Interpretive Summary: Covid-19 pandemic has become an international public health emergency due to its high infectivity and mortality rate. Protection from vaccines has become less effective due to the continuous generation of the "escape variants". Alternative approaches to control SARS-CoV2 infection and COVID-19 development are in high demand. This study characterized the chemical compositions of clove water and ethanol extracts and demonstrated their anti-COVID-19 and antioxidant properties. Six novel compounds were identified in clove extracts. The inhibitory effects of clove extracts on the interaction between SARS-CoV-2 spike protein and ACE2 and ACE2 activity were demonstrated for the first time. Compared with clove ethanol extract, clove water extract had higher inhibitory effects and RDSC and ABTS values, whereas the ethanol extract had higher TPC and HOSC values on a dry weight basis. Also, clove extracts exhibited higher radical scavenging capacities than that of other spices reported previously. This study demonstrated that clove has the great potential to reduce the risk of COVID-19 infection and progression. However, in vivo studies are needed to verify the benefits and elucidate the underlying mechanisms.

Technical Abstract: COVID-19 is initiated by binding the SARS-CoV-2 spike protein to angiotensin-converting enzyme 2 (ACE2) on host cells. Food factors capable of suppressing the binding between SARS-CoV-2 spike protein and ACE2, or reducing the ACE2 availability through ACE2 inhibitions may reduce the risk of SARS-CoV-2 infection and COVID-19. In this study, the chemical compositions of clove water and ethanol extracts were investigated, along with their potential in suppressing SARS-CoV-2 spike protein-ACE 2 binding, reducing ACE2 availability, and scavenging free radicals. Thirty-four compounds were tentatively identified in the clove water and ethanol extracts, with six reported in clove for the first time. Clove water and ethanol extracts dose-dependently suppressed SARS-CoV-2 spike protein binding to ACE2 and inhibited ACE2 activity. The water extract had stronger inhibitory effects than that of the ethanol extract on a dry weight basis. Clove water extract also had more potent free radical scavenging activities against DPPH•'and ABTS•+ (536.9 and 3525.06 µmol TE/g, respectively) than that the ethanol extract (58.44 and 2298.01 µmol TE/g, respectively). In contrast, the ethanol extract had greater TPC and HOSC values (180.03 mg GAE/g and 2181.08 µmol TE/g, respectively) than that of the water extract (120.12 mg GAE/g and 1483.02 µmol TE/g, respectively). The present study demonstrated the potential of clove in reducing the risk of SARS-CoV-2 infection and COVID-19 development.