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 the SARS-CoV-2 spike protein and ACE2 or reducing the ACE2 availability through ACE2 inhibitions may potentially 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 potentials in suppressing SARS-CoV-2 spike protein−ACE2 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 dosedependently suppressed SARS-CoV-2 spike protein binding to ACE2 and inhibited ACE2 activity. The water extract had stronger inhibitory effects than the ethanol extract on a dry weight basis. The 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 the ethanol extract (58.44 and 2298.01 μmol TE/g, respectively). In contrast, the ethanol extract had greater total phenolic content (TPC) and relative HO • scavenging capacity (HOSC) values (180.03 mg GAE/g and 2181.08 μmol TE/g, respectively) than 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.

Cinnamon (Cinnamomum verum J. Presl) bark and its extracts are popular ingredients added to food and supplement products. It has various health effects, including potentially reducing the risk of coronavirus disease-2019 . In our study, the bioactives in cinnamon water and ethanol extracts were chemically identified, and their potential in suppressing SARS-CoV-2 spike protein−angiotensin-converting enzyme 2 (ACE2) binding, reducing ACE2 availability, and scavenging free radicals was investigated. Twenty-seven and twenty-three compounds were tentatively identified in cinnamon water and ethanol extracts, respectively. Seven compounds, including saccharumoside C, two emodin−glucuronide isomers, two physcion−glucuronide isomers, and two type-A proanthocyanidin hexamers, were first reported in cinnamon. Cinnamon water and ethanol extracts suppressed the binding of SARS-CoV-2 spike protein to ACE2 and inhibited ACE2 activity in a dose-dependent manner. Cinnamon ethanol extract had total phenolic content of 36.67 mg gallic acid equivalents (GAE)/g and free radical scavenging activities against HO • and 2,2′azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTS •+ ) of 1688.85 and 882.88 μmol Trolox equivalents (TE)/g, which were significantly higher than those of the water extract at 24.12 mg GAE/g and 583.12 and 210.36 μmol TE/g. The free radical scavenging activity against 2,2-diphenyl-1-picrylhydrazyl radical (DPPH • ) of cinnamon ethanol extract was lower than that of the water extract. The present study provides new evidence that cinnamon reduces the risk of SARS-CoV-2 infection and COVID-19 development.