Chemical Composition of Rosemary (Rosmarinus officinalis L.) Extract and Its Inhibitory Effects on SARS-CoV-2 Spike Protein-ACE2 Interaction and ACE2 Activity and Free Radical Scavenging Capacities.

ABSTRACT

This study evaluated the chemical composition of rosemary water extract (RWE) and its influence on mechanisms by which the SARS-CoV-2 virus enters into cells as a potential route for reducing the risk of COVID-19 disease. Compounds in RWE were identified using UHPLC-MS/MS. The inhibitory effect of RWE was then evaluated on binding between the SARS-CoV-2 spike protein (S-protein) and ACE2 and separately on ACE2 activity/availability. Additionally, total phenolic content (TPC) and free radical scavenging capacities of RWE against HO•, ABTS•+, and DPPH• were assessed. Twenty-one compounds were tentatively identified in RWE, of which tuberonic acid hexoside was identified for the first time in rosemary. RWE dose of 33.3 mg of rosemary equivalents (RE)/mL suppressed the interaction between S-protein and ACE2 by 72.9%, while rosmarinic and caffeic acids at 3.3 µmol/mL suppressed the interaction by 36 and 55%, respectively. RWE at 5.0, 2.5, and 0.5 mg of RE/mL inhibited ACE2 activity by 99.5, 94.5, and 68.6%, respectively, while rosmarinic acid at 0.05 and 0.01 µmol/mL reduced ACE2 activity by 31 and 8%, respectively. RWE had a TPC value of 72.5 mg GAE/g. The results provide a mechanistic basis on which rosemary may reduce the risk of SARS-CoV-2 infection and the development of COVID-19.