Chemical Composition of the Red Sea Green Algae : Isolation and In Silico Studies of New Anti-COVID-19 Ceramides.

Coronavirus disease 2019 (COVID-19) is the disease caused by the virus SARS-CoV-2 responsible for the ongoing pandemic which has claimed the lives of millions of people. This has prompted the scientific research community to act to find treatments against the SARS-CoV-2 virus that include safe antiviral medicinal compounds. The edible green algae  . is known to exhibit diverse biological activities such as anti-influenza virus, anti-Japanese encephalitis virus, immunomodulatory, anticoagulant, antioxidant and antibacterial activities. Herein, four new ceramides in addition to two known ones were isolated from  . The isolated ceramides, including and showed promising antiviral activity against SARS-CoV-2 when investigated using in silico approaches by preventing its attachment to human cells and/or inhibiting its viral replication. and were the most effective in inhibiting the human angiotensin converting enzyme (hACE)-spike protein complex which is essential for the virus to enter the human host. In addition to this, also showed an inhibition of the SARS-CoV-2 protease (M) that is responsible for its viral replication and transcription. In this study, we also used liquid chromatography coupled to electrospray ionization high-resolution mass spectroscopy (LC-ESI-HRMS) to identify several metabolites of  , including metabolites such as fatty acids, their glyceride derivatives, terpenoids, sterols and oxysterols from the organic extract. Some of these metabolites also possessed promising antiviral activity, as previously reported.