The antifungal, antibacterial, and antiviral activities of a Echinosterol isolated from the red sea Echinoclathria sponge.

The emergence of drug-resistant pathogenic microbes is a global medical concern. Our aim was to evaluate the anti-infective activities of a novel marine sterol isolated from the Red Sea Echinoclathria sponge. An agar-plate diffusion assay was used to evaluate antifungal and antibacterial activity, while a rapid antiviral assay was used to assess antiviral activity. In silico analysis via the PASS-Online platform was used to predict and explain the potential anti-infective mechanisms of action. Echinosterol was effective against Candida albicans, Cryptococcus neoformans, Aspergillus fumigatus, Aspergillus flavus, and Aspergillus niger. Compared with the positive control, the relative antifungal activity ranged from 90 to 156 %. Echinosterol showed promising antibacterial activity against Methicillin-resistant Staphylococcus aureus, Staphylococcus epidermidis, Bacillus subtilis, Bacillus cereus, Streptococcus mutans, and Enterococcus faecalis. Compared with the positive control, the relative antibacterial activity ranged from 50 to 100 %. Except for Enterobacter cloacae, no activity was detected against Escherichia coli, Klebsiella pneumoniae, Salmonella typhimurium, Proteus vulgaris, or Pseudomonas aeruginosa. Echinosterol showed moderate to low activity against COVID-19 and H1N1, but no antiviral activity was detected against Adeno-7, Adeno-40, or HSV-2. Echinosterol demonstrated promising antifungal and antibacterial activity, and its molecular structure seems to be a potential basis for the development of new antimicrobial agents.