Bioactive metabolites from marine fungal sources: evaluation of antimicrobial and cytotoxic activities.

Marine associated fungi were isolated from marine sponges collected at two ecologically distinct localities in Hurghada. Macroscopic characteristics were employed to identify and classify distinct fungal strains using ethanol-hypochlorite surface sterilization. The fungal isolates, identified as marine fungi, were cultivated on Egyptian white rice media to yield bioactive crude extracts following ethyl acetate extraction. The most potent isolate was strain DI7S9. This strain, morphologically and genetically identified as Penicillium rubens (GenBank: OP709283.1), was extensively fermented to yield biomass for subsequent experiments. The primary component of the extract was trans-9-octadecenoic acid, pentyl ester, as determined by GC-MS analysis. According to SwissADME, this compound exhibits moderate drug-likeness, limited gastrointestinal absorption, and low permeability across the blood-brain barrier. The crude extracts exhibited selective cytotoxicity, effectively inhibiting malignant HCT-116 and A-498 cells at low IC₅₀ values (30.44 and 37.99 µg/mL), while inflicting minimal damage on normal HEK-293 cells (IC₅₀ = 77.89 µg/mL). Notable suppression of E. coli, S. aureus, A. niger, and C. albicans was observed. The metabolites of P. rubens DI7S9 exhibit significant pharmacological potential, warranting further investigation into their mechanisms of action and potential therapeutic applications.