Bioactive Secondary Metabolites and Anti-Infective Properties of Two Sordariomycetes Taxa Characterized by HR-ESI-MS Technique

The emergence of antimicrobial resistance and the increasing incidence of cancer have highlighted the urgent need to develop new drugs; therefore, the discovery of new bioactive molecules is an important goal for future research. In this study, freshwater fungi isolated from submerged Phragmites australis from Egypt were screened for antimicrobial and cytotoxic activities. Using ITS1 and ITS4 primers, eight frequently occurring Sordariomycetes taxa were identified and were then selected for further evaluation of bioactivity. Ethyl acetate crude extracts (A–H) were evaluated for antimicrobial activity using the agar disk-diffusion method. Extracts A and E, derived from Chaetomium globosum SCUF0000404 (PX596738) and Chaetomium madrasense SCUF0000401 (PX596735), respectively, showed broad-spectrum activity at 100 mg/mL against bacterial pathogens, including Staphylococcus aureus ATCC 29213 (15.33 and 18.00 mm), Streptococcus pyogenes ATCC 19615 (11.00 mm), Escherichia coli ATCC 35218 (10.33 and 10.67 mm), Klebsiella pneumoniae ATCC 700603 (14.00 and 16.67 mm), and Pseudomonas aeruginosa ATCC 27853 (13.33 and 16.33 mm), and show antifungal activity against Candida albicans ATCC 14053 (20.33 mm), Candida krusei ATCC 6258 (15.67 and 15.33 mm), Trichosporon asahii AMS 187 (17.00 and 17.67 mm), Exserohilum rostratum AMS 1077 (34.00 and 33.67 mm), and Trichophyton indotineae AMS 180 (38.33 and 34.00 mm). Selective cytotoxic effects on the breast cancer cell line MDA-MB-231 were observed by extracts A and E at IC50 = 309 and 277 μg/mL, while non-selective cytotoxic effects on the normal HUVEC cell line were found with IC50 = 919 and 796 μg/mL, respectively. Characterization of the most effective extracts A and E by high-resolution electrospray ionization mass spectrometry (HR-ESI-MS) shows that they have a wide range of secondary metabolites, including cytochalasans, azaphilone alkaloids, steroids, terpenoids, flavonoids, and phenols. These findings underscore the chemical diversity and therapeutic potential of freshwater fungi from Egypt.