New marine-derived indolymethyl pyrazinoquinazoline alkaloids with promising antimicrobial profiles?

RSC Advances Pub Date: 2020-08-21 DOI: 10.1039/D0RA05319H

Abstract

Due to the emergence of multidrug-resistant pathogenic microorganisms, the search for novel antimicrobials is urgent. Inspired by marine alkaloids, a series of indolomethyl pyrazino [1,2-b]quinazoline-3,6-diones was prepared using a one-pot microwave-assisted multicomponent polycondensation of amino acids. The compounds were evaluated for their antimicrobial activity against a panel of nine bacterial strains and five fungal strains. Compounds 26 and 27 were the most effective against Staphylococcus aureus ATCC 29213 reference strain with MIC values of 4 μg mL?1, and a methicillin-resistant Staphylococcus aureus (MRSA) isolate with MIC values of 8 μg mL?1. It was possible to infer that enantiomer (?)-26 was responsible for the antibacterial activity (MIC 4 μg mL?1) while (+)-26 had no activity. Furthermore, compound (?)-26 was able to impair S. aureus biofilm production and no significant cytotoxicity towards differentiated and non-differentiated SH-SY5Y cells was observed. Compounds 26, 28, and 29 showed a weak antifungal activity against Trichophyton rubrum clinical isolate with MIC 128 μg mL?1 and presented a synergistic effect with fluconazole.

Graphical abstract: New marine-derived indolymethyl pyrazinoquinazoline alkaloids with promising antimicrobial profiles
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