New Unnatural Gallotannins: A Way toward Green Antioxidants, Antimicrobials and Antibiofilm Agents

• Main Authors: Zuzana Hricovíniová (Author), Šárka Mascaretti (Author), Jana Hricovíniová (Author), Alois Čížek (Author), Josef Jampílek (Author)
• Format: Book
• Published: MDPI AG, 2021-08-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.

Summary

Nature has been a source of inspiration for the development of new pharmaceutically active agents. A series of new unnatural gallotannins (GTs), derived from <span style="font-variant: small-caps;">d</span>-lyxose, <span style="font-variant: small-caps;">d</span>-ribose, <span style="font-variant: small-caps;">l</span>-rhamnose, <span style="font-variant: small-caps;">d</span>-mannose, and <span style="font-variant: small-caps;">d</span>-fructose have been designed and synthesized in order to study the protective and antimicrobial effects of synthetic polyphenols that are structurally related to plant-derived products. The structures of the new compounds were confirmed by various spectroscopic methods. Apart from spectral analysis, the antioxidant activity was evaluated by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging and iron reducing power (FRAP) assays. Antibacterial activity of compounds was tested in vitro against <i>Staphylococcus aureus</i> ATCC 29213, <i>Enterococcus faecalis</i> ATCC 29212 (reference and control strains), three methicillin-resistant isolates of <i>S. aureus</i>, and three isolates of vancomycin-resistant <i>E. faecalis</i>. For screening of antimycobacterial effect, a virulent isolate of <i>Mycobacterium tuberculosis</i> and two non-tuberculous mycobacteria were used. Furthermore, antibiofilm activity of structurally different GTs against <i>S. aureus</i>, and their ability to inhibit sortase A, were inspected. Experimental data revealed that the studied GTs are excellent antioxidants and radical-scavenging agents. The compounds exhibited only a moderate antibacterial effect against Gram-positive pathogens <i>S. aureus</i> and <i>E. faecalis</i> and were practically inactive against mycobacteria. However, they were efficient inhibitors and disruptors of <i>S. aureus</i> biofilms in sub-MIC concentrations, and interacted with the quorum-sensing system in <i>Chromobacterium</i><i>violaceum</i>. Overall, these findings suggest that synthetic GTs could be considered as promising candidates for pharmacological, biomedical, consumer products, and for food industry applications.

Item Description

10.3390/antiox10081288
2076-3921