Epigallocatechin gallate has antibacterial and antibiofilm activity in methicillin resistant and susceptible Staphylococcus aureus of different lineages in non-cytotoxic concentrations.

Staphylococcus aureus is an opportunistic agent that can cause a variety of infections, both hospital and community-acquired. Epigallocatechin gallate (EGCG), a flavonoid present in the leaves of Camellia sinensis, has different biological activities, including antimicrobial potential. Here we evaluate the antibacterial and antibiofilm potential of EGCG in nine clinical strains of S. aureus with different genetic profile and antimicrobial susceptibilities. The minimum inhibitory concentrations (MIC) of EGCG ranged from 7.81 to 62.5 µg/mL, and bactericidal activity was observed at 4 times the MIC. Sub-inhibitory concentrations were able to inhibit biofilm production. Concentrations ≤62.5 µg/mL of EGCG were non-cytotoxic for murine macrophages. EGCG significantly reduced the mortality of infected Galleria mellonella larvae with the S. aureus, having shown relevant antibiofilm properties and efficacy in inhibiting the growth of different clinical isolates of S. aureus, thus being a promising substance for the treatment of infections caused by this agent.

Virola oleifera-capped gold nanoparticles showing radical-scavenging activity and low cytotoxicity.

The development of effective nanoparticle therapeutics has been hindered by their surface characteristics, such as hydrophobicity and charge. Therefore, the success of biomedical applications with nanoparticles is governed by the control of these characteristics. In this article, we report an efficient green capping method for gold nanoparticles (AuNPs) by a reduction with sodium citrate and capping with Virola oleifera (Vo), which is a green exudate rich in polyphenols and flavonoids. The Vo-capped AuNPs were characterized by UV, DLS, FTIR, Raman, TEM, DPPH, FRAP and their cytotoxicity was evaluated on the viability of Murine macrophage cell. The AuNPs had an average particle size of 15 nm and were stable over a long time, as indicated by their unchanged SPR and zeta potential values. These nanoparticles were assessed for their antioxidant potential using DPPH and FRAP and demonstrated the highest antioxidant activities and low cytotoxicity. We propose that the Virola oleifera-capped AuNPs have potential biomedical applications.