Oblongifolin B isolated from Brazilian red propolis exhibits anti-methicillin-resistant Staphylococcus aureus action...

Methicillin-resistant Staphylococcus aureus (MRSA) is a Gram-positive bacterium found in hospital-acquired infections, particularly in immunosuppressed individuals. Brazilian red propolis is a beekeeping product with antimicrobial and immunomodulatory properties. Its composition includes flavonoids and benzophenones, such as oblongifolin B (OBLB). This study investigated the antibacterial activity of OBLB isolated from Brazilian red propolis against MRSA in vitro and its modulatory effects on macrophages.

The activity of OBLB was assessed both alone and in combination with antimicrobials. The minimum inhibitory and minimum bactericidal concentrations were determined for the USA300 MRSA strain and for a clinical isolate. The interaction between OBLB and the antimicrobials against MRSA was analysed using the checkerboard method. The effects of OBLB on THP-1 cells differentiated into macrophages were analysed regarding cytokine and eicosanoid production, cell surface marker expression, bactericidal activity, and hydrogen peroxide production.

OBLB exhibited anti-MRSA activity and had no synergistic effects with antimicrobials or cytotoxic effects on macrophages. It stimulated tumor necrosis factor-α and interleukin-1β production, CD80 expression, and increased the bactericidal activity of macrophages suppressed or not by dexamethasone against MRSA.

OBLB exerted anti-MRSA properties and modulated macrophage activity, suggesting it is a potential candidate in new therapeutic approaches for MRSA infections.