Neonatal infections remain a major global health challenge because of antimicrobial resistance, biofilm-associated persistence, and limited antiviral therapies. This study evaluated the antimicrobial, antibiofilm, in vivo efficacy, and antiviral activities of Brazilian red propolis (BRP) and Brazilian green propolis from the “Caatinga” biome (BGP-C) against pathogens associated with neonatal infections. Antimicrobial activity was determined by broth microdilution, whereas antibiofilm activity was assessed through biofilm biomass and metabolic activity inhibition and structural alterations were evaluated by fluorescence microscopy, and scanning electron microscopy. In vivo efficacy was assessed in a Caenorhabditis elegans infection model, and antiviral activity was investigated against Zika virus (ZIKV, PE243 strain). Both extracts exhibited antibacterial activity, mainly against Gram-positive bacteria, with minimum inhibitory concentrations of 6.25–400 µg/mL and minimum bactericidal concentrations of 25 to >400 µg/mL. MBIC₅₀ and IC₅₀ values ranged from 1.56–400 µg/mL and 0.64–163 µg/mL, respectively. Microscopy findings suggested reduced cell viability and compromised membrane integrity, together with biofilm disorganization. BRP consistently increased nematode survival across the infection models in which it was tested, whereas BGP-C showed no consistent protective effect. Under non-cytotoxic conditions, BRP and BGP-C reduced ZIKV infectivity by approximately 34% and 40%, respectively. These findings support the antimicrobial and antiviral potential of both extracts, while BRP demonstrated more consistent in vivo efficacy.

Arboviral diseases such as Zika, Mayaro and chikungunya fevers are neglected infections transmitted by arthropod vectors. The search for alternatives to circumvent the effects of arboviruses by modifying molecules previously known for their antiviral activities can be considered a good strategy to obtain new antiviral drugs. Here, we describe the synthesis of novel adamantane‑derived Schiff bases and their antiviral activities against Zika (ZIKV), Mayaro (MAYV) and chikungunya (CHIKV) viruses. Amantadine Schiff base was prepared by reaction of amantadine and 2-thiophenecarboxyaldehyde (atdTiof), while rimantadine Schiff base was prepared by reaction of rimantadine and 5-fluoro-2-hydroxybenzaldehyde (rtdFhba). The compositions of the Schiff bases were determined by elemental and mass spectrometric analyses as C15H19NS and C19H24FNO for atdTiof and rtdFhba, respectively. Spectroscopic characterizations added to single crystal X-ray diffraction permitted proposing the structures of Schiff bases. Cell viability and antiviral activities of the compounds were evaluated against ZIKV, MAYV and CHIKV viruses. The atdTiof and rtdFhba species exhibited the best inhibition rates of 58.5% over ZIKV and 69.5% over CHIKV, respectively. The results obtained in the in vitro studies open perspectives for future in vivo investigations of the synthesized Schiff bases in the search for alternatives for the treatment of arboviruses.