RESUMO
BACKGROUND: Extensive antifungal drug use has enhanced fungal resistance, resulting in persistent mycoses. Combining antifungal plant extracts/compounds with these drugs offers good alternatives to increase the activity of both partners, minimize side effects, and overcome drug resistance. In our previous study, Phytolacca tetramera berries extracts demonstrated activity against Candida spp., correlating with the amount of the main constituent phytolaccoside B and its genin, phytolaccagenin. The extracts and phytolaccagenin altered the fungal plasma membrane by binding to ergosterol, whereas phytolaccoside B increased chitin synthase activity. However, the presence of triterpenoid saponins in Phytolacca spp. has been linked to acute toxicity in humans. PURPOSE: This study aimed to evaluate combinations of P. tetramera berries extracts, phytolaccoside B and phytolaccagenin, together with commercial antifungals [amphotericin B, fluconazole, itraconazole, posaconazole, and caspofungin] against Candida albicans and Candida glabrata, to find synergistic effects with multi-target actions, in which the doses of both partners are reduced, and therefore their toxicity. Additionally, we intended to explore their anti-virulence capacity, thereby hindering the development of drug-resistant strains. METHODS: The effects of these combinations were evaluated using both the checkerboard and isobologram methods. Fractional Inhibitory Concentration Index and Dose Reduction Index were calculated to interpret the combination results. To confirm the multi-target effect, studies on mechanisms of action of synergistic mixtures were performed using ergosterol-binding and quantification assays. The ability to inhibit Candida virulence factors, including biofilm formation and eradication from inert surfaces, was also evaluated. Quantification of active markers was performed using a validated UHPLC-ESI-MS method. RESULTS: Eight synergistic combinations of P. tetramera extracts or phytolaccagenin (but not phytolaccoside B) with itraconazole or posaconazole were obtained against C. albicans, including a resistant strain. These mixtures acted by binding to ergosterol, decreasing its whole content, and inhibiting Candida biofilm formation in 96-well microplates and feeding tubes in vitro, but were unable to eradicate preformed biofilms. CONCLUSIONS: This study demonstrated the synergistic and anti-virulence effects of P. tetramera berries extracts and phytolaccagenin with antifungal drugs against Candida spp., providing novel treatment avenues for fungal infections with reduced doses of both natural products and commercial antifungals, thereby mitigating potential human toxicity concerns.
Assuntos
Antifúngicos , Candida albicans , Sinergismo Farmacológico , Frutas , Testes de Sensibilidade Microbiana , Phytolacca , Extratos Vegetais , Antifúngicos/farmacologia , Antifúngicos/química , Extratos Vegetais/farmacologia , Extratos Vegetais/química , Frutas/química , Candida albicans/efeitos dos fármacos , Phytolacca/química , Candida glabrata/efeitos dos fármacos , Saponinas/farmacologia , Candida/efeitos dos fármacosRESUMO
Due to the current concerns against opportunistic pathogens and the challenge of antimicrobial resistance worldwide, alternatives to control pathogen growth are required. In this sense, this work offers a new nanohybrid composed of zinc-layered hydroxide salt (Simonkolleite) and thymol for preventing bacterial growth. Materials were characterized with XRD diffraction, FTIR and UV-Vis spectra, SEM microscopy, and dynamic light scattering. It was confirmed that the Simonkolleite structure was obtained, and thymol was adsorbed on the hydroxide in a web-like manner, with a concentration of 0.863 mg thymol/mg of ZnLHS. Absorption kinetics was described with non-linear models, and a pseudo-second-order equation was the best fit. The antibacterial test was conducted against Escherichia coli O157:H7 and Staphylococcus aureus strains, producing inhibition halos of 21 and 24 mm, respectively, with a 10 mg/mL solution of thymol-ZnLHS. Moreover, biofilm formation of Pseudomonas aeruginosa inhibition was tested, with over 90% inhibition. Nanohybrids exhibited antioxidant activity with ABTS and DPPH evaluations, confirming the presence of the biomolecule in the inorganic matrix. These results can be used to develop a thymol protection vehicle for applications in food, pharmaceutics, odontology, or biomedical industries.