RESUMEN
BACKGROUND: Opportunistic fungal infections are increasingly common, with Candida albicans being the most common etiological agent; however, in recent years, episodes of candidiasis caused by non-albicans Candida species have emerged. Plants belonging to the Lauraceae family have shown remarkable antifungal effects. This study assessed the anti-Candida activity of Ocotea glomerata extracts and fractions, time of death and the synergistic effects with conventional antifungals. The possible mechanism of action was also addressed. METHODS: Minimal inhibitory concentrations (MIC) were determined by broth microdilution technique, and the mechanism of action was assessed by ergosterol, sorbitol, cell viability, reactive oxygen species (ROS) generation and phosphatidylserine externalization tests. RESULTS: All the tested extracts evidenced antifungal activity, but the methanol extract was revealed to be the most effective (MIC = 3.12 µg/mL) on C. krusei. The combination of methanol extract with ketoconazole and fluconazole revealed a synergistic effect for C. krusei and C. albicans, respectively. Fractions 1 and 5 obtained from the methanol extract had fungicidal activity, mainly against C. krusei. Methanol extract did not reveal effects by ergosterol and sorbitol assays; however, it led to an increase in intracellular ROS levels, decreased cell viability, and consequently, cell death. CONCLUSION: O. glomerata methanol extract may be viewed as a rich source of biomolecules with antifungal activity against Candida spp.
RESUMEN
The Candida parapsilosis complex has been associated with highly refractory infections mainly due to the presence of biofilms. High glucose levels enable the development of this virulence factor which can aggravate the clinical condition of patients with diabetes mellitus, those using parenteral nutrition, with invasive medical device, including others. Combined antifungal therapy, such as azole and cyclooxygenase inhibitors, may be an alternative in such infections since they modulate prostaglandin production favoring the adhesion and development of biofilms. Thus, the present study aimed to evaluate the influence of glucose supplementation in the formation and detection of Candida parapsilosis complex biofilms and to treat them using fluconazole and a cyclooxygenase inhibitor in combination. Protein spectra evaluation allowed the differentiation between species from the complex (score > 2) in our studies. All isolates were able to form active biofilms at different glucose concentrations. In addition, a significant reduction in biofilm formation was observed when fluconazole and acetylsalicylic acid were combined. The ultrastructural analysis presented typical biofilm characteristics by species from the complex. These data support new combined therapies for the treatment of fungal infections, especially with those which are resistant and therapeutic failure is associated with virulence factors.
