Efeito dos inibidores da bomba de prótons na sensibilidade in vitro e inibição da produção de melanina em Cryptococcus spp.

Abstract

Cryptococcus neoformans sensu latu and Cryptococcus gattii sensu latu are hyaline yeasts capable of producing melanin, being associated with a condition called cryptococcosis.For installation and its spread, several virulence factors have been associated, such as melanin production, which is produced by phenoloxidase called laccase, which oxidizes phenolic compounds. Studies have shown that proton pump inhibitors (PPI´s) have an inhibitory effect on melanin production, in melanocytes,produced by a phenoloxidase, called tyrosinase. This effect on inhibition of melanogenesis was associated with inhibition of tyrosinase.Since melanocytes and Cryptococcus spp. produce the melanin with a similar oxidation action of phenolic compounds, the objective of this work was to test the effect of PPI´s on the inhibition of melanin production in Cryptococcusneoformans/gattii lato sensu. For this, a new methodology was initially developed for the quantification of melanin, through the gray scale. In this experiment, 12 strains of Cryptococcus spp., 1 strain of Candidaparapsilosis ATCC 22019 (negative control) and 1 strain of Hortaeawerneckii (positive control) were analyzed, resulting in an adequate production and quantification of melanin in testedstrains. Next, PPIs were tested (omeprazole, rabeprazole, lansoprazole, esomeprazole and pantoprazole), classical antifungal agents (fluconazole and amphotericin B) and glyphosate (inhibitor of melanogenesis in Cryptococcus spp.) on the susceptibility of 20 strains of Cryptococcus spp.and 1 strain of C. parapsilosis ATCC 22019, based on the protocol M27-A3 of the Clinical Laboratory Standart Institute (CLSI).The following MIC50 values were observed: for omeprazole 166.7 ± 91.29 μg/ml, esomeprazole 256 ± 115.1 μg/ml, lansoprazole 226 ± 200.1 μg/ml, rabeprazole 142.6 ± 74.6 μg/ml, pantoprazole 428.6 ± 297.3 μg/ml, glyphosate 952.4 ± 150.4 μg/ml, fluconazole 4,757 ± 1,6 μg/ml and amphotericin B 1,464 ± 2.6 μg/ml. Finally, subinhibitory concentrations of PPIs were tested on melanin production in Cryptococcus spp., resulting in an inhibition of melanin for protons pump inhibitors, the best effect being obtained with omeprazole, lansoprazole and pantoprazole. Therefore, PPI´s has an important effect on the inhibition of melanin in Cryptococcus spp., and further studies are needed to understand the mechanisms of inhibition and its potential in reducing virulence, dissemination and infection of the CNS.