Avaliação de Lavandula angustifolia Mill. e Lavandula dentata L. sobre células planctônicas e biofilmes de Candida albicans e espécies não-albicans de Candida spp

Abstract

Some species of Candida spp. present important factors associated with virulence, among which the formation of biofilms stands out, which may be associated with changes in the sensitivity profile of the isolates, to the available antifungals. Due to these factors, it is necessary to search for new therapeutic options for the treatment of infections caused by Candida spp., Thus highlighting the importance of the search for bioactive agents in natural sources. Plants of the genus Lavandula spp. are used worldwide due to their therapeutic properties. The aim of this work was to evaluate and compare, in vitro, the antifungal activities of Lavandula angustifolia Mill. and Lavandula dentata L. on Candida albicans and non-albicans Candida spp. grown in planktonic state and in sessile form, that is, biofilm. First, the phytochemical characterization was performed, by thin layer chromatography, of the hydroethanolic extracts of leaves and flowers of L. angustifolia and L. dentata and the presence of saponins, terpenes and flavonoids has been suggested. Subsequently, an agar diffusion test was carried out to screen the antifungal activity of the extracts. Afterwards, the evaluation of the inhibitory concentration of 50% and 90% (IC50 and IC90) of the growth of the isolates was made, in which of the hydroethanolic extracts of Lavandula spp. were added to the cultures of Candida albicans, Candida krusei and Candida glabrata. L. angustifolia was active in planktonic cells of C. krusei and C. glabrata: fresh flowers and leaves in C. krusei, and fresh leaves in C. glabrata. L. dentata was active in C. krusei in planktonic state: fresh flowers and leaves. In C. krusei biofilms, the extract of fresh flowers of L. angustifolia caused a reduction in the metabolic activity of cells and extracts of fresh flowers and leaves caused a reduction in biomass. As for L. dentata, the extract of fresh flowers decreased the metabolic activity of the cells and led to the reduction of fungal biomass, while the extract of fresh leaves decreased the metabolic activity of the cells. In C. glabrata biofilms, fresh leaf extract from L. angustifolia caused a reduction in fungal biomass. There was no significant activity of extracts on C. albicans in planktonic state and biofilm. As for the cytotoxicity test, the highest cytotoxic concentration values for 50% of the cells (CC50): were presented by the extract of fresh leaves of L. angustofolia, followed by the extract of fresh leaves of L. dentata, a fact that suggests that they may be the safest extracts to use. The other extracts showed lower CC50 values: fresh flowers of L. angustifolia and fresh flowers of L. dentata. Therefore, the extract of fresh leaves of L. angustifolia was chosen for the continuity of the evaluations and it was submitted to phytochemical evaluation by high performance liquid chromatography (HPLC). Through this evaluation, the presence of flavonoids and ellagitannins was detected. Regarding the evaluation of the combined effect between the extract of fresh leaves of L. angustifolia and antifungals of conventional use in planktonic cells, an additive effect was observed in the combination of this extract with fluconazole against C. krusei (FICI: 0.516) and C. glabrata (FICI: 0.625); as for the extract combined with caspofungin, there was an indifferent effect against C. krusei (FICI: 2.00) and an antagonistic effect against C. glabrata (FICI: 4.282). The interaction of fresh leaf extract of L. angustifolia in biofilm was indifferent to C. krusei (FICI fluconazole: 1.25; FICI amphotericin B: 1.125). However, the interaction of the extract with amphotericin B for C. glabrata proved to be additive (FICI: 0.503), and can become an option to combat biofilms in formation. There was no minimum fungicidal concentration in any of the situations (planktonic cells, biofilm and synergism) of any Candida species evaluated.