Flavonoids from Dalea boliviana as antifungal agents against Candida albicans

ORTEGA, MARÍA G.; LOMBARDO CARAMELO ANDREA; CABRERA JOSE L.; GALLERANO LUCIANO; PERALTA MARIANA A

Capital Federal

Congreso; 8TH INTERNATIONAL PHYTOCOSMETICS & PHYTOTHERAPY CONGRESS; 2018

International Society for Phytocosmetic Science (ISPS)

Flavonoids from Dalea boliviana as antifungal agents against Candida albicans A.E. Lombardo Caramello 1,2, L.J. Gallerano 1,2, M. G. Ortega1,2, J. L. Cabrera1,2, M. A. Peralta1,2.1 Departamento de Ciencias Farmacéuticas, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Argentina 2 Instituto Multidisciplinario de Biología Vegetal (IMBIV) - Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET).Introduction. The bioactivity studies of a prenylflavonoid from Dalea elegans, revealed an important antifungal activity, and inhibition of azole efflux pumps and the mature biofilm of an azole-resistant Candida albicans strain. The chemical evaluation of D. boliviana Britton, a species that grows in the provinces of Jujuy, Catamarca and Salta, allowed to isolation and elucidation of new prenylated flavanones: (2S)-5,2'-dihydroxy-6",6"-dimethylchromen-(7,8: 2",3'')-3'-prenylflavanone (F1B), (2S)-5,7,2'-trihydroxy-8,3'-diprenylflavanone (F2) and (2S)-5,7,2'-trihydroxy-5'-(1'",1'"- dimethylallyl)-8-prenylflavanone (F3). In view of the studies of antifungal activity reported for prenylated flavonoids from Dalea species, the aim of this work was to evaluate the potential of D. boliviana flavonoids as antifungal agents against azole-resistant C. albicans strain.Materials and methods. Prenyl flavonoids F1B, F2 and F3 were obtained and characterized from roots extract of D. boliviana according to previously reported methodology. Antifungal properties of these compounds against an azole-sensitive (SCa) and an azole-resistant (RCa) C. albicans strains, were studied in vitro according to CLSI guidelines. The growth was quantified by measuring the absorbance at 540 nm in the absence or in the presence of the compounds at different concentrations, using the 96-w ell plate format. The results were expressed as relative percentages of growth compared to growth control (cells without treatment).Minimal inhibitory concentration (MIC) was defined as the minimal concentration that exerted a 50% or more of absorbance reduction with respect to the control.Results and discussion. The results showed that the inhibition achieved by the three compounds is concentration-dependent. The chromene flavanone F1B was the most active against both strains, with MICs values of 62.5 µM. MICs for compounds F2 and F3 were 250 µM and 500 µM against RCa and SCa, respectively. These results are of interest due to the resistance to fluconazole presented by the former.Conclusions. Three flavonoids previously reported in D. boliviana, were evaluated as growth inhibitors of a C. albicans strain resistant to imidazole antifungals. The activity observed for these compounds is comparable to that of the flavonoid isolated from D. elegans, 8PP, with a similar structure. Remarkably, the compound F1B exerted an important inhibition of growth of C. albicans mainly, against the azole-resistant strain, RCa. These results encourage continuing the research into the antifungal activity of these compounds as potential phytotherapeutics obtained from our native flora. Keywords: Dalea boliviana; prenylated flavonoids; Candida albicans; azole resistance