A new chromene flavanone from Dalea boliviana britton (fabaceae) against Candida tropicalis biofilms.

LOMBARDO CARAMELLO, AE; ORTEGA, MG; CABRERA, JL; PERALTA, MA; PARAJE, MG.

Congreso; Congreso conjunto SAMIGE-SAIB 2020; 2020

SAMIGE-SAIB

Currently, awide variety of natural products are used for medicinal purposes, both toprevent and treat health problems, as well as in the research and developmentof new drugs. Previous studies on the species Dalea elegans Gilliesex Hook. et Arn, led to the isolation and elucidation of a prenylatedflavonoid: 2´, 4´-dihydroxy-5´- (1´´´, 1´´´-dimethylallyl) -8 prenylpinocembrin(8PP). This compound exhibited antimicrobial activity against bacterial andfungal strains and was also reported  with activity against  Candidaalbicans mature biofilms. This species is the most frequently isolatedfrom candidiasis, however, the incidence of fungal infections produced by C.non-albicans has increased in recent years in Latin America. Antifungaltreatment can be difficult, often associated with the ability to form a biofilm,with high resistance to antifungal agents. This work aimed to perform thechemical study and evaluations of the antibiofilm activity of the species D.boliviana Britton (Fabaceae) as a potential source of new structuresfor the investigation of antifungal drugs. The chemical study of D.boliviana was performed by obtaining the hexane extract from its roots.This extract was purified by column chromatography and thin-laye chromatography.A solid, amorphous, and orange-colored compound (N3) was isolated andpurified. N3 structure was determined by spectroscopic methodologies (NMR H1and C13 in one and two dimensions) and UV-Visspectrophotometry. N3 activity was evaluated in vitro onmature biofilms of C. tropicalis (NCPF 1111). The maturebiofilm was treated with N3 dissolved in dimethyl sulfoxide(2% DMSO), at a final concentration of 25 µg/ml; with Amphotericin B (AmB) at100 µg/ml, and with the combination of both. The results were reported asrelative percentages of inhibition with respect to the control (mature biofilmswithout treatment). As a result of the analysis of the spectral data, the newstructure named 5,2′-dihydroxy-6 ″, 6 ″ -dimethylchromeno- (7,8: 2 ″, 3 ″) -flavanone (N3), is postulated. It is a chromeno flavanone reported forthe first time in the species D. boliviana. Compound N3 byitself reduced 54 ± 4% of the mature biofilm of C. tropicalis,while Amb reduced 86 ± 2%. For the combination of both compounds, theinhibition resulted in 98 ± 3%. In conclusion, this work presents a newcompound obtained from the Argentine native flora showing activity against ahighly resistant structure such as the mature biofilm of C. tropicalis.Furthermore, when the compound N3 was combined with AmB, thetotal eradication of the biofilm was obtained. Since Candida biofilmshave marked resistance to antifungals for clinical use, it is important toobtain new active compounds against this form of growth, so it would merit thecontinuity of this research, especially in the search for synergisticcombinations and studies on the mechanism of action.