Pharmacognostic analysis and photoactivity of extracts of Trichocline plicata (Asteraceae)

PETENATTI E. ; PASCUALI M; FUNES M.; CARDOSO-SCHIAVI P; SORTINO M.

Congreso; XXXVII Reunión Científica Anual de la Sociedad de Biología de Cuyo; 2019

Despite recent major advances in phototherapy durgs, natural products are known to be the main source of new phototoxic molecules. Since the potential of the midwestern Argentinian flora remains unexplored, isolating new photoactive compounds or plant extracts from this region may provide boundless opportunities to obtain fungicides with high phototoxic potential. Candida albicans, as a kind of major opportunistic fungal pathogens, can cause infections in immunocompromised hosts. The resistant of C. albicans to several commonly utilized antifungal drugs has been reported and it may be increasing. Antimicrobial photodynamic therapy (aPDT) is a recently developed therapeutic option, based on utilizing non-toxic photosensitizer (PS) and visible light to induce the production of reactive oxygen species (ROS) that can kill the microbial pathogens that have bound with PS. Natural compounds, such as coumarins, thiophenes, hyperkin and chlorophyll, can act against a variety of pathogenic microorganisms. When these compounds are activated by light at specific wavelengths, they convert triplet oxygen (3O2) into singlet oxygen (O2(1∆g)), which is a very strong oxidant. Macro- and micrographic parameters, both quantitative and qualitative, were established for Trichocline plicata by applying macro- and micromorphological and taxonomic methods. The extracts were obtained from successive extraction with solvents of different kinds of polarity. In order to evaluate the ability of T. plicata (?contrayerba?) extract as photofungicides facing Candida albicans, profiles of extracts were developed employing spectroscopy and chromatographic techniques. All extracts present the same UV spectra resembling furanocoumarin compound (maximum absorbance at 309, 267 and 247 nm). Using standard compounds, for HPLC-DAD we determined that extracts are constituted of three major furanocoumarins: xanthotoxin, bergapten and trichoclin. The minority extract composition was determined employing CG-Ms, finding a great number of furanocoumarins, such as dihidroxitrichoclin, psoralene, isopipinellin and other phototoxic compounds like Angelicin. The results were promising for extracts of T. plicata. To determine the photodynamic mechanism by which extracts act as photo fungicides, we measured the production of reactive oxygen species. This considerable body of data allowed us to conclude that extracts of T. plicata act as photo fungicides against C. albicans.