Phenolic profile, chemical relationship and antifungal activity of Andean Hypericum species

Fungal infections represent a major and increasing threat to public health resulting in a growing demand for new drugs. The genus Hypericum is a rich source of bioactive secondary metabolite, including antimicrobials and the exploration of uninvestigated species holds the potential for the discovery of novel molecules for the pharmaceutical market. Here the chemical composition, phytochemical relationships and the antifungal potential of seven of neglected Andean Hypericum species has been investigated. Through liquid chromatography and mass spectrometry analysis, 34 phenolic compounds have been identified and quantified. Quercetin derivatives, catechin and epicatechin, procyanidin B2 and chlorogenic acid derivatives represented the most abundant compounds in all extracts. The antifungal activity was evaluated against a panel of clinical isolates of pathogenic fungi. Four of the tested extracts were active against C. albicans (MIC50 < 353.25 μg/ml) and five against C. parapsilosis (MIC50 < 1000 μg/ml). Noteworthy was the activity of H. garciae, that was subjected to a comprehensive investigation against a broad panel of Candida spp. clinical strains. H. garciae extracts showed higher activity than fluconazole against C. intermedia and C. parapsilosis. The methanolic extract was active against all of the tested species with MIC50 values as low as 4 μl/ml and 5 μl/ml against C. lusitaniae and C. albicans respectively and 64 μl/ml against C. glabrata. The chloroformic extract displayed a higher activity than fluconazole against C. tropicalis. The presented data represent an advancement in the knowledge of the chemistry and antifungal potential of Hypericum species and offer interesting suggestions for deeper studies in the field of chemotaxonomy and drug discovery.