Antifungal and antioxidant activities of extracts from Drosophyllum lusitanicum

Abstract

Drosophyllum lusitanicum (L.) Link is an insectivorous plant of the family Drosophyllaceae native to the western Iberian Peninsula and northwest Morocco. Leaves of this species contain flavonoids, phenolic compounds and higher amounts of the naphthoquinone plumbagin [1,2,3]. The antimicrobial (against bacteria and yeasts) and insecticidal activities of the hexane extract from this species were previously demonstrated by our group [4,5]. The purpose of this study was to study the antifungal and the antioxidant activities of aqueous, methanol and hexane extracts from D. lusitanicum. Antifungal activity was tested against several mycotoxigenic fungi using the agar diffusion method followed by the determination of minimum inhibitory concentrations in liquid medium (MIC). The antioxidant activity was determined by Folin-Ciocalteau (F-C), trolox equivalent antioxidant capacity (TEAC) and oxygen radical antioxidant capacity (ORAC) assays. Results demonstrate that hexane extract is the most effective in inhibiting fungi growth, with inhibition zones ranging from 14.00 to 49.00mm and with MIC values ranging from 15.6 to 62.5µg ml-1, which may be related with its higher content in plumbagin [3]. Moreover, the most susceptible fungus to all the extracts was Aspergillus fumigatus. The results show that the methanol extract has the highest antioxidant activity in all the assays (F-C: 1188.06±52.96µmolGAE/mgextract; TEAC: 432.23±6.71µmolTE/mgextract; ORAC: 764.18±61.18µmolTE/mgextract), possibly due to its higher phenolic content. These results indicate that D. lusitanicum extracts have strong antioxidant and antifungal activities, and thus could be used as sources of agents for the food and pharmaceutical industries.