Phenol content related to antioxidant and antimicrobial activities of Passiflora spp. extracts

Methanolic extracts were prepared from different organs of plants from five Passiflora species obtained by zygotic embryo culture and evaluated for their capacity to quench DPPH and ABTS^•+ radicals in comparison to that of Trolox, a water soluble vitamin-E analogue. Moreover their antimicrobial activity against E. coli was tested by agar diffusion and turbidity assays. P. nitida, P. foetida, and P. palmeri showed antimicrobial activity. P. nitida and P. palmeri also showed high antioxidant activity. P. tenuifila and P. coriacea demonstrated antioxidant power but not antimicrobial activity. The phenolic content of the different extracts was studied and quantified by spectrophotometric methods, HPLC, and mass spectrometry. High antioxidant activity correlated with high amounts of o-diphenol and catechin. An unknown component, tentatively identified as structural isomer of isoschaftoside, appeared to correlate with antimicrobial activity.