Bioactivity-guided Study of Passiflora caerulea L. Leaf Extracts

摘要

Passiflora species were known by their anticonvulsant, anxiolytic and sedative activities. The aim of this study was to investigate the chemical composition of the most active leaf extract of Passiflora caerulea L. grown in Egypt. The ethanolic extract of the leaves exhibited higher activity than aqueous extract as anticonvulsant (63% potency relative to carbamazepine), analgesic (70% potency relative to indomethacin), antioxidant (71% potency relative to vitamin E), anti-inflammatory (90% potency relative to indomethacin) and antipyretic (90% potency relative to paracetamol). Fractions obtained successively from the ethanolic extract were then subjected to the same biological testing demonstrating that the ethyl acetate fraction was the most active in all activities (50, 96, 80, 63 % potency relative to reference standards used in each of the selected activity, respectively) followed by n-butanol then n-hexane and chloroform fractions. Purification of the anticonvulsant sub-fractions obtained by column chromatography of ethyl acetate fraction, led to the isolation of three compounds that were identified by physical and spectroscopic techniques as Lucenin II (1), 4-hydroxycinnamic acid (2) and Chrysin 6-C-β-D-glucoside (3). The amount of Chrysin 6-C-β-D-glucoside was found to be 0.0184 g % w/w of the dried leaves using HPLC method that showed linearity (R² = 0.9996) over the range 0.015-0.25 mg/mL. C-glycosyl flavones and hydroxycinnamic acid derivatives may thus be the responsible principles for the biological activity of the plant under investigation. Moreover, RAPD technique was performed for the genetic characterization and authentication of the plant, where 106 fragments were recorded after DNA amplification with fifteen primers.