A new alkaloid and flavonoids isolated from Solanum cernuum leaves by high-performance countercurrent chromatography

Solanum cernuum is a medicinal plant widely distributed in south-east regions of Brazil and popularly used to treat several disorders. Despite their utilisation as a medicine, few studies on its chemical composition are reported. An efficient separation method for the ethyl acetate fraction was developed by high-performance countercurrent chromatography using n-butanol/chloroform/methanol/water (3:7:3:4, v/v/v/v) as the solvent system, affording five compounds (1-5) in one-step separation. A new cyclic guanidine alkaloid named cernidine (5) was obtained, besides four glycosylated flavonoids: afzelin (1), astragalin (2), kaempferol 3-O-α[apiofuranosyl-(1 → 2)]-α-rhamnopyranoside (3) and kaempferol 3-O-α[apiofuranosyl-(1→2)]-β-galactopyranoside (4). A further purification step afforded a mixture of trans- and cis-tiliroside (6-7). Countercurrent chromatography proved itself as a powerful tool for the isolation of similar compounds since compounds 1-2 and 3-4 possess little structural differences.