Investigation of phenolic acids in yacon (Smallanthus sonchifolius) leaves and tubers.
Thin-layer chromatographic (TLC) screening of crude extracts of dried leaves and tubers of yacon (Smallanthus sonchifolius, Asteraceae) and products of acid hydrolysis of tubers on the silica gel HPTLC plates using the developing solvents ethyl acetate-formic acid-water (85:10:15, v/v/v) and n-hexane-ethyl acetate-formic acid (20:19:1, v/v/v) proved the presence of chlorogenic, caffeic and ferulic acid. These phenolic acids were isolated from the crude extract of yacon leaves by preparative TLC, and identified after elution by HPLC/MS, as well as by direct injection of the crude extract into the HPLC/MS system. Acid hydrolysis of tubers released the increased amount of phenolic acids (e.g. caffeic acid and ferulic acid), flavonoid quercetin and an unidentified flavonoid, which was detected by TLC analysis. Ferulic acid, isomers of dicaffeoylquinic acid and still an unidentified derivative of chlorogenic acid (Mr = 562) as constituents of yacon leaves and ferulic acid as constituent of yacon tubers are reported here for the first time. These acids gave significant contribution to the radical scavenging activity detected directly on the TLC plate sprayed with 1,1-diphenyl-2-picrylhydrazyl (DPPH).
National Institute of Chemistry, Laboratory for Food Chemistry, Hajdrihova 19, SI-1000 Ljubljana, Slovenia. breda.simonovska@ki.si
Breda
B
Simonovska
Irena
I
Vovk
Samo
S
Andrensek
Katerina
K
Valentová
Jitka
J
Ulrichová
D019659:Asteraceae / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D002855:Chromatography, Thin Layer; D062385:Hydroxybenzoates / Q000032:analysis*; D013058:Mass Spectrometry; D018515:Plant Leaves / Q000737:chemistry*; D035281:Plant Tubers / Q000737:chemistry*; D013050:Spectrometry, Fluorescence
D062385:Hydroxybenzoates; C017616:phenolic acid