Simultaneous quantification and validation of caffeoylquinic acids and flavonoids in Hemistepta lyrata and peroxynitrite-scavenging activity

Traditionally, Hemistepta lyrata is consumed as a mountainous vegetable or a medicinal herb to treat inflammation, fever, hemorrhage, and hemorrhoids. In order to provide the scientific evidence of traditional uses of this plant, we identified and quantified thirteen active substances (caffeic acid, chlorogenic acid, and 3,5-di-O-caffeoylquinic acid as caffeoylquinic acids; apigenin, isorhoifolin, acacetin, linarin, diosmetin, diosmin, pectolinarigenin, and pectolinarin as flavones or their glycosides; kaempferol 3-O-rutinoside and rutin as flavonol glycosides) from H. lyrata and evaluated their peroxynitrite-scavenging activity. The chromatographic separation was performed on a Capcell Pak C18 column (5 mu m, 250 mm x 4.6 mm i.d.) with a gradient elution of 0.05% TFA (trifluoroacetic acid) and 0.05% TFA in MeOH-CH3CN (60:40). Validation of HPLC methods on the linearity, LOD, LOQ intra-day and inter-day variabilities, recovery, and repeatability proved that this method is selective, sensitive, precise, accurate, and reproducible. In peroxynitrite-scavenging assay, caffeic acid derivatives (chlorogenic acid, caffeic acid, and 3,5-di-O-caffeoylquinic acid) exhibited relatively lower IC50 values than other substances tested. And HPLC simultaneous quantification showed that the 70% MeOH extract and the BuOH fraction contain a higher quantity of caffeic acid derivatives (17.82 and 30.09 mg/g, consecutively). Therefore, caffeic acid derivatives could be the main contributors to the peroxynitrite-scavenging activity of H. lyrata than other phenolic substances. (C) 2012 Elsevier B.V. All rights reserved.