Cymbopogon citratus leaves:: Characterisation of flavonoids by HPLC-PDA-ESI/MS/MS and an approach to their potential as a source of bioactive polyphenols

Leaves from cultivated Cymbopogon citratus were extracted with methanol, 80% aqueous ethanol and water (infusion and decoction) and the extracts were assessed for their antiradical capacity by 2,2-diphenyl-1-picrylhydrazyl (DPPH center dot) assay; the infusion extract exhibited the strongest activity. Tannins, phenolic acids (caffeic and p-coumaric acid derivatives) and flavone glycosides (apigenin and luteolin derivatives) were identified in three different fractions obtained from an essential oil-free infusion, and a correlation with their scavenger capacity for reactive oxygen species was studied. The tannin and flavonoid fractions were the most active against species involved in oxidative damage processes. In the flavonoid fraction, representing 6.1% of the extract, thirteen compounds (O- and C-glycosylflavones) were tentatively identified by high performance liquid chromatography, coupled to photodiode-array and electrospray ionization mass spectrometry detectors (HPLC-PDA-ESI/MS), nine of which were identified for the first time in this plant, all of them being C-glycosylfavones (mono-C-, di-C- and O,C-diglycosylflavones). The potential beneficial and protective value of the identified polyphenols for human health is discussed. (C) 2008 Elsevier Ltd. All rights reserved.