Free radical scavengers from Cymbopogon citratus (DC.) stapf plants cultivated in bioreactors by the temporary immersion (TIS) principle

Abstract

The biomass production of Cymbopogon citratus shoots cultivated in bioreactors according tothe temporary immersion (TIS) principle was assessed under different growth conditions. Theeffect of gassing with CO2-enriched air, reduced immersion frequency, vessel size and culturetime on total phenolic and flavonoid content and free radical scavenging effect of the methanolicextracts was measured. From the TIS-culture of C. citratus, seven compounds were isolated andidentified as caffeic acid (1), chlorogenic acid (2), neochlorogenic acid (3), p-hydroxybenzoicacid (4), p-hydroxybenzoic acid 3-O--d-glucoside (5), glutamic acid (6) and luteolin 6-C-fucopyranoside (7). The occurrence of compounds 1Ð7 and their variability in C. citratus grown under different TIS conditions was determined by HPLC. The free radical scavenging effect of the methanolic extract and compounds was measured by the discoloration of the free radical 1,1- diphenyl-2-picrylhydrazyl (DPPH). The main metabolites in 6- and 8-week-old cultures, both in 5 and 10 l vessels, were chlorogenic acid (2) (100Ð113 mg%) and neochlorogenic acid (3) (80Ð 119 mg%), while in the cultures with CO2-enriched air and reduced immersion frequency the main compound detected in the extracts was glutamic acid (6) (400 and 670 mg% for the green and white biomass and 619 and 630 mg% for the green and white biomass, respectively). The most active compounds, as free radical scavengers, in the DPPH discoloration assay were caffeic acid (1), chlorogenic acid (2), neochlorogenic acid (3) and the flavonoid luteolin 6-C-fucopyranoside(7).