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

The biomass production of Cymbopogon citratus shoots cultivated in bioreactors according to the temporary immersion (TIS) principle was assessed under different growth conditions. The effect of gassing with CO2-enriched air, reduced immersion frequency, vessel size and culture time on total phenolic and flavonoid content and free radical scavenging effect of the methanolic extracts was measured. From the TIS-culture of C. citratus, seven compounds were isolated and identified as caffeic acid (1), chlorogenic acid (2), neochlorogenic acid (3), p-hydroxybenzoic acid (4), p-hydroxybenzoic acid 3-O-beta-D-glucoside (5), glutamic acid (6) and luteolin 6-C-fucopyranoside (7). The occurrence of compounds 1-7 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 1 vessels, were chlorogenic acid (2) (100-113 mg%) and neochlorogenic acid (3) (80-119 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).

Estimulación de cardenólidos en brotes de Digitalis purpurea L. cultivados in vitro mediante elicitores / Stimulation of cardenolides production in Digitalis purpurea L. shoot cultures by elicitors addition

Digitalis purpurea L. es una de las principales fuentes de cardenólidos tales como digoxina y digitoxina. Estos fármacos son ampliamente usados en la disfunción cardíaca y para regular las arritmias del corazón. El presente trabajo se realizó con el objetivo de estudiar el efecto de tres elicitores en el cultivo de brotes de Digitalis purpurea var. Roter Berggold para incrementar la producción in vitro de cardenólidos. La elicitación es una estrategia para incrementar la producción de biomasa y metabolitos secundarios en el cultivo in vitro. Los elicitores evaluados fueron ChitoPlant (0,001; 0,01; 0,1 g.L-1); SilioPlant (0,01; 0,1; 1,0 g.L-1) y Jasmonato de metilo (60, 80 y 100 µM), descritos por primera vez para el incremento de cardenólidos. Se demostró que la elicitación es una estrategia viable para el incremento de cardenólidos en brotes de D. purpurea. El ChitoPlant®, redujo la altura sin afectación en el resto de las variables morfológicas evaluadas. Además indujo un incremento significativo en el contenido de cardenólidos. El SilioPlant® (0,01 g.L-1) no provocó afectaciones en la biomasa e incrementó significativamente la síntesis de cardenólidos en los brotes en 3,6 y 6,9 veces el contenido de digoxina y digitoxina respectivamente. La elicitación con el jasmonato de metilo provocó una reducción de la biomasa. Los contenidos de digoxina y digitoxina se incrementaron ligera y significativamente con 80 y 100 µM de jasmonato de metilo respectivamente. El mejor resultado integral se obtuvo con 0,01 g.L-1 de SilioPlant, el cual indujo la mayor producción neta de cardenólidos por frasco de cultivo (4,72 µg digoxina y 88,27 µg digitoxina).

Digitalis purpurea L. is one of the main sources of cardenolides such as digitoxin and digoxin. These drugs are widely used to strengthen cardiac diffusion and to regulate heart rhythm. The aim of this study was to evaluate the influence of three elicitors on shoots of Digitalis purpurea var. Roter Berggold in semisolid media in order to increase cardenolides biosynthesis. Elicitation is a strategy to increase biomass and secondary metabolites production on in vitro cultures. The elicitors evaluated were ChitoPlant (0,001; 0,01; 0,1 g.L-1); SilioPlant (0,01; 0,1; 1,0 g.L-1) and Methyl jasmonate (60, 80, 100 µM), which are reported here to induce cardenolide production for first time. Elicitation resulted an effective strategy to increase cardenolide production on D. purpurea shoot cultures. ChitoPlant induced a decrease in shoots length, but had no effect on the rest of morphological parameters evaluated. As well, ChitoPlant increased cardenolide content. SilioPlant (0,01 g.L-1) did not affect biomass production and at the same time, increased in 3,6-fold and 6,9-fold digoxin and digitoxin content respectively. Elicitation with Methyl jasmonate resulted in decreased biomass production. Digoxin and digitoxin content was slight and significantly increased by Methyl jasmonate 80 and 100 µM respectively. The best integral result was reached with 0,01 g.L-1 of SilioPlant, which induced the highest net yields per culture flask (4,72 µg of digoxin and 88,27 µg of digitoxin).