Influence of carbohydrate source on xanthone content in root cultures of Gentiana dinarica Beck

Abstract

The effects of different types and concentrations of sugars on root growth and xanthone production in root culture of Gentiana dinarica were investigated. The results showed that sucrose, glucose and fructose all supported root growth, and sucrose was superior in terms of growth index, dry mass and fresh/dry mass ratio then fructose or glucose at the same concentrations. However, considering equimolar concentration of sugars, their contribution to the root growth was similar. The HPLC analysis of roots indicated the presence of xanthone compounds, and the contents of norswertianin-1-O-primeveroside (1), norswertianin-1-O-glucoside (2), gentioside (3) and norswertianin (4) were evaluated. In all samples, norswertianin-1-O-primeveroside (1) was present in highest concentration, followed by norswertianin-1-O-glucoside (2), whereas gentioside (3) and norswertianin (4) were present in lower amounts. The production of xanthones was affected by both type and concentration of sugar. In general, roots growing in media supplemented with sucrose contained higher levels of xanthones. The amounts of xanthone primeveroses (1) and (3) increased with the increase of concentrations of all types of sugars, whereas higher sugar concentrations resulted in reduction of the contents of norswertianin-1-O-glucoside (2) and aglycone norswertianin (4). The roots were also evaluated regarding the content of total phenolics and higher accumulation of total phenolic compounds was observed in roots grown in fructose-containing medium. Antioxidant activity was determined by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay, and high correlation between total phenolic content and antiradical activity was observed (r = -0.83).