Optimum conditions for regulating content change of secondary metabolites of Gentiana macrophylla by orthogonal method

Abstract

Gentiana macrophylla is a traditional Chinese herbal medicine for treating jaundice, hepatitis, and stomachic and choleretic ailments, and its main secondary metabolites are secoiridiod glycosides represented by gentiopicroside. The biosynthetic pathway of gentiopicroside is via methylerythritol phosphate pathway (MEP) and mevalonate pathway (MVA) pathways. Fosmidomycin and lovastatin are specific inhibitors of 1-deoxy-D-xylulose-5-phosphate reductoisomerase (DXR) of the MEP pathway and hydroxymethylglutaryl-CoA reductase (HMGR) of the MVA pathway, and are widely used in the research of the biosynthesis pathway and regulation mechanism of secondary metabolites. The article aims to test and search for the optimal condition for decreasing the contents of four secoiridiod glycosides compounds (loganic acid, sweroside, swertiamarin and gentiopicroside) in G. macrophylla by using the orthogonal test designs. In this study, the concentration of fosmidomycin(A), concentration of lovastatin(B) and sampling days (C) were taken as three factors, and each factor was taken as four levels to design an orthogonal test, with 16 groups of treatment. HPLC was used to determine the contents of four secoiridiod glycosides, and the data were statistically analyzed. The results were as follows: (1) The contents of the four secoiridiod glycosides compounds in G. macrophylla were most affected by sampling time, followed by fosmidomycin concentration and then lovastatin concentration. (2) After treatment with the optimal inhibitory conditions, the contents of loganic acid, swertiamarin, gentiopicroside and sweroside decreased by 69%, 36%, 33% and 4% respectively. In conclusion, optimal inhibition conditions are determined to be fosmidomycin 400 μmol·L-1, lovastatin 50 μmol·L-1, samples are harvested on six days, which provides the reference for further research on the regulatory mechanism of MEP and MVA pathways in the metabolism and synthesis of secoiridiod glycosides.

Keywords

• orthogonal test
• mva pathway
• mep pathway
• lovastatin
• fosmidomycin
• secoiridiod glycosides