[Simultaneous determination of eight hydroxyl naphthoquinones in different parts of Arnebiae euchroma by HPLC]

This present study is to develop an HPLC method for simultaneous determination of eight hydroxyl naphthoquinones, shikonin, β-hydroxy-isovalerylshikonin, acetylshikonin, β-acetoxy-isovalerylshikonin, deoxyshikonin, isobutyrylshikonin, β,β'-dimethylacrylshikonin and isovalerylshikonin. The eight constituents were measured on a Waters Xbridge C18 column (4.6 mm×250 mm，5 μm) with isocratic elution of acetonitrile-0.05% formic acid solution (70∶30) at a flow rate of 1.0 mL•min⁻¹. The detection wavelength was 275 nm and the column temperature was 30 ℃. The results of content determination indicated that significant differences of the eight compounds exist in every part of Arnebia euchroma，in which the highest part was the root bark, followed with the root, then the stem residues. The content of the xylem of root and aerial part was lower than the above parts. The results provided scientific basis for the medicinal parts of A. euchroma.

[Transcriptome-based gene mining and bioinformatics analysis of p-hydroxybenzoate geranyltransferase genes in Arnebia euchroma]

The p-hydroxybenzoate geranyltransferases(PGT) play an important role in the biosynthesis pathways of shikonin derivatives. Six PGTs were obtained from transcriptome datebase of Arnebia euchroma by using bioinformatics methods and the proteins＇physiochemical properties they encoded were predicted. The result of protein domain prediction showed all of the six protein sequences contained the conserved domain of Ubia prenyltransferase family and possessed the motif NDxxDxxxD for prenyldiphosphate binding and a GX(K/Y)STAL sequence for putative aromatic ring binding. The phylogenetic tree showed that PGT and p-hydroxybenzoate polyprenyltransferase(PPT) belonged to two different clades. The results of gene expression analyses showed that the expression levels in the red shikonin-proficient line and the overground part of A. euchroma that could produce shikonin derivatives was much higher than the white shikonin-deficient line and the underground part, which suggested a positive correlation between the expression levels of PGT genes and shikonin production. This study aims to lay a foudation for further understanding of the function and enzymatic properties of PGT and provide a basis for the biosynthesis pathways and metabolic regulation of shikonin derivatives.