Biosynthetic pathways of Polygonatum cyrtonema polysaccharide and diosgenin based on its transcriptomic data / 中国中药杂志

Polygonatum cyrtonema belongs to the plant family Liliaceae, and its dried rhizome is one of the sources of Chinese traditional medicine of Polygonati Rhizoma. It possesses the dual function as both medicine and food. Its main chemical components are polysaccharides and saponins. In order to understand the biosynthesis pathway of polysaccharides and diosgenin in P. cyrtonema, the corresponding transcriptomic data were obtained by extracting and sequencing the RNA of four parts of P. cyrtonema, namely, leaves, stems, rhizomes and roots. By adopting BGISEQ-500 sequencing platform, 42.03 Gb data were retrieved. Subsequently, the de novo assembly was carried out by Trinity software to obtain 137 233 transcripts, of which 68.13% of unigenes were annotated in seven databases including KEGG, GO, NR, NT, SwissProt, Pfam and KOG. Transcripts that may be involved in the biosynthesis of polysaccharides and diosgenin were analyzed by data mining. With help of qPCR, we validated expression data of four genes that were possibly involved in the biosynthesis of target metabolites. This experiment provides data for the study of biosynthetic pathways of P. cyrtonema secondary metabolites and the clarification of related structural gene functions.

Cloning and quantitative expression analysis of GMPP gene from Dendrobium huoshanense / 中国中药杂志

In order to understand the function of GDP-mannose pyrophosphorylase(GMPP) function and its regulation in polysaccharide biosynthesis mechanism in Dendrobium. D. huoshanense was used to clone GMPP gene. GMPP gene expression in D. huoshanense,D. officinale and D. moniliforme was also determined by qPCR. The results showed that the length of D. huoshanense GMPP gene c DNA sequence is 1 867 bp,containing 1 245 bp open reading frame(ORF),encoding 415 amino acids. Phylogenetic tree analysis showed that D. huoshanense,D. officinale and D. moniliforme are closely related with GMPP taken into consideration. Bioinformatics analysis demonstrated that GMPP sequence similarity among the three species reached as high as 99%. qPCR results indicated that GMPP genes was highly expressed in stem of D. huoshanense compared with its leaf,flower and root. According to GMPP gene expression profile in D. huoshanense,D. officinale and D. moniliforme grown in Huoshan area,it was clear that GMPP in D. huoshanense showed the highest expression level. Furthermore,our findings of GMPP gene expression profile will facilitate future researches into its polysaccharide biosynthetic mechanism.

Simultaneous determination of five saponins in Bupleuri Radix by HPLC-DAD dual wavelength method / 中国中药杂志

Epoxy ether type and isophthalene type saponin are the main saponins of Bupleurum chinense. However,due to the difference of their UV spectrum,there is no quantitative method for simultaneous determination of these two kinds of saponins. In this paper,a dual-wavelength high performance liquid chromatography(HPLC) was developed for simultaneous determination of five saponins in epoxidized ether(saikosaponin a,c,d) and isosorbide type(saikosaponin b1,b2). The mobile phase was eluted with acetonitrile-water(0.1% phosphoric acid) gradient at a column temperature of 30 °C and a flow rate of 1.0 mL·min⁻¹. The detection wavelengths were 208 nm for saikosaponins a,c, and d, and 254 nm for saikosaponins b₁ and b₂. The results showed that the separation of five kinds of saikosaponin was good, with the linear range of 9.70-1 935.00(=0.999 4),8.20-1 380.00(=0.999 3),6.90-1 640.00(=0.999 0),5.25-630.00(=0.999 4), and 5.15-618.00 mg·L⁻¹(=0.999 5), respectively. The average recoveries were 97.70%-100.2% and the RSD was less than 3%(=6). The method is simple,rapid and reproducible. It can be used for the determination of five kinds of saikosaponins in B. chinense.