Evaluation of matrix effects for pesticide residue analysis by QuEChERs coupled with UHPLC-MS/MS in complex herbal matrix.

Matrix effects (MEs) can heavily affect the accuracy and reproducibility of a pesticide residue analysis method, especially in complex matrices such as herbs. Therefore, it is of great importance to assess MEs of pesticides in herbal matrices. In this research, the MEs of 28 pesticides and their metabolites in five types of herbs representing different medicinal parts were evaluated by UHPLC-MS/MS analysis after QuEChERs pretreatment. Suppression MEs were found for most organophosphorus and carbamate pesticides while enhancement MEs were observed for sulfonylurea. Besides, stronger inhibition effects were observed for early or late elution pesticides and in matrices of Lonicerae japonicae flos and Perillae folium. Some pesticides were observed with enhancement MEs in Astragali radix. These results indicated that MEs were mainly affected by the retention time of the analytes, the ionization mode of the precursor ions, the overall structure of the compounds, and the chemical composition of the matrices.

Integrated metabolomic and transcriptomic profiling reveals the tissue-specific flavonoid compositions and their biosynthesis pathways in Ziziphora bungeana.

BACKGROUND: Ziziphora bungeana Juz. is a folk medicine from the Xinjiang Uygur Autonomous Region. The herb or the aerial parts of it have been used to medicinally treat cardiovascular diseases. Flavonoids are the main pharmacologically active ingredients in Z. bungeana. Identification of the tissue-specific distribution of flavonoids in Z. bungeana is crucial for effective and sustainable medicinal use of the plant. Furthermore, understanding of the biosynthesis pathways of these flavonoids in Z. bungeana is of great biological significance. METHODS: The flavonoids from different tissues of Z. bungeana were identified using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The full-length transcriptome of Z. bungeana was determined using a strategy based on a combination of Illumina and PacBio sequencing techniques. The functions of differentially expressed unigenes were predicted using bioinformatics methods and further investigated by real-time quantitative PCR and phylogenetic relationship analysis. RESULTS: Among the 12 major flavonoid components identified from Z. bungeana extracts, linarin was the most abundant component. Nine flavonoids were identified as characteristic components of specific tissues. Transcriptome profiling and bioinformatic analysis revealed that 18 genes were putatively involved in flavonoid biosynthesis. The gene expression and phylogenetic analysis results indicated that ZbPALs, Zb4CL3, ZbCHS1, and ZbCHI1 may be involved in the biosynthesis of the main flavonoid intermediate. ZbFNSII, ZbANS, and ZbFLS may be involved in the biosynthesis of flavones, anthocyanins, and flavonols, respectively. A map of the biosynthesis pathways of the 12 major flavonoids in Z. bungeana is proposed. CONCLUSIONS: The chemical constituent analysis revealed the compositions of 9 characteristic flavonoids in different tissues of Z. bungeana. Linarin can be hydrolysed into acacetin to exert a pharmaceutical role. Apigenin-7-O-rutinoside is hypothesised to be the precursor of linarin in Z. bungeana. There was greater content of linarin in the aerial parts of the plant than in the whole herb, which provides a theoretical basis for using the aerial parts of Z. bungeana for medicine. These results provide a valuable reference for further research on the flavonoid biosynthesis pathways of Z. bungeana and will be significant for the effective utilisation and ecological protection of Z. bungeana.

Modification of isoprene synthesis to enable production of curcurbitadienol synthesis in Saccharomyces cerevisiae.

Cucurbitane-type triterpenoids such as mogrosides and cucurbitacins that are present in the plants of Cucurbitaceae are widely used in Asian traditional medicine. Cucurbitadienol is the skeleton of cucurbitane-type triterpenoids. As an alternative production strategy, we developed baker's yeast Saccharomyces cerevisiae as a microbial host for the eventual transformation of cucurbitadienol. The synthetic pathway of cucurbitadienol was constructed in Saccharomyces cerevisiae by introducing the cucurbitadienol synthase gene from different plants, resulting in 7.80 mg cucurbitadienol from 1 L of fermentation broth. Improving supplies of isoprenoid precursors was then investigated for increasing cucurbitadienol production. Cucurbitadienol production increased to 21.47 mg/L through the overexpression of a global regulatory factor (UPC2) gene of triterpenoid synthase. In addition, knockout of the ERG7 gene increased cucurbitadienol production from 21.47 to 61.80 mg/L. Finally, fed-batch fermentation was performed, and 63.00 mg/L cucurbitadienol was produced. This work is an important step towards the total biosynthesis of valuable cucurbitane-type triterpenoids and demonstrates the potential for developing a sustainable and secure yeast biomanufacturing platform for triterpenoids.

[Research of seed quality grading of Glycyrrhiza uralensis].

OBJECTIVE: To formulate the seed quality grading standard of Glycyrrhiza uralensis. METHOD: Thousand-grain weight, seed moisture, germination rate, purity of G. uralensis seed samples from 24 regions were tested. Through statistical analysis, the key indicator and the reference indicators for seed quality grading were defined. RESULT: Germination percentage was the primary indicator of seed quality grading, thousand-grain weight, cleanliness and moisture content were important reference indicators. CONCLUSION: The seed quality of each grade should reach the following requirements: for first grade seeds, germination percentage > or = 85% , purity > or = 92%, thousand-grain weight > or = 13 g, seed moisture < or = 11%; for second grade seeds, germination percentage 75%-85%, purity 83%-92%, thousand-grain weight 11-13 g, seed moisture < or = 11%; for third grade seeds, germination percentage 65%-75%, purity 74%-83%, thousand-grain weight 9-11 g, seed moisture < or = 11%.