Effects of Forchlorfenuron on the Morphology, Metabolite Accumulation, and Transcriptional Responses of Siraitia grosvenorii Fruit.

Siraitia grosvenorii fruit, called luo-han-guo (LHG), have been used as a traditional Chinese medicine (TCM) and dietary supplements for many years. Mogrosides, the main bioactive ingredients in LHG, are commercially available worldwide as a non-sugar-based and noncaloric sweetener. However, the production cannot meet the increasing market demand because of the low content of mogrosides and the small size of LHG. Therefore, some advanced technologies have been applied for improving the quality of LHG. Forchlorfenuron (CPPU), a plant growth regulator, is widely applied to promote plant yield and the secondary metabolite synthesis. Here, the content of nine mogrosides and three intermediates in LHG that were treated with three different concentrations of CPPU were determined by LC-MS/MS and GC-MS, respectively. The total content of mogrosides in LHG treated with CPPU was not enhanced, and the proportion of some main bioactive ingredients, including mogroside V (MV), were decreased relative to that of the control treatment. Morphological and cytological observations showed CPPU could make an early lignification in fruit epidermal cells, and 5 or 25 mg L-1 CPPU could inhibit LHG growth. The expression levels of 24 key genes in the mogroside biosynthesis pathway were measured and revealed that genes downregulated in upstream, and different expressions of SgUGTs would affect the accumulations and proportions of mogrosides in LHG induced by CPPU. This was the first study that applied CPPU individually on LHG, and assessed effects of CPPU on the morphology, the accumulation of metabolites, and expression profiles of 24 structural genes. The CPPU effects on LHG were undesirable, including development inhibition and the decrease of main mogroside content. These will provide guidance for the rational application of CPPU.

[Research advance of functional plant pharmaceutical cycloartenol about pharmacological and physiological activity].

Cycloartenol, a phytosterol compound, also one of the key precusor substances for biosynthesis of numerous sterol compounds, has a variety of pharmacological activities such as anti-inflammatory, anti-tumor, antioxidant, antibiosis and anti-alzheimer's disease. Furthermore, cycloartenol also plays an important role in the process of plant growth and development. This article reviewed the research progress on cycloartenol pharmacological activity in domestic and foreign articles, and summarized the effect of cycloartenol and "cycloartenol pathway" on the plant growth and development, laying foundation for the its further study, development and utilization.

Liquid chromatography with tandem mass spectrometry method for the simultaneous determination of multiple sweet mogrosides in the fruits of Siraitia grosvenorii and its marketed sweeteners.

A high-performance liquid chromatography with electrospray ionization tandem mass spectrometry method has been developed and validated for the simultaneous quantification of eight major sweet mogrosides in different batches of the fruits of Siraitia grosvenorii and its marketed sweeteners. The sample preparation procedure and chromatographic and mass spectrographic conditions were optimized. Chromatographic separation was achieved on a reversed-phase Poroshell 120 SB C18 column in 10.0 min with gradient elution with acetonitrile and water, both of which contained 0.1% formic acid. The multiple reaction monitoring scanning mode was employed for quantification in the negative ion mode. The developed method was validated with acceptable linearity (r2 = 0.9984-0.9998) over a wide concentration range, precision (relative standard deviations = 1.09-3.91%), stability (relative standard deviations = 1.21-3.01%), and recovery in the range of 91.22-106.58% (relative standard deviations ≤ 3.79%) under optimum conditions. The proposed method was demonstrated to be simple, rapid, specific, and reliable and was successfully applied for the quality control of the fruits of S. grosvenorii and its marketed sweeteners.

Development of an efficient transient expression system for Siraitia grosvenorii fruit and functional characterization of two NADPH-cytochrome P450 reductases.

Siraitia grosvenorii (Luo hanguo or monk fruit) is a valuable medicinal herb for which the market demand has increased dramatically worldwide. As promising natural sweeteners, mogrosides have received much attention from researchers because of their extremely high sweetness and lack of calories. Nevertheless, owing to the absence of genetic transformation methods, the molecular mechanisms underlying the regulation of mogroside biosynthesis have not yet been fully elucidated. Therefore, an effective method for gene function analysis needs to be developed for S. grosvenorii fruit. As a powerful approach, transient expression has become a versatile method to elucidate the biological functions of genes and proteins in various plant species. In this study, PBI121 with a ß-glucuronidase (GUS) marker and tobacco rattle virus (TRV) were used as vectors for overexpression and silencing, respectively, of the SgCPR1 and SgCPR2 genes in S. grosvenorii fruit. The effectiveness of transient expression was validated by GUS staining in S. grosvenorii fruit, and the expression levels of SgCPR1 and SgCPR2 increased significantly after infiltration for 36 h. In addition, TRV-induced gene silencing suppressed the expression of SgCPR1 and SgCPR2 in S. grosvenorii fruit. More importantly, the production of the major secondary metabolites mogrol, mogroside IIE (MIIE) and mogroside III (MIII) was activated by the overexpression of SgCPR1 and SgCPR2 in S. grosvenorii fruit, with levels 1-2 times those in the control group. Moreover, the accumulation of mogrol, MIIE and MIII was decreased in the SgCPR1 and SgCPR2 gene silencing assays. Therefore, this transient expression approach was available for S. grosvenorii fruit, providing insight into the expression of the SgCPR1 and SgCPR2 genes involved in the mogroside biosynthesis pathway. Our study also suggests that this method has potential applications in the exploration of the molecular mechanisms, biochemical hypotheses and functional characteristics of S. grosvenorii genes.

Complete chloroplast genomes of two Siraitia Merrill species: Comparative analysis, positive selection and novel molecular marker development.

Siraitia grosvenorii fruit, known as Luo-Han-Guo, has been used as a traditional Chinese medicine for many years, and mogrosides are its primary active ingredients. Unfortunately, Siraitia siamensis, its wild relative, might be misused due to its indistinguishable appearance, not only threatening the reliability of the medication but also partly exacerbating wild resource scarcity. Therefore, high-resolution genetic markers must be developed to discriminate between these species. Here, the complete chloroplast genomes of S. grosvenorii and S. siamensis were assembled and analyzed for the first time; they were 158,757 and 159,190 bp in length, respectively, and possessed conserved quadripartite circular structures. Both contained 134 annotated genes, including 8 rRNA, 37 tRNA and 89 protein-coding genes. Twenty divergences (Pi > 0.03) were found in the intergenic regions. Nine protein-coding genes, accD, atpA, atpE, atpF, clpP, ndhF, psbH, rbcL, and rpoC2, underwent selection within Cucurbitaceae. Phylogenetic relationship analysis indicated that these two species originated from the same ancestor. Finally, four pairs of molecular markers were developed to distinguish the two species. The results of this study will be beneficial for taxonomic research, identification and conservation of Siraitia Merrill wild resources in the future.

Development and Validation of a Sensitive LC-MS-MS Method for Quantification of Mogrol in Rat Plasma and Application to Pharmacokinetic Study.

Mogrol, the aglycone of mogrosides, is a potential pharmacologically active ingredient isolated from the fruits of Siraitia grosvenorii. The aim of this study was to develop and validate an LC-MS-MS method for the quantification of mogrol in rat plasma. Protein precipitation extraction procedure using methanol/water (1:1, v/v) was employed to extract mogrol from rat plasma. Chromatographic separation was performed on a reverse-phase Agilent Zorbax XDB C18 column (50 mm × 2.1 mm, 3.5 µm) with gradient elution using a mobile phase containing methanol and water, both of which contained 0.1% formic acid at a flow rate of 0.50 mL/min. The analyte was monitored by tandem-mass spectrometry with positive electrospray ionization mode. The precursor/product transitions (m/z) in the positive ion mode were 459.3→423.3 and 386.2→122.3 for mogrol and internal standard, respectively. The method was validated over the concentration range of 10.0-10,000 ng/mL with a lower limit of quantification of 10.0 ng/mL in rat plasma. Validation experiments included tests for specificity, precision, accuracy, matrix effect, and stability under different storage and handling conditions. This method was successfully utilized to pharmacokinetic evaluation of mogrol after intravenous and oral administration of a single dose in rats at 2.0 and 5.0 mg/kg, respectively. The oral absolute bioavailability (F) of mogrol was estimated to be 10.3 ± 2.15% with an elimination half-life (t1/2) value of 2.41 ± 0.11 h.