Determination of 18 Intact Glucosinolates in Brassicaceae Vegetables by UHPLC-MS/MS: Comparing Tissue Disruption Methods for Sample Preparation

The Tandem of Liquid Chromatography and Network Pharmacology for the Chemical Profiling of Pule'an Tablets and the Prediction of Mechanism of Action in Treating Prostatitis

Prostatitis, a prevalent urinary tract disorder in males, has a complex etiology that leads to severe clinical discomfort. Pule'an Tablets, a classic single-component formulation primarily based on rapeseed pollen, have been clinically proven to have a beneficial therapeutic effect on both prostatitis and benign prostatic hyperplasia. However, there is currently a lack of research on the chemical composition and mechanisms of action of Pule'an Tablets in treating prostatitis. In this study, using liquid chromatography-mass spectrometry (LC-MS), a total of 53 compounds in Pule'an Tablets were identified, including flavonoids, phenylpropionamides, lipids, glucosinolates, and nucleic acids. Subsequently, through a network pharmacology analysis, potential target genes and their mechanisms of action were predicted accordingly. The results suggested that genes such as LPAR5, LPAR6, LPAR4, LPAR3, LPAR2, LPAR1, F2, ENPP2, MMP9, and TNF, along with pathways like prostate cancer, endocrine resistance, bladder cancer, and the IL-17 signaling pathway, may represent potential pathways involved in the therapeutic effects of Pule'an Tablets. This study represents the first systematic investigation into the chemical composition of Pule'an Tablets, shedding light on the potential mechanisms underlying their efficacy in treating prostatitis. These findings could serve as a valuable reference for future pharmacological research on Pule'an Tablets.

Glucoraphanin Accumulation via Glucoraphanin Synthesis Promotion during Broccoli Germination

Glucoraphanin is an important glucosinolate which is widely distributed in Brassica vegetables and poses an anticancer effect to humans. Although researchers have paid a lot of attention to the changes in glucoraphanin concentration in seedlings of broccoli over 1-2 weeks, there has been little research focusing on the total whole-sprout glucoraphanin content within broccoli seedlings over 1-5 weeks. However, it is necessary to clarify the changes in total glucoraphanin content during the broccoli sprouting stage as broccoli seedlings are novel plant foods. This research explored glucoraphanin absolute accumulation and the biosynthesis mechanism in broccoli seedlings during a 5-week growth period. The results showed that glucoraphanin accumulation content was higher at week 4 than in the seeds. Moreover, the relative DL-methionine contents increased significantly after 3 weeks. Glucoraphanin synthetic gene expression levels were increased after 3 weeks, but the gene expressions of AOP3 (encoding 2-oxoglutarate-dependent dioxygenases) and MYR (encoding myrosinase) were significantly decreased. Furthermore, the 20 essential DEGs obtained can provide new insight into understanding the developmental regulation of broccoli seedlings. In addition, the results can also provide information on how to obtain higher glucoraphanin contents in broccoli sprouts.

Dynamic profiling of intact glucosinolates in radish by combining UHPLC-HRMS/MS and UHPLC-QqQ-MS/MS

Glucosinolates (GSLs) and their degradation products in radish confer plant defense, promote human health, and generate pungent flavor. However, the intact GSLs in radish have not been investigated comprehensively yet. Here, an accurate qualitative and quantitative analyses of 15 intact GSLs from radish, including four major GSLs of glucoraphasatin (GRH), glucoerucin (GER), glucoraphenin (GRE), and 4-methoxyglucobrassicin (4MGBS), were conducted using UHPLC-HRMS/MS in combination with UHPLC-QqQ-MS/MS. Simultaneously, three isomers of hexyl GSL, 3-methylpentyl GSL, and 4-methylpentyl GSL were identified in radish. The highest content of GSLs was up to 232.46 μmol/g DW at the 42 DAG stage in the 'SQY' taproot, with an approximately 184.49-fold increase compared to the lowest content in another sample. That the GSLs content in the taproots of two radishes fluctuated in a similar pattern throughout the five vegetative growth stages according to the metabolic profiling, whereas the GSLs content in the '55' leaf steadily decreased over the same period. Additionally, the proposed biosynthetic pathways of radish-specific GSLs were elucidated in this study. Our findings will provide an abundance of qualitative and quantitative data on intact GSLs, as well as a method for detecting GSLs, thus providing direction for the scientific progress and practical utilization of GSLs in radish.

Polyphenolics, glucosinolates and isothiocyanates profiling of aerial parts of Nasturtium officinale (Watercress)

Watercress (Nasturtium officinale) is a rich source of secondary metabolites with disease-preventing and/or health-promoting properties. Herein, we have utilized extraction procedures to isolate fractions of polyphenols, glucosinolates and isothiocyanates to determine their identification, and quantification. In doing so, we have utilized reproducible analytical methodologies based on liquid chromatography with tandem mass spectrometry by either positive or negative ion mode. Due to the instability and volatility of isothiocyanates, we followed an ammonia derivatization protocol which converts them into respective ionizable thiourea derivatives. The analytes' content distribution map was created on watercress flowers, leaves and stems. We have demonstrated that watercress contains significantly higher levels of gluconasturtiin, phenethyl isothiocyanate, quercetin-3-O-rutinoside and isorhamnetin, among others, with their content decreasing from flowers (82.11 ± 0.63, 273.89 ± 0.88, 1459.30 ± 12.95 and 289.40 ± 1.37 ng/g of dry extract respectively) to leaves (32.25 ± 0.74, 125.02 ± 0.52, 1197.86 ± 4.24 and 196.47 ± 3.65 ng/g of det extract respectively) to stems (9.20 ± 0.11, 64.7 ± 0.9, 41.02 ± 0.18, 65.67 ± 0.84 ng/g of dry extract respectivbely). Pearson's correlation analysis has shown that the content of isothiocyanates doesn't depend only on the bioconversion of individual glucosinolates but also on other glucosinolates of the same group. Overall, we have provided comprehensive analytical data of the major watercress metabolites thereby providing an opportunity to exploit different parts of watercress for potential therapeutic applications.

All Ion Fragmentation Analysis Enhances the Untargeted Profiling of Glucosinolates in Brassica Microgreens by Liquid Chromatography and High-Resolution Mass Spectrometry

An analytical approach based on reversed-phase liquid chromatography coupled to electrospray ionization Fourier-transform mass spectrometry in negative ion mode (RPLC-ESI-(-)-FTMS) was developed for the untargeted characterization of glucosinolates (GSL) in the polar extracts of four Brassica microgreen crops, namely, garden cress, rapeseed, kale, and broccoli raab. Specifically, the all ion fragmentation (AIF) operation mode enabled by a quadrupole-Orbitrap mass spectrometer, i.e., the systematic fragmentation of all ions generated in the electrospray source, followed by the acquisition of an FTMS spectrum, was exploited. First, the best qualifying product ions for GSL were recognized from higher-energy collisional dissociation (HCD)-FTMS² spectra of representative standard GSL. Extracted ion chromatograms (EIC) were subsequently obtained for those ions from RPLC-ESI(-)-AIF-FTMS data referred to microgreen extracts, by plotting the intensity of their signals as a function of retention time. The alignment of peaks detected in the EIC traces was finally exploited for the recognition of peaks potentially related to GSL, with the EIC obtained for the sulfate radical anion [SO₄]^•- (exact m/z 95.9523) providing the highest selectivity. Each putative GSL was subsequently characterized by HCD-FTMS² analyses and by collisionally induced dissociation (CID) multistage MSⁿ (n = 2, 3) acquisitions based on a linear ion trap mass spectrometer. As a result, up to 27 different GSLs were identified in the four Brassica microgreens. The general method described in this work appears as a promising approach for the study of GSL, known and novel, in plant extracts.

7,8-Dihydroxyflavone attenuates the virulence of Staphylococcus aureus by inhibiting alpha-hemolysin

Staphylococcus aureus (S. aureus), a Gram-positive bacteria, is an incurable cause of hospital and community-acquired infections. Inhibition bacterial virulence is a viable strategy against S. aureus infections based on the multiple virulence factors secreted by S. aureus. Alpha-hemolysin (Hla) plays a crucial role in bacteria virulence without affecting bacterial viability. Here, we identified that 7,8-Dihydroxyflavone (7,8-DHF), a natural compound, was able to decrease the expression of and did not affect the in vitro growth of S. aureus USA300 at a concentration of 32 μg/mL. It was verified by western blot and RT-qPCR that the natural compound could inhibit the transcription and translation of Hla. Further mechanism studies revealed that 7,8-DHF has a negative effect on transcriptional regulator agrA and RNAIII, preventing the upregulation of virulence gene. Cytotoxicity assays showed that 7,8-DHF did not produce significant cytotoxicity to A549 cells. Animal experiments showed that the combination of 7,8-DHF and vancomycin had a more significant therapeutic effect on S. aureus infection, reflecting the synergistic effect of 7,8-DHF with antibiotics. In conclusion, 7,8-DHF was able to target Hla to protect host cells from hemolysis while limiting the development of bacterial resistance.