Two Novel Phenylpropanoid Trimers From Ligusticum chuanxiong Hort With Inhibitory Activities on Alpha-Hemolysin Secreted by Staphylococcus aureus.

The emergence of antibiotic resistance in Staphylococcus aureus has necessitated the development of innovative anti-infective agents acting on novel targets. Alpha-hemolysin (Hla), a key virulence factor of S. aureus, is known to cause various cell damage and death. In this study, with bioassay-guided fractionation, a pair of unusual epimeric lignan trimers, ligustchuanes A and B (1 and 2), were isolated from the rhizomes of Ligusticum chuanxiong Hort, together with two known phthalides being identified by UPLC-QTOF-MS. To the best of our knowledge, trimers with rare C8-C9″-type neolignan and ferulic acid fragments have not been identified in any natural product. Both of them were isolated as racemic mixtures, and their absolute configurations were determined by comparing experimental and calculated ECD spectra after enantioseparation. Ligustchuane B exhibited an outstanding inhibitory effect on α-hemolysin expression in both MRSA USA300 LAC and MSSA Newman strains at concentrations of 3 and 6 µM, respectively. Notably, a mouse model of infection further demonstrated that ligustchuane B could attenuate MRSA virulence in vivo.

The anti-infective activity of Salvia miltiorrhiza against Staphylococcus aureus by attenuating accessory gene regulator system-mediated virulence.

Due to the rapid evolution of antibiotic resistance in Staphylococcus aureus, antivirulence therapy may be a promising alternative for the effective control of the spread of resistant pathogens. The Chinese Materia Medica has been widely used for the treatment of diseases and production of health foods, and it remains a valuable resource for the discovery of compounds possessing antivirulence activity. Through a Caenorhabditis elegans infection model, an EtOAc-soluble fraction of 80% EtOH extract of Salvia miltiorrhiza Bunge (SMEA) was found to possess potential anti-infective activity against S. aureus. Then, several in vitro assays indicated that SMEA had robust antivirulence activity at the dose of 400 µg mL-1, reducing hemolytic activity and α-hemolysin expression in S. aureus. Furthermore, at 100 mg kg-1, SMEA reduced abscess formation in the main organs of mice challenged with S. aureus. In order to identify the bioactive components of SMEA and investigate the mechanisms underlying the antivirulence activity, SMEA was separated using bioassay-guided fractionation. As a result, eight compounds were identified in SMEA. Among them, tanshinone IIB (TNB) showed strong antivirulence activity both in vitro and in vivo. Furthermore, at 24 µg mL-1, TNB significantly reduced the expression of RNAIII and psmα, indicating that the mechanism underlying TNB activity was related to the accessory gene regulator quorum sensing system. In conclusion, TNB's antivirulence properties make it a promising candidate for drug development against S. aureus infections.

Structural Revision of Guttiferone F and 30-epi-Cambogin.

Guttiferone F, a natural polyprenylated polycyclic acylphloroglucinol, was originally assigned as the 30-epimer of garcinol by NMR data analyses. Conversion of guttiferone F in the presence of acid afforded its cyclized form (2a), which was previously assigned as 30-epi-cambogin. However, the absolute configurations of guttiferone F and 2a have not been determined. Reinvestigation of the structures of those two compounds, using X-ray and NMR data analyses and chemical transformation, revealed that the original assignment of the C-30 absolute configuration in guttiferone F and 2a should be inverted. Guttiferone F is indeed garcinol, and 2a, which was previously identified as 30-epi-cambogin, is cambogin.

Prenylated xanthones and biphenyls from Garcinia esculenta with antistaphylococcal activity.

One new xanthone, (±) garciesculenxanthone C (1), two new biphenyls, garciesculenbiphenyls A (2) and B (3), together with two known compounds, doitungbiphenyl B (4) and morusignin D (5), were isolated from Garcinia esculenta. The structures of new compounds were elucidated by spectroscopic analysis, and the absolute configuration of (±) garciesculenxanthone C (1) was assigned by a modified Mosher's method. All isolates were evaluated for their antistaphylococcal activities against Staphylococcus aureus Newman, USA300 LAC, USA400 MW2, and Mu50 strains. Among these, (±) garciesculenxanthone C (1) showed the best antistaphylococcal activity, and its effect was determined to be bactericidal by time-kill experiment.

Uncariitannin, a polyphenolic polymer from Uncaria gambier, attenuates Staphylococcus aureus virulence through an MgrA-mediated regulation of α-hemolysin.

A global transcriptional regulator, MgrA, was previously identified as a key determinant of virulence in Staphylococcus aureus. An 80% EtOH extract of Uncaria gambier was found to attenuate the virulence of S. aureus via its effects on MgrA. Using bioassay-guided fractionation, a polyphenolic polymer, uncariitannin, was found to be the main bioactive constituent of the extract, and its structure was characterized using spectral and chemical analysis. The molecular weight and polydispersity of uncariitannin were determined by gel permeation chromatography-refractive index-light scattering analysis. An electrophoretic mobility shift assay showed that uncariitannin could effectively inhibit the interaction of MgrA with DNA in a dose-dependent manner. Treatment with uncariitannin could decrease the mRNA and protein levels of Hla in both the S. aureus Newman and USA300 LAC strains. Further analysis of Hla expression levels in the Newman ΔmgrA and Newman ΔmgrA/pYJ335-mgrA strains indicated that uncariitannin altered Hla expression primarily in an MgrA-dependent manner. A mouse model of infection indicated that uncariitannin could attenuate MRSA virulence. In conclusion, uncariitannin may be a potential candidate for further development as an antivirulence agent for the treatment of S. aureus infection.

Multiorgan toxicity induced by EtOH extract of Fructus Psoraleae in Wistar rats.

BACKGROUND: The fruits of Psoralea corylifolia L. (Fructus Psoraleae, FP) has a long history and a wide range of applications in the treatment of osteoporosis and leukoderma. Although it is well known that FP could cause hepatotoxicity and reproductive toxicity, less is known about its potential toxicity on multiple organs. PURPOSE: This study aims to determine the multiorgan toxicity of EtOH extract of FP (EEFP) and to investigate the underlying mechanisms through a systematic evaluation in Wistar rats. STUDY DESIGN AND METHODS: Wistar rats were orally administered with the EEFP at doses of 1.5, 1.0 and 0.5 g/kg for 28 days. Histopathologic and clinicopathologic analyses were performed, and the hormone levels in serum and the mRNA levels of enzymes related to the production of steroid hormones in adrenal glands were detected. The area of each band of adrenal glands and the steroid levels in the adrenal glands were also measured. RESULTS: After the treatment, both the histopathologic and clinicopathologic examination showed that EEFP caused liver, prostate, seminal vesicle and adrenal gland damage. Among the enzymes involved in the regulation of adrenal steroid hormone production, NET, VMAT2, and CYP11B1 were upregulated, while CYP17A1 was downregulated. Among the adrenal steroid hormones, COR and NE were upregulated, while levels of DHT and serum ACRH and CRH decreased. CONCLUSION: Our results indicated that adrenal gland, prostate, and seminal vesicles could also be the target organs of FP-induced toxicity. Abnormal enzyme and hormone production related to the hypothalamic pituitary adrenal (HPA) axis caused by the EEFP may be the potential toxic mechanism for changes in the adrenal gland and secondary sex organs of male rats.

Hepatotoxicity induced by psoralen and isopsoralen from Fructus Psoraleae: Wistar rats are more vulnerable than ICR mice.

Fructus Psoraleae (FP) causes cholestatic liver injury; however, its main toxic constituents that are responsible for causing hepatotoxicity remained undetermined in previous studies. In the present study, psoralen and isopsoralen, the two main constituents of FP, were administered orally to rats (80 and 40 mg/kg, respectively) and mice (320 and 160 mg/kg, respectively) for 28 days, followed by biochemical and histopathological examinations to evaluate their hepatotoxicity. The results showed that psoralen and isopsoralen could induce the toxic reactions of liver and other organs in rats, while mice were not sensitive to these two compounds. Furthermore, the corresponding results indicated that administration of psoralen and isopsoralen repressed the expression of CYP7A1, BSEP, MRP2 and SULT2A1 and increased the expression of FXR and MRP3 in the rat liver. In summary, the toxic reactions of psoralen and isopsoralen are different in different species. In this study, multiple organ toxicity, such as cholestatic liver injury, occurs in rats, but not in mice. Psoralen and isopsoralen are the two main toxic constituents of FP. In addition, psoralen and isopsoralen cause liver injury, possibly through inhibiting bile acid excretion in the liver, leading to the accumulation of toxin in hepatocytes.

A multidimensional analytical approach based on time-decoupled online comprehensive two-dimensional liquid chromatography coupled with ion mobility quadrupole time-of-flight mass spectrometry for the analysis of ginsenosides from white and red ginsengs.

Here, time-decoupled comprehensive two-dimensional ultra-high liquid chromatography (UHPLC) coupled with an ion mobility (IM)-high resolution mass spectrometer (HRMS) was established and used to analyze ginsenosides from the main roots of white ginseng (WG) and red ginseng (RG), which enabled the separation of complex samples in four dimensions (2D-LC, ion mobility, and mass spectrometry). The incompatibility of mobile phases, dilution effect, and long analysis time, which are the main shortcomings of traditional comprehensive 2D-LC methods, were largely avoided in this newly established 2D-UHPLC method. The orthogonality of this system was 55%, and the peak capacity was 4392. Under the optimized 2D-UHPLC-IM-MS method, 201 ginsenosides were detected from white and red ginseng samples. Among them, 10 pairs of co-eluting isobaric ginseng saponins that were not resolved by 2D-UHPLC-HRMS were further resolved using 2D-UHPLC-IM-MS. In addition, 24 ginsenoside references were analyzed by UHPLC-IM-MS to obtain their collision cross section (CCS) values and ion mobility characteristics. Finally, the established new method combined with multivariate statistical analysis was successfully applied to differentiate WG and RG, and 9 ginsenosides were found to be the potential biomarkers by S-Plot and the values of max fold change, which could be used for classifying WG and RG samples. Overall, the obtained results demonstrate the applicability and potential of the established time-decoupled online comprehensive 2D-UHPLC-IM-MS system, and it will be extended to the analysis of other targeted or untargeted compounds, especially co-eluting isomers in more herbal extracts.