Design, synthesis and biological evaluation of novel pleuromutilin derivatives containing piperazine and 1,2,3-triazole linker

A series of novel pleuromutilin derivatives containing piperazine ring, 1, 2, 3-triazoles and secondary amines on the side chain of C14 were synthesized under mild conditions via click reaction. The in vitro antibacterial activities of the synthesized derivatives against four strains of Staphylococcus aureus (MRSA ATCC 43300, ATCC 29213 ,144 and AD3) and one strain of Escherichia coli (ATCC 25922) were evaluated by the broth dilution method. Among these derivatives, 22-[2-(4-((4-nitrophenyl piperazine)methyl)-1,2,3-triazol-1-yl)-1-(piperazine-1-yl) ethyl-1-one] deoxy pleuromutilin (compound 59) showed the most prominent in vitro antibacterial effect against MRSA (MIC = 1 μg/mL). Furthermore, compound 59 displayed more rapid bactericidal kinetic than tiamulin time-kill studies and possessed a longer PAE than tiamulin against MRSA in vitro. In addition, in vivo antibacterial activities of compound 59 against MRSA were further evaluated employing thigh infection model. And compound 59 (-8.89 log10 CFU/mL) displayed superior activities than tiamulin. Compound 59 was further evaluated in CYP450 inhibition assay and the results showed that it exhibited low to moderate inhibitory effects on CYP1A2, CYP2E1, CYP2D6 and CYP3A4 enzymes. The PK properties of compound 59 were then measured. The half-life (t1/2), clearance rate (Cl) and the area under the plasma concentration time curve (AUC0→∞) of compound 59 were 0.74 h, 0.29 L/h/kg and 46.28 μg·h/mL, respectively.

Design, synthesis and biological activities of novel pleuromutilin derivatives with a substituted triazole moiety as potent antibacterial agents

A series of novel pleuromutilin derivatives possessing 1,2,3-triazole moieties were synthesized via click reactions under mild conditions. The in vitro antibacterial activities of these derivatives against 4 strains of S. aureus (MRSA ATCC 43300, ATCC 29213, AD 3, and 144) and 1 strain of E. coli (ATCC 25922) were tested by the broth dilution method. The majority of the synthesized derivatives displayed potent antibacterial activities against MRSA (MIC = 0.125-2 μg/mL). It was also found that most compounds had no significant inhibitory effect on the proliferation of RAW264.7 cells at the concentration of 8 μg/mL. Among these derivatives, compound 32 (∼1.71 log10 CFU/g) containing dimethylamine group side chain displayed more effective than tiamulin (∼0.77 log10 CFU/g) at the dose of 20 mg/kg in reducing MRSA load in thigh infected mice. Additionally, compound 32 (the survival rate was 50%) also displayed superior in vivo efficacy to that of tiamulin (the survival rate was 20%) in the mouse systemic model. Structure-activity relationship (SAR) studies resulted in compound 32 with the most potent in vitro and in vivo antibacterial activity among the series. Moreover, compound 32 was evaluated in CYP450 inhibition assay and showed moderate in vitro inhibition of CYP3A4 (IC50 = 6.148 μM).

Dual antagonists of α5β1/αvβ1 integrin for airway hyperresponsiveness

Inhibition of integrin α5β1 emerges as a novel therapeutic option to block transmission of contractile forces during asthma attack. We designed and synthesized novel inhibitors of integrin α5β1 by backbone replacement of known αvβ1 integrin inhibitors. These integrin α5β1 inhibitors also retain the nanomolar potency against αvβ1 integrin, which shows promise for developing dual integrin α5β1/αvβ1 inhibitor. Introduction of hydrophobic adamantane group significantly boosted the potency as well as selectivity over integrin αvβ3. We also demonstrated one of the inhibitors (11) reduced airway hyperresponsiveness in ex vivo mouse tracheal ring assay. Results from this study will help guide further development of integrin α5β1 inhibitors as potential novel asthma therapeutics.

Efficiency comparison of apigenin-7-O-glucoside and trolox in antioxidative stress and anti-inflammatory properties

OBJECTIVES

Chamomile has long been used as a medicinal plant due to its antioxidative and anti-inflammatory activity. Apigenin-7-O-glucoside (AG) is one of the major ethanol extract components from chamomile; however, the underlying mechanism remains unclear.

METHODS

In this study, the antioxidant potential and the anti-inflammatory activities of AG were analysed and compared with those of trolox. We demonstrate the protective effects of AG on free radical-induced oxidative damage of DNA, proteins and erythrocytes. Flow cytometry assay was used to detect ROS production. Additionally, the expression of anti-oxidation-related and inflammation-related factors was detected by ELISA and Western blotting, respectively.

KEY FINDINGS

AG and trolox showed different efficiency as antioxidant in different experimental systems. AG had similar effect as trolox to inhibit H₂ O₂ -induced ROS production in RAW264.7 cells, while exerted stronger inhibition against free radical-induced oxidative damage on erythrocytes than trolox. Interestingly, compared with trolox, AG also had stronger inhibitory effect on LPS-induced NF-κB/NLRP3/caspase-1 signalling in RAW246.7 cells.

CONCLUSIONS

These results suggest the potential of AG as a pharmaceutical drug for anti-oxidation and anti-inflammation, and the combined usage of AG and trolox might promote its efficacy. Our findings will provide new insights into the development of new drugs with antioxidative and anti-inflammatory functions.

Synergistic Effect of a Pleuromutilin Derivative with Tetracycline against Streptococcus suis In Vitro and in the Neutropenic Thigh Infection Model

Tetracycline (TET) has been widely used in the treatment of Streptococcus suis (S. suis) infection. However, it was found that the efficacy of many antibiotics in S. suis decreased significantly, especially tetracycline. In this study, GML-12 (a novel pleuromutilin derivative) was used in combination with TET against 12 S. suis isolates. In the checkerboard assay, the TET/GML-12 combination exhibited synergistic and additive effects against S. suis isolates (n = 12). In vitro time-killing assays and in vivo therapeutic experiments were used to confirm the synergistic effect of the TET/GML-12 combination against S. suis strains screened based on an FICI ≤ 0.5. In time-killing assays, the TET/GML-12 combination showed a synergistic effect or an additive effect against three isolates with a bacterial reduction of over 2.4-log10 CFU/mL compared with the most active monotherapy. Additionally, the TET/GML-12 combination displayed potent antimicrobial activity against four isolates in a mouse thigh infection model. These results suggest that the TET/GML-12 combination may be a potential therapeutic strategy for S. suis infection.

Design, synthesis and biological evaluation of novel pleuromutilin derivatives possessing acetamine phenyl linker

A series of novel acetamine phenyl pleuromutilin derivatives incorporating 2-aminothiophenol moieties into the C14 side chain were synthesized via acylation reactions under mild conditions. The in vitro antibacterial activities of the synthesized derivatives against three Staphylococcus aureus (MRSA ATCC 43300, ATCC 29213 and AD 3) and two Escherichia coli (ATCC 25922 and 9-1) were evaluated by the broth dilution method. Most of the synthesized derivatives displayed potent activities. Compound 27 was found to be the most active antibacterial derivative against MRSA (minimal inhibitory concentration = 0.015 μg/mL) which may lead to a promising antibacterial drug. Furthermore, compound 27 displayed more rapid bactericidal kinetic than tiamulin in in vitro time-kill studies and possessed a longer PAE than tiamulin against MRSA. The PK properties of compound 27 were then measured. The half life (t1/2), clearance rate (Cl) and the area under the plasma concentration-time curve (AUC0→∞) of compound 27 were 6.88 h, 21.64 L/h/kg and 0.48 μg h/mL, respectively. The in vivo antibacterial activities of compound 27 against MRSA were further evaluated using thigh infection model and systemic infection model. Compound 27 possessed superior antibacterial efficacy to tiamulin against MRSA infection in both model.

Plasmid-encoded tet(X) genes that confer high-level tigecycline resistance in Escherichia coli

Tigecycline is one of the last-resort antibiotics to treat complicated infections caused by both multidrug-resistant Gram-negative and Gram-positive bacteria1. Tigecycline resistance has sporadically occurred in recent years, primarily due to chromosome-encoding mechanisms, such as overexpression of efflux pumps and ribosome protection2,3. Here, we report the emergence of the plasmid-mediated mobile tigecycline resistance mechanism Tet(X4) in Escherichia coli isolates from China, which is capable of degrading all tetracyclines, including tigecycline and the US FDA newly approved eravacycline. The tet(X4)-harbouring IncQ1 plasmid is highly transferable, and can be successfully mobilized and stabilized in recipient clinical and laboratory strains of Enterobacteriaceae bacteria. It is noteworthy that tet(X4)-positive E. coli strains, including isolates co-harbouring mcr-1, have been widely detected in pigs, chickens, soil and dust samples in China. In vivo murine models demonstrated that the presence of Tet(X4) led to tigecycline treatment failure. Consequently, the emergence of plasmid-mediated Tet(X4) challenges the clinical efficacy of the entire family of tetracycline antibiotics. Importantly, our study raises concern that the plasmid-mediated tigecycline resistance may further spread into various ecological niches and into clinical high-risk pathogens. Collective efforts are in urgent need to preserve the potency of these essential antibiotics.

Synthesis and antibacterial activities of novel pleuromutilin derivatives bearing an aminothiophenol moiety

We synthesized a series of novel thioether pleuromutilin derivatives incorporating 2-aminothiophenol moieties into the C14 side chain via acylation reactions under mild conditions. We evaluated the in-vitro antibacterial activities of the derivatives against methicillin-resistant Staphylococcus aureus (MRSA, ATCC 43300), Staphylococcus aureus (ATCC 29213) and Escherichia coli (ATCC 25922). The majority of the synthesized derivatives possessed moderate antibacterial activities. Compound 8 was found to be the most active antibacterial derivative against MRSA. We conducted docking experiments to understand the possible mode of interactions between compounds 8, 9b, 11a and 50S ribosomal subunit. The docking results proved that there is a reasonable correlation between the binding free energy and the antibacterial activity. Compound 8 was evaluated for its in-vivo antibacterial activity and showed higher efficacy than tiamulin against MRSA in mouse infection model.

Synthesis and Antibacterial Activity Against MRSA of Pleuromutilin Derivatives Possessing a Mercaptoethylamine Linker

BACKGROUND

Methicillin resistant Staphylococcus aureus (MRSA) usually invalidate powerful antibiotics in the clinic. Pleuromutilin derivatives have been reported to possess antibacterial activity against MRSA.

OBJECTIVE

The antibacterial activities against MRSA of a series of thirteen synthetic pleuromutilin derivatives were investigated through in vitro models.

METHODS

A series of novel thioehter pleuromutilin derivatives incorporating various aromatic substituents into the C14 side chain have been reported. The in vitro antibacterial activities of these derivatives against MRSA and Escherichia coli were tested by the broth dilution method.

RESULTS

Twelve pleuromutilin derivatives were designed, synthesized and evaluated for in vitro antibacterial activities against four Staphylococcus aureus strains. From structure-activity relationship studies, compound 11c was identified as promising compounds with the most potent in vitro antibacterial activity among the series (MIC = 0.0625-0.125 µg/ml) against Staphylococcus aureus strains. The binding of compound 11c to the 50s ribosome was investigated by molecular modeling.

CONCLUSION

It was found that there is a reasonable correlation between the binding free energy and the antibacterial activity.

Inhibition of pro-inflammatory mediators in RAW264.7 cells by 7-hydroxyflavone and 7,8-dihydroxyflavone

OBJECTIVES

Flavonoids are a class of compounds that having the benzo-γ-pyrone skeleton, which possess anti-inflammatory properties in vitro and in vivo. The aim of this study was to investigate the inhibition of two flavonoids 7-hydroxyflavone (HF) and 7,8-dihydroxyflavone (DHF) on the production of pro-inflammatory mediators in RAW264.7 cells activated by lipopolysaccharides (LPS).

METHODS

For this purpose, we selected four pro-inflammatory mediators including nitric oxide (NO), prostaglandin E₂ (PGE₂ ), tumour necrosis factor-α (TNF-α) and interleukin-6 (IL-6) as markers to evaluate the anti-inflammatory activity of HF and DHF.

KEY FINDINGS

In this regard, we showed that HF and DHF dose-dependently reduced the production of NO, PGE₂ , TNF-α and IL-6 through downregulating mRNA expression of inducible nitric oxide synthase (iNOS), cyclooxygenase 2 (COX2), TNF-α and IL-6, respectively. Moreover, DHF generally possesses more efficient than HF in reducing these markers secretion in this study.

CONCLUSIONS

Consider together, these findings suggest that DHF and HF can inhibit LPS-induced inflammation via attenuating the production of NO, PGE₂ , TNF-α and IL-6, indicating that they may be lead compounds for developing anti-inflammatory agent.

Design, synthesis and antibacterial evaluation of novel pleuromutilin derivatives possessing piperazine linker

A series of pleuromutilin derivatives bearing piperazine ring have been reported. The in vitro antibacterial activities of the synthetic derivatives against MRSA (ATCC 43300), Staphylococcus aureus (ATCC 29213), Enterococcus faecalis (ATCC 29212), Enterococcus faecium (ATCC35667) and Escherichia coli (ATCC25922) were evaluated by the broth dilution method. Most of the synthesized derivatives displayed potent activities. Compounds 11c, 12a and 12c were found to be the most active antibacterial derivatives against MRSA (minimum inhibitory concentration = 0.015 μg/mL). The binding of compounds 11c, 12a and 12c to the 50s ribosome were investigated by molecular modeling. Compound 11c possessed lower binding free energy compared with compounds 12a and 12c. Compound 11c was further evaluated in MRSA systemic infection model and displayed superior in vivo efficacy to that of tiamulin.

Design, synthesis, and structure-activity relationship studies of novel pleuromutilin derivatives having a piperazine ring

A series of novel pleuromutilin derivatives possessing piperazine moieties were synthesized under mild conditions. The in vitro antibacterial activities of these derivatives against Staphylococcus aureus and Escherichia coli were tested by the agar dilution method. Structure-activity relationship studies resulted in compounds 11b, 13b, and 14a with the most potent in vitro antibacterial activity among the series (minimal inhibitory concentration = 0.0625-0.125 μg/mL). The binding of compounds 11b, 13b, and 14a to the E. coli ribosome was investigated by molecular modeling, and it was found that there is a reasonable correlation between the binding free energy and the antibacterial activity.

Exploring N-Arylsulfonyl-l-proline Scaffold as a Platform for Potent and Selective αvβ1 Integrin Inhibitors

One small molecule inhibitor of αvβ1 integrin, c8, shows antifibrotic effects in multiple in vivo mouse models. Here we synthesized c8 analogues and systematically investigate their structure-activity relationships (SAR) in αvβ1 integrin inhibition. N-Phenylsulfonyl-l-homoproline analogues of c8 maintained excellent potency against αvβ1 integrin while retaining good selectivity over other RGD integrins. In addition, 2-aminopyridine or cyclic guanidine analogues were shown to be equally potent to c8. A rigid phenyl linker increased the potency compared to c8, but the selectivity over other RGD integrins diminished. These results can provide further insights on design of αvβ1 integrin inhibitors as antifibrotics.

Imaging of rare medullary adrenal tumours in adults

Although adrenal medullary tumours are rare, they have important clinical implications. They form a heterogeneous group of tumours, ranging from benign, non-secretory, incidental masses to hormonally active tumours presenting acutely, or malignant tumours with disseminated disease and a poor prognosis. Increasingly, benign masses are incidentally detected due to the widespread use of imaging and routine medical check-ups. This review aims to illustrate the multimodality imaging appearances of rare adrenal medullary tumours, excluding the more common phaeochromocytomas, with clues to the diagnosis and to summarise relevant epidemiological and clinical data. Careful correlation of clinical presentation, hormone profile, and various imaging techniques narrow the differential diagnosis. Image-guided percutaneous adrenal biopsy can provide a definitive diagnosis, allowing for conservative management in selected cases. A close collaboration between the radiologist, endocrinologist, and surgeon is of the utmost importance in the management of these tumours.

Association of complement factor H gene polymorphisms with age-related macular egeneration susceptibility

OBJECTIVE

This study was aimed to confirm whether I62V and Y402H polymorphisms of complement factor H (CFH) were risk factors for age-related macular degeneration (AMD).

METHOD

109 AMD patients and 165 AMD-free controls were enrolled in the study. The I62V and Y402H polymorphisms were analyzed by polymerase chain reaction-restriction fragment length of polymorphism (PCR-RFLP). Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated by the X2 test to assess the relationship of I62V and Y402H polymorphisms with AMD risk. Analysis of haplotype and stratification by age and smoking status was conducted as well.

RESULTS

AA genotype and A allele of I62V polymorphism was significantly associated with increased risk for AMD (OR=3.75, 95% CI=1.70-8.30; OR=1.64, 95% CI=1.14-2.36). For Y402H polymorphism, CT genotype showed strong effects on the occurrence of AMD (OR=2.10, 95% CI=1.04-4.27). Moreover, C allele was also a risk factor for AMD (OR=1.95, 95% CI=1.02-3.72). The haplotypes analysis suggested that the risk for AT haplotype carriers was high, compared with GT haplotype (OR=3.91, 95% CI=2.58-5.94). In addition, we found that smoking status could affect the genotype distribution of Y402H polymorphism (P<0.05).

CONCLUSIONS

Our results revealed that CFH polymorphisms I62V and Y402H might be associated with the susceptibility to AMD in Chinese population.

Dosage assessment of valnemulin in pigs based on population pharmacokinetic and Monte Carlo simulation

To estimate the valnemulin pharmacokinetic profile in a swine population and to assess a dosage regimen for increasing the likelihood of optimization. This study was, respectively, performed in 22 sows culled by p.o. administration and in 80 growing-finishing pigs by i.v. administration at a single dose of 10 mg/kg to develop a population pharmacokinetic model and Monte Carlo simulation. The relationships among the plasma concentration, dose, and time of valnemulin in pigs were illustrated as C(i,v) = X(0 )(8.4191 × 10(-4) × e(-0.2371t) + 1.2788 × 10(-5) × e(-0.0069t)) after i.v. and C(p.o) = X(0) (-8.4964 × 10(-4) × e(-0.5840t) + 8.4195 × e(-0.2371t) + 7.6869 × 10(-6) × e(-0.0069t)) after p.o. Monte Carlo simulation showed that T(>MIC) was more than 24 h when a single daily dosage at 13.5 mg/kg BW in pigs was administrated by p.o., and MIC was 0.031 mg/L. It was concluded that the current dosage regimen at 10-12 mg/kg BW led to valnemulin underexposure if the MIC was more than 0.031 mg/L and could increase the risk of treatment failure and/or drug resistance.

Control of metamorphic buffer structure and device performance of In(x)Ga(1-x)As epitaxial layers fabricated by metal organic chemical vapor deposition

Using a step-graded (SG) buffer structure via metal-organic chemical vapor deposition, we demonstrate a high suitability of In0.5Ga0.5As epitaxial layers on a GaAs substrate for electronic device application. Taking advantage of the technique's precise control, we were able to increase the number of SG layers to achieve a fairly low dislocation density (∼10(6) cm(-2)), while keeping each individual SG layer slightly exceeding the critical thickness (∼80 nm) for strain relaxation. This met the demanded but contradictory requirements, and even offered excellent scalability by lowering the whole buffer structure down to 2.3 μm. This scalability overwhelmingly excels the forefront studies. The effects of the SG misfit strain on the crystal quality and surface morphology of In0.5Ga0.5As epitaxial layers were carefully investigated, and were correlated to threading dislocation (TD) blocking mechanisms. From microstructural analyses, TDs can be blocked effectively through self-annihilation reactions, or hindered randomly by misfit dislocation mechanisms. Growth conditions for avoiding phase separation were also explored and identified. The buffer-improved, high-quality In0.5Ga0.5As epitaxial layers enabled a high-performance, metal-oxide-semiconductor capacitor on a GaAs substrate. The devices displayed remarkable capacitance-voltage responses with small frequency dispersion. A promising interface trap density of 3 × 10(12) eV(-1) cm(-2) in a conductance test was also obtained. These electrical performances are competitive to those using lattice-coherent but pricey InGaAs/InP systems.

Use of an internal reference in semi-quantitative dynamic contrast-enhanced MRI (DCE MRI) of indeterminate adnexal masses

OBJECTIVE

Semi-quantitative dynamic contrast-enhanced MRI (DCE MRI) has proven useful in discriminating benign from borderline/malignant adnexal lesions. Our aim was to assess if the use of a lesion-to-internal-reference ratio improved the performance in characterizing adnexal masses and which internal reference was suitable.

METHODS

Semi-quantitative DCE MRI images of 71 indeterminate adnexal lesions were retrospectively reviewed. A region of interest was manually drawn onto the enhancing solid component, psoas muscle and normal outer myometrium. The DCE parameters were evaluated, and the lesion-to-internal-reference ratios were calculated.

RESULTS

When the wash in rate of the lesion was higher than that of the myometrium, 97% specificity and 12% sensitivity for borderline/malignancy was reached. When the maximum relative enhancement and maximum absolute enhancement (SImax) of the lesion was less than those of the psoas, 100% specificity for benignity was achieved. The highest area under the curve (AUC) (0.807) was achieved using a SImax lesion-myometrium ratio. A slightly lower AUC (0.799) was achieved using a SImax lesion-psoas ratio, but the psoas muscle was more frequently measurable in the same slice as the lesion ROI. Although the AUC was higher, when using ratios instead of individual DCE values, this was not significantly different.

CONCLUSION

DCE MRI has added diagnostic value in the assessment of adnexal lesions, and the use of internal references enables high specificity for malignancy and benignity. Lesion-internal-reference ratios have no added diagnostic value over DCE values alone.

ADVANCES IN KNOWLEDGE

Both psoas muscle and myometrium are suitable internal references in the DCE assessment of adnexal lesions enabling high specificity for malignancy and benignity.

Wogonoside displays anti-inflammatory effects through modulating inflammatory mediator expression using RAW264.7 cells

ETHNOPHARMACOLOGICAL RELEVANCE

The root of Scutellaria baicalensis Georgi, also called Huangqin in China, is an herbal-based nutraceutical which is usually used in Chinese medicated diet (CMD). As an abundant ingredient in Huangqin, wogonoside is a flavonoid glycoside. The present work investigated the anti-inflammatory activities of wogonoside in lipopolysaccharides (LPS)-induced RAW264.7 cells.

MATERIALS AND METHODS

RAW264.7 cells were used. The inhibition of wogonoside against nitric oxide (NO), prostaglandin E2 (PGE2), tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in LPS-induced RAW264.7 cells were measured. Additionally, the effects of wogonoside on mRNA expression of inducible nitric oxide synthase (iNOS), cyclooxygenase 2 (COX2), TNF-α and IL-6 were also investigated.

RESULTS AND DISCUSSION

Wogonoside not only dose-dependently decreased the production of inflammatory mediators including NO and PGE2 but also inhibited the release of pro-inflammatory cytokines including TNF-α and IL-6 in LPS-induced RAW264.7 cells. Furthermore, wogonoside possessed significantly in vitro inhibitory effects on the gene expression of iNOS, COX2, TNF-α and IL-6.

CONCLUSION

These results suggest that wogonoside may be used as a functional food component for prevention and treatment of inflammation.

Imaging features of colovesical fistulae on MRI

OBJECTIVES

MRI is routinely used in the investigation of colovesical fistulae at our institute. Several papers have alluded to its usefulness in achieving the diagnosis; however, there is a paucity of literature on its imaging findings. Our objective was to quantify the MRI characteristics of these fistulae.

METHODS

We selected all cases over a 4-year period with a final clinical diagnosis of colovesical fistula which had been investigated with MRI. The MRI scans were reviewed in a consensus fashion by two consultant uroradiologists. Their MRI features were quantified.

RESULTS

There were 40 cases of colovesical fistulae. On MRI, the fistula morphology consistently fell into three patterns. The most common pattern (71%) demonstrated an intervening abscess between the bowel wall and bladder wall. The second pattern (15%) had a visible track between the affected bowel and bladder. The third pattern (13%) was a complete loss of fat plane between the affected bladder and bowel wall. MRI correctly determined the underlying aetiology in 63% of cases.

CONCLUSIONS

MRI is a useful imaging modality in the diagnosis of colovesical fistulae. The fistulae appear to have three characteristic morphological patterns that may aid future diagnoses of colovesical fistulae. To the authors' knowledge, this is the first publication of the MRI findings in colovesical fistulae.

Identification and determination of the saikosaponins in Radix bupleuri by accelerated solvent extraction combined with rapid-resolution LC-MS

A method based on accelerated solvent extraction combined with rapid-resolution LC-MS for efficient extraction, rapid separation, online identification and accurate determination of the saikosaponins (SSs) in Radix bupleuri (RB) was developed. The RB samples were extracted by accelerated solvent extraction using 70% aqueous ethanol v/v as solvent, at a temperature of 120 degrees C and pressure of 100 bar, with 10 min of static extraction time and three extraction cycles. Rapid-resolution LC separation was performed by using a C(18) column at gradient elution of water (containing 0.5% formic acid) and acetonitrile, and the major constituents were well separated within 20 min. A TOF-MS and an IT-MS were used for online identification of the major constituents, and 27 SSs were identified or tentatively identified. Five major bioactive SSs (SSa, SSc, SSd, 6''-O-acetyl-SSa and 6''-O-acetyl-SSd) with obvious peak areas and good resolution were chosen as benchmark substances, and a triple quadrupole MS operating in multiple-reaction monitoring mode was used for their quantitative analysis. A total of 16 RB samples from different regions of China were analyzed. The results indicated that the method was rapid, efficient, accurate and suitable for use in the quality control of RB.