Pharmacokinetic study and determination of imperialine, the major bioactive component in antitussive Fritillaria cirrhosa, in rat by high-performance liquid chromatography coupled with evaporative light-scattering detector

Bulbus Fritillariae Cirrhosae as a Respiratory Medicine: Is There a Potential Drug in the Treatment of COVID-19?

Bulbus fritillariae cirrhosae (BFC) is one of the most used Chinese medicines for lung disease, and exerts antitussive, expectorant, anti-inflammatory, anti-asthmatic, and antioxidant effects, which is an ideal therapeutic drug for respiratory diseases such as ARDS, COPD, asthma, lung cancer, and pulmonary tuberculosis. Through this review, it is found that the therapeutic mechanism of BFC on respiratory diseases exhibits the characteristics of multi-components, multi-targets, and multi-signaling pathways. In particular, the therapeutic potential of BFC in terms of intervention of “cytokine storm”, STAT, NF-κB, and MAPK signaling pathways, as well as the renin-angiotensin system (RAS) that ACE is involved in. In the “cytokine storm” of SARS-CoV-2 infection there is an intense inflammatory response. ACE2 regulates the RAS by degradation of Ang II produced by ACE, which is associated with SARS-CoV-2. For COVID-19, may it be a potential drug? This review summarized the research progress of BFC in the respiratory diseases, discussed the development potentiality of BFC for the treatment of COVID-19, explained the chemical diversity and biological significance of the alkaloids in BFC, and clarified the material basis, molecular targets, and signaling pathways of BFC for the respiratory diseases. We hope this review can provide insights on the drug discovery of anti-COVID-19.

Aqueous extract of bulbus Fritillaria cirrhosa induces cytokinesis failure by blocking furrow ingression in human colon epithelial NCM460 cells

Bulbus Fritillariacirrhosa D. Don (BFC) has been widely used as an herbal medicament for respiratory diseases in China for over 2000 years. The ethnomedicinal effects of BFC have been scientifically verified, nevertheless its toxicity has not been completely studied. Previously, we have reported that the aqueous extract of BFC induces mitotic aberrations and chromosomal instability (CIN) in human colon epithelial NCM460 cells via dysfunctioning the mitotic checkpoint. Here, we extend this study and specifically focus on the influence of BFC on cytokinesis, the final step of cell division. One remarkable change in NCM460 cells following BFC treatment is the high incidence of binucleated cells (BNCs). More detailed investigation of the ana-telophases reveals that furrow ingression, the first stage of cytokinesis, is inhibited by BFC. Asynchronous cultures treatment demonstrates that furrow ingression defects induced by BFCs are highly associated with the formation of BNCs in ensuing interphase, indicating the BNCs phenotype after BFC treatment was resulted from cytokinesis failure. In line with this, the expression of genes involved in the regulation of furrow ingression is significantly de-regulated by BFC (e.g., LATS-1/2 and Aurora-B are upregulated, and YB-1 is downregulated). Furthermore, long-term treatment of BFC elucidates that the BNCs phenotype is transient and the loss of BNCs is associated with increased frequency of micronuclei and nuclear buds, two biomarkers of CIN. In supporting of these findings, the Nin Jiom Pei Pa Koa and Chuanbei Pipa Gao, two commercially available Chinese traditional medicines containing BFC, are able to induce multinucleation and CIN in NCM460 cells. Altogether, these data provide the first in vitro experimental evidence linking BFC to cytokinesis failure and suggest the resultant BNCs may be intermediates to produce CIN progenies.

Investigation of association of chemical profiles with the tracheobronchial relaxant activity of Chinese medicinal herb Beimu derived from various Fritillaria species

ETHNOPHARMACOLOGICAL RELEVANCE

Fritillariae Bulbus (Beimu in Chinese) is derived from the bulbus of many Fritillaria species (family Liliaceae), which has been used as an antitussive herb in traditional Chinese medicine for more than 2000 years. Due to the complexity of plant origins and significant variations in chemical profiles, the characterization of the profile of the major bioactive constituents and its association with pharmacological activity are important for the quality control of Beimu herbs from different origins.

AIM OF THE STUDY

This study aims to investigate the distribution of major bioactive isosteroidal alkaloids in Beimu herbs of different origins and its correlation with the tracheobronchial relaxant activity.

METHODS

Quantification of 7 main bioactive 5α-cevanine isosteroidal alkaloids, including ebeiedine, ebeiedinone, hupehenine, isoverticine, verticine, verticinone and imperialine, in 23 Fritillaria species was performed using gas chromatography. The relaxant effect of different extracts of 4 commonly used Beimu herbs, namely Zhe-Beimu (F. thunbergii Miq.), Chuan-Beimu (F. cirrhosa D. Don), Hubei-Beimu (F. hupehensis Hsiao et K. C. Hsia) and Yi-Beimu (F. pallidiflora Schrenk), was evaluated using rat isolated tracheal and bronchial preparations pre-contracted with carbachol, the well established in vitro antitussive model.

RESULTS

Amongst 23 Fritillaria species detected, significant variations of the types and quantities of 7 major isosteroidal alkaloids were determined, which served as an important indicator for the classification of different Beimu herbs with distinct geographic distributions. Based on the type and quantity of these alkaloids, different origins of Beimu could be clearly clustered into several subgroups by principal component analysis. Furthermore, both crude alkaloid and water extracts of all 4 Beimu herbs showed a dose-dependent tracheobronchial relaxation with different potencies. The total content of alkaloids (weight adjusted based on the activity of individual alkaloids) in Beimu extracts significantly correlated with their tracheobronchial relaxation effects (r² > 0.9, p < 0.001).

CONCLUSIONS

The results demonstrated that the differences in chemical profile of major bioactive isosteroidal alkaloids and pharmacological activity of Beimu could be incorporated into a simple and unified method for quality control and potential prediction of activity of Beimu herbs from different origins.

A non-derivative method for the quantitative analysis of isosteroidal alkaloids from Fritillaria by high performance liquid chromatography combined with charged aerosol detection

A non-derivative method was developed for the qualitative and quantitative analysis of isosteroidal alkaloids from Fritillaria thunbergii. During method development the performance of two universal detectors, the charged aerosol detector (CAD) and evaporative light scattering detector (ELSD), were evaluated. The CAD was found to be 30 to 55 times more sensitive than ELSD enabling the measurement of low levels of reference compound impurities that could not be detected by ELSD. The peak area percent of the reference compound, peimisine, obtained by CAD was 50.10%, but 91.66% by ELSD showing that CAD is suitable to estimate the presence of impurities. The CAD showed good reproducibility with overall intra- and inter-day peak area RSD values of less than 1.8% and 2.7%, respectively and had a linear dynamic range of up to 4 orders of magnitude (0.06-44mg/L) for peimine and peiminine. The optimized method was used for the quantitative analysis of peimine and peiminine from F. thunbergii.

Authentication of Bulbus Fritillariae Cirrhosae by RAPD-derived DNA markers

Bulbus Fritillariae is the most commonly used antitussive herb in China. Eleven species of Fritillaria are recorded as Bulbus Fritillariae in the Chinese Pharmacopoeia. Bulbus Fritillariae Cirrhosae is a group of six Fritillaria species with higher efficiency and lower toxicity derived mainly from wild sources. Because of their higher market price, five other Fritillaria species are often sold deceptively as Bulbus Fritillariae Cirrhosae in the herbal market. To ensure the efficacy and safety of medicinal herbs, the authentication of botanical resources is the first step in quality control. Here, a DNA based identification method was developed to authenticate the commercial sources of Bulbus Fritillariae Cirrhosae. A putative DNA marker (0.65 kb) specific for Bulbus Fritillariae Cirrhosae was identified using the Random Amplified Polymorphic DNA (RAPD) technique. A DNA marker representing a Sequence Characterized Amplified Region (SCAR) was developed from a RAPD amplicon. The SCAR marker was successfully applied to differentiate Bulbus Fritillariae Cirrhosae from different species of Fritillaria. Additionally, the SCAR marker was also useful in identifying the commercial samples of Bulbus Fritillariae Cirrhosae. Our results indicated that the RAPD-SCAR method was rapid, accurate and applicable in identifying Bulbus Fritillariae Cirrhosae at the DNA level.

Novel LC-MS/MS method for analyzing imperialine in rat plasma: development, validation, and application to pharmacokinetics

A sensitive, selective, rapid liquid chromatography-electrospray ionization-tandem mass spectrometric method was developed and validated in rat plasma to quantify imperialine, a major active constituent extracted from Bulbus Fritillariae Cirrhosae. Before analysis, plasma samples were pre-treated using cost-effective protein precipitation in order to extract imperialine and the internal standard, carbamzepine. The two analytes were then separated on a Diamonsil ODS chromatography column using gradient elution with a mobile phase of 0.1% aqueous formic acid and acetonitrile. Mass spectrometry was carried out in multiple reaction monitoring mode using a positive electrospray ionization interface. The calibration curve was linear (r(2)=0.9998) over the concentration range 2-1000ng/mL, while the validated limit of determination (LOD) was 0.5ng/mL. Precision varied from 0.1% to 7.1%, and the accuracy varied within ±2%. The method proved robust to sample freezing and thawing, as well as short- and long-term sample storage. The developed method was successfully applied to the pharmacokinetic study of imperialine in rats. Different amounts of imperialine were administered in single doses orally or through the caudal vena cava, and pharmacokinetic parameters were evaluated. Oral bioavailability with a dose of 1mg/kg was 31.2%; 5mg/kg, 53.6%; and 10mg/kg, 47.4%.

Direct pharmacokinetic analysis of puqietinone by in vivo microdialysis sampling and turbulent-flow chromatography coupled with liquid chromatography-mass spectrometry

Sample pretreatment is a key step in bioanalytical process because of possible interference and matrix effects in mass spectrometry analysis. In this work, a novel strategy towards high speed and sensitivity was developed combining in vivo microdialysis (MD) sampling, turbulent-flow chromatography (TFC), and liquid chromatography-mass spectrometry (LC-MS). The procedures of cleanup, preconcentration, and separation were completed on-line in one step within 10min. During the MD optimization procedure, 1% hydroxypropyl-β-cyclodextrin (HP-β-CD) was used to improve the relative recovery of the analyte. Untreated MD samples were directly injected, and a TFC precolumn was flushed for 1min with aqueous phase of 4mL/min flow rate to desalt and concentrate biosamples. The retained analytes were then back-flushed by a switching valve onto a fast LC column (4.6mm×50mm, 1.8μm) for separation. Another diverter valve was employed to prevent the HP-β-CD that interferes with the ESI process from entering the MS. Puqietinone, a lipophilic alkaloid from Fritillaria puqiensis, was used as a case for validation. Results showed that the limit of quantification for puqietinone was 0.10ng/mL, and good linearity (R(2)=0.9993) was maintained over the range of 1.02-200.02ng/mL. Accuracy and precision were satisfactory within the range of the standard curve. This approach was able to effectively eliminate the influences of matrix effect and carry-over as the injection volume increased up to 20μL. The developed method was successfully applied to pharmacokinetic study of puqietinone after intravenous administration to rat. Results demonstrate the potential of using MD with TFC-LC/MS for in vivo monitoring experiments.

Development of a faradic impedimetric immunosensor for the detection of Salmonella typhimurium in milk

The development of a faradic impedimetric immunosensor for the detection of S. typhimurium in milk is described for first time. Polyclonal anti-Salmonella was cross-linked, in the presence of glutaraldehyde, on gold electrodes modified with a single 11-amino-1-undecanethiol (MUAM) self-assembled monolayer (SAM) or a mixed SAM of MUAM and 6-mercapto-1-hexanol at a constant 1 + 3 proportion, respectively. The mixed SAM was also deposited in the presence of triethylamine, which was used to prevent the formation of interplane hydrogen bonds among amine-terminated thiols. The effect of the different surface modifications on both the sensitivity and the selectivity of the immunosensors was investigated. The alteration of the interfacial features of the electrodes due to different modification or recognition steps, was measured by faradic electrochemical impedance spectroscopy in the presence of a hexacyanoferrate(II)/(III) redox couple. A substantial amplification of the measuring signal was achieved by performing the immunoreaction directly in culture samples. This resulted in immunosensors with great analytical features, as follows: (i) high sensitivity; the response of the immunosensors increases with respect to the detection time as a consequence of the simultaneous proliferation of the viable bacteria cells in the tested samples; (ii) validity; the response of the immunosensors is practically insensitive to the presence of dead cells; (iii) working simplicity; elimination of various centrifugation and washing steps, which are used for the isolation of bacteria cells from the culture. The proposed immunosensors were successfully used for the detection of S. typhimurium in experimentally inoculated milk samples. The effect of different postblocking agents on the performance of the immunosensors in real samples was also examined.

Pyrene excimer signaling molecular beacons for probing nucleic acids

Molecular beacon DNA probes, containing 1-4 pyrene monomers on the 5' end and the quencher DABCYL on the 3' end, were engineered and employed for real-time probing of DNA sequences. In the absence of a target sequence, the multiple-pyrene labeled molecular beacons (MBs) assumed a stem-closed conformation resulting in quenching of the pyrene excimer fluorescence. In the presence of target, the beacons switched to a stem-open conformation, which separated the pyrene label from the quencher molecule and generated an excimer emission signal proportional to the target concentration. Steady-state fluorescence assays resulted in a subnanomolar limit of detection in buffer, whereas time-resolved signaling enabled low-nanomolar target detection in cell-growth media. It was found that the excimer emission intensity could be scaled by increasing the number of pyrene monomers conjugated to the 5' terminal. Each additional pyrene monomer resulted in substantial increases in the excimer emission intensities, quantum yields, and excited-state lifetimes of the hybridized MBs. The long fluorescence lifetime ( approximately 40 ns), large Stokes shift (130 nm), and tunable intensity of the excimer make this multiple-pyrene moiety a useful alternative to traditional fluorophore labeling in nucleic acid probes.

Simultaneous identification of Bulbus Fritillariae cirrhosae using PCR-RFLP analysis

Bulbus Fritillariae (BF) is the most commonly used antitussive herb in China. There are nine species of Fritillaria recorded as the drug BF in the Chinese Pharmacopoeia. Bulbus Fritillariae cirrhosae (BF cirrhosae) is a group that includes four species of BF; these four species come from wild sources with higher efficiency and lower toxicity compared to the other five species of BF. Due to reasons of carelessness and reduced costs, the other five species are often sold as BF cirrhosae. Analysis through appearance, microscopic and chemical techniques has limitations. Identifying botanical resources is a primary step in the standardization of herbal medicine. In the present article, the internal transcribed spacer 1 (ITS1) regions of the nuclear ribosomal DNA (nrDNA) of nine species and one variety of Fritillaria genus have been sequenced. A mutation site in the ITS1 region among BF cirrhosae and other species of BF has been found and can be recognized by the restriction endonuclease SmaI. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis of the nuclear ribosomal ITS1 region was used to differentiate BF cirrhosae from other species of BF and is a successful method in distinguishing the subgroups.

A microfluidic platform using molecular beacon-based temperature calibration for thermal dehybridization of surface-bound DNA

This work presents a simple microfluidic device with an integrated thin-film heater for studies of DNA hybridization kinetics and double-stranded DNA melting temperature measurements. The heating characteristics of the device were evaluated with a novel, noninvasive indirect technique using molecular beacons as temperature probes inside reaction chambers. This is the first microfluidic device in which thermal dehybridization of surface-bound oligonucleotides was performed for measurement of double-stranded DNA melting temperatures with +/- 1 degrees C precision. Surface modification and oligonucleotide immobilization were performed by continuously flowing reagents through the microchannels. The resulting reproducibility of oligonucleotide surface densities, at 9% RSD, was better than for the same modification chemistries on glass slides in unstirred reagent solutions (RSD=20%). Moreover, the surface density of immobilized DNA probe molecules could be varied controllably by changing the concentration of the reagent solution used for immobilization. Thus, excellent control of surface characteristics was made possible, something which is often difficult to achieve with larger devices. Solid-phase hybridization reactions, a fundamental aspect of microarray technologies often taking several hours in conventional systems, were reduced to minutes in this device. It was also possible to determine forward rate constants for hybridization, k. These varied from 820,000 to 72,000 M(-1) s(-1), decreasing as surface densities increased. Surface densities could therefore be optimized to obtain rapid hybridization using such an approach. Taken together, this combined microfluidic/small-volume heating approach represents a powerful tool for surface-based DNA analysis.

Chromatographic analysis of Fritillaria isosteroidal alkaloids, the active ingredients of Beimu, the antitussive traditional Chinese medicinal herb

Bulbus Fritillariae derived from plants of various Fritillaria species is the most commonly used antitussive traditional Chinese medicinal herb and is called Beimu. Herbs derived from similar and/or different species of Fritillaria are also used in Japan and Turkey as traditional or folk medicines. Isosteroidal alkaloids are the main bioactive ingredients in Fritillaria species. As the contents and structure types of these bioactive alkaloids vary in different Fritillaria species, quality control of these active principles in herbal Beimu is very important to ensure its safe and effective clinical use. This review describes the development of chromatographic analyses for the simultaneous qualitative and quantitative determination of the main bioactive Fritillaria isosteroidal alkaloids in herbal and biological samples. The recently developed direct HPLC-evaporative light scattering detection method is the most simple, selective and sensitive assay, and is readily used as a suitable quality control method for the analysis of the active principles of herbal Beimu.

Real-time monitoring of intracellular mRNA hybridization inside single living cells

A molecular beacon, an oligonucleotide probe with inherent signal transduction mechanisms, is an optimal tool for visualizing real-time mRNA hybridization in single living cells. Each molecular beacon (MB) consists of a single-stranded DNA molecule in a stem-loop conformation with a fluorophore linked to the 5' end and a quencher at the 3' end. In this study, we demonstrate real-time monitoring of mRNA-DNA hybridization inside living cells using molecular beacons. A MB specific for beta-actin mRNA has been designed and synthesized. After microinjection into the cytoplasm of single living kangaroo rat kidney cells (PtK2 cells), the MB hybridizes with beta-actin mRNA as shown by fluorescence measurements over time. Hybridization dynamics have been followed. Strict control experiments have been carried out to confirm that the fluorescence signal increase is indeed due to the hybridization of mRNA inside single living cells. Variation in the MB/mRNA hybridization fluorescent signal has been observed for different PtK2 cells, which indicates the amount of mRNA in different cells is different. We have also monitored the beta-1 andrenergic receptor mRNA inside the PtK2 cells. These studies demonstrate the feasibility of using MBs and the ultrasensitivity achieved in our fluorescence imaging system for real-time detection of mRNA hybridization and for the visualization of oligonucleotide/mRNA interactions inside single living cells.