Structural Characterisation of Alkaloids in Leaves and Roots of Stephania kwangsiensis by LC-QTOF-MS

Corydalis tomentella Franch. Exerts anti-inflammatory and analgesic effects by regulating the calcium signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Corydalis tomentella Franch. is a perennial cespitose plant commonly used to treat stomachaches as a folk medicine. The C. tomentella total alkaloids have good protective effects against acute liver injury and potential anti-hepatoma and anti-Alzheimer's disease activities.

AIM OF THE STUDY

To establish an effective purification process for total alkaloids from C. tomentella and investigate the mechanism of their anti-inflammatory effects.

MATERIALS AND METHODS

Corydalis tomentella were purified using macroporous resin. Then the crude and purified C. tomentella extracts (cCTE and pCTE) were qualitatively analyzed using UPLC-Triple-TOF-MS/MS. The cCTE and pCTE were used to investigate and compare their anti-inflammatory effects on lipopolysaccharide (LPS)-induced RAW264.7 cells. Doses at 100, 200 and 400 mg/kg/d of pCTE were used to study their anti-inflammatory and analgesic activities in mice with xylene-induced ear swelling and acetic acid-induced writhing tests. Content of nitric oxide (NO), interleukin-6 (IL-6), interleukin-1β (IL-1β), and tumor necrosis factor-α (TNF-α) were determined both in RAW264.7 cells and mice. Network pharmacology was used to predict the anti-inflammatory mechanism of C. tomentella, and the key enzymes were validated using qPCR and Western Blot analysis. Concentration of intracellular Ca2+ was detected using flow cytometric analysis.

RESULTS

The C. tomentella total alkaloid purity increased from 6.29% to 47.34% under optimal purification conditions. A total of 54 alkaloids were identified from CTE. Both cCTE and pCTE could suppress the LPS-induced production of NO, IL-6, IL-1β, and TNF-α in RAW264.7 cells. The pCTE exhibited a more potent anti-inflammatory effect; it also inhibited pain induced by xylene and acetic acid in mice. The calcium signaling pathway is associated with the anti-inflammatory and analgesic activities of C. tomentella. The mRNA expression of nitric oxide synthase (NOS) 2, NOS3 and calmodulin1 (CALM1) was regulated by C. tomentella through the reduction of inflammation-induced Ca2+ influx, and it also exhibited a more pronounced effect than the positive control (L-NG-nitro arginine methyl ester).

CONCLUSIONS

Purified C. tomentella extract shows anti-inflammatory effect both in vitro and in vivo. It exerts anti-inflammatory and analgesic effects through the calcium signaling pathway by down-regulating NOS2 and CALM1 expression and up-regulating NOS3 expression in LPS-induced RAW264.7 cells, and decreasing intracellular Ca2+ concentration.

Cepharanthine analogs mining and genomes of Stephania accelerate anti-coronavirus drug discovery

Cepharanthine is a secondary metabolite isolated from Stephania. It has been reported that it has anti-conronaviruses activities including severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Here, we assemble three Stephania genomes (S. japonica, S. yunnanensis, and S. cepharantha), propose the cepharanthine biosynthetic pathway, and assess the antiviral potential of compounds involved in the pathway. Among the three genomes, S. japonica has a near telomere-to-telomere assembly with one remaining gap, and S. cepharantha and S. yunnanensis have chromosome-level assemblies. Following by biosynthetic gene mining and metabolomics analysis, we identify seven cepharanthine analogs that have broad-spectrum anti-coronavirus activities, including SARS-CoV-2, Guangxi pangolin-CoV (GX_P2V), swine acute diarrhoea syndrome coronavirus (SADS-CoV), and porcine epidemic diarrhea virus (PEDV). We also show that two other genera, Nelumbo and Thalictrum, can produce cepharanthine analogs, and thus have the potential for antiviral compound discovery. Results generated from this study could accelerate broad-spectrum anti-coronavirus drug discovery.

Chemistry and biology of ent-morphinan alkaloids

Morphinan alkaloids have attracted constant attention since the isolation of morphine by Sertürner in 1805. However, a group of 45 compounds possessing a complete ent-morphinan backbone can also be found in the literature. These compounds are related to the morphinandienone subgroup and display a substitution pattern which is different from the morphinans. In particular, these alkaloids could be substituted at position C-2 and C-8 either by a hydroxy function or a methoxy moiety. Four groups of ent-morphinan alkaloids can be proposed, the salutaridine, pallidine, cephasugine and erromangine series. Interestingly, the botanical distribution of the ent-morphinans is more widespread than for the morphinans and includes the Annonaceae, Berberidaceae, Euphorbiaceae, Fumariaceae, Hernandiaceae, Lauraceae, Menispermaceae, Monimiaceae, Papaveraceae, and Ranunculaceae families. To date, their exact mode of production remains elusive and their interplay with the biosynthetic pathway of other classes of benzyltetrahydroisoquinoline alkaloids, in particular aporphines, should be confirmed. Exploration of the biological and therapeutic potential of these compounds is limited to some areas, namely central nervous system (CNS), inflammation, cancer, malaria and viruses. Further studies should be conducted to identify the cellular/molecular targets in view of promoting these compounds as new scaffolds in medicinal chemistry.

An integrated strategy for characterization of chemical constituents in Stephania tetrandra using LC-QTOF-MS/MS and the target isolation of two new biflavonoids

LC-MS has been a widely used analytical technique for identification of natural compounds. However, sophisticated and laborious data analysis is required to identify chemical components, especially new compounds, from a large LC-MS dataset. The aim of this study is to develop an integrated data-mining strategy that combines molecular networking (MN), in-house polygonal mass defect filtering (MDF), and diagnostic fragment ion filtering (DFIF) to identify phytochemicals in Stephania tetrandra based on LC-MS data. S. tetrandra samples were prepared by matrix solid-phase dispersion extraction methods and then raw MS spectra were acquired using LC-QTOF-MS/MS. MN and in-house polygonal MDF classified the compounds roughly. Modified DFIF were then used in succession to place each spectrum into a specific class. Finally, the exact structures were deduced by fragmentation pathways and related botanical biogenesis, with the help of the narrowed classification from MN and MDF. The total workflow was a combination of data filtering and identification methods for rapid characterization of known compounds (dereplication) and discovery of new compounds. Consequently, 144 compounds were identified or tentatively identified in the aerial parts and roots of S. tetrandra, including 11 potentially new compounds and 63 compounds first identified in this species. Among 144 compounds, 61 were from the aerial parts exclusively, 8 were from the roots exclusively, and 75 were found in both parts. Furthermore, two new biflavonoids were isolated with the guide of LC-MS analysis and structurally elucidated by spectroscopic methods. In conclusion, the proposed data-mining strategy based on LC-MS can be used to profile chemical constituents with high efficiency and guide the isolation of new compounds from medicinal plants. The comparison of the components of the aerial parts and roots of S. tetrandra would be helpful for the rational utilization of the medicinal plant.

A Systematic Method for the Identification of Aporphine Alkaloid Constituents in Sabia schumanniana Diels Using UHPLC-Q-Exactive Orbitrap/Mass Spectrometry

Sabia schumanniana Diels (SSD) is a plant whose stems are used in traditional folk medicine for the treatment of lumbago and arthralgia. Previous studies have revealed chemical constituents of SSD, including triterpenoids and aporphine alkaloids. Aporphine alkaloids contain a variety of active components, which might facilitate the effective treatment of lumbago and arthralgia. However, only 5-oxoaporphine (fuseine) has been discovered in SSD to date. In this study, we sought to systematically identify the aporphine alkaloids in SSD. We established a fast and reliable method for the detection and identification of these aporphine alkaloids based on ultra-high-performance liquid chromatography (UHPLC)-Q-Exactive-Orbitrap/mass spectrometry combined with parallel reaction monitoring (PRM). We separated all of the analyzed samples using a Thermo Scientific Hypersil GOLD™ aQ C18 column (100 mm × 2.1 mm, 1.9 μm). Finally, we identified a total of 70 compounds by using data such as retention times and diagnostic ions. No fewer than 69 of these SSD aporphine alkaloids have been reported here for the first time. These findings may assist in future studies concerning this plant and will ultimately contribute to the research and development of new drugs.

In Vitro and In Silico Evaluation of Cholinesterase Inhibition by Alkaloids Obtained from Branches of Abuta panurensis Eichler

Alkaloids are natural products known as ethnobotanicals that have attracted increasing attention due to a wide range of their pharmacological properties. In this study, cholinesterase inhibitors were obtained from branches of Abuta panurensis Eichler (Menispermaceae), an endemic species from the Amazonian rainforest. Five alkaloids were isolated, and their structure was elucidated by a combination of 1D and 2D 1H and 13C NMR spectroscopy, HPLC-MS, and high-resolution MS: Lindoldhamine isomer m/z 569.2674 (1), stepharine m/z 298.1461 (2), palmatine m/z 352.1616 (3), 5-N-methylmaytenine m/z 420.2669 (4) and the N-trans-feruloyltyramine m/z 314.1404 (5). The compounds 1, 3, and 5 were isolated from A. panurensis for the first time. Interaction of the above-mentioned alkaloids with acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes was investigated in silico by molecular docking and molecular dynamics. The molecules under investigation were able to bind effectively with the active sites of the AChE and BChE enzymes. The compounds 1–4 demonstrated in vitro an inhibitory effect on acetylcholinesterase with IC50 values in the range of 19.55 µM to 61.24 µM. The data obtained in silico corroborate the results of AChE enzyme inhibition.

Identification of alkaloidal compounds from leaves and roots of Stephania succifera by HPLC-QTOF-MS and prediction of potential bioactivity with PharmMapper

INTRODUCTION

The roots of Stephania succifera are used in traditional medicine for the treatment of several diseases. Research on this plant has mainly focused on bioactive alkaloids from the roots, and no previous work on compounds from the abundant leaves has yet been reported.

OBJECTIVE

To identify and compare alkaloidal compounds in S. succifera roots and leaves and to predict the potential bioactivity of some alkaloids.

METHODS

High-performance liquid chromatography with quadrupole time-of-flight tandem mass spectrometry (HPLC-QTOF-MS/MS) was employed to identify alkaloidal compounds from S. succifera. The potential targets and bioactivities of most alkaloids were predicted using the PharmMapper server.

RESULTS

Fifty-six alkaloidal compounds, including protoberberine-, aporphine-, proaporphine-, benzylisoquinoline-, and lactam-type alkaloids, were identified or tentatively identified in S. succifera roots and leaves based on the HPLC-MS data. Forty-one compounds have not been previously reported in S. succifera and eight of them have not been previously reported in the literature. Twenty-four alkaloidal compounds were found in both roots and leaves. Twelve potential targets with different indications were predicted for some alkaloids.

CONCLUSION

Comparison of chemical constituents and their potential bioactivities for S. succifera roots and leaves indicated that diverse bioactive alkaloids were present in the leaves as well as the roots. PharmMapper provided new directions for bioactivity screening. This study will be helpful for further understanding the medicinal components of S. succifera and the rational utilisation of plant resources.

Alkaloids of Abuta panurensis Eichler: In silico and in vitro study of acetylcholinesterase inhibition, cytotoxic and immunomodulatory activities

Natural products obtained from species of the genus Abuta (Menispermaceae) are known as ethnobotanicals that are attracting increasing attention due to a wide range of their pharmacological properties. In this study, the alkaloids stepharine and 5-N-methylmaytenine were first isolated from branches of Abuta panurensis Eichler, an endemic species from the Amazonian rainforest. Structure of the compounds was elucidated by a combination of 1D and 2D NMR spectroscopic and MS and HRMS spectrometric techniques. Interaction of the above-mentioned alkaloids with acetylcholinesterase enzyme and interleukins IL-6 and IL-8 was investigated in silico by molecular docking. The molecules under investigation were able to bind effectively with the active sites of the AChE enzyme, IL-6, and IL-8 showing affinity towards the proteins. Along with the theoretical study, acetylcholinesterase enzyme inhibition, cytotoxic, and immunomodulatory activity of the compounds were assessed by in vitro assays. The data obtained in silico corroborate the results of AChE enzyme inhibition, the IC50 values of 61.24μM for stepharine and 19.55μM for 5-N-methylmaytenine were found. The compounds showed cytotoxic activity against two tumor cell lines (K562 and U937) with IC50 values ranging from 11.77 μM to 28.48 μM. The in vitro assays revealed that both alkaloids were non-toxic to Vero and human PBMC cells. As for the immunomodulatory activity, both compounds inhibited the production of IL-6 at similar levels. Stepharine inhibited considerably the production of IL-8 in comparison to 5-N-methylmaytenine, which showed a dose dependent action (inhibitory at the IC50 dose, and stimulatory at the twofold IC50 one). Such a behavior may possibly be explained by different binding modes of the alkaloids to the interleukin structural fragments. Occurrence of the polyamine alkaloid 5-N-methylmaytenine was reported for the first time for the Menispermaceae family, as well as the presence of stepharine in A. panurensis.

DNA barcodes for the identification of Stephania (Menispermaceae) species

Stephania is a medicinal plants-rich genus of Menispermaceae. However, the identification of morphologically-similar species in Stephania is difficult using the currently reported methods. The indiscriminate overexploitation of Stephania plants has resulted in clinical misuse and endangerment of many species, which necessitates the development of an efficient and reliable method for species authentication. Therefore, six candidate DNA barcode sequences (ITS, ITS2, psbA-trnH, matK, rbcL, and trnL-F) were tested for their capacity to identify Stephania species. The barcodes were analyzed either as a single region or in combination by tree-based [neighbor-joining (NJ) and Bayesian inference (BI)], distance-based (PWG-distance), and sequence similarity-based (TaxonDNA) methods. Amplification and sequencing success rates were 100% for all six candidate barcodes. A comparison of six barcode regions showed that ITS exhibited the highest number of variable and informative sites (182/179), followed by psbA-trnH (173/162). DNA barcoding gap assessment showed that interspecific distances of the six barcodes were greater than intraspecific distances. The identification results showed that species discrimination rates of combination barcodes were higher than those of single-region barcodes. Based on best match and best close match methods, the ITS+psbA-trnH combination exhibited the highest discrimination power (93.93%). Further, all Stephania species could be resolved in the phylogenetic trees based on ITS+psbA-trnH (NJ, BI). This study demonstrates that DNA barcoding is an efficient method to identify Stephania species and recommends that the ITS+psbA-trnH combination is the best DNA barcode for the identification of Stephania species.

Advances in Chemistry and Bioactivity of Magnoflorine and Magnoflorine-Containing Extracts

The review collects together some recent information on the identity and pharmacological properties of magnoflorine, a quaternary aporphine alkaloid, that is widely distributed within the representatives of several botanical families like Berberidaceae, Magnoliaceae, Papaveraceae, or Menispermaceae. Several findings published in the scientific publications mention its application in the treatment of a wide spectrum of diseases including inflammatory ones, allergies, hypertension, osteoporosis, bacterial, viral and fungal infections, and some civilization diseases like cancer, obesity, diabetes, dementia, or depression. The pharmacokinetics and perspectives on its introduction to therapeutic strategies will also be discussed.

Antihypertensive constituents in Sanoshashinto

It has been reported that Sanoshashinto (SanHuangXieXinTang, 三黃瀉心湯), which is composed of Rhei Rhizoma, Scutellariae Radix, and Coptidis Rhizoma, exhibits vasorelaxant effects in vitro and lowers blood pressure of patients. Based on this discovery, in this study, a mixture containing those three materials and combinations of them were extracted with methanol, and the extracts were fractionated into different parts. Effects of all extracts and fractions on high concentration of potassium chloride (High K⁺)- or noradrenaline (NA)-induced contractions of isolated rat aortic rings or helical strips were examined. Qualitative and quantitative HPLC analyses of the extracts and the fractions revealed that the contents of baicalin and berberine in Sanoshashinto methanol extract (SHXXTM) were higher than those of the other constituents. All pharmacological and HPLC data were analyzed by principal component analysis (PCA) software and the results indicated that baicalin, berberine, palmatine, baicalein, and wogonoside contributed significantly to the pharmacological activity. Furthermore, spontaneously hypertensive rats (SHRs) that were orally given SHXXTM or a baicalin–berberine combination showed significantly reduced increase in the rate of systolic blood pressure (SBP) compared to the control group. These findings suggested that Sanoshashinto has significant vasorelaxant effects in vitro and antihypertensive effects in vivo, and baicalin and berberine, which were the principal constituents of Scutellariae Radix and Coptidis Rhizoma, were the main antihypertensive constituents in Sanoshashinto. It was speculated that baicalin and berberine produced vasorelaxant effects by activating the NO/cGMP pathway and that the BK_Ca channel and the DAG/PKC/CPI-17 pathway were also involved.

Differentiation, chemical profiles and quality evaluation of five medicinal Stephania species (Menispermaceae) through integrated DNA barcoding, HPLC-QTOF-MS/MS and UHPLC-DAD

Stephania species is one of the alkaloid-rich genus of the family Menispermaceae. Most plants of the genus Stephania possess medicinal value, whose main components are alkaloids. However, the non-medical species are often mistakenly used as herbs because of the difficulty in identification of the species. A systematic method which involved the combination of DNA barcoding, HPLC-QTOF-MS/MS and UHPLC was established for differentiation, chemical profiles and quality evaluation of medicinal Stephania species. Firstly, twenty batches of Stephania species samples were classified into five Stephania species by DNA barcoding. Secondly, 114 alkaloids including 22 tetrahydroprotoberberines, 13 protoberberines, 27 aporphines, 13 benzylisoquinolines, 12 hasubanans, 3 morphines and 24 other alkaloids were clearly or tentatively identified. Thirdly, thirteen representative components were simultaneously detected by UHPLC-DAD to characterize the differences of chemical compositions among five Stephania species. In conclusion, this method was comprehensive and effective for identification, chemical profiles and quality evaluation of medicinal Stephania species. It will provide a basis for holistic quality evaluation of medicinal Stephania species.

Identification of structurally diverse alkaloids in Talguenea quinquinervia (gill. Et hook) by liquid chromatography/electrospray ionisation tandem mass spectroscopy and insecticidal activity

INTRODUCTION

Talguenea quinquinervia has been used in folk medicine and to dye wool, and the main constituents are alkaloids and triterpenes. Identification of these type of compounds in this specie is a necessary step to understand the biological properties.

OBJECTIVE

To evaluate the relationship between the chemical composition of root from T. quinquinervia and its insecticidal properties using liquid chromatography electrospray ionisation tandem mass spectrometry (LC-ESI-MS/MS).

METHODS

Alkaloids were extracted using Soxhlet extraction with methanol. Total extract was partitioned at pH 2 and 12 to enrich alkaloid constituents and to remove interferences. The separation of alkaloids in the Talguenea extract was performed on a C18 column using gradient elution and their tandem mass spectra were obtained by quadrupole time-of-flight tandem mass spectrometry (QTOF-MS/MS) to perform accurate mass measurements of fragment ions for the alkaloid constituents.

RESULTS

Several types of alkaloids were separated and identified by LC-ESI-MS/MS. The structural assignment of individual alkaloids was performed based on convergence of MS/MS spectral data, pH partitioning behaviour, LC retention behaviour, and accurate mass measurements. The pH partition of the extract provided structural information about unknown alkaloids extracted from T. quinquinervia. A total of 20 compounds were identified and tentatively characterised, and of these 15 alkaloids were reported for the first time in the investigated T. quinquinervia.

CONCLUSION

The chemical profiling of alkaloids in T. quinquinervia with different origins was performed for the first time and provided diagnostic ions for diverse alkaloids in T. quinquinervia. Insecticidal activity observed can be explain by the presence of alkaloid and pentacyclic triterpenes on the fractions assayed.