Repurposing bioactive aporphine alkaloids as efflux pump inhibitors.

Extrusion of drugs or drug-like compounds through bacterial efflux pumps is a serious health issue that leads to loss in drug efficacy. Combinatorial therapies of low-efficacy drugs with efflux pump inhibitors may help to restore the activities of such drugs. In this quest, natural products are attractive molecules, since in addition to their wide range of bioactivities they may inhibit efflux pumps. The current work repurposed the bioactive alkaloid roemerine as a potential efflux pump inhibitor. In Bacillus subtilis, both Bmr and BmrA, belonging to the major facilitator and the ATP-binding cassette superfamilies, respectively, were found to be inhibited by roemerine. Scanning electron microscopy and RNA-Seq analyses showed that it potentiated the effect of berberine. Growth rates and checkerboard assays confirmed the synergy of roemerine and berberine and that roemerine prevented berberine efflux by inhibiting Bmr. Transport assays with inverted membrane vesicles prepared from Escherichia coli overexpressing BmrA showed that increasing roemerine concentration decreased the transport of doxorubicin, the BmrA substrate, confirming that roemerine may also be considered as an inhibitor of BmrA. Thus, these findings suggest that conjugation of roemerine to substrates of efflux pumps, Bmr and BmrA, may help to potentiate the activity of their drug substrates.

Research progress on chemical constituents and lipid-lowering mechanism of alkaloids in Nelumbinis Folium / 中草药

Nelumbinis Folium is a Chinese herbal medicine with the effect of regulating lipid and losing weight recorded in “Compendium of Materia Medica”. The alkaloids extracted from lotus leaves have bacteriostatic, lipid-lowering, antispasmodic and other biological activities. In recent years, much attention has been paid to the health problems caused by obesity, so the effect of alkaloids in Nelumbinis Folium on lowering fat and losing weight has become a research hotspot. The chemical constituents, lipid-lowering mechanisms and application in medicine of alkaloids in Nelumbinis Folium were reviewed, which provides a theoretical reference for the development of slimming products and lipid-lowering mechanism of alkaloids in Nelumbinis Folium.

An LC-ESI-MS/MS method for the simultaneous determination of pronuciferine and roemerine in some Papaver species.

Papaver species, well known for their alkaloids, have been used for the treatment of several diseases, such as inflammation, diarrhea, depression, and sleep disorders in certain parts of Anatolia. In this study, four Papaver species (P. lacerum, P. syriacum, P. glaucum and P. rhoeas) were collected from different localities of Turkey. Methanolic extracts were prepared from the aerial parts of the plants. A rapid analytical method was developed for the simultaneously quantitative analysis of two alkaloids, pronuciferine and roemerine, using liquid chromatography tandem mass spectrometry. Multiple reaction monitoring in the positive ionization mode was used for detection. Pronuciferine and roemerine were analyzed on a C18 column (2.1 × 50 mm, 3 µm) with the mobile phase run in the gradient mode with 0.1% formic acid in water (A) and 0.1% formic acid in acetonitrile at a flow rate of 0.3 mL/min. The transitions 312.1→283.1 m/z and 280.0→249.0 m/z were used to monitor pronuciferine and roemerine, respectively. The assay was linear in the concentration range of 0.01 µg/mL to 1 µg/mL (r = 0.996 for roemerine, r = 0.998 for pronuciferine). The validation studies revealed that the method was linear, sensitive, accurate, precise, selective, repeatable, robust, and rugged. Finally, the developed method was applied to quantify pronuciferine and roemerine in the selected species. The amounts of pronuciferine and roemerine were respectively found as 8.5 to 48 µg/g and 4.4 to 43,000 µg/g.

An OMIC approach to elaborate the antibacterial mechanisms of different alkaloids.

Plant-derived substances have regained interest in the fight against antibiotic resistance owing to their distinct antimicrobial mechanisms and multi-target properties. With the recent advances in instrumentation and analysis techniques, OMIC approaches are extensively used for target identification and elucidation of the mechanism of phytochemicals in drug discovery. In the current study, RNA sequencing based transcriptional profiling together with global differential protein expression analysis was used to comparatively elaborate the activities and the effects of the plant alkaloids boldine, bulbocapnine, and roemerine along with the well-known antimicrobial alkaloid berberine in Bacillus subtilis cells. The transcriptomic findings were validated by qPCR. Images from scanning electron microscope were obtained to visualize the effects on the whole-cells. The results showed that among the three selected alkaloids, only roemerine possessed antibacterial activity. Unlike berberine, which is susceptible to efflux through multidrug resistance pumps, roemerine accumulated in the cells. This in turn resulted in oxidative stress and building up of reactive oxygen species, which eventually deregulated various pathways such as iron uptake. Treatment with boldine or bulbocapnine slightly affected various metabolic pathways but has not changed the growth patterns at all.

Transcriptomic analysis displays the effect of (-)-roemerine on the motility and nutrient uptake in Escherichia coli.

Among the different families of plant alkaloids, (-)-roemerine, an aporphine type, was recently shown to possess significant antibacterial activity in Escherichia coli. Based on the increasing demand for antibacterials with novel mechanisms of action, the present work investigates the potential of the plant-derived alkaloid (-)-roemerine as an antibacterial in E. coli cells using microarray technology. Analysis of the genome-wide transcriptional reprogramming in cells after 60 min treatment with 100 µg/mL (-)-roemerine showed significant changes in the expression of 241 genes (p value <0.05 and fold change >2). Expression of selected genes was confirmed by qPCR. Differentially expressed genes were classified into functional categories to map biological processes and molecular pathways involved. Cellular activities with roles in carbohydrate transport and metabolism, energy production and conversion, lipid transport and metabolism, amino acid transport and metabolism, two-component signaling systems, and cell motility (in particular, the flagellar organization and motility) were among metabolic processes altered in the presence of (-)-roemerine. The down-regulation of the outer membrane proteins probably led to a decrease in carbohydrate uptake rate, which in turn results in nutrient limitation. Consequently, energy metabolism is slowed down. Interestingly, the majority of the expressional alterations were found in the flagellar system. This suggested reduction in motility and loss in the ability to form biofilms, thus affecting protection of E. coli against host cell defense mechanisms. In summary, our findings suggest that the antimicrobial action of (-)-roemerine in E. coli is linked to disturbances in motility and nutrient uptake.

Chemical profiling of the tuber of Stephania cambodica Gagnep. (Menispermaceae) and analytical control by UHPLC-DAD.

A new aporphine glycoside (1), named 'angkorwatine', and eight known alkaloids: oblongine (2), stepharine (3), asimilobine-ß-d-glucopyranoside (4), isocorydine (5), tetrahydropalmatine (THP) (6), jatrorrhizine (7), palmatine (PAL) (8), and roemerine (ROE) (9) were simultaneously isolated from the tuber of Stephania cambodica. The development and validation of UHPLC-DAD method was carried out for the quantification of marker compounds (PAL, ROE, THP) of S. cambodica. In addition to good selectivity and linearity (r2 > 0.997), trueness, precision, and accuracy of the method did not exceed the acceptance limit of ±10% for ROE, THP and ±20% for PAL. Consequently, this method is able to provide accurate results between 1.39-4.18 µg/mL, 2.01-30.72 µg/mL, and 4.29-64.42 µg/mL for PAL, ROE, and THP, respectively. This study shows that the validated UHPLC method is a rapid, innovative and effective analytical approach to control quality of tubers of S. cambodica and to regulate the usage of this plant in traditional medicine.

Anti-prostate cancer effect of roemerine: An experimental study / 中华男科学杂志

Objective@#To investigate the anti-prostate cancer (PCa) effect of roemerine in vitro and in vivo in the mouse model of PCa.@*METHODS@#We detected the effects of roemerine on the proliferation, apoptosis and migration of PCa cells DU145, LNCaP, PC-3 and 22RV1, screened out the sensitive cell line and constructed a tumor-bearing model in mice for verification of the antitumor efficacy of roemerine in vivo.@*RESULTS@#Roemerine inhibited the proliferation and migration of the DU145, LNCaP, PC-3 and 22RV1 cells and induced their apoptosis in different degrees, particularly those of the LNCaP cells. The average tumor weight was less in the roemerine intervention group (［1.99±0.95］ g) than in the control (［2.95±1.04］ g), the least in the high-dose roemerine (30 mg/kg) plus paclitaxel intervention group (［0.90±0.16］ g). The mean heart, liver, and kidney indexes were markedly lower in the roemerine (0.58±0.06, 6.20±0.42 and 1.49±0.33) than in the paclitaxel group (0.66±0.04, 6.99±0.72 and 1.95±0.34), while the mean spleen and thymus indexes were remarkably higher in the former (0.54±0.11 and 0.06±0.01) than in the latter (0.41±0.09 and 0.05±0.01). Pathological staining showed a lower degree of malignancy and metastasis in both the roemerine and the roemerine + paclitaxel intervention group than in the control, as well as a lower degree of visceral injury in the roemerine and roemerine + paclitaxel groups than in the paclitaxel group.@*CONCLUSIONS@#Roemerine has some anti-PCa effect and alleviates adverse reactions in paclitaxel combination administration.

[Anti-prostate cancer effect of roemerine: An experimental study].

OBJECTIVE: To investigate the anti-prostate cancer (PCa) effect of roemerine in vitro and in vivo in the mouse model of PCa. METHODS: We detected the effects of roemerine on the proliferation, apoptosis and migration of PCa cells DU145, LNCaP, PC-3 and 22RV1, screened out the sensitive cell line and constructed a tumor-bearing model in mice for verification of the antitumor efficacy of roemerine in vivo. RESULTS: Roemerine inhibited the proliferation and migration of the DU145, LNCaP, PC-3 and 22RV1 cells and induced their apoptosis in different degrees, particularly those of the LNCaP cells. The average tumor weight was less in the roemerine intervention group (ï¼»1.99±0.95ï¼½ g) than in the control (ï¼»2.95±1.04ï¼½ g), the least in the high-dose roemerine (30 mg/kg) plus paclitaxel intervention group (ï¼»0.90±0.16ï¼½ g). The mean heart, liver, and kidney indexes were markedly lower in the roemerine (0.58±0.06, 6.20±0.42 and 1.49±0.33) than in the paclitaxel group (0.66±0.04, 6.99±0.72 and 1.95±0.34), while the mean spleen and thymus indexes were remarkably higher in the former (0.54±0.11 and 0.06±0.01) than in the latter (0.41±0.09 and 0.05±0.01). Pathological staining showed a lower degree of malignancy and metastasis in both the roemerine and the roemerine + paclitaxel intervention group than in the control, as well as a lower degree of visceral injury in the roemerine and roemerine + paclitaxel groups than in the paclitaxel group. CONCLUSIONS: Roemerine has some anti-PCa effect and alleviates adverse reactions in paclitaxel combination administration.

Potent Activities of Roemerine against Candida albicans and the Underlying Mechanisms.

Roemerine (RM) is an aporphine alkaloid isolated from the fresh rattan stem of Fibraurea recisa, and it has been demonstrated to have certain antifungal activity. This study aimed to investigate the antifungal activity of RM and the underlying mechanisms in Candida albicans (C. albicans). The in vitro antifungal activity of RM was evaluated by a series of experiments, including the XTT reduction assay, confocal laser scanning microscopy assay, scanning electron microscope assay. Results showed that 1 µg/mL RM inhibited biofilm formation significantly (p < 0.01) both in Spider medium and Lee's medium. In addition, RM could inhibit yeast-to-hyphae transition of C. albicans in a dose-dependent manner. The biofilm-specific and hypha-specific genes such as YWP1, SAP5, SAP6, HWP1, ECE1 were up-regulated and EFG1 was down-regulated after 8 µg/mL RM treatment. Furthermore, the toxicity of RM was investigated using C. elegans worms, three cancer cells and one normal cell. The date showed that RM had no significant toxicity. In conclusion, RM could inhibited the formation of C. albicans biofilm in vitro, but it had no fungicidal effect on planktonic C. albicans cells, and the anti-biofilm mechanism may be related to the cAMP pathway.

Plasma pharmacokinetics and tissue distribution study of roemerine in rats by liquid chromatography with tandem mass spectrometry (LC-MS/MS).

In the present study, a new LC-MS/MS method for the determination of roemerine in rat plasma and tissue samples was developed and successfully used to study the pharmacokinetics and tissue distribution of roemerine after oral and intravenous (i.v.) administration in rats. The plasma and tissue samples were processed by liquid-liquid extraction with n-hexane. Isocorydine was used as the internal standard (IS) for sample processing and analysis. The MS/MS detection was carried out by monitoring the transitions of m/z 280→249 and m/z 342→279 for roemerine and the IS, respectively. The calibration curve displayed excellent linearity over the concentration range of 10-2000ng/mL (n=8, r(2)≥0.995), and the lower limit of quantification (LLOQ) was determined to be 10ng/mL. This method was rapid, accurate, highly sensitive, and fully validated. The pharmacokinetic study showed that roemerine was rapidly absorbed and eliminated with a tmax of 0.22±0.08h, t1/2 of 1.59±0.46h, CL of 4.44±0.42L/h/kg, and Vd of 10.16±2.95µg/L following oral administration. Additionally, roemerine showed an excellent oral bioavailability of 84% and a wide tissue distribution with brain penetration. Highest concentrations of roemerine were found in the liver and lung, followed by kidney, spleen, heart, and brain, in that order.

Ethnobotany, phytochemistry and pharmacology of Stephania rotunda Lour.

ETHNOPHARMACOLOGICAL RELEVANCE: Stephania rotunda Lour. (Menispermaceae) is an important traditional medicinal plant that is grown in Southeast Asia. The stems, leaves, and tubers have been used in the Cambodian, Lao, Indian and Vietnamese folk medicine systems for years to treat a wide range of ailments, including asthma, headache, fever, and diarrhoea. AIM OF THE REVIEW: To provide an up-to-date, comprehensive overview and analysis of the ethnobotany, phytochemistry, and pharmacology of Stephania rotunda for its potential benefits in human health, as well as to assess the scientific evidence of traditional use and provide a basis for future research directions. MATERIAL AND METHODS: Peer-reviewed articles on Stephania rotunda were acquired via an electronic search of the major scientific databases (Pubmed, Google Scholar, and ScienceDirect). Data were collected from scientific journals, theses, and books. RESULTS: The traditional uses of Stephania rotunda were recorded in countries throughout Southeast Asia (Cambodia, Vietnam, Laos, and India). Different parts of Stephania rotunda were used in traditional medicine to treat about twenty health disorders. Phytochemical analyses identified forty alkaloids. The roots primarily contain l-tetrahydropalmatine (l-THP), whereas the tubers contain cepharanthine and xylopinine. Furthermore, the chemical composition differs from one region to another and according to the harvest period. The alkaloids exhibited approximately ten different pharmacological activities. The main pharmacological activities of Stephania rotunda alkaloids are antiplasmodial, anticancer, and immunomodulatory effects. Sinomenine, cepharanthine, and l-stepholidine are the most promising components and have been tested in humans. The pharmacokinetic parameters have been studied for seven compounds, including the three most promising compounds. The toxicity has been evaluated for liriodenine, roemerine, cycleanine, l-tetrahydropalmatine, and oxostephanine. CONCLUSION: Stephania rotunda is traditionally used for the treatment of a wide range of ailments. Pharmacological investigations have validated different uses of Stephania rotunda in folk medicine. The present review highlights the three most promising compounds of Stephania rotunda, which could constitute potential leads in various medicinal fields, including malaria and cancer.

Separation and preparation of alkaloids in Nelumbinis Folium by pH-zone-refining counter-current chromatography / 中草药

Objective: A novel method for the separation of alkaloids from Nelumbinis Folium by pH-zone-refining counter-current chromatography (pH-ZRCCC). Methods: The two-phase solvent system composed of MtBE-methanol-water (4:1:5), 10 mmol/L triethylamine (TEA) in organic stationary phase and 5 mmol/L HCl in aqueous mobile phase. The upper phase was used as the stationary phase, while the lower phase was used as the mobile phase. In one-step elution under the conditions of a flow rate of 1.5 mL/min, 800 r/min and the effluent was detected at 254 nm. Results: From 2.18 g of the crude extract, 110 mg N-nornuciferin, 420 mg O-nornuciferin, 310 mg nuciferine, and 190 mg roemerine were obtained and each with a purity of over 98% as determined by HPLC. The structures of the isolated compounds were identified by HPLC, MS, and 1H-NMR. Conclusion: The present pH-ZRCCC method may be applied to the purification of other various alkaloids from natural products.

Constituents of Nelumbo nucifera leaves and their antimalarial and antifungal activity.

From the leaves of Nelumbo nucifera (an aquatic plant), one new compound, 24(R)-ethylcholest-6-ene-5α-ol-3-O-ß-D-glucopyranoside (1), along with 11 known metabolites (2-12), were isolated and identified by spectroscopic methods including 1D- and 2D NMR. Antifungal activity for (R)-roemerine (3) (IC50/MIC = 4.5/10 µg/mL against Candida albicans) and antimalarial activity for (R)-roemerine (3) and N-methylasimilobine (5) (IC50 = 0.2 and 4.8 µg/mL for the D6 clone, respectively, and 0.4 and 4.8 µg/mL for the W2 clone, respectively) was observed. None of the compounds were cytotoxic to Vero cells up to a concentration of 23.8 µg/mL. NMR data for 10-eicosanol (7) and 7,11,15-trimethyl-2-hexadecanone (10) are presented for the first time. An analysis of the structure-activity relationship shows that the substituents in position C-1 and C-2 of aporphine alkaloids are crucial for the antimalarial activity.