piperidines and virosecurinine

Multidrug resistance (MDR) is a main cause of chemotherapy failure and patient death. This situation usually involves a glycoprotein (P-gp) mediated drug efflux, resulting in a low cellular drug concentration and insensitivity. Here we report the design, synthesis and evaluation of novel (+/-)-securinine bivalents as P-gp inhibitors in vitro and in vivo. MTT assays reflected that bivalent mimetics of securinine particularly the virosecurinine bivalent mimetic 8C showed promissing MDR reversal potential in both P-gp highly expressed cell line HepG2/DOX and MCF-7/ADM. At a 10 μM concentration, 8C can entirely reverse the resistance of HepG2/DOX to doxorubicin (DOX), and is more effective than the positive control verapamil (VRP). Fluorescence, flow cytometry, and DOX efflux assays demonstrated that 8C can facilitate the accumulation and diminish the efflux of intracellular DOX. Molecular docking analysis and western blot assays indicated that 8C accomplished this by competitively inhibiting the activity of P-gp rather than by affecting its expression. Compound 8C was also observed to reverse drug resistance effectively in xenograft models when combined with DOX. This study lays a foundation for the discovery of (+/-)-securinine ramifications as P-gp inhibitors and provides a promising lead compound 8C as a P-gp mediated MDR reversal agent.

Topics: Alkaloids; Animals; Antineoplastic Agents; ATP Binding Cassette Transporter, Subfamily B, Member 1; Azepines; Cell Line, Tumor; Cell Survival; Doxorubicin; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Heterocyclic Compounds, Bridged-Ring; Humans; Lactones; Male; Mice, Inbred BALB C; Mice, Nude; Piperidines; Verapamil

Time-dependant density functional theory-electronic circular dichroism spectra prediction was carried out to study the absolute configuration of phyllanthidine-type derivatives 5 and 6, derived from securinine (1) and its enantiomer virosecurinine (2), respectively. This method demonstrated to be very reliable in this alkaloid series. Thus, 5 and 6 shared the same stereochemistry as their parent precursors, confirming the retentive nature of the oxidation sequence. In addition, this study highlighted the key role of the methylene bridge (BC ring) in the chiroptical activity of these compounds. These results fully clarified the stereochemical relationships between the phyllanthidine and the securinine subgroups.

Topics: Alkaloids; Azepines; Circular Dichroism; Euphorbiaceae; Heterocyclic Compounds, Bridged-Ring; Lactones; Models, Molecular; Molecular Structure; Piperidines; Plant Components, Aerial; Stereoisomerism

Virosecurinine is a major alkaloid of the plant Securinega suffruticosa and has been found to be a potent agent in inducing the differentiation of cancer cells. The present study aimed to investigate the antitumor effects of virosecurinine by inducing the apoptosis of leukemic K562 cells and to examine the underlying mechanisms. K562 cells were treated with different concentrations of virosecurinine (6.25, 12.5, 25, 50, 100 and 200 µmol/l) for 24, 48 and 72 h. The cell counting kit (CCK)‑8 method was used to detect the antitumor effect of K562 cells in vitro. Flow cytometry was used to observe the apoptotic ratio and analyze the cell cycle following treatment with virosecurinine in K562 cells. Light and electron microscopy was used to identify morphological alterations in the virosecurinine‑treated K562 cells. The mRNA levels of mammalian target of rapamycin (mTOR), SH2 domain‑containing inositol‑5'‑phosphatase 2 (SHIP2), phosphatase and tensin homologue (PTEN) and breakpoint cluster region (BCR)/Abelson (ABL) were detected pre and post‑virosecurinine treatment using reverse transcription quantitative polymerase chain reaction (RT‑qPCR). The generation depression effects of K562 cells cultured in vitro were detected using CCK‑8 technology, which revealed a dose and time‑dependent association. The IC50 was 32.984 µmol/l at 48 h. Flow cytometric analysis indicated that treatment with virosecurinine at concentrations of 6.25, 25 and 50 µmol/l increased the apoptotic rate of the K562 cells and caused G1/S phase arrest. RT‑qPCR indicated that virosecurinine upregulated the gene expression of PTEN and downregulated the expression of mTOR, SHIP‑2 and BCR/ABL in K562 cells. Virosecurinine inhibited the growth and proliferation of the K562 cell lines and induced apoptosis in K562 cells by affecting the expression of mTOR, SHIP2, BCR/ABL and PTEN.

Topics: Alkaloids; Antineoplastic Agents; Apoptosis; Azepines; Cell Proliferation; Cell Survival; Drug Screening Assays, Antitumor; Fusion Proteins, bcr-abl; Gene Expression; Humans; K562 Cells; Lactones; Leukemia, Myeloid; Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases; Phosphoric Monoester Hydrolases; Piperidines; PTEN Phosphohydrolase; TOR Serine-Threonine Kinases

Virosecurinine, the major alkaloid isolated from Securinega suffruticosa Pall Rehd was found to exhibit growth inhibition and cytotoxicity against huaman colon cancer SW480 cells via the microculture tetrazolium (MTT) assay. Due to its greater cytotoxic potency and selectivity towards SW480 cells, flow cytometry was used to analyze the cell cycle distribution of control and treated SW480 cells whereas Annexin V-FITC/PI flow cytometry analysis was carried out to confirm apoptosis induced by virosecurinine in SW480 cells. Apoptotic regulatory genes were determined by RT-PCR analysis. Virosecurinine was found to induce G1/S cell cycle arrest which led to predominantly apoptotic mode of cell death. Mechanistically, virosecurinine was found to up-regulated the Bax gene expression and down-regulated the Bcl-2 expression in SW480, The ratio of Bcl-2 to Bax was significantly decreased. Hence, we suggest that virosecurinine induced apoptosis in SW480 cells by affecting the expression of bcl-2 and bax.

Topics: Actins; Alkaloids; Antineoplastic Agents, Phytogenic; Apoptosis; Azepines; bcl-2-Associated X Protein; Cell Cycle; Cell Line, Tumor; Cell Survival; Colonic Neoplasms; Coloring Agents; Euphorbiaceae; Gene Expression; Humans; Lactones; Piperidines; Proto-Oncogene Proteins c-bcl-2; Real-Time Polymerase Chain Reaction; Tetrazolium Salts; Thiazoles

A new and versatile synthetic route to Securinega alkaloids is reported. The first synthesis of allosecurinine has been accomplished in seven steps and 40% yield, starting from (+)-menisdaurilide, using a vinylogous Mannich reaction as the key transformation. Similarly, viroallosecurinine has been synthesized from (-)-menisdaurilide.

Topics: Alkaloids; Azepines; Benzofurans; Euphorbiaceae; Heterocyclic Compounds, Bridged-Ring; Lactones; Piperidines; Stereoisomerism

Investigations on callus cultures of Securinega suffruticosa indicated that the cell line of S. suffruticosa callus was able to accumulate four known Securinega alkaloids with dextro rotation but not levo rotation as reported before: virosecurinine (1), viroallosecurinine (2), 14,15-dihydrovirosecurinine (3) and ent-phyllanthidine (4). Time course studies on the growth of callus cultures were carried out. The effects of different plant growth regulators, sucrose concentrations on callus growth and virosecurinine production were also reported.

Topics: Alkaloids; Azepines; Cell Division; Cell Line; Chromatography, High Pressure Liquid; Culture Media; Cytokinins; Euphorbiaceae; Heterocyclic Compounds, 4 or More Rings; Heterocyclic Compounds, Bridged-Ring; Indoleacetic Acids; Lactones; Magnetic Resonance Spectroscopy; Piperidines; Plant Stems; Stereoisomerism

To investigate the chemical constituents of Securinega suffruticosa.. It was isolated and purified by silica gel chromatography. Their structures were elucidated by means of spectral analysis.. Four compounds were isolated and identified as ent-phyllanthidine (1), virosecurinine (2), 14,15-dihydrovirosecurinine (3) and viroallosecurinine (4).. All of four compounds were isolated from S. suffruticosa for the first time and were the enantiomers isolated from this plant before.

Topics: Alkaloids; Azepines; Euphorbiaceae; Heterocyclic Compounds, 4 or More Rings; Lactones; Molecular Structure; Piperidines; Plant Leaves; Plants, Medicinal

Pharmacological activities of virosecurinine (Vse) and securinine (Sec) were studied. The results showed that acute toxicity of Vse was 1/13.6 that of Sec, and Vse had no convulsive effects on rats or frogs, while Sec had. The results also showed that Vse and Sec could elevate blood pressure and excite respiration in cats.

Topics: Alkaloids; Animals; Azepines; Blood Pressure; Cats; Drugs, Chinese Herbal; Heterocyclic Compounds, 4 or More Rings; Heterocyclic Compounds, Bridged-Ring; Lactones; Piperidines; Ranidae; Rats; Respiration

Virosecurinine (1) and viroallosecurinine (2) were isolated as two cytotoxic alkaloids from the leaves of Securinega virosa. A comparison of the cytotoxicity of 1 and several of its derivatives indicates that an alpha,beta- and a gamma,delta-unsaturated lactone located in a strained ring system, such as rings -B, -C, and -D of 1, is structurally required for significant cytotoxicity.

Topics: Alkaloids; Animals; Antineoplastic Agents, Phytogenic; Azepines; Cell Survival; Drug Screening Assays, Antitumor; Lactones; Piperidines; Plants, Medicinal; Structure-Activity Relationship; Tumor Cells, Cultured

Topics: Alkaloids; Azepines; Chemistry Techniques, Analytical; Chemistry, Pharmaceutical; Euphorbiaceae; Heterocyclic Compounds, Bridged-Ring; Lactones; Piperidines; Research; Stereoisomerism