Vincamine alleviates brain injury by attenuating neuroinflammation and oxidative damage in a mouse model of Parkinson's disease through the NF-κB and Nrf2/HO-1 signaling pathways.

Parkinson's disease (PD) is a neurodegenerative disease featured by progressive loss of nigrostriatal dopaminergic neurons, the etiology of which is associated with the existence of neuroinflammatory response and oxidative stress. Vincamine is an indole alkaloid that was reported to exhibit potent anti-inflammatory and antioxidant properties in many central and/or peripheral diseases. Nevertheless, the specific role of vincamine in PD development remains unknown. In our study, dopaminergic neuron loss was determined through immunohistochemistry staining and western blot analysis of tyrosine hydroxylase (TH) expression in the substantia nigra (SN) of PD mice. Reactive oxygen species (ROS) production and malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione (GSH) levels were detected through DHE staining and commercially available kits to assess oxidative stress. Pro-inflammatory cytokine (TNF-α, IL-1ß, and IL-6) levels in the SN were measured via RT-qPCR and western blot analysis. Microglial and astrocyte activation was examined through immunofluorescence staining of Iba-1 (microglia marker) and GFAP (astrocyte marker) in the SN. The regulation of vincamine on the NF-κB and Nrf2/HO-1 pathway was estimated through western blot analysis. Our results showed that vincamine treatment decreased TNF-α, IL-1ß, and IL-6 mRNA and protein levels, reduced GFAP and Iba-1 expression, decreased ROS production and MDA level, and increased SOD activity and GSH level in the SN of PD mice. Mechanically, vincamine repressed the phosphorylation levels of p65, IKKß, and IκBα but enhanced the protein levels of Nrf2 and HO-1 in PD mice. Collectively, vincamine plays a neuroprotective role in PD mouse models by alleviating neuroinflammation and oxidative damage via suppressing the NF-κB pathway and activating the Nrf2/HO-1 pathway.

Vincamine, from an antioxidant and a cerebral vasodilator to its anticancer potential.

Vincamine is a naturally occurring indole alkaloid showing antioxidant activity and has been used clinically for the prevention and treatment of cerebrovascular disorders and insufficiencies. It has been well documented that antioxidants may contribute to cancer treatment, and thus, vincamine has been investigated recently for its potential antitumor activity. Vincamine was found to show cancer cell cytotoxicity and to modulate several important proteins involved in tumor growth, including acetylcholinesterase (AChE), mitogen-activated protein kinase (MAPK), nuclear factor-κB (NF-κB), nuclear factor erythroid 2-related factor 2 (Nrf2), and T-box 3 (TBX3). Several bisindole alkaloids, including vinblastine and vincristine and their synthetic derivatives, vindesine, vinflunine, and vinorelbine, have been used as clinically effective cancer chemotherapeutic agents. In the present review, the discovery and development of vincamine as a useful therapeutic agent and its antioxidant and antitumor activity are summarized, with its antioxidant-related mechanisms of anticancer potential being described. Also, discussed herein are the design of the potential vincamine-based oncolytic agents, which could contribute to the discovery of further new agents for cancer treatment.

Vincamine as an agonist of G-protein-coupled receptor 40 effectively ameliorates diabetic peripheral neuropathy in mice.

Diabetic peripheral neuropathy (DPN) is a common complication of diabetes, which has yet no curable medication. Neuroinflammation and mitochondrial dysfunction are tightly linked to DPN pathology. G-protein-coupled receptor 40 (GPR40) is predominantly expressed in pancreatic ß-cells, but also in spinal dorsal horn and dorsal root ganglion (DRG) neurons, regulating neuropathic pain. We previously have reported that vincamine (Vin), a monoterpenoid indole alkaloid extracted from Madagascar periwinkle, is a GPR40 agonist. In this study, we evaluated the therapeutic potential of Vin in ameliorating the DPN-like pathology in diabetic mice. Both STZ-induced type 1 (T1DM) and db/db type 2 diabetic (T2DM) mice were used to establish late-stage DPN model (DPN mice), which were administered Vin (30 mg·kg-1·d-1, i.p.) for 4 weeks. We showed that Vin administration did not lower blood glucose levels, but significantly ameliorated neurological dysfunctions in DPN mice. Vin administration improved the blood flow velocities and blood perfusion areas of foot pads and sciatic nerve tissues in DPN mice. We demonstrated that Vin administration protected against sciatic nerve myelin sheath injury and ameliorated foot skin intraepidermal nerve fiber (IENF) density impairment in DPN mice. Moreover, Vin suppressed NLRP3 inflammasome activation through either ß-Arrestin2 or ß-Arrestin2/IκBα/NF-κB signaling, improved mitochondrial dysfunction through CaMKKß/AMPK/SIRT1/PGC-1α signaling and alleviated oxidative stress through Nrf2 signaling in the sciatic nerve tissues of DPN mice and LPS/ATP-treated RSC96 cells. All the above-mentioned beneficial effects of Vin were abolished by GPR40-specific knockdown in dorsal root ganglia and sciatic nerve tissues. Together, these results support that pharmacological activation of GPR40 as a promising therapeutic strategy for DPN and highlight the potential of Vin in the treatment of this disease.

Screening potential anaphylactoid components in vinpocetine injection using a high expression Mas-related G-protein-coupled receptor X2 cell membrane chromatography.

Vinpocetine injection is often used in clinical treatment of acute cardiovascular and cerebrovascular diseases. However, it was reported that vinpocetine injection caused allergic reactions in clinical use; therefore, its safety needs urgent attention. Until now, research on its sensitization is rarely reported. Here, the components contained in three vinpocetine injections were examined. It was found that besides vinpocetine, the synthetic raw material vincamine, the excipients benzyl alcohol and ethyl p-toluenesulfonate, and the impurities A, B, C, and D, which are excipients specified in the European Pharmacopoeia, were also present in them. Then the Mas-related G-protein-coupled receptor X2 (MRGPRX2)-HEK293 cell membrane chromatography was used to investigate the affinity of them with MRGPRX2 and found that vinpocetine, vincamine, and impurities A, B, C, and D bind to MRGPRX2. Afterwards, these compounds were further used to investigate the local sensitization ability in vivo. The results showed that vinpocetine, vincamine, and impurity C could induce swelling of the paw and decrease body temperature in mice, but only impurity C could cause local skin mast cell degranulation and serum histamine release increase. In vitro, the results also indicated that impurity C could increase intracellular [Ca2+ ] in MRGPRX2-HEK293 cells, whereas vinpocetine and vincamine did not. Therefore, the impurity C was the potential anaphylactoid component in vinpocetine injection, which may be one of the reasons for the occurrence of allergic reactions in the clinical use of vinpocetine injection. This work provides evidence on the sensitization of impurity C and also contributes to promoting the clinical safety of vinpocetine injection.

Potentiating Biosynthesis of Alkaloids and Polyphenolic Substances in Catharanthus roseus Plant Using ĸ-Carrageenan.

Catharanthus roseus is a medicinal plant that produces indole alkaloids, which are utilized in anticancer therapy. Vinblastine and vincristine, two commercially important antineoplastic alkaloids, are mostly found in the leaves of Catharanthus roseus. ĸ-carrageenan has been proven as plant growth promoting substance for a number of medicinal and agricultural plants. Considering the importance of ĸ-carrageenan as a promoter of plant growth and phytochemical constituents, especially alkaloids production in Catharanthus roseus, an experiment was carried out to explore the effect of ĸ-carrageenan on the plant growth, phytochemicals content, pigments content, and production of antitumor alkaloids in Catharanthus roseus after planting. Foliar application of ĸ-carrageenan (at 0, 400, 600 and 800 ppm) significantly improved the performance of Catharanthus roseus. Phytochemical analysis involved determining the amount of total phenolics (TP), flavonoids (F), free amino acids (FAA), alkaloids (TAC) and pigments contents by spectrophotometer, minerals by ICP, amino acids, phenolic compounds and alkaloids (Vincamine, Catharanthine, Vincracine (Vincristine), and vinblastine) analysis uses HPLC. The results indicated that all examined ĸ-carrageenan treatments led to a significant (p ≤ 0.05) increase in growth parameters compared to the untreated plants. Phytochemical examination indicates that the spray of ĸ-carrageenan at 800 mg L-1 increased the yield of alkaloids (Vincamine, Catharanthine and Vincracine (Vincristine)) by 41.85 µg/g DW, total phenolic compounds by 3948.6 µg gallic/g FW, the content of flavonoids 951.3 µg quercetin /g FW and carotenoids content 32.97 mg/g FW as compared to the control. An amount of 400 ppm ĸ-carrageenan treatment gave the best contents of FAA, Chl a, Chl b and anthocyanin. The element content of K, Ca, Cu, Zn and Se increased by treatments. Amino acids constituents and phenolics compounds contents were altered by ĸ-carrageenan.

Determination of Active Ingredients, Mineral Composition and Antioxidant Properties of Hydroalcoholic Macerates of Vinca minor L. Plant from the Dobrogea Area.

In recent decades, new alternative therapies using drugs containing active ingredients of natural origin have been a hot topic for medical research. Based on the confirmed therapeutic potential of the Vinca minor plant, considered in the specialized literature to be of pharmaceutical interest, the purpose of this study is to determine the chemical and mineral composition of the Vinca minor plant grown in the Dobrogea area, with a view to its use in the formulation of dermal preparations. For this purpose, plant materials were collected from the mentioned area and hydroalcoholic macerates of different concentrations were obtained: 40%, 70% and 96% from leaves (F40, F70, F96) and stems (T40, T70, T96) of Vinca minor plant to determine the optimal extraction solvent. The hydroalcoholic macerates were analyzed via the HPLC method for the identification and quantification of the main bioactive compounds, and two methods were used to evaluate their antioxidant properties: the DPPH radical scavenging test and the photochemiluminescence method. HPLC analysis showed the presence of four indole alkaloids: vincamine, 1,2-dehydroaspidospermidine, vincaminoreine and eburnamonine. Vincamine was the alkaloid found in the highest concentration in Vinca leaves (2.459 ± 0.035 mg/100 g d.w.). The antioxidant activity of Vinca minor hydroalcoholic macerates showed values between 737.626-1123.500 mg GAE/100 g d.w (DPPH test) and 77.439-187.817 mg TE/100 g d.w (photochemiluminescence method). The concentrations of toxic metals Cd, Cu, Ni, Pb in dried leaves and stems of Vinca minor, determined by AAS, were below detection limits.

Vincamine Ameliorates Epithelial-Mesenchymal Transition in Bleomycin-Induced Pulmonary Fibrosis in Rats; Targeting TGF-ß/MAPK/Snai1 Pathway.

Idiopathic pulmonary fibrosis is a progressive, irreversible lung disease that leads to respiratory failure and death. Vincamine is an indole alkaloid obtained from the leaves of Vinca minor and acts as a vasodilator. The present study aims to investigate the protective activity of vincamine against EMT in bleomycin (BLM)-induced pulmonary fibrosis via assessing the apoptotic and TGF-ß1/p38 MAPK/ERK1/2 signaling pathways. In bronchoalveolar lavage fluid, protein content, total cell count, and LDH activity were evaluated. N-cadherin, fibronectin, collagen, SOD, GPX, and MDA levels were determined in lung tissue using ELISA. Bax, p53, bcl2, TWIST, Snai1, and Slug mRNA levels were examined using qRT-PCR. Western blotting was used to assess the expression of TGF-ß1, p38 MAPK, ERK1/2, and cleaved caspase 3 proteins. H & E and Masson's trichrome staining were used to analyze histopathology. In BLM-induced pulmonary fibrosis, vincamine reduced LDH activity, total protein content, and total and differential cell count. SOD and GPX were also increased following vincamine treatment, while MDA levels were decreased. Additionally, vincamine suppressed the expression of p53, Bax, TWIST, Snail, and Slug genes as well as the expression of factors such as TGF-ß1, p/t p38 MAPK, p/t ERK1/2, and cleaved caspase 3 proteins, and, at the same time, vincamine increased bcl2 gene expression. Moreover, vincamine restored fibronectin, N-Catherine, and collagen protein elevation due to BLM-induced lung fibrosis. In addition, the histopathological examination of lung tissues revealed that vincamine attenuated the fibrotic and inflammatory conditions. In conclusion, vincamine suppressed bleomycin-induced EMT by attenuating TGF-ß1/p38 MAPK/ERK1/2/TWIST/Snai1/Slug/fibronectin/N-cadherin pathway. Moreover, it exerted anti-apoptotic activity in bleomycin-induced pulmonary fibrosis.

Evaluation of vincamine against Acetylcholinesterase enzyme.

The current article deals with the in-silico along with enzyme kinetics approach to search for a prominent AChE enzyme inhibitor among the known natural compounds. The computational tools were involved for this purpose and eventual vincamine, a monoterpenoid indole alkaloid, was selected based on several parameters, including free energy of binding (-10.77 kcal/mol) and ADME parameter. Computationally, it confirmed the interaction between vincamine and AChE at an indistinguishable locus from that of substrate AChI (-3.94 kcal/mol) but with much higher binding energy. Interestingly, amino acid residues Gly120, Gly121, Gly122, Glu202, Trp86, Tyr133, Ser203, Phe297, and His447 of AChE were found to be common in these interactions. Further, these findings were approved with wet lab tests where detailed kinetics was studied. It was found that vincamine inhibited AChE with the inhibition constant Ki (239 µM). The value of  IC50 (239 µM) and KM (0.598 mM) was determined and further confirmed by Dixon, Lineweaver- Burk reciprocal, Hanes, and Eadie- Hofstee plots, respectively. The mode of interaction of the compound was found to be competitive for AChE. Thus, the present computational and enzyme kinetics studies conclude that vincamine can be a promising inhibitor of AChE for the effective management of AD.

Vincamine Modulates the Effect of Pantoprazole in Renal Ischemia/Reperfusion Injury by Attenuating MAPK and Apoptosis Signaling Pathways.

Pantoprazole has an antioxidant function against reactive oxygen species (ROS). Vincamine, a herbal candidate, is an indole alkaloid of clinical use against brain sclerosis. The aim of the present experiment is to evaluate, on a molecular level for the first time, the value of vincamine in addition to pantoprazole in treating experimentally induced renal ischemia/reperfusion injury (IRI). One-hundred-and-twenty-eight healthy male Wistar albino rats were included. Serum creatinine, blood urea nitrogen, and malondialdehyde levels were assessed. ELISA was used to estimate the pro-inflammatory cytokines. The expression of Bcl-2 and Bax genes was assessed by quantitative real-time PCR. ERK1/2, JNK1/2, p38, cleaved caspase-3, and NF-κB proteins expressions were estimated using western blot assay. The kidneys were also histopathologically studied. The IRI resulted in impaired cellular functions with increased creatinine, urea nitrogen, malondialdehyde, TNF-α, IL-6, and IL-1ß serum levels, and up-regulated NF-ĸB, JNK1/2, ERK1/2, p38, and cleaved caspase-3 proteins. Furthermore, it down-regulated the expression of the Bcl-2 gene and upregulated the Bax gene. The treatment with vincamine, in addition to pantoprazole multiple doses, significantly alleviated the biochemical and histopathological changes more than pantoprazole or vincamine alone, whether the dose is single or multiple, declaring their synergistic effect. In conclusion, vincamine with pantoprazole multiple doses mitigated the renal IRI through the inhibition of apoptosis, attenuation of the extracellular signaling pathways through proinflammatory cytokines' levels, and suppression of the MAPK (ERK1/2, JNK, p38)-NF-κB intracellular signaling pathway.

Fluorometric quantification of alkaloids in the homeopathic mother tinctures of Vinca minor L. and Fumaria officinalis L.

To assess the toxic potential of the alkaloids, a quantification method is necessary. An ion pair extraction method was used for quantitative fluorometric determination of vincamine, protopine and all contained alkaloids in the mother tinctures of Vinca minor and Fumaria officinalis. The non-fluorescent alkaloids were transformed into an ion pair with sodium-9,10-dimethoxy-anthracene-sulfonate and then fluorometrically determined and quantified in this study. The applicable ion pair was extracted in a suitable organic solvent, where dichloromethane has proven to be beneficial. Conditions for the ion pairing and fluorometric quantification are given. The recovery rate was used to investigate the quality of determinability and the influence of the mother tincture matrix. The method was applied to determine the concentration of protopine in the range 0.1 - 15 µg/ml and of vincamine in the range of 0.5 - 20 µg/ml. The limit of detection was < 0.3 µg/ml, and the limit of quantification < 0.9 µg/ml for both alkaloids.

Analysis of two mixtures containing racetams in their pharmaceuticals using simple spectrophotometric methodologies.

BACKGROUND: Green spectrophotometric methods were developed and validated for determination of some CNS active drugs as antiepileptics and brain stimulants. OBJECTIVE: Piracetam (PIR), Levetiracetam (LEV) and Brivaracetam (BRV) were assayed as a ternary mixture using double divisor-ratio spectra derivative (DDRSD) (method I). One more binary co-formulated mixture of Piracetam (PIR) and Vincamine (VIN) was assayed using difference spectrophotometric procedures (method II). METHOD: I was applied to determine PIR at 302nm in the first derivative of the ratio spectra in the selected spectral region. The content of LEV was determined by measuring the spectra at 215nm in the first derivative of the ratio spectra in the selected spectral region. The concentration of BRV was estimated by measuring the first derivative of the ratio spectra in the chosen spectral region and detecting the signals at 229.7nm. The application of method (II) procedures resulted in measuring the absorbance of PIR at 220nm which is the zero crossing point on the difference spectra of VIN in 0.1M NaOH vs. 0.1M HCl. Similarly, the absorbance of VIN was measured at 245.0nm, which is the zero crossing point on the difference spectra of PIR. RESULTS: The suggested methods were fully validated adopting ICH guidelines. The linearity ranged from 10-100µg/mL for the three racetams and from 2-20 for VIN. The recovery percentages were ranged from 98.72% to 101.8% for method I and from 98.13% to 101.06% for method II. Moreover, the proposed methods were proved environmentally benign using the most recent assessment tool named AGREE. CONCLUSION: Both procedures were successfully applied for the determination of each drug in bulk powder, checked using laboratory prepared mixtures, and directly applied on commercially available pharmaceutical products without interference. The obtained results revealed a good agreement with those obtained by the reported methods.

Vincamine, a safe natural alkaloid, represents a novel anticancer agent.

Vincamine, a well-known plant alkaloid, has been used as a dietary supplement and as a peripheral vasodilator to combat aging in humans. In this study, for the very first time, we demonstrated that vincamine can function as an anticancer agent in a human alveolar basal epithelial cell line A549 (IC50 = 309.7 µM). The anticancer potential of vincamine in A549 cells was assessed by molecular assays to determine cell viability, generation of intracellular ROS, nuclear condensation, caspase-3 activity and inhibition, and change in mitochondrial membrane potential (ΔΨm). In silico studies predicted that the anti-proliferative potential of vincamine is enhanced by its interaction with the apoptotic protein caspase-3, and that this interaction is driven by two hydrogen bonds and has a high free energy of binding (-5.64 kcal/mol) with an estimated association constant (Ka) of 73.67 µM. We found that vincamine stimulated caspase-3-dependent apoptosis and lowered mitochondrial membrane potential, which ultimately led to cytochrome C release. Vincamine was also found to quench hydroxyl free radicals and deplete iron ions in cancer cells. As a dietary supplement, vincamine is almost non-toxic in BEAS-2B and 3T3-L1 cells. Therefore, we propose that vincamine represents a safe anticancer agent in lung cancer cells. Its role in other cancers has yet to be explored.

Improvement of vincamine production of endophytic fungus through inactivated protoplast fusion.

Improvement of the production of vincamine in endophytic fungus VINI-7 was performed by using the inactivated protoplast fusion method. The preparation conditions of protoplasts were optimized by systematic trials with various parameters, and inactivated protoplast fusion was subsequently performed. The mycelium in logarithmic growth phase was treated with 1500 U/mL lywallzyme, 1500 U/mL lysozyme, 2000 U/mL cellulase, and 1000 U/mL snailase solution for 3 h at 30 °C and had the best conditions, in which the concentration of the protoplast was 3.17 × 107 cells/mL. Protoplasts were inactivated by heat, ultraviolet, microwave, sodium nitrite, and diethyl sulfate, respectively. Subsequently, protoplasts inactivated by different methods were subjected to respective protoplast fusion. The results showed that the yield of vincamine in fusants inactivated by mutagens was generally higher than that of fusants inactivated by heat. The highest yield of vincamine in two fusants (U-U1 and N-N1) was 31.6 and 38.7 mg, which increased to 162.24 and 221.16%, respectively, as compared to the parent strain (12.05 mg). LC-MS/MS analysis showed that U-U1 and N-N1 fusants could produce vincamine. Furthermore, the results of genetic stability experiments indicated that U-U1 and N-N1 were genetically stable.

Involvement of Nrf2/HO-1 antioxidant signaling and NF-κB inflammatory response in the potential protective effects of vincamine against methotrexate-induced nephrotoxicity in rats: cross talk between nephrotoxicity and neurotoxicity.

Methotrexate (MTX) is a cytotoxic chemotherapeutic agent widely used in the treatment of cancer and autoimmune diseases like rheumatoid arthritis. However, its use has been limited by its nephrotoxicity. MTX-induced renal injury results in uremia which may influence both the peripheral and central nervous systems causing cognitive and memory problems. The nephroprotective and neuroprotective activities of vincamine (10, 20 and 40 mg/kg), a natural alkaloid with known anti-oxidant, anti-apoptotic and neuroprotective properties, were investigated against MTX-induced toxicity. MTX treatment increased the markers of kidney injury and relative kidney weight, lipid peroxidation, nuclear factor-κB (NF-κB), inflammatory markers, tumor necrosis factor-α, interleukin-1ß, myeloperoxidase and cyclooxygenase-2 and caspase-3 expressions, decreased catalase and superoxide dismutase activities, interleukin-10 and ATP levels and antioxidant proteins, nuclear factor erythroid 2-related factor 2 (Nrf2) and hemeoxygenase-1 (HO-1). Moreover, it disturbed rats' behavior in the locomotor activity test, Y-maze and passive avoidance task. Treatment with vincamine (40 mg/kg) effectively ameliorated MTX-induced renal injury via increasing the expression of Nrf2 and HO-1 suppressing oxidative stress, decreasing the expression of inflammatory markers, NF-κB and caspase-3 pathways and enhancing ATP levels. Additionally, it restored locomotor activity in the locomotor test and memory functions in passive avoidance and Y-maze tests.

Treatment of Vinca minor Leaves with Methyl Jasmonate Extensively Alters the Pattern and Composition of Indole Alkaloids.

Alkaloids extracted from mature Vinca minor leaves were fractionated by preparative HPLC. By means of HRMS and NMR data, the main alkaloids were identified as vincamine, strictamine, 10-hydroxycathofoline, and vincadifformine. Upon treatment with methyl jasmonate (MeJA), the pattern and composition of the indole alkaloids changed extensively. While 10-hydroxycathofoline and strictamine concentrations remained unaltered, vincamine and vincadifformine levels showed a dramatic reduction. Upon MeJA treatment, four other indole alkaloids were detected in high quantities. Three of these alkaloids have been identified as minovincinine, minovincine, and 9-methoxyvincamine. Whereas minovincinine and minovincine are known to occur in trace amounts in V. minor, 9-methoxyvincamine represents a novel natural product. Based on the high similarities of vincamine and 9-methoxyvincamine and their inverse changes in concentrations, it is postulated that vincamine is a precursor of 9-methoxyvincamine. Similarly, vincadifformine seems to be converted first to minovincinine and finally to minovincine. Because MeJA treatment greatly altered the alkaloidal composition of V. minor, it could be used as a potential elicitor of alkaloids that are not produced under normal conditions.

Application of π acceptors to the spectrophotometric and spectrofluorimetric determination of vincamine and naftidrofuryl oxalate in their pharmaceutical preparations.

Three different spectrophotometric and two spectrofluorimetric methods have been developed and validated for the determination of vincamine (VN) and naftidrofuryl oxalate (NF) in tablets. The spectrophotometric methods depend on charge transfer complex formation between each of VN and NF with 7,7,8,8-tetracyano-quinodimethane (TCNQ), 2,6-dichloroquinone-4-chloroimide (DCQ) and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) at 843, 580 and 588 nm, respectively. The spectrofluorimetric methods are based on the formation of charge transfer complex between each of the two drugs and TCNQ, with measurement of the fluorophore formed at 312/375 and 284/612 nm, respectively, or with DDQ at 400/475 and 284/396 nm, respectively. In the spectrophotometric measurements, Beer's law was obeyed at concentration ranges of 1.5-16, 10-180 and 12-140 µg/ml for VN with TCNQ, DCQ, and DDQ, respectively. For NF, the corresponding concentrations were 2-28, 5-75 and 25-150 µg/ml with TCNQ, DCQ, and DDQ, respectively. In the spectrofluorimetric measurements, the ranges for VN were 0.05-0.9 and 0.3-4 µg/ml with TCNQ and DDQ, respectively, whereas for NF the ranges were 0.05-0.85 and 0.5-8 µg/ml with TCNQ and DDQ, respectively. The different experimental parameters affecting the development and stability of the formed color or fluorophore were studied and optimized and the molar ratios of the complexes were calculated. The proposed methods were validated according to ICH guidelines and were successfully applied for the determination of VN and NF in their tablet dosage forms.

Stereoselective synthesis of (-)-desethyleburnamonine, (-)-vindeburnol and (-)-3-epitacamonine: observation of a substrate dependent diastereoselectivity reversal of an aldol reaction.

Starting from (-)-acetoxyglutarimide, the enantioselective multistep synthesis of (-)-desethyleburnamonine, (-)-vindeburnol and (-)-3-epitacamonine has been demonstrated via a common hydroxyl-lactam intermediate with very good overall yields. The acetoxy function from (-)-acetoxyglutarimide was initially used as a handle to induce enantioselectivity and then as a latent source of the ketone carbonyl group. Most importantly, substrate dependent reversal of the diastereoselectivity in ester aldol reactions of hexahydroindolo[2,3-a]quinolizinones has been reported.

Ibogan, Aspidosperman, Vincamine, and Bisindole Alkaloids from a Malayan Tabernaemontana corymbosa: Iboga Alkaloids with C-20α Substitution.

Ten new indole alkaloids (1-10) comprising five ibogan, two aspidosperman, one vincamine, and two bisindole alkaloids, in addition to 32 known alkaloids, were isolated from the stem-bark extract of a Malayan Tabernaemontana corymbosa. The structures of these alkaloids were determined based on analysis of the NMR and MS data and, in five instances (1, 3, 5, 6, 8), confirmed by X-ray diffraction analysis. Two of the iboga alkaloids, conodusines B (2) and C (3), and the iboga-containing bisindole tabernamidine B (10) are notable for the presence of an α-substituted acetyl group at C-20 of the iboga carbon skeleton. The iboga alkaloid (+)-conodusine E (5) had MS and NMR data that were identical to those of (-)-ervatamine I, recently isolated from Ervatamia hainanensis. Establishment of the absolute configuration of (+)-conodusine E (5) was based on analysis of the ECD data, correlation with (-)-heyneanine, and X-ray analysis, which showed that (+)-5 belongs to the same enantiomeric series as exemplified by (-)-coronaridine. The configuration at C-20' of the previously reported Tabernaemontana bisindole alkaloid 19'-oxotabernamine (renamed tabernamidine B) required revision based on the present results. Several of the bisindoles showed pronounced in vitro growth inhibitory activity against drug-sensitive and vincristine-resistant KB cells.

Determination of terpenoid indole alkaloids in hairy roots of Rhazya stricta (Apocynaceae) by GC-MS.

INTRODUCTION: Rhazya stricta Decne. (Apocynaceae) is a medicinal plant rich in terpenoid indole alkaloids (TIAs), some of which possess important pharmacological properties. The study material including transgenic hairy root cultures have been developed and their potential for alkaloid production are being investigated. OBJECTIVE: In this study, a comprehensive GC-MS method for qualitative and quantitative analysis of alkaloids from Rhazya hairy roots was developed. METHODS: The composition of alkaloids was determined by using GC-MS. In quantification, the ratio between alkaloid and internal standard was based on extracted ion from total ion current (TIC) analyses. RESULTS: The developed method was validated. An acceptable precision with RSD ≤ 8% over a linear range of 1 to 100 µg/mL was achieved. The accuracy of the method was within 94-107%. Analysis of hairy root extracts indicated the occurrence of a total of 20 TIAs. Six of them, pleiocarpamine, fluorocarpamine, vincamine, ajmalicine and two yohimbine isomers are reported here for the first time in Rhazya. Trimethylsilyl (TMS) derivatisation of the extracts resulted in the separation of two isomers for yohimbine and also for vallesiachotamine. Clearly improved chromatographic profiles of TMS-derivatives were observed for vincanine and for minor compounds vincamine and rhazine. CONCLUSION: The results show that the present GC-MS method is reliable and well applicable for studying the variation of indole alkaloids in Rhazya samples.

Studies on the interaction between vincamine and human serum albumin: a spectroscopic approach.

The interaction between vincamine (VCM) and human serum albumin (HSA) has been studied using a fluorescence quenching technique in combination with UV/vis absorption spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, circular dichroism (CD) spectroscopy and molecular modeling under conditions similar to human physiological conditions. VCM effectively quenched the intrinsic fluorescence of HSA via static quenching. The binding constants were calculated from the fluorescence data. Thermodynamic analysis by Van't Hoff equation revealed enthalpy change (ΔH) and entropy change (ΔS) were -4.57 kJ/mol and 76.26 J/mol/K, respectively, which indicated that the binding process was spontaneous and the hydrophobic interaction was the predominant force. The distance r between the donor (HSA) and acceptor (VCM) was obtained according to the Förster's theory of non-radiative energy transfer and found to be 4.41 nm. Metal ions, viz., Na(+), K(+), Li(+), Ni(2+), Ca(2+), Zn(2+) and Al(3+) were found to influence binding of the drug to protein. The 3D fluorescence, FT-IR and CD spectral results revealed changes in the secondary structure of the protein upon interaction with VCM. Furthermore, molecular modeling indicated that VCM could bind to the subdomain IIA (site I) of HSA.