Synthesis of (+)-vinblastine and its analogues

A synthetic route to vinblastine and its analogues with an ethynyl group, which features a stereoselective coupling of an 11-membered key intermediate with vindoline, is described. Transformations of the alkynyl moiety including a partial reduction as well as a Sonogashira coupling furnished a variety of analogues.     

Liquid chromatography mass spectrometry simultaneous determination of vindoline and catharanthine in rat plasma and its application to a pharmacokinetic study

Vinblastine and vincristine, both of which are bisindole alkaloids derived from vindoline and catharanthine, have been used for cancer chemotherapy; their monomeric precursor molecules are vindoline and catharanthine. A simple and selective liquid chromatography mass spectrometry method for simultaneous determination of vindoline and catharanthine in rat plasma was developed. Chromatographic separation was achieved on a C₁₈ (2.1 × 50 mm, 3.5 µm) column with acetonitrile–0.1% formic acid in water as mobile phase with gradient elution. The flow rate was set at 0.4 mL/min. An electrospray ionization source was applied and operated in positive ion mode; selective ion monitoring mode was used for quantification. Mean recoveries were in the range of 87.3–92.6% for vindoline in rat plasma and 88.5–96.5% for catharanthine. Matrix effects for vindoline and catharanthine were measured to be between 95.3 and 104.7%. Coefficients of variation of intra‐day and inter‐day precision were both <15%. The accuracy of the method ranged from 93.8 to 108.1%. The method was successfully applied in a pharmacokinetic study of vindoline and catharanthine in rats. The bioavailability of vindoline and catharanthine were 5.4 and 4.7%, respectively. Copyright © 2014 John Wiley & Sons, Ltd.     

Disproof of the Overall Enzymatic Biosynthesis of Vindoline from Tryptamine and Secologanin by Cell-Free Extracts from the Leaves of Catharanthus roseus (L.) G. DON

A cell-free extract, which was isolated from the leaves of mature Catharanthus roseus plants by a previously published procedure, does not convert a mixture of secologanin and radiolabelled tryptamine to vindoline, as was recently claimed. The radioactivity in the purified alkaloid extract determined by earlier workers is certainly due to ‘impurities’ in the presumed ‘vindoline’. This was shown by extensive purification of the alkaloid extract (which contained added unlabelled vindoline as a carrier) followed by chemical conversion of vindoline to two derivatives and subsequent purification, ultimately giving unlabelled deacetylvindoline.     

Synthesis and study of a molecularly imprinted polymer for the specific extraction of indole alkaloids from Catharanthus roseus extracts

Two molecularly imprinted polymers (MIP) for catharanthine and vindoline have been synthesized in order to specifically extract these natural indole alkaloids from Catharanthus roseus by solid-phase extraction (SPE). Each MIP was prepared by thermal polymerisation using catharanthine (or vindoline) as template, methacrylic acid (or itaconic acid) as functional monomer, ethylene glycol dimethacrylate (EDMA) as cross-linking agent and acetonitrile (or acetone) as porogenic solvent.For catharanthine-MIP, a SPE protocol (ACN–AcOH 99/1 washing and MeOH–AcOH 90/10 elution) allows a good MIP/NIP selectivity (imprinting factor 12.6). The specificity of catharanthine-MIP versus related bisindole alkaloids was assessed by cross-reactivity study. The catharanthine-MIP specifically retained catharanthine and its N-oxide analogue but displayed a weak cross-reactivity for other Vinca alkaloids (vinorelbine, vincristine, vinblastine, vindoline, vinflunine). It appears that the catharanthine-like unit of these molecules are hardly trapped in catharanthine cavities located in the MIP, probably due to the sterical hindrance of the vindoline moiety. Finally, the MIP-SPE applied to C. roseus extract enabled quantitative recovery of catharanthine (101%) and the total removal of vindoline. Its capacity was determined and was equal to 2.43 μmol g⁻¹.Vindoline is a weaker base than catharanthine, so the vindoline-MIP was achieved with a strong acidic monomer (itaconic acid) to increase vindoline–monomer interactions and a modified washing solvent (ACN–HCOOH 99/1) to reduce non-specific interactions. The influence of the amount of HCOOH (protic modifier) percolated during the washing step upon the elution yield and the imprinting factor for vindoline was investigated. This preliminary optimisation of the washing step, and in particular the number of moles of acid percolated, seems useful to emphasize the use of MIP in conditions of high selectivity or high yield. A compromise was obtained with an imprinting factor equal to 7.6 and an elution recovery of 33%. However MIP-vindoline failed to achieve a specific extraction of vindoline since catharanthine was also extracted probably because of strong non-specific interactions occurring between catharanthine and the sorbent.     

Total synthesis of indole and dihydroindole alkaloids. VIII. Studies on the synthesis of bisindole alkaloids in the vinblastine-vincristine series. The chloroindolenine approach.

Studies on the syntheses of 18′-epi-4′-deoxo-4′-epivinblastine (IX, R = CO₂CH₃; R₁ = H), 18′-decarbomethoxy-18′-epi-4′-deoxo-4′-epivinblastine (IX, R = R₁ = H) and related analogues are described. The synthetic method employs a coupling reaction involving chloroindolenine derivatives of the cleavamine series (for example, III) with vindoline (V) under acidic conditions. The complete structures, including absolute configuration, of the resulting dimers are established by a combination of chemical and spectroscopic techniques, including X-ray analysis.     

Alkaloid Production in Catharanthus roseus Cell Cultures. VII.. Effect of parameter changes and catabolism studies on cell line PRL No. 953

Catharanthus roseus cells suspended in production medium showed the presence of four Aspidosperma-type alkaloids, however, no vindoline. Cells grown in media with the pH adjusted to 7.0 produced 3.3 mg total alkaloids/g dry weight. At pH 5.0, 1.7 mg of alkaloid/g dry weight was produced. (S)-Adenosyl-methionine did not stimulate the production of vindoline. When added to cell suspensions for 21 days, vindoline and catharanthine were degraded to non-alkaloidal substances, not dimerized to bisindole alkaloids.     

Vince alkaloids XXXIV). Preparation of des-Na-methyl-vindoline by microbiological conversion of vindoline, a major alkaloid from Vinca rosea L

The conversion of vindoline (II) using S. albogriseolus led to the isolation of several compounds including des-N_a-methyl vindoline (III) in 8–10% yield.     

Optimization of Tabersonine Methoxylation to Increase Vindoline Precursor Synthesis in Yeast Cell Factories

Plant specialized metabolites are widely used in the pharmaceutical industry, including the monoterpene indole alkaloids (MIAs) vinblastine and vincristine, which both display anticancer activity. Both compounds can be obtained through the chemical condensation of their precursors vindoline and catharanthine extracted from leaves of the Madagascar periwinkle. However, the extensive use of these molecules in chemotherapy increases precursor demand and results in recurrent shortages, explaining why the development of alternative production approaches, such microbial cell factories, is mandatory. In this context, the precursor-directed biosynthesis of vindoline from tabersonine in yeast-expressing heterologous biosynthetic genes is of particular interest but has not reached high production scales to date. To circumvent production bottlenecks, the metabolic flux was channeled towards the MIA of interest by modulating the copy number of the first two genes of the vindoline biosynthetic pathway, namely tabersonine 16-hydroxylase and tabersonine-16-O-methyltransferase. Increasing gene copies resulted in an optimized methoxylation of tabersonine and overcame the competition for tabersonine access with the third enzyme of the pathway, tabersonine 3-oxygenase, which exhibits a high substrate promiscuity. Through this approach, we successfully created a yeast strain that produces the fourth biosynthetic intermediate of vindoline without accumulation of other intermediates or undesired side-products. This optimization will probably pave the way towards the future development of yeast cell factories to produce vindoline at an industrial scale.     

高效液相色谱法同时测定长春花中的文多灵、长春质碱和脱水长春碱

运用高效液相色谱（HPLC）梯度洗脱同时测定了长春花中的文多灵、长春质碱和脱水长春碱等3种生物碱。色谱柱为Waters 5C18-MS-Ⅱ(4.6 mm×250 mm),流动相为甲醇-1%二乙胺(磷酸调pH至7.3)系统,梯度洗脱,检测波长220 nm,柱温25 ℃。实验结果表明,文多灵、长春质碱和脱水长春碱等3种生物碱分别在0.03～1 mg/mL,0.03～1 mg/mL和0.01～0.5 mg/mL时线性关系良好,平均加样回收率分别为96.8%,97.0%和96.4%,相对标准偏差(RSD)分别为1.53%,1.37%和1.96%。用该法同时检测了不同干旱条件处理下长春花样品中的文多灵、长春质碱和脱水长春碱,方法准确、快速、简便。     

In Vitro Antidiabetic and Antioxidant Effects of Different Extracts of Catharanthus roseus and Its Indole Alkaloid,Vindoline

The Catharanthus roseus plant has been used traditionally to treat diabetes mellitus. Scientific evidence supporting the antidiabetic effects of this plant’s active ingredient-vindoline has not been fully evaluated. In this study, extracts of C. roseus and vindoline were tested for antioxidant activities, alpha amylase and alpha glucosidase inhibitory activities and insulin secretory effects in pancreatic RIN-5F cell line cultured in the absence of glucose, at low and high glucose concentrations. The methanolic extract of the plant showed the highest antioxidant activities in addition to the high total polyphenolic content (p < 0.05). The HPLC results exhibited increased concentration of vindoline in the dichloromethane and the ethylacetate extracts. Vindoline showed noticeable antioxidant activity when compared to ascorbic acid at p < 0.05 and significantly improved the in vitro insulin secretion. The intracellular reactive oxygen species formation in glucotoxicity-induced cells was significantly reduced following treatment with vindoline, methanolic and the dichloromethane extracts when compared to the high glucose untreated control (p < 0.05). Plant extracts and vindoline showed weaker inhibitory effects on the activities of carbohydrate metabolizing enzymes when compared to acarbose, which inhibited the activities of the enzymes by 80%. The plant extracts also exhibited weak alpha amylase and alpha glucosidase inhibitory effects.     

Isolation of indole alkaloids from Catharanthus roseus by centrifugal partition chromatography in the pH-zone refining mode.

Centrifugal partition chromatography (CPC) in the pH-zone refining mode allowed a preparative and efficient isolation of vindoline, vindolinine, catharanthine and vincaleukoblastine from a crude mixture of Catharanthus roseus alkaloids. The separation protocol was tested with a synthetic mixture of vindoline, catharanthine and vincaleukoblastine. The fraction content was analyzed and the results compared with theoretical chromatograms obtained by numerical simulation. The increase in injected sample mass results in an improvement of the purity of the isolated compounds. This observation, confirmed by theory, is of prime importance for the development of preparative pH-zone refining CPC as a preparative separation method.     

Laccase-catalyzed coupling of catharanthine and vindoline: an efficient approach to the bisindole alkaloid anhydrovinblastine

The efficient enzyme-catalyzed coupling of the indolic alkaloids catharanthine and vindoline was carried out by exploiting the oxidoreductases laccases and atmospheric oxygen. Following NaBH₄ reduction of the eniminium cationic intermediate, the synthetically useful dimer anhydrovinblastine (AVBL) was isolated and characterized. Several reaction parameters were investigated in detail and, under the optimized reaction conditions, AVBL was isolated in 56% yield. The practicability of this bioconversion was further confirmed through the condensation of catharanthine with the vindoline analogue 11-methoxy-dihydrotabersonine.     

Voltammetric oxidation of vinblastine and related compounds

The indole alkaloids, vinblastine, catharanthine, and vindoline, gave oxidation waves in mixed aqueous/organic media by cyclic, normal-pulse, and differential-pulse voltammetry (d.p.v). Of the systems investigated, d.p.v. at carbon paste anodes in pH 5.6 acetate buffer in ethanol/water (1:1) is recommended for general analytical work; calibration graphs were linear up to about 1 mM, with limits of detection of 4, 20, and 1.5 μM for vinblastine, catharanthine, and vindoline, respectively. Results obtained by cyclic voltammetry as well as by pulse techniques suggest that electron transfer is preceded by deprotonation and followed by additional chemical reactions. Products of the electrode processes form mechanically unstable films on the electrode surface.     

Inhibition of gastric H+, K(+)-ATPase activity by compounds from medicinal plants

H+, K(+)-ATPase enzyme is a therapeutic target for the treatment of gastric disturbances. Several medicinal plants and isolated compounds inhibit the acid gastric secretion through interaction with the proton pump. In order to add new properties to some natural constituents, five compounds, a benzylated derivative of vincoside, a diterpene (abietic acid) and three alkaloids (cephaeline, vinblastine and vindoline), were tested for their activities on gastric H+, K(+)-ATPase isolated from rabbit stomach. All the compounds inhibited H+, K(+)-ATPase activity with varied potency. The IC50 value for benzylvincoside was 121 (50-293) microM, and for abietic acid 177 (148-211) microM. The alkaloids cephaeline, vinblastine and vindoline inhibited the H+, K(+)-ATPase activity with IC50 values of 194, 761 and 846 microM, respectively. The results suggest that benzylvincoside, abietic acid and cephaeline can be important sources for the development of anti-secretor agents.     

Screening of Catharanthus roseus secondary metabolites by high-performance liquid chromatography

Two direct HPLC analytical methods for the screening of the major indole alkaloids of Catharanthus roseus hairy roots and their iridoid precursors have been developed. Photodiode array and fluorescence detection were performed. The separation was achieved on a reversed-phase C18 column. The first method allowed the separation of catharanthine, serpentine, tabersonine, vindoline, vinblastine, and vincristine in 20 min. Ajmalicine, tryptophan, tryptamine and secologanine were separated using the second method in 13 min. The identification of the compounds was based on the retention time and the comparison of UV spectra with those of authentic standards. A simplified alkaloid extraction method was developed in order to accelerate sample preparation. The assays were successfully used to quantify major compounds of the secondary metabolism of hairy root cultures of C. roseus, thus providing a reliable tool for rapid screening of C. roseus secondary metabolite samples. In these cultures, ajmalicine, serpentine, catharanthine, tabersonine, and tryptamine were detected, but tryptophan, vindoline, vinblastine and vincristine were not.     

Simultaneous determination of vinblastine and its monomeric precursors vindoline and catharanthine in Catharanthus roseus by capillary electrophoresis-mass spectrometry

Catharanthus roseus is an important dicotyledonous medicinal plant that contains various anticancer components, such as vinblastine (VLB) and its monomeric precursors (vindoline and catharanthine). A capillary electrophoresis-mass spectrometry (CE-MS) approach for the simultaneous determination of three components was developed in this work. Baseline separation for three components was achieved by using a running buffer consisting of 20 mM ammonium acetate and 1.5% acetic acid in <20 min. Quantification of three components was assigned in positive-ion mode at a protonated molecular ion [M+H](+). The CE-MS method was validated for linearity, sensitivity, accuracy and precision, and then used to determine the content of the above components. The detection limits of VLB, catharanthine and vindoline are 0.8, 0.1 and 0.1 μg/mL, respectively. The precision was not more than 4.54% and the mean recovery of the analytes was 95.04-97.04%. The CE-MS method was successfully applied to determine VLB and its monomeric precursors in real sample C. roseus.     

Biosynthesis of the Indole Alkaloids. Cell-free Systems from Catharanthus roseus Plants

Cell-free systems from Catharanthus roseus plants are utilized for various studies relating to the biosynthesis of indole alkaloids. Tryptamine ( 5 ) and secologanin ( 6 ), two fundamental building units, are shown to be incorporated into the alkaloid vindoline ( 7 ). In another study, catharanthine ( 18 ) and vindoline ( 7 ) are utilized by this enzyme system and coupled to the important bisindole biointermediate 3′,4′-anhydrovinblastine

1 The previously [20] used name for 17 , 3′, 4′-dehydrovinblastine, is incorrect.

( 17 ). The latter substance is, in turn, incorporated and converted to the natural alkaloids leurosine ( 8 ), Catharine ( 9 ) and vinblastine ( 10 ), thereby providing information about the biosynthesis of these complex molecules. High pressure liquid chromatography assay of the enzymic mixture sheds light on the enzymes involved in the coupling of 18 and 7 .     

A mainly NMR-based structure elucidation of a surprising vindoline trimer with the aid of non-uniform sampled 1H-13C HSQC and HMBC spectra

Structural Chemistry - Two unexpected and unusual vindoline trimers, a ketone and a methyl ether cation, were isolated from a reaction aimed at producing new, synthetically modified vinca...     

An approach to vindoline skeleton utilizing substituted methylenetetrahydrofolate (5,10-CHR-THF) models

Starting from a substituted methylenetetrahydrofolate model [4-(2-N(1)-tosyl-N(3)-methyl-4,4-dimethylimidazolidyl)-3-ketobutanoate], an efficient synthesis of the pentacyclic system corresponding to vindoline is described.