Bis-nor-diterpene from Cnidoscolus quercifolius (Euphorbiaceae) induces tubulin depolymerization-mediated apoptosis in BRAF-mutated melanoma cells.

A phytochemical investigation of cytotoxic extract and fractions of Cnidoscolus quercifolius Pohl led to isolation of five terpenoids, including three lupane-type triterpenes (1-3) and two bis-nor-diterpenes (4-5). Compounds 4 (phyllacanthone) and 5 (favelanone) are commonly found in this species and have unique chemical structure. Although their cytotoxic activity against cancer cells has been previously reported, the anticancer potential of these molecules remains poorly explored. In this paper, the antimelanoma potential of phyllacanthone (PHY) was described for the first time. Cell viability assay showed a promising cytotoxic activity (IC50 = 40.9 µM) against chemoresistant human melanoma cells expressing the BRAF oncogenic mutation (A2058 cell line). After 72 h of treatment, PHY inhibited cell migration and induced apoptosis and cell cycle arrest (p < 0.05). Immunofluorescence assay showed that the pro-apoptotic effect of PHY is probably associated with tubulin depolymerization, resulting in cytoskeleton disruption of melanoma cells. Molecular docking investigation confirmed this hypothesis given that satisfactory interaction between PHY and tubulin was observed, particularly at the colchicine binding site. These results suggest PHY from C. quercifolius could be potential leader for the design of new antimelanoma drugs.

In Silico Exploration of Novel Tubulin Inhibitors: A Combination of Docking and Molecular Dynamics Simulations, Pharmacophore Modeling, and Virtual Screening.

Microtubules play a critical role in mitosis and cell division and are regarded as an excellent target for anticancer therapy. Although microtubule-targeting agents have been widely used in the clinical treatment of different human cancers, their clinical application in cancer therapy is limited by both intrinsic and acquired drug resistance and adverse toxicities. In a previous work, we synthesized compound 9IV-c, ((E)-2-(3,4-dimethoxystyryl)-6,7,8-trimethoxy-N-(3,4,5-trimethoxyphenyl)quinoline-4-amine) that showed potent activity against multiple human tumor cell lines, by targeting spindle formation and/or the microtubule network. Accordingly, in this study, to identify potent tubulin inhibitors, at first, molecular docking and molecular dynamics studies of compound 9IV-c were performed into the colchicine binding site of tubulin; then, a pharmacophore model of the 9IV-c-tubulin complex was generated. The pharmacophore model was then validated by Güner-Henry (GH) scoring methods and receiver operating characteristic (ROC) analysis. The IBScreen database was searched by using this pharmacophore model as a screening query. Finally, five retrieved compounds were selected for molecular docking studies. These efforts identified two compounds (b and c) as potent tubulin inhibitors. Investigation of pharmacokinetic properties of these compounds (b and c) and compound 9IV-c displayed that ligand b has better drug characteristics compared to the other two ligands.

Screening the elite chemotypes of Gloriosa superba L. in India for the production of anticancer colchicine: simultaneous microwave-assisted extraction and HPTLC studies.

BACKGROUND: Gloriosa superba L. (Colchicaceae) is a high-value medicinal plant indigenous to Africa and Southeast Asia. Its therapeutic benefits are well-established in traditional medicines including Ayurveda. It is well known for its natural bioactive compound colchicine which exhibits a wide range of pharmacological activities i.e. rheumatism, gout and was also introduced into clinical practices. The increasing demand as well as its illegal harvesting has brought this valuable plant under threatened category. METHODS: The present investigation describes a microwave assisted extraction (MAE) strategy coupled with a densitometric-high performance thin layer chromatographic (HPTLC) methodology for the analysis of colchicine from 32 different populations of G. superba. A Box-Behnken statistical design (3 level factor) has been employed to optimize MAE, in which power of microwave, time of irradiation, aqueous ethanol and pH were used as independent variables whereas colchicine was used as the dependent variables. Chromatography was carried out on Silica gel 60 F254 TLC plates with toluene: methanol, 85:15 (v/v) being used as solvent system. Densitometric measurement was performed at λ=254 nm following post-derivatization (10% methanolic sulphuric acid). RESULTS: Optimal conditions for extraction to obtain the maximum colchicine yield was found to be 7.51 mg g- 1 which was very close to be predicted response 7.48 mg g- 1 by maintaining microwave power (460 W), irradiation time (6.4 min), aqueous ethanol-30, pH -3. Colchicine content ranged between 2.12-7.58 mg g- 1 among 32 G. superba populations in which only three chemotypes viz. GS- 1, GS- 3, and GS- 2 collected from West Bengal and Sikkim, respectively exhibited maximum yield of colchicine. CONCLUSION: Therefore, this newly developed optimized MAE coupled with HPTLC densitometry methodology not only quantifies colchicine in order to identify elite chemotypes of G. superba, but it also encourages in selecting high yielding populations of the plants for industrial use and economic boost for the farmers. This validated, simple and reproducible HPTLC protocol is being used for the first time to estimate colchicine from natural populations of G. superba obtained from 32 different geographical regions of India.

Discovery and engineering of colchicine alkaloid biosynthesis.

Few complete pathways have been established for the biosynthesis of medicinal compounds from plants. Accordingly, many plant-derived therapeutics are isolated directly from medicinal plants or plant cell culture1. A lead example is colchicine, a US Food and Drug Administration (FDA)-approved treatment for inflammatory disorders that is sourced from Colchicum and Gloriosa species2-5. Here we use a combination of transcriptomics, metabolic logic and pathway reconstitution to elucidate a near-complete biosynthetic pathway to colchicine without prior knowledge of biosynthetic genes, a sequenced genome or genetic tools in the native host. We uncovered eight genes from Gloriosa superba for the biosynthesis of N-formyldemecolcine, a colchicine precursor that contains the characteristic tropolone ring and pharmacophore of colchicine6. Notably, we identified a non-canonical cytochrome P450 that catalyses the remarkable ring expansion reaction that is required to produce the distinct carbon scaffold of colchicine. We further used the newly identified genes to engineer a biosynthetic pathway (comprising 16 enzymes in total) to N-formyldemecolcine in Nicotiana benthamiana starting from the amino acids phenylalanine and tyrosine. This study establishes a metabolic route to tropolone-containing colchicine alkaloids and provides insights into the unique chemistry that plants use to generate complex, bioactive metabolites from simple amino acids.

Identification of Essential 2D and 3D Chemical Features for Discovery of the Novel Tubulin Polymerization Inhibitors.

BACKGROUND: Tubulin polymerization inhibitors interfere with microtubule assembly and their functions lead to mitotic arrest, therefore they are attractive target for design and development of novel anticancer compounds. OBJECTIVE: The proposed novel and effective structures following the use of three-dimensionalquantitative structure activity relationship (3D-QSAR) pharmacophore based virtual screening clearly demonstrate the high efficiency of this method in modern drug discovery. METHODS: Combined computational approach was applied to extract the essential 2D and 3D features requirements for higher activity as well as identify new anti-tubulin agents. RESULTS: The best quantitative pharmacophore model, Hypo1, exhibited good correlation of 0.943 (RMSD=1.019) and excellent predictive power in the training set compounds. Generated model AHHHR, was well mapped to colchicine site and three-dimensional spatial arrangement of their features were in good agreement with the vital interactions in the active site. Total prediction accuracy (0.92 for training set and 0.86 for test set), enrichment factor (4.2 for training set and 4.5 for test set) and the area under the ROC curve (0.86 for training set and 0.94 for the test set), the developed model using Extended Class FingerPrints of maximum diameter 4 (ECFP_4) was chosen as the best model. CONCLUSION: Developed computational platform provided a better understanding of requirement features for colchicine site inhibitors and we believe the results of this study might be useful for the rational design and optimization of new inhibitors.

MOF-5(Zn)-Fe2O4 nanocomposite based magnetic solid-phase microextraction followed by HPLC-UV for efficient enrichment of colchicine in root of colchicium extracts and plasma samples.

In present work, facile method is developed for determination of colchicine in human plasma sample, autumn and spring root of colchicium extracts by ultrasound assisted dispersive magnetic solid phase microextraction followed by HPLC-UV method (UAD-MSPME-HPLC-UV). Magnetic (Fe2O4-nanoparticles) metal organic framework-5, (MOF-5(Zn)-Fe2O4NPs) was synthesized by dispersing MOF-5 and Fe(NO3)3.9H2O in ethylene glycol (as capping agent) and NaOH (pH adjustment agent) by hydrothermal method. The prepared sorbent was characterized via XRD and SEM analysis and applied as magnetic solid phase in UAD-MSPME-HPLC-UV method. In this method, colchicine molecules were sorbed on MOF-5(Zn)-Fe2O4NPs sorbent by various mechanisms like ion exchange, hydrogen bonding and electrostatic, á´¨-á´¨, hard-hard and dipole-ion interaction followed by exposing sonication waves as incremental mass transfer agent and then the sorbent was separated from the sample matrix by an external magnetic fields. Subsequently, accumulated colchicine were eluted by small volume of desorption organic solvent. Influence of operational variables such as MOF-5(Zn)-Fe2O4NPs mass, volume of extracting solvent and sonication time on response property (recovery) were studied and optimized by central composite design (CCD) combined with desirability function (DF) approach. Under optimum condition, the method has wide linear calibration rang (0.5-1700ngmL-1) with reasonable detection limit (0.13ngmL-1) and R2=0.9971. Finally, the UAD-MSPME-HPLC-UV method was successfully applied for determination of colchicine autumn and spring root of colchicium extracts and plasma samples.

Comparison of Seeds of Colchicum speciosum and Gloriosa superba in respect to Colchicine and Colchicoside Contents by RP-LC.

In this study, colchicine (CLN) and colchicoside (CLS) contents of the methanolic extracts of the seeds of Colchicum speciosum Steven that were collected from Uzungöl, Trabzon and also the seeds belonging to two different samples of Gloriosa superba Linn. imported from India were compared by using RP-LC (Reversed Phase High Pressure Liquid Chromatography). This proposed method is advantageous in terms of sample preparation and selective separation of the compounds. Also the method was successfully validated in accordance with the International Conference on Harmonization (ICH) guideline acceptance criteria for system suitability, linearity and range, precision, specificity and accuracy. As a conclusion of this analysis, the colchicoside and colchicine contents of G. superba (GSI), G. superba (GSII) and C. speciosum (CS) were found to be 312.9 mg/100 g and 333.1 mg/100 g; 434.0 mg/100 g and 471.1 mg/100 g, and 51.9 mg/100 g and 75.9 mg/100 g, respectively.

Omega 3 fatty acid-enriched nanoemulsion of thiocolchicoside for transdermal delivery: formulation, characterization and absorption studies.

Thiocolchicoside (TCC) is an effective therapeutic agent against the orthopaedic, traumatic and rheumatologic disorders but it suffer from the drawback of poor bioavailability due to extensive first pass metabolism and low permeability via the oral route. The aim of the present study was to evaluate the potential of nanoemulsion (NE) for bioavailability enhancement of TCC through the transdermal route. The NEs were developed using Linseed: sefsol in 1:1 ratio as the oil phase, span 80, Transcutol P and distilled water as surfactant, co-surfactant and aqueous phase. Furthermore, selected formulations were subjected to physical stability and consequently evaluated for in vitro permeation using porcine skin. The optimized formulation had small average globule diameter of 117 nm with polydispersity index of 0.285. The globules were spherical in shape as observed by transmission electron microscopy. The in vitro skin permeation profile of optimized NE was compared with aqueous solution of TCC. Significant increase in permeability parameters were observed in NEs formulation (p < 0.05) as compared to aqueous solution of TCC. The steady-state flux (Jss) and permeability coefficient (Kp) for optimized NE formulation (C1) were found to be 30.63 ± 4.18 µg/cm(2)/h and 15.21 × 10(-3) ± 2.81cm(2)/h, respectively. The results of enhanced permeation through transdermal route suggest that water-in-oil NEs which are compatible with the lipophilic sebum environment of the hair follicle facilitate the transport of TCC, and such transport might be predominantly transfollicular in nature. Overall, these results suggested that water-in-oil NEs are good carriers for transdermal delivery of TCC.

Morphological analysis of ghrelin neurons in the hypothalamus.

Ghrelin, which is mainly produced in the A/X-like cells of the oxyntic glands of the stomach, transduces an appetite-stimulatory signal from peripheral tissues to the central nervous system. Ghrelin is also localized in the hypothalamic arcuate nucleus of rodents. While ghrelin acts on the hypothalamus to promote feeding behavior and energy metabolism, it is important to clarify the neuronal circuits that involve ghrelin so as to elucidate the action of ghrelin in the brain. Immunoelectron microscopy reveals that ghrelin neurons send synaptic outputs to other feeding-regulating neurons (e.g., to neurons containing orexin, proopiomelanocortin, or neuropeptide Y) and receive synaptic inputs from other feeding-regulating neurons (proopiomelanocortin or neuropeptide Y). This chapter describes the immunohistochemical techniques employed to elucidate the neuronal interactions between ghrelin and other kinds of feeding-regulating peptide-containing neurons in the hypothalamus based on evidence at both light microscopic and ultrastructural levels.

High-throughput screening of microtubule-interacting drugs.

Drugs that affect microtubule dynamics are among the most effective anticancer agents in routine clinical use. The standard assay for antimicrotubule agents observes the ability of a particular substance to affect in vitro microtubule assembly. We have modified these procedures so that they can be performed in 96-well plates using a standard fluorescence plate reader. Two different protocols are provided in this chapter. One of these protocols is for ligands that inhibit microtubule polymerization, such as colchicine and related molecules. The second is for ligands that promote in vitro microtubule assembly, such as Taxol.

Skin permeation enhancement potential of Aloe Vera and a proposed mechanism of action based upon size exclusion and pull effect.

The aim of this study was to determine in vitro the potential of Aloe Vera juice as a skin permeation enhancer; a secondary aim was to probe the extent to which Aloe Vera itself permeates the skin. Saturated solutions of caffeine, colchicine, mefenamic acid, oxybutynin, and quinine were prepared at 32 degrees C in Aloe Vera juice and water (control) and used to dose porcine ear skin mounted in Franz diffusion cells with water as receptor phase. Receptor phase samples were taken over a 48 h period and permeants determined by reverse-phase HPLC. For caffeine and mefenamic acid no significant enhancements occurred between Aloe Vera and water as vehicles (p>0.05). However, for colchicine, oxybutynin and quinine the presence of Aloe Vera within the formulation provided enhancements (p < or = 0.05). Enhancement potential was dependent upon the molecular weight of the drug in formulation, with the enhancement effect attributable to as yet unidentified components within the Aloe Vera. Colchicine, with a molecular weight of 399.44, achieved the best enhancement with an enhancement ratio of 10.97. No correlation with lipophilicity was apparent. In a further experiment, where freeze-dried Aloe Vera was reconstituted at 200% residue level, permeation of quinine was 2.8 x that from normal Aloe Vera, providing further evidence for the presence of an enhancing factor within Aloe Vera. Certain, although unidentified, components of Aloe Vera readily permeated skin and the relative amount by which they permeated skin was inversely related to the molecular weight of the drug in solution, thus enhancement ratio. A new mechanistic rationale is proposed whereby larger drug solutes inhibit the permeation of Aloe Vera components, but also are then able to interact more effectively with the enhancing factor and be subject to the pull effect.

[Preparation and characterization of transfersomes of three drugs in vitro].

OBJECTIVE: To investigate the influence of drug properties on the encapsulation effiency (EE) and drug release of transfersomes for a proper transfersome preparation. METHOD: To prepare the transfersomes of colchicines (CLC), vincristine sulfate (VCR) and mitoxantrone hydrochloride (DHAD) with the same materials and methods, and then measure their EE. To find out the relationship between drug properties like solubility, molecular weight and charges, and EE. To performe the drug release experiments of various types of transfersomes in vitro, and compare their differences. RESULT: VCR and DHAD are lipophilic or hydrophilic, owing positive charges and large molecular weight, as a result, their EE are high, while CLC is amphipathic, neutral, and of small molecular weight, its EE is very low. As DHAD can insert into the membrane of transfersome, the drug release of DHAD-T in vitro is much slower than that of VCR-T. CONCLUSION: To prepare transfersomes with high EE, drugs that are lipophilic or hydrophilic, high molecular weight and opposite charges to the membrane should be chosen. Interaction between drugs and membrane will influnce the rate of drug release.

Phytochemical studies and cytotoxicity evaluations of Colchicum tunicatum Feinbr and Colchicum hierosolymitanum Feinbr (Colchicaceae): two native Jordanian meadow saffrons.

As a part of our continuing investigation of Jordanian Colchicum species, the biologically active components of Colchicum hierosolymitanum Feinbr and Colchicum tunicatum Feinbr (Colchicaceae) were pursued. The brine shrimp lethality test (BSLT) was used to direct the fractionation and isolation of active components. Five and four known colchicinoids were isolated and characterized from C. tunicatum and C. hierosolymitanum, respectively. The known colchicinoids, reported for the first time from these two species are: (-)-colchicine (I), 3-demethyl-(-)-colchicine (II), (-)-cornigerine (III), beta-lumicolchicine (IV), and (-)-androbiphenyline (V) from C. tunicatum, and (-)-colchicine (I), 2-demethyl-(-)-colchicine (VI), (-)-cornigerine (III), and beta-lumicolchicine (IV) from C. hierosolymitanum. The chemical structures of the isolated compounds have been elucidated using a series of spectroscopic and spectrometric techniques principally; 1D-NMR (1H and 13C) and low resolution EI-MS and APCIMS. All pure compounds were evaluated for cytotoxicity against three human cancer cell lines; MCF-7 human breast carcinoma, NCI-H460 human large cell lung carcinoma, and SF-268 human astrocytoma. (-)-Colchicine (I) and (-)-cornigerine (III) were found to be the most bioactive of the identified compounds with EC50 values in the range of 0.016-0.097 microM.

Synthesis and hepatic transport of strongly fluorescent cholephilic dipyrrinones.

A new class of highly fluorescent (phi(F) 0.3-0.8) low molecular weight water-soluble cholephilic compounds has been synthesized in two steps from dipyrrinones. The dipyrrinone nitrogens are first bridged by reaction with 1,1'-carbonyldiimidazole to form an N,N'-carbonyldipyrrinone (3H,5H-dipyrrolo[1,2-c:2',1'-f]pyrimidine-3,5-dione) nucleus, and a sulfonic acid group is then introduced at C(8) by reaction with concd H(2)SO(4). The resulting sulfonated N,N'-carbonyl-bridged dipyrrinones ("sulfoglows") are isolated as their sodium salts. When the alkyl substituents of the lactam ring are lengthened from ethyl to decyl, sulfoglows become increasingly lipophilic while maintaining water solubility. Low molecular weight sulfoglows were rapidly excreted intact in both bile and urine after intravenous infusion into rats, but higher molecular weight sulfoglows were excreted more selectively in bile. Hepatobiliary excretion of sulfoglows was partially, but not completely, blocked in mutant rats deficient in the multidrug-resistance associated transport protein Mrp2 (ABCC2). These observations point to the feasibility of developing simple sulfoglows with clinical diagnostic potential that are normally excreted in bile but appear in urine when hepatic elimination is impaired by cholestatic liver disease.

New colchicinoids from a native Jordanian meadow saffron, colchicum brachyphyllum: isolation of the first naturally occurring dextrorotatory colchicinoid.

As part of our continuing investigation of Jordanian Colchicum species, the biologically active components of Colchicum brachyphyllum were pursued. Using bioactivity-directed fractionation, nine colchicinoids were isolated and characterized. One of these has a novel ring system, to which we have ascribed the trivial name (+)-demecolcinone (9), and it represents the first naturally occurring dextrorotatory colchicinoid. Another isolated compound was a new colchicinoid analogue, (-)-2,3-didemethyldemecolcine (8), while the remaining seven known colchicinoids were new to the species: (-)-colchicine (1), (-)-3-demethylcolchicine (2), (-)-cornigerine (3), beta-lumicolchicine (4), (-)-androbiphenyline (5), (-)-demecolcine (6), and (-)-3-demethyldemecolcine (7). The brine shrimp lethality test was used to direct the isolation of these colchicinoids. Moreover, all pure compounds were evaluated for cytotoxicity against a human cancer cell panel, for antimicrobial activity in an array of bacteria and fungi (including yeast), and for their potential to be allosteric modulators of the gamma-aminobutyric acid type A receptor.

Methanethiosulfonate derivatives of rhodamine and verapamil activate human P-glycoprotein at different sites.

The human multidrug resistance P-glycoprotein (P-gp, ABCB1) actively extrudes a broad range of potentially cytotoxic compounds out of the cell. Key steps in understanding the transport process are binding of drug substrates in the transmembrane domains, initiation of ATPase activity, and subsequent drug efflux. We used cysteine-scanning mutagenesis of the transmembrane segment residues and reaction with the thiol-reactive drug substrate analog of rhodamine, methane-thiosulfonate-rhodamine (MTS-rhodamine), to test whether P-gp could be trapped in an activated state with high levels of ATPase activity. The presence of such an activated P-gp could be used to further investigate P-gp-drug substrate interactions. Single cysteine mutants (149) were treated with MTS-rhodamine, and ATPase activities were determined after removal of unreacted MTS-rhodamine. One mutant, F343C(TM6), showed a 5.8-fold increase in activity after reaction with MTS-rhodamine. Pre-treatment of mutant F343C with rhodamine B protected it from activation by MTS-rhodamine, indicating that residue Cys-343 contributes to the rhodamine-binding site. The ATPase activity of MTS-rhodamine-treated mutant F343C, however, was not stimulated further by colchicine or calcein-AM. By contrast, verapamil and Hoechst 33342 stimulated and inhibited, respectively, the ATPase activity of the MTS-rhodamine-treated mutant F343C. These results indicate that the MTS-rhodamine binding site overlaps that of colchicine and calcein-AM but not that of verapamil and Hoechst 33342 within the common drug-binding pocket.

Virtual screening and rational drug design method using structure generation system based on 3D-QSAR and docking.

An efficient virtual and rational drug design method is presented. It combines virtual bioactive compound generation with 3D-QSAR model and docking. Using this method, it is possible to generate a lot of highly diverse molecules and find virtual active lead compounds. The method was validated by the study of a set of anti-tumor drugs. With the constraints of pharmacophore obtained by DISCO implemented in SYBYL 6.8, 97 virtual bioactive compounds were generated, and their anti-tumor activities were predicted by CoMFA. Eight structures with high activity were selected and screened by the 3D-QSAR model. The most active generated structure was further investigated by modifying its structure in order to increase the activity. A comparative docking study with telomeric receptor was carried out, and the results showed that the generated structures could form more stable complexes with receptor than the reference compound selected from experimental data. This investigation showed that the proposed method was a feasible way for rational drug design with high screening efficiency.

Physicochemical compatibility between thiocolchicoside injections (Miotens) and pharmaceutical products frequently used for combined therapy.

Thiocolchicoside (Miotens), a muscle relaxant agent, is frequently administered in association regimen with other drugs, such as anti-inflammatory drugs or vitamins. The aim of this study was to investigate the physicochemical compatibility between thiocolchicoside (Miotens) and other injectable drugs frequently used in association. Physicochemical properties of thiocolchicoside mixtures with different drugs, including colour, clarity, pH and drug content were observed or measured before and after (3 h) mixing at room temperature. Results show that the association of Miotens with different anti-inflammatory drugs and vitamins does not cause, up to 3 h from mixing, any significant variation in the physicochemical parameters mentioned above. In conclusion the results obtained demonstrated the physicochemical compatibility of thiocolchicoside (Miotens) with diverse anti-inflammatory drugs and vitamins.

Evaluation of commercial ginkgo and echinacea dietary supplements for colchicine using liquid chromatography-tandem mass spectrometry.

In response to concerns that commercial dietary supplements containing Ginkgo biloba (ginkgo) and Echinacea purpurea, Echinacea angustifolia, or Echinacea pallida (echinacea) might be contaminated with colchicine, a highly selective and sensitive assay was developed for colchicine that is based on high-performance liquid chromatography-tandem mass spectrometry (LC-MS-MS). The method utilizes reversed-phase HPLC separation of compounds in a methanolic extract of the dietary supplement or botanical sample followed by positive ion electrospray ionization with collision-induced dissociation and multiple reaction monitoring of three characteristic fragmentation pathways of the protonated molecule of colchicine, m/z 400 --> 358, 400 --> 326, and 400 --> 310. The minimal detectable concentration of colchicine using this assay was 10 pg on-column, which is equivalent to 20 ppb colchicine in a 0.5 g ginkgo leaf sample. The method was validated by analyzing 0.5 g samples spiked with colchicine and determining the recovery. A total of 26 commercial ginkgo and echinacea dietary supplements were purchased from pharmacies in Chicago, IL, and analyzed for colchicine. In contrast to a recent report, no colchicine was detected in any of the samples. In addition, authenticated ginkgo leaves were collected, assayed, and found to contain no colchicine, which is consistent with the botanical literature. On the basis of the results obtained using this new LC-MS-MS assay, which is more sensitive and more selective than previously published methods for colchicine, we find no cause for concern regarding colchicine contamination of ginkgo or echinacea dietary supplements.

In vitro permeation screening of a new formulation of thiocolchicoside containing various enhancers.

Thiocolchicoside, a muscle relaxant agent with anti-inflammatory and analgesic actions, also is used topically for the treatment of muscular spasms and for rheumatologic, orthopedic, and traumatologic disorders. In this study, thiocolchicoside was formulated to use as foam to avoid contact with the afflicted area during the spreading phase. To enhance drug penetration, various enhancers were added to the base formulation. The tested enhancers were ethoxyethylendiglycol (Transcutol), highly purified phosphatidylcholine (Lipoid S20), capsaicin, propylene glycol dipelargonate (DPPG), and glycolysed ethoxylated glycerides (Labrafil M1944 CS). The transdermal absorption of the tested formulations containing enhancers, in comparison with base formulation, was evaluated in vitro through rat skin using standard Franz diffusion cells. Base formulation was found to have a higher permeation profile than the simple aqueous and hydroalcoholic solutions of the drug, meaning that the base formulation by itself enhances the drug permeation. Among the tested formulations, only the formulation containing DPPG/ethanol was found to be statistically different, showing an enhancement factor of 3.58. In the same experimental session, Muscoril ointment, the commercially available pharmaceutical product containing the same thiocolchicoside concentration (0.25%), also was tested. The formulation containing DPPG/ethanol showed a 4.86 times increase of permeability constant in comparison with Muscoril ointment. The formulation containing DPPG/ethanol as an enhancer could be a good candidate for a new topical foam, considering its good characteristics of permeability and compliance.