Continuous Flow Synthesis of Propofol.

Herein, we report a continuous flow process for the synthesis of 2,6-diisopropylphenol-also known as Propofol-a short-acting intravenous anesthesia, widely used in intensive care medicine to provide sedation and hypnosis. The synthesis is based on a two-step procedure: a double Friedel-Crafts alkylation followed by a decarboxylation step, both under continuous flow.

Efficient and flexible synthesis of new photoactivatable propofol analogs.

Propofol is a widely used general anesthetic, which acts by binding to and modulating several neuronal ion channels. We describe the synthesis of photoactivatable propofol analogs functionalized with an alkyne handle for bioorthogonal chemistry. Such tools are useful for detecting and isolating photolabeled proteins. We designed expedient and flexible synthetic routes to three new diazirine-based crosslinkable propofol derivatives, two of which have alkyne handles. As a proof of principle, we show that these compounds activate heterologously expressed Transient Receptor Potential Ankyrin 1 (TRPA1), a key ion channel of the pain pathway, with a similar potency as propofol in fluorescence-based functional assays. This work demonstrates that installation of the crosslinkable and clickable group on a short nonpolar spacer at the para position of propofol does not affect TRPA1 activation, supporting the utility of these chemical tools in identifying and characterizing potentially druggable binding sites in propofol-interacting proteins.

Design, Synthesis, and Activity Study of Water-Soluble, Rapid-Release Propofol Prodrugs.

In this work, a series of water-soluble propofol prodrugs were synthesized, and their propofol release rate and pharmacodynamic characteristics were measured. We found that inserting glycolic acid as a linker between propofol and the cyclic amino acid accelerated the release of propofol from prodrugs into the plasma while preserving its safety. In animal experiments, prodrugs (3e, 3g, and 3j) were significantly better than fospropofol (the only water-soluble propofol prodrug that has been used clinically) in terms of safety, onset, and duration time of anesthesia. Their molar dose, onset time, and anesthesia duration time were comparable to those of propofol, helping to maintain the clinical benefits of propofol. The experimental results showed the potential of such compounds as water-soluble prodrugs of propofol.

A potent photoreactive general anesthetic with novel binding site selectivity for GABAA receptors.

The pentameric γ-aminobutyric acid type A receptors (GABAARs) are the major inhibitory ligand-gated ion channels in the central nervous system. They mediate diverse physiological functions, mutations in them are associated with mental disorders and they are the target of many drugs such as general anesthetics, anxiolytics and anti-convulsants. The five subunits of synaptic GABAARs are arranged around a central pore in the order ß-α-ß-α-γ. In the outer third of the transmembrane domain (TMD) drugs may bind to five homologous intersubunit binding sites. Etomidate binds between the pair of ß - α subunit interfaces (designated as ß+/α-) and R-mTFD-MPAB binds to an α+/ß- and an γ+/ß- subunit interface (a ß- selective ligand). Ligands that bind selectively to other homologous sites have not been characterized. We have synthesized a novel photolabel, (2,6-diisopropyl-4-(3-(trifluoromethyl)-3H-diazirin-3-yl)phenyl)methanol or pTFD-di-iPr-BnOH). It is a potent general anesthetic that positively modulates agonist and benzodiazepine binding. It enhances GABA-induced currents, shifting the GABA concentration-response curve to lower concentrations. Photolabeling-protection studies show that it has negligible affinity for the etomidate sites and high affinity for only one of the two R-mTFD-MPAB sites. Exploratory site-directed mutagenesis studies confirm the latter conclusions and hint that pTFD-di-iPr-BnOH may bind between the α+/ß- and α+/γ- subunits in the TMD, making it an α+ ligand. The latter α+/γ- site has not previously been implicated in ligand binding. Thus, pTFD-di-iPr-BnOH is a promising new photolabel that may open up a new pharmacology for synaptic GABAARs.

Design, synthesis and in vitro anticancer evaluation of a stearic acid-based ester conjugate.

AIM: Chemical synthesis and characterization of a lipophilic ester conjugate, propofol stearate and evaluation of its anticancer efficacy on human breast cancer cell lines MDA-MB-361, MCF-7 and MDA-MB-231. MATERIALS AND METHODS: The chemical structure of the synthesized conjugate was characterized by spectroscopic studies. Its anticancer potential was evaluated on the basis of growth inhibition, cancer cell adhesion and migration and apoptosis induction. RESULTS: Propofol stearate exhibited significant (p<0.05) growth inhibition of breast cancer cells in a concentration-dependent manner. MDA-MB-231 cells showed highest susceptibility towards the inhibitory effect of the conjugate. Moreover, treatment of MDA-MB-231 cancer cells with 25 µM propofol stearate potentially suppressed their adhesion (~34%) and migration (~41%), and induced apoptosis (~25%). CONCLUSION: Exogenously-applied stearic acid as an ester derivative, inhibits the growth of human breast cancer cells and shows a beneficial role in the treatment of breast cancer, in vitro.

Synthesis and characterization of novel quick-release propofol prodrug via lactonization.

The water-soluble derivatives of propofol have gained attention as a method to increase solubility of propofol. According to the principle of lactonization, the lead compound HX0969 was synthesized first and then the pharmacological features of HX0969 were evaluated in a comparison with those of propofol in the SD rats. Then, HX0969 disodium phosphate monoester (HX0969W) and glycine ester trifluoroacetic acid salt (HX101230) were synthesized, and their pharmacological features were compared with those of Lusedra®, which has been recognized and marketed as a water-soluble prodrug of propofol since 2008. The results showed that HX0969 could produce an anesthetic effect within a few seconds (3.6±3.0s) and its therapeutic index was 4.66 in the SD rat. The pharmacodynamic characteristics of HX0969W were similar to those of the Lusedra®. HX101230 could still produce an anesthetic effect within 60s in the rats though its therapeutic index was not so high (TI=2.96). Therefore, our study has indicated that HX0969 is a potentially useful lead compound of propofol derivative. Its rapid anesthetic effect is probably associated with lactonization.

p-(4-Azipentyl)propofol: a potent photoreactive general anesthetic derivative of propofol.

We synthesized 2,6-diisopropyl-4-[3-(3-methyl-3H-diazirin-3-yl)propyl]phenol (p-(4-azipentyl)propofol), or p-4-AziC5-Pro, a novel photoactivable derivative of the general anesthetic propofol. p-4-AziC5-Pro has an anesthetic potency similar to that of propofol. Like propofol, the compound potentiates inhibitory GABA(A) receptor current responses and allosterically modulates binding to both agonist and benzodiazepine sites, assayed on heterologously expressed GABA(A) receptors. p-4-AziC5-Pro inhibits excitatory current responses of nACh receptors expressed in Xenopus oocytes and photoincorporates into native nACh receptor-enriched Torpedo membranes. Thus, p-4-AziC5-Pro is a functional general anesthetic that both modulates and photoincorporates into Cys-loop ligand-gated ion channels, making it an excellent candidate for use in identifying propofol binding sites.

Synthesis and characterization of novel PUFA esters exhibiting potential anticancer activities: an in vitro study.

Polyunsaturated fatty acids (PUFAs) have been reported to play a regulatory role in tumour growth progression. In the present study, we have synthesized ester derivatives of two important PUFA viz., linoleic acid (LA) and arachidonic acid (AA) with propofol, a widely used general anaesthetic-sedative agent. The novel propofol ester analogues have been found to inhibit various cancer cell lines in a dose-dependent manner. Moreover, the compounds have been found to induce apoptotic cell death by enhancing the release of cytochrome c and expression of caspase-3. The data of the present study suggest that novel propofol-PUFA esters have strong potential to emerge as effective anticancer agents.

The anticonvulsant effects of propofol and a propofol analog, 2,6-diisopropyl-4-(1-hydroxy-2,2,2-trifluoroethyl)phenol, in a 6 Hz partial seizure model.

BACKGROUND: Propofol is a general anesthetic having good anticonvulsant properties, but is limited in antiseizure use because of its potent anesthetic/sedative properties. It is proposed that substitution of the propofol molecule in the para position may yield compounds having less toxicity, yet possessing anticonvulsant properties because of retention of the 2,6-diisopropylphenol configuration. Reported herein is the synthesis of a para-substituted analog of propofol, 2,6-diisopropyl-4-(1-hydroxy-2,2,2-trifluoroethyl)phenol (MB003), and a similar analog of 2,6-di-sec-butylphenol (MB050), and their comparative anticonvulsant effects in National Institute of Neurological Disorders and Stroke screening models. METHODS: MB003 and MB050 were synthesized by the reaction of propofol or 2,6-di-sec-butylphenol, respectively, with trifluoroacetaldehyde ethyl hemiacetal in the presence of catalytic amounts of K(2)CO(3). Compounds were purified to >98% purity. Propofol, MB003, 2,6-di-sec-butylphenol, and MB050 were screened for protective effects by the National Institute of Neurological Disorders and Stroke Anticonvulsant Screening Program in the mouse maximal electroshock, subcutaneous metrazol, and 6 Hz (32 mA) partial seizure models. All compounds were administered by i.p. injection. The toxicity of each compound was assessed by the ability of the animals to stay on a Rotorod after dosing. RESULTS: Propofol, MB003, and MB050 were found to be most protective in the 6 Hz model with lesser protective effects in the mouse maximal electroshock and subcutaneous metrazol models. In the 6 Hz model, propofol yielded a 50% effective dose of 32.8 mg/kg; MB003, 38.4 mg/kg; and MB050, 74.0 mg/kg. Propofol, and to a greater degree, 2,6-di-sec-butylphenol, exhibited high toxicity. The corresponding 2,6-dimethylphenol analog to MB003 and MB050, 2,6-dimethyl-4-(1-hydroxy-2,2,2-trifluoroethyl)phenol, was not protective in the 6 Hz model and exhibited no toxicity at any dose tested. CONCLUSION: These results show that the anesthetics propofol and 2,6-di-sec-butylphenol may be substituted in the para position with a 1-hydroxy-2,2,2-trifluoroethyl moiety and the resulting molecules have anticonvulsant activity in the 6 Hz model while exhibiting less toxicity (ataxia) than the parent 2,6-dialkylphenols. The effectiveness of propofol, MB003, 2,6-di-sec-butylphenol, and MB050 and the ineffectiveness of 2,6-dimethyl-4-(1-hydroxy-2,2,2-trifluoroethyl)phenol, in the 6 Hz model shows that the 2,6-diisopropyl or 2,6-di-sec-butyl phenolic configuration is more important to anticonvulsant activity than having the phenolic para position free of substituents. These results suggest that 1-hydroxy-2,2,2-trifluoroethyl substituted 2,6-di-alkylphenols may have useful anticonvulsant activities.

m-Azipropofol (AziPm) a photoactive analogue of the intravenous general anesthetic propofol.

Propofol is the most commonly used sedative-hypnotic drug for noxious procedures, yet the molecular targets underlying either its beneficial or toxic effects remain uncertain. In order to determine targets and thereby mechanisms of propofol, we have synthesized a photoactivateable analogue by substituting an alkyldiazirinyl moiety for one of the isopropyl arms but in the meta position. m-Azipropofol retains the physical, biochemical, GABA(A) receptor modulatory, and in vivo activity of propofol and photoadducts to amino acid residues in known propofol binding sites in natural proteins. Using either mass spectrometry or radiolabeling, this reagent may be used to reveal sites and targets that underlie the mechanism of both the desirable and undesirable actions of this important clinical compound.

Synthesis, in vitro and in vivo characterization of novel ethyl dioxy phosphate prodrug of propofol.

A novel ethyl dioxy phosphate prodrug of propofol (3) was synthesized and characterized in vitro and in vivo as safer alternative for phosphonooxymethyl prodrugs. The synthesis of 3 was achieved via vinyl and 1-chloroethyl ether intermediates, followed by addition of phosphate group. Aqueous solubility and chemical stability of 3 was determined in buffer solutions and the bioconversion of 3 to propofol was determined in vitro and in vivo. The results show that 3 greatly enhanced the aqueous solubility of propofol (solubility over 10 mg/mL) and the stability in buffer solution (t1/2=5.2+/-0.2 days at pH 7.4, r.t.) was sufficient for i.v. administration. The enzymatic hydrolysis of 3 to propofol was extremely rapid in vitro (t1/2=21+/-3s) and 3 was readily converted to propofol in vivo in rats. During bioconversion, 3 releases acetaldehyde, a less toxic compound than the formaldehyde released from the phosphonooxymethyl prodrug of propofol (Aquavan), currently undergoing clinical trials. The maximum plasma concentration of propofol, 3.0+/-0.2 microg/mL, was reached within 2.1+/-0.8 min after the i.v. administration of 3. The present study indicates that ethyl dioxy phosphate represents a potentially useful water-soluble prodrug structure suitable for i.v. administration.

Antibacterial activity of dipropofol and related compounds.

Phenolic compounds, in general, exhibit antioxidant and antibacterial activities. We studied antimicrobial activity of the phenolic antioxidants, propofol (2,6-diisopropylphenol), tocopherol, eugenol, butylated hydroxyanisole (BHA), and several of their dimer compounds. Dipropofol (dimer of 2,6-diisopropylphenol) showed strong antibacterial activity against gram-positive strains including methicillin resistant Staphylococcus aureus (MRSA) and vancomycin resistant Enterococci (VRE), while propofol and other monomeric and dimeric phenols having methyl or tert-butyl groups showed no remarkable activity. The results indicated that the dimeric structure of 2,6-diisopropylphenol moiety may play an important role in the antibacterial activity.

Novel inhibitors of neuronal nitric oxide synthase with potent antioxidant properties.

A series of hybrid compounds possessing an nNOS pharmacophore linked to an antioxidant fragment has been synthesized. Among them, compound 8d, a propofol derivative, displayed the greatest dual potencies against nNOS (IC(50)=0.12 microM) and lipid peroxidation (IC(50)=0.4 microM) accompanied with e/nNOS selectivity (67.5). This shows that nNOS was able to accommodate very bulky groups such as di-tert-butyl or di-iso-propyl phenol in its active site.

Estudio de compatibilidad galénica de mezclas anestésicas pPpofol-Midazolam / Study of pharmacotechnical compatibility of Popofol-Midazolam anesthetic mixture

Se realiza el estudio de compatibilidad galénica de una mezcla de propofol y midazolam con: objeto de determinar su posible formulación y acondicionamiento en jeringas precargadas previamente a la perfusión de la misma, o si por el contrario resulta necesaria su preparación extemporánea. En la muestra se llevan a cabo análisis del pH, del diámetro promedio y distribución de las gotitas lipídicas; así como un estudio fotomicrográfico y visual al inicio del ensayo y a intervalos de dos horas con objeto de detectar posibles variaciones significativas de dichos parámetros: Estas pueden resultar indicativas del grado de inestabilización físico-química del sistema. Las tomas de muestra se prolongan durante 36 horas que corresponden al vaciado de 3 jeringas precargadas con la emulsión anestésica previamente elaborada, en condiciones análogas a las de perfusión al paciente. La variación observada tanto en el pH como en el tamaño medio de gotitas, así como la ausencia de precipitados en el transcurso del ensayo, evidencian que no existen problemas de estabilidad físico-química de la mezcla anestésica en las condiciones habituales de aplicación a nivel hospitalario (AU)

Propofol analogues. Synthesis, relationships between structure and affinity at GABAA receptor in rat brain, and differential electrophysiological profile at recombinant human GABAA receptors.

A number of propofol (2,6-diisopropylphenol) congeners and derivatives were synthesized and their in vitro capability to affect GABAA receptors determined by the inhibition of the specific [35S]-tert-butylbicyclophosphorothionate ([35S]TBPS) binding to rat whole brain membranes. Introduction of halogen (Cl, Br, and I) and benzoyl substituents in the para position of the phenyl group resulted in ligands with higher potency at inhibiting [35S]TBPS binding. A quantitative structure-affinity relationship (QSAR) study demonstrated that affinity is enhanced by increases in lipophilicity of the ligand whereas affinity is adversely affected by increases in size of the substituent para to the phenolic hydroxyl group. Consistent with the displacement of [35S]TBPS and with the activation of GABAA receptors, we demonstrate that ligands displaying high affinity (i.e., 2-4, and 8) are able to increase GABA-stimulated chloride currents in oocytes expressing human GABAA receptors and to directly activate chloride currents in an electrophysiological assay. Among them, compound 4 showed a rather peculiar profile in the electrophysiological examination with cloned alpha1beta2gamma2 GABAA receptors. Indeed, compared to propofol, it displayed a much greater efficacy at potentiating GABA-elicited chloride currents, but a much lower efficacy at producing a direct activation of the chloride channel in the absence of GABA. This behavior may give to compound 4 pharmacological properties that are more similar to anxiolytic and anticonvulsant drugs than to those of general anesthetics.

Preparation and central action of propofol/hydroxypropyl-beta-cyclodextrin complexes in rabbits.

Inclusion complexes of propofol (CAS 2078-54-8) and hydroxypropyl-beta-cyclodextrin (HP-beta-CD) were examined in aqueous solution and in the solid state by phase solubility technique, IR-spectroscopy and differential scanning calorimetry. Solid complexes obtained by kneading method were dissolved in artificial plasma leading to a colloidal solution which was suitable for intravenous administration. In the in vivo studies propofol (15 mg/kg) was given intravenously to rabbits in equimolar doses as cyclodextrin complexes and as Diprivan. The central action of the drug was verified by recording the bioelectrical activity of the precentral cortex. The statistical evaluation of the results do not indicate differences in onset, duration and maximum of action between the two dosage forms.