MXPA99006733A - Production of new polymer liquid crystals capable of having an interaction with liposomes - Google Patents

Abstract

Process comprising the following steps:(a) preparation of liposomes (bilayers) by extrusion from lipids, such as dimirisoilphosphatidylcholine;(b) preparation of the polymers (-)PTOBEE (C26H20O8)n and PTOBDME (C34H36O8)n, both being liquid crystals of the cholesteric type;(c) addition of the polymers to the suspension of liposomes. These systems have biomedical and pharmacologic applications such as"stealth liposomes"or"ghost liposomes", for the encapsulation of drugs with, as a result, an extension of their average life in the blood flow.

Description

© B? -E? EGOS CITIZE CRI_KHU-gS LÍQUIDOS PQ? .ÍM &3Q5 CAPACES BE ISRCBI CCIOMAli COK? .IP0SÍ3M-S SKCTOK DE? -ü. _FifeCf? ICk The present invention is framed within a first chemical sector with bit-medical and pharmacological applications.

STATE BS?.? K "E? OT? Ci-- The liquid crystals are systema-suto-organizable.They do not pass directly from the crystalline state to the isotropic melt, when heated, but form mesophase that combine the order of the perfect crxatal with The mobility of the liquid Its molecular b is almost always simple: they form anisatropic or ani-ifilicaa molecules with a "rigid" geometry (Jiesolopxc unit) joined to another flexible part (spacer), which pack blocks with anisotropic properties ( fí- Ringsdorf, B- schalarb and J. Vensmer, "Molecwlaz- ñishitect re and F ncziají of Polymerxc Oriented Syst &s: Models for the Stu? and af 0? -qamzaT-? on, Sur face 8.ecogn? .tj .on, arxi Dynamxcs af Biomemhranes. "Ang. Chera, Int. Ed. Engl. 1986 f 27 r pp 116). The parallel orientation of its longitudinal molecular axis ejs is common to the mesophase. Dns main classes can be distinguished: Nematic (with its molecular centers isotropic distributed, camente) * is ectics (molecular centers organized in planes). The spatial arrangement of infant planes to aplillate them in a helical superstructure, characterized for a preferential preference, is known as cholesteric meeophase. Cholesterics reflect incident light and when their helix pitch is comparable to the wavelength of visible light, they exhibit typical bright colors.

U.S. Patent No. 4,999,348 shows compositions for topical use, which provide release and penetration. controlled biologically active substances comprising cholesteric liquid crystals, whose lamellar molecular structure traps the biologically active sü __- £ ártc? a. Specifically, the compositions comprise vitamin A, the cholesteric liquid crystal and a poly & cronic gel that forms, a poiymetric revealing around the liquid crystals. WO-A-9319735 discloses a process for preparing microcapsules or liposomes of controlled size, which can be encapsulated in the polymer coatings where they are used to be able to palmerise within the liposomes or -nicroCflL eulse, - and where the totality of ursacicroca suia or an iiposome and the poly-etheric atoms form the liquid crystal- The development of polymeric liquid crystals followed that of the manome- tics and ro enzymes. with polymers whose main chain, eat a whole, mesogenically active, chant repaired 4 from solution (liatropics) as well as from the melt (terotropic). Subsequently, the mesogenic units were introduced either hung from the main chain through a flexible spacer (side chain) or joined along the main chain by a flexible aliphatic spacer (main chain). In 1982, Lenz et al (C Ober, J.-T. Jin, RW Lenz, Polym-J. 1982, 14, 9) synthesized thermo-tropic liquid crystal polymers whose mesogénrca unit, previously studied in low molecular weight works, was based on "a central residue of terephthalic acid flanked by two pa ib ibenzoyl residues connected by flexible polymethylene spacers. transition temperatures to the mesophase and the isotripic melt. Also in 1982, Galli and collaborators (G. Galli, E. Chiellini, CK Obert, W. Lez, Makromol, Chem., 1902, 183, pp. 2693), introduced flexible spacers compatible with the aqueous system under physiological conditions, ie, spaced! is hydrophilic low molecular weight hydroxy termination, oligo-sxyethylene type and oligo-oxpropylenic, the latter containing chiral centers in each unit- These spacers had also been used in liquid crystals of low weight molecular, in order to decrease the transition temperatures, they preserved the influence of the type. Length and dietribution of the spacers in the middle of the formed pitches, limiting the liquid crystal character of the polymers to 10 units in the spacer. _- In 1983, Malanga et al. (C. Malanga, N.

Spassky Menicagly E. Chiellini, Polymer Bulletin 1903, 9, pp. 336), they extended the syntepis using as flexible spacers optically active dxes of different length and degree of substitution, capable not only of imparting to the polymers or hydrophilic character but also the choreogenic stereochemical disposition to their mesofaee. Starting from chiral glycols (an enantio ero of determined sign) as a spacer, they obtained in all cases polymer with the same optical sign. Using starting the recémica mixture of glycol co or spacer, always obtained non-chiral polymer, "racemic" with raesof is nematic, never cholesteric. { E. Chielli i, fc. pa, s, Carrozzino, G. Galli ñá B. Gallot "Cárral J, lqni (] - Crystall? ne oZymers, IX, The Effect of Chirs.1 Sp cer Struczure m ermoZfopic Palyeszers", Mol, Cryst. Liq. Cryst., 1990, Vol. 179, 405-418, E. Chiellini, R. Salaro, G. Leonardi, R.

Lisciani, G. Haz2anti, Eur. Pat. Appl ,, 19 pp, EP 509968 Al 921021; E. Chillini, R. Solaro, L- Bemporad, S-DrAntone, Eur. Pat. Appl., 11 pp,? P 486445 A2 920520, - E. Chiellíni, R. Solaro, L, Be porad, Eur. Pat appl., 13 pp. EP 486437 A2 92Q52Ü). The compound { C26ll20 ° a) Neitrotome obtained from the racemic mixture of the corresponding giicol of the spacer, has been described by Chiellíni (E, Chiellíni, R. PQ, S. Carrozzino, G, Galli and - Gallot, "Chirsl Lxqmdi-Crystalli Polymers, The B cz of Chxral spacer Szruct re in Hermotrapic Palyesters, Mol.Cryst, Liq, Cryst., 1990 Val. 179, 405-418), as non-toxic, compatible with blood and permeable to different solutes. { É'- Chiellini, G- Galli, R.W. Lenz and C., Ober Preprints IUFAC SympOBíum on Hacromoleculee, Amherst, 1982, p. 365). In the same work, a series of polycarbonates synthesized from mixtures of Bisphenol A and oligoethers hydrolyzed with phosgene in pyridine-dioxane solution are described. The authors claim to have synthesized gel membranes from these polycarbonates by the faee inversion technique (E. Chillinl, G. Galli, R. Lenz and C. Ober Preprints IUPAC Syp? Pas_iu? J? On Macromolecules, Amherst, 19B2, p.365), obtaining improved mechanical properties. A parallel can be drawn between the behavior of liquid crystals in materials science, and lipids in the life sciences (H-Ringdorf, B. Schlarb and __t. Venzmer, "Molecular Arc itectur and function of Polymerxc Or.ej. ted Systems: Mo els for zh &Study of X Organizaza, Sutf? C &-Recognition, and Dynamics of Blomembraxtes. "Ang. Chem-Int. Ed. Engl. 1988, 27, pp. 116), LipidcJs are also auto- Organizable combining order and mobility- The ordering of their amphiphilic molecules in water form lipasomes, bilayer structures or spherical multilayers that are useful cellular models to study membrane properties and cellular interactions. { fl. Bajer etnd H. Ringsdorf Preprints IÜPAC Symposium on Macromolecules, ftmherst, 1982, p. 341) - /.LQS Jiposomes are particularly interesting as potential agents for encapsulating sensitive biomaterials (G-Gregory, A, C. Allison, eds, "Liposomes in biologisal systems", John Wiley and Sons, Chichester, New York (1980). )). However, a severe drawback in the application of liposomes as a vehicle of drugs for their release into the body, is their rapid ingestion by cells of the reticuloendoterial system, varying the half-life of liposomes in the blood, t? 2 > between minutes and dozens of minutes (B. D, Lasic, "Liposomes from Physics to Applications"; Elsevier Science Publishers B, V. Amsterdam, London, New York, Takyo (1993)), which eliminates many of the intravenous applications of Liposomae, Ls Publication WO-A-9420073 shows lipid-polymer conjugates and their combination with liposoins, said conjugates comprise a lipid fappadar of vesicles and a polymer covalently bound to the lipid. To make lipid binding possible, the lipid has to have a terminal group and they have developed different procedures to lengthen the life time of the liposomes in the blood. One of them is the concept of the "phantom liposome", developed by Lasic (D. 0. Lasic, "The Stealth Liposome", Chemical Review, Vol. 95, No. 8 (1995), 2505), where polymer chains , normally polyethylene glycol, ingested on its surface "concealing" it and achieving circulation times of "1 to 2 orders of magnitude greater. Obtaining new liquid poremic crystals capable of interacting with liposomes is by taato of great interest for its potential use in the design of lipose "antasmas" - Our cholesteric liquid crystals seemed at first sight potentially capable. ßESSR? PCIÉH DE JA IHrVEWCléH 0? al and as claimed, the present invention relates to a process for preparing polymer-coated liposomes, where the preparation is prepared in the form of IQS terfliatropic polyether esters. { - > PTOBEE CC2 &H20OS) - .. and PTOBDME (C34: f? 36Qß) n; - H TC-H.

/ Both crystalline liquid crystals whose structure indicates their possible utility as a liposome stabilizer. Both have been found to interfere with liposomes of a certain lipid, both in bilayers and in multilayers as evidenced by the displacement of the gel to fluid transition (liquid crystal state) of the pure liposome. Polytene groups could be attached to the surface of a lipopoma by insertion of the hydrophobic anchor group into the membrane.

EXAMPLE 1 To check the interaction polymer-liposama ee prepared liposomes (bilayer-) by extrusion, about 0.1 p in diameter. The selected lipid was the iristoylphosphatidylcholine dime (DMPC), saturated chain lipid whose gel phase - fluid phase transition temperature is 24aC. The polymers, previously synthesized (M. Pérez-Méndez, C. Marco Rocha, Spanish Patent 3 9700100) a) (-) PTOBEE C26H2? C! 8 n, Y b) PTOBPME (C34H3608) n, both, liquid-crystals of coleetérica nature.

The polymers were respectively added to the suspension of liposomes in the concentrations: 10% and 20% in each case. The techniques selected to study the 3 rd interaction were, the e3ec ronic transmission microscopy (TEM). { by the techniques of sample preparation of cryomycoscopy and negative staining) and fluorescence in stationary diet. The fluorescent probe used for its study by fluorescence was diphenylhexatriene (DPH). This probe was introduced into the liposome in a relacón: 1 sapda / 500 lipids. Measuring steady state anieotropy of the eqnda in the lipoastoma without polymer was the phase transition at 242C. By introducing 10% PTOBDME, whose lateral aliphatic chain is 10 carbon atoms, this transition shifted to 22sc. The addition of 20% PTOBPWE shifted the transition to 20se. Something analogous occurred when introducing the polymer (-) PTOBEE- Assumes the insertion of the hydrophobic aliphatic chain of the polymer between the lipid of the liposome and the subsequent liposome surface coating by the rigid rheosogen of the liquid crystal. These data confirm the interaction of both polymers with the liposome (DPMC).

Claims (2)

1. R & IVIMBJC &CIOWES l._ A process for preparing polymer-coated liposomes, the method comprises the steps of preparing a suspension of liposomes selected from bilayer or multilayer liposomes, from a lipid pair extrusion. X providing the liposomes with a polymer coating, adding polymer to the liposome suspension; wherein the polymer coating is prepared from liquid crystalline crystals having hydrophobic, chosen from PTOBEE, of formula PTOBDME, of formula - H -c -H H '-5c- -H H * c- -H H- ^ c- -H H-C-H or mixtures thereof, said liquid crystals interacting with the liposormae? ~~ the colegtheric crystals are added to the liposome suspension in a proportion of IQ-20%, * - in which the polymer coating comprises a rigid mesogen that 2. The process according to claim 1, wherein the liquid crystals are PTOBEE-3, a process according to claim 1, wherein the liquid crystals are PTOBDME. i, wherein the liquid crystals are (-) FTQBEE 5. t a procedure according to claim 1, wherein the lipid is dimeristoiphosphatidylcholine. 6. A polymer coated Ixpoeoma having a membrane that forms a surface and a polymer coating. lipoeoma originates from a suspension of lipases selected from bilayer liposomes or ulticapae liposomes prepared from a lipid by; and that the polymer coating is formed of cholesteric liquid crystals having selected hydrophobic groups 4e F? BEE, of formula H -C-Ji H-C-H H * G -H HiC ~ H H-C - H H or mixtures thereof; _- said liquid crystals interacting with the oxides when added to the suspension of liposorates in concentrations of 10-20%; X whereby the polymer coating comprises an igneous mesogen coating the surface of the liposomes. 7. A polymer-coated liposome according to claim 6, in which the liquid crystals are PTOBEE 8. A polymer-coated liposome according to claim B, wherein the liquid crystals are P-KSBBHE. 9. A polymer coated liposome according to claim 5 wherein the liquid crystals san. { -) P «£ OBE £ - 10. A polymer-coated lipasopifi according to claim 6, in which the lipids are tetratherophos- ididylcholine-11. ui). polymer coated lipoeopia according to claim f > , in which the hydrophobic groups of the liquid crystals are introduced into said liposome membrane a. 12- Use of polymer-coated liposomes prepared according to the method of any of claims 1-5, for the drug capsule. 13. Use of lipo omas. polymer coated according to any of claims 6-11, for epcapsulam? epto drug.