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Potential drug delivery systems from maleic anhydride copolymers and phenothiazine derivatives
European Polymer Journal 38 (2002) 1509–1513 www.elsevier.com/locate/europolj
Potential drug delivery systems from maleic anhydride copolymers and phenothiazine derivatives Elena Bacu a, Gabrielle Charlotte Chitanu b,*, Axel Couture c, Pierre Grandclaudon c, Gh. Singurel d, Adrian Carpov b a
b
c
Department of Organic Chemistry, Faculty of Chemistry, Bd. Carol I 11, ‘‘Al. I. Cuza’’ University, RO-6600 Iasi, Romania Department of Bioactive and Biocompatible Polymers, Romanian Academy, ‘‘Petru Poni’’ Institute of Macromolecular Chemistry, Aleea Grigore Ghica Voda 41A, RO-6600 Iasi, Romania Laboratoire de Chimie Organique Physique, UPRES A 8009, B^ atiment C3(2), Universit e des Sciences et Technologies de Lille 1, F-59655 Villeneuve d’Ascq Cedex, France d Department of Optics-Spectroscopy, Faculty of Physics, Bd. Carol I 11, ‘‘Al. I. Cuza’’ University, RO-6600 Iasi, Romania Received 24 September 2001; received in revised form 29 November 2001; accepted 17 January 2002
Abstract New functionalized derivatives of phenothiazine containing amino or hydroxy groups with potential pharmacological properties were synthesized and characterized. They were reacted with maleic anhydride copolymers in order to obtain conjugates which can be used as controlled-release systems. Ó 2002 Elsevier Science Ltd. All rights reserved. Keywords: Maleic copolymers; Phenothiazine; Polymer–drug conjugates
1. Introduction Controlled-release technology has rapidly emerged over the past 25 years as a new interdisciplinary science that offers novel approaches to the delivery of bioactive agents including pharmaceutical, agricultural, and veterinary compounds. One of the most important ways to achieve this goal is the use of so-called polymer conjugates which involve small molecules (drugs, etc.) chemically linked to a polymer backbone [1]. In the last years, it can be seen an increase of the interest for synthesis and characterization of maleic anhydride/acid copolymers, their interactions with various molecules, macromolecules, particles and surfaces and a large number of applications [2,3]. The uses of maleic copolymers in the medicine or pharmacy were described as drugs per se [4] or drug carriers, supports for enzymes
*
Corresponding author. Tel.: +40-32-260-332; fax: +40-32211- 299. E-mail address: [email protected] (G.C. Chitanu).
or protein modifiers [5–7]. The advantages of these copolymers are their regular alternating reproducible structure, their bicompatibility, their pH-dependent solubility, the possibility to vary the hydrophobicity depending on the comonomer, etc. Another facility is due to the reactivity of the anhydride cycle with nucleophilic agents (OH, NH). It is well known that the phenothiazine derivatives are used in many topics as dyes, semiconductors and photoconductors, charge transfer complexes for solid piles, but especially they are used in the modern pharmacotherapy, due to their antipsychotic properties. Chemical modifications on phenothiazine had led to a great number of derivatives with different activities as: neuroleptic, antihistaminic, antiallergenic, anti-inflammatory, antibacterial, anticancer, etc. [8]. In our paper we present the results regarding the synthesis of new derivatives of phenothiazine with potential pharmacological properties and the obtention of controlled release systems by their reaction with maleic anhydride copolymers. In this view several N-heterocycles with various size and composition were linked to the N-atom of the phenothiazine [9–12]. Such kind of
0014-3057/02/$ - see front matter Ó 2002 Elsevier Science Ltd. All rights reserved. PII: S 0 0 1 4 - 3 0 5 7 ( 0 2 ) 0 0 0 4 0 - X
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E. Bacu et al. / European Polymer Journal 38 (2002) 1509–1513
derivatives could possess new pharmacological properties by creating of some favourable synergetic effects.
standard methods. Benzene and toluene were dried over sodium. 2.2. Synthesis
2. Experimental 2.1. Materials Phenothiazine, cyanuric chloride, hydrazine hydrate 98%, b-hydroxyethylpiperazine and 2-amino-2-methyl1-propanol were obtained from Aldrich. Ethanol and acetone p.a. were used as such. Maleic anhydride (MA), N-vinylpyrrolidone (NVP), styrene (St), benzoyl peroxide and azobisisobutyronitrile were carefully purified by
2.2.1. Functionalized phenothiazinyl-S-triazine derivatives 4–6. General procedure Compounds 4–6 were obtained by the heteroarylation of phenothiazine (1) with cyanuric chloride (2) followed by nucleophilic substitution of the two chlorine atoms from 10-(4,6-dichloro-[1,3,5]triazin-2-yl)-10H-phenothiazine (3) [12] (Scheme 1). A solution of 3 (3.4 g, 10 mmol) and appropriate amino compound (hydrazine hydrate 98%, b-hydroxy-
Scheme 1. Synthesis of new phenothiazine derivatives.
E. Bacu et al. / European Polymer Journal 38 (2002) 1509–1513
ethylpiperazine or 2-amino-2-methyl-1-propanol, 46 mmol) in ethanol (40 ml) was refluxed for 2 h. After cooling and dilution with water a white product was separated and washed with water. 10-(4,6-Dihydrazino-[1,3,5]triazin-2-yl)-10H-phenothiazine (4). White solid (72%); m.p.: 276–277 °C. (C15 H14 N8 S) (338.4): Calcd. C, 53.24; H, 4.17; N, 33.11. Found C, 53.46; H, 4.19; N, 32.95. IR (KBr): 3195– 3320 (NH), 3424 (NH2 ), 1527 cm1 (C@N). 1 H NMR (DMSO-d6 ): d ¼ 4:10 (s,NH2 ), 7.20–7.80 (m,aromatic H), 8.10 (s,NH). 13 C NMR (DMSO-d6 ): d ¼ ðCHÞ 125.8, 126.3, 127.4, 129.4; (C) 132.0, 139.4, 163.4, 167.2. 2-(4-{4-[4-(2-Hydroxy-ethyl)-piperazin-1-yl]-6-phenothiazin-10-yl-[1,3,5]triazin-2-yl}-piperazin-1-yl)-ethanol (5). Recrystallization from ethanol–acetone (78%); m.p.: 242–243 °C. (C27 H34 N8 O2 S) (534.7): Calcd. C, 60.65; H, 6.41; N, 20.96. Found C, 60.96; H, 6.52; N, 21.20. IR (KBr): 3250–3550 (OH and NH), 1555 (C@N), 1030 cm1 (C–O). 1 H NMR (DMSO-d6 ): d ¼ 2:35 (m,NCH2 ), 3.48 (m,NCH2 ), 3.62 (m,OCH2 ), 4.43 (OH), 7.16–7.70 (m,aromatic H). 13 C NMR (DMSO-d6 ): d ¼ ðCH2 ) 42.7, 52.9, 58.5, 60.2; (CH) 125.8, 125.9, 127.4, 128.9; (C) 131.8, 139.1, 163.6, 164.3. 2-[4-(2-Hydroxy-1,1-dimethyl-ethylamino)-6-phenothiazin-10-yl-[1,3,5]triazin-2-yl-amino]-2-methyl-propan1-ol (bi 6). White solid (64%); m.p. 185–186 °C. (C23 H28 N6 O2 S) (452.6): Calcd. C, 61.04; H, 6.24; N, 18.57. Found C, 61.33; H, 6.38; N, 18.22. IR (KBr): 3200-3500 (NH and OH), 1450 and 1370 ðCðCH3 Þ2 Þ, 1050 cm1 (C@O). 1 H NMR (DMSO-d6 ): d ¼ 1:01 (s,CH3 ), 3.25 (s,OCH2 ), 4.84 (OH), 7.26–7.67 (m, aromatic H), 8.10 (s,NH). 13 C NMR (DMSO-d6 ): d ¼ ðCH3 Þ 23.6, (CH2 ) 53.7; (CH) 125.9, 126.3, 127.3, 129.6; (C) 68.1, 132.2, 139.4, 164.9. 2.2.2. MA copolymers MA copolymers with NVP and St were obtained by solution–suspension radical polymerization in benzene or toluene, respectively [13,14]. The chemical composition of the copolymers was assessed by conductometric titration with 0.1 N aqueous NaOH in a 1:1 mixture acetone–water [15] and confirmed by FTIR spectra. The molecular weight was estimated from viscometric measurements in acetone at 30 °C for MA–St copolymer [16] or in aqueous solution at pH ¼ 2:1 for MA–NVP copolymer [17]. The chemical structure of MA copolymers is depicted in Scheme 2 and characteristic data are reported in Table 1. 2.3. Conjugates of MA copolymers with phenothiazine derivatives The reactions between MA copolymers and the phenothiazine derivatives are given in Scheme 3. Conjugate 7 of MA–St copolymer with 4. Dihydrazine 4 (0.48 g, 1.42 mmol) was added to a solution of co-
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Scheme 2. Chemical structure of maleic anhydride copolymers.
Table 1 Maleic copolymers used for obtaining conjugates with phenothiazine derivatives Sample code
Copolymer
Ia
Copolymer composition MA:comonomer (mol)
Molecular weight
S P
MA–St MA–NVP
0.396 0.382
1:1 1:1
150,000 28,000
Ia ¼ acid number (g NaOH/g copolymer).
Scheme 3. Reaction between maleic anhydride copolymers and phenothiazine derivatives.
polymer (0.278 g, 1.37 mmol of structural unit) in dioxane (7 ml). The mixture was heated for 4 h at 60 °C. After cooling and precipitation with water the compound 7 was obtained as a white powder. Conjugate 8 of MA–NVP copolymer with 4. From a solution of copolymer (0.252 g, 1.20 mmol) and 4 (0.44 g, 1.30 mmol) in DMSO (8 ml) heated at 80°C for 3 h. Conjugate 9 of MA–St copolymer with 5. From a solution of copolymer (0.14 g, 0.69 mmol) and 5 (0.37 g, 0.69 mmol) in acetone (4.5 ml) refluxed for 4 h.
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Conjugate 10 of MA–NVP copolymer with 5. From a solution of copolymer (0.19 g, 0.91 mmol) and 5 (0.50 g, 0.91 mmol) in acetone (7 ml) refluxed for 4 h. Conjugate 11 of MA–St copolymer with 6. From a solution of copolymer (0.144 g, 0.71 mmol) and 6 (0.35 g, 0.77 mmol) in dioxane (5 ml) heated at 70°C for 5 h. Conjugate 12 of MA–NVP copolymer with 6. From a solution of copolymer (0.144 g, 0.69 mmol) and 6 (0.35 g, 0.77 mmol) in DMSO (5 ml) heated at 80°C for 5 h. 2.4. Measurements
The solubilities of the conjugates are reported in Table 2. It may be observed that the conjugates are insoluble both in DMF and in aqueous diluted alkali solution. However the conjugates having as support MA–NVP copolymers are swellable in alkali solution, due to the hydrophilic character of NVP. This fact can be expected taking into account that all phenothiazine derivatives are bulky and possess a reduced solubility. Consequently, the conjugates have been characterized by means of FTIR spectra (Table 2). In Fig. 1 the spectrum of the conjugate 7 is compared with that of functionalized phenothiazinyl-S-triazine 4 and that of
The melting points were determined on a MELTEMP II apparatus and have not been corrected. The IR spectra were recorded on a FT-IR BOMEM MB 104 spectrometer in KBr pellet from 3 to 4 mg compound and 500 mg KBr in order to facilitate the comparison. The 1 H-NMR and 13 C-NMR spectra were recorded on a Bruker AM-300 spectrometer using DMSO-d6 as solvent.
3. Results and discussion The syntheses of symmetrically functionalized phenothiazinyl-S-triazine were performed by nucleophilic substitution of both halogen atoms from the positions 40 and 60 of triazine cycle with difunctional nucleophilic agents such as an aminoalcohol or hydrazine. The elemental analysis and the NMR and FTIR data confirmed the structure and purity of all phenothiazine derivatives. Two MA copolymers were used as supports for the low molecular phenothiazine derivatives. The copolymer (P) with NVP is rather hydrophilic, while the second (S) with St is hydrophobic. The copolymer (P) is supposed to be more biocompatible, due to the presence of NVP units.
Fig. 1. FTIR spectra of the copolymer S (1), conjugate 7 (2) and phenothiazine derivative 4 (3).
Table 2 Characteristics of conjugates between S or P copolymers and phenothiazine derivatives Conjugate 7 8 9 10 11 12
IR (KBr), m, cm1 1729 (COamide ), 1576 (NHamideII ), 1780 (COcarboxylic ), 3404 (NH2 ), 2900–3350 (NH and OHassociated ) 1732 (CONHcyclic ), 1689 (COamide ), 1570 (NHamideII ), 2850–3550 (NH and OHassociated ) 1727 (COester ), 1700 (COcarboxylic ), 2500–3100 (OHcarboxylic associated ), 3200–3500 (OHalcholic associated ) 1730 (broad band CONHcyclic and COester ), 2700–3000 (OHcarboxylic ), 3100–3500 (strongly H-bonded OH group) 1781 (COcarboxylic ), 1736 (COester ), 2800–3600 (OHcarboxylic and OHalcholic associated ) 1730 (CONHcyclic ), 1682 (COester ), 2500–3350 (OHcarboxylic and OHalcholic associated )
Solubility DMF
NaOH 0.01 N solution
–
Swollen
–
Swollen
–
Swollen
Swollen
–
Swollen
E. Bacu et al. / European Polymer Journal 38 (2002) 1509–1513
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4. Conclusion Some new functionalized derivatives of phenothiazinyl-S-triazine with potential pharmacological properties were obtained by nucleophilic substitution of halogen atoms with hydrazine or amino alcohols in good yield and purity as confirmed by elemental analysis and NMR or FTIR spectra. They were reacted with maleic anhydride copolymers in mild conditions in order to obtain new conjugates which could be used as controlled release systems. Pharmacological tests of the low molecular compounds and polymeric conjugates are in progress.
References
Fig. 2. FTIR spectra of the copolymer S (1), conjugate 9 (2) and phenothiazine derivative 5 (3).
the parent copolymer S. The spectra of conjugate 9, phenothiazine derivative 5 and S are displayed in Fig. 2. It can be observed that the bands at 1780 and 1850 cm1 assigned to the unreacted maleic anhydride moities have disappeared and that new bands characteristic of the new amide or ester type functions occurred. Indeed the spectra of conjugates 7 and 8 displayed characteristic absorption bands of amide group (an intensive band at 1729 cm1 ) and characteristic absorption bands of the carboxylic group as well (two bands at 1700 and 1780 cm1 for C@O and a broad band at 2500–3100 cm1 corresponding to associated OH). The absorption patterns peculiar for phenothiazinyl-S-triazine hybrid are maintained. In the conjugates 7 and 8 the absorption of the NH2 group appears at 3404 cm1 , but only at a half of intensity, which seems to indicate that the conjugates are not crosslinked by reaction of both functions. The spectra of conjugates 9–12 exhibit new bands characteristic of the new formed ester groups located at 1730 and 1680 cm1 together with the broad bands at 2700–3000 cm1 (associated OH of the COOH group) and 3200–3500 cm1 (associated OH of a free OH group).
[1] Park K, editor. Controlled drug delivery, challenges and strategies, ACS professional reference book. Washington DC: American Chemical Society; 1997. [2] Culbertson BM. Maleic and fumaric polymers. In: Encycl. Polym. Sci. Eng., 2nd ed., vol. 14. New York: John Wiley and Sons; 1987. p. 225–94. [3] Chitanu GC, Zaharia IL, Carpov A. Int J Polym Anal Charact 1997;4:1. [4] See for instance Breslow DS. Pure Appl Chem 1976;46:103. [5] Maeda H. Adv Drug Deliv Rev 1991;6:181. [6] Hirano T, Todoroki T, Kato S, Yamamoto H, Calicetti P, Veronese F, et al. J Controlled Release 1994;28:203; Hirano T, Todoroki T, Morita R, Kato S, Ito Y, Kim KH, et al. J Controlled Release 1997;48:131. [7] Hirano T, Ohashi S, Morimoto S, Tsuda K. Makromol Chem 1986;187:2815. [8] Gupta RR. In: Bioactive molecules: Phenothiazines and 1,4-benzothiazines, chemical and biological aspects, vol. 4. Amsterdam: Elsevier; 1988. [9] B^acu E, Petrovanu M, Grandclaudon P, Couture A. Phosphorus, Sulfur and Silicon 1996;108:231. [10] B^acu E, Petrovanu M, Antohie C, Mungiu ICOC. Ann Pharm Fr 1997;55:269. [11] B^acu E, Petrovanu M, Couture A, Grandclaudon P. Phosphorus, Sulfur and Silicon 1999;149:207. [12] B^acu E, Petrovanu M, Grandclaudon P. Rev Roum Chim 1999;44:231. [13] Houben-Weyl, Methoden der organischen chemie, Bd. E 20, Makromolekulare Stoffe. Stuttgart: Georg Thieme Verlag; 1987. p. 1239–43. [14] Chitanu GC, Anghelescu-Dogaru AG, Carpov A. Rom. 116478B, 28.02.2001. [15] Caze C, Loucheux C. J Macromol Sci Chem A 1975;9:29. [16] Endo R, Hinokuma T, Takeda M. J Polym Sci A-2 1968;6:665. [17] Csakvari E, Azori M, T€ ud€ os F. Polym Bull 1981;5:413.
Potential drug delivery systems from maleic anhydride copolymers and phenothiazine derivatives Elena Bacu a, Gabrielle Charlotte Chitanu b,*, Axel Couture c, Pierre Grandclaudon c, Gh. Singurel d, Adrian Carpov b a
b
c
Department of Organic Chemistry, Faculty of Chemistry, Bd. Carol I 11, ‘‘Al. I. Cuza’’ University, RO-6600 Iasi, Romania Department of Bioactive and Biocompatible Polymers, Romanian Academy, ‘‘Petru Poni’’ Institute of Macromolecular Chemistry, Aleea Grigore Ghica Voda 41A, RO-6600 Iasi, Romania Laboratoire de Chimie Organique Physique, UPRES A 8009, B^ atiment C3(2), Universit e des Sciences et Technologies de Lille 1, F-59655 Villeneuve d’Ascq Cedex, France d Department of Optics-Spectroscopy, Faculty of Physics, Bd. Carol I 11, ‘‘Al. I. Cuza’’ University, RO-6600 Iasi, Romania Received 24 September 2001; received in revised form 29 November 2001; accepted 17 January 2002
Abstract New functionalized derivatives of phenothiazine containing amino or hydroxy groups with potential pharmacological properties were synthesized and characterized. They were reacted with maleic anhydride copolymers in order to obtain conjugates which can be used as controlled-release systems. Ó 2002 Elsevier Science Ltd. All rights reserved. Keywords: Maleic copolymers; Phenothiazine; Polymer–drug conjugates
1. Introduction Controlled-release technology has rapidly emerged over the past 25 years as a new interdisciplinary science that offers novel approaches to the delivery of bioactive agents including pharmaceutical, agricultural, and veterinary compounds. One of the most important ways to achieve this goal is the use of so-called polymer conjugates which involve small molecules (drugs, etc.) chemically linked to a polymer backbone [1]. In the last years, it can be seen an increase of the interest for synthesis and characterization of maleic anhydride/acid copolymers, their interactions with various molecules, macromolecules, particles and surfaces and a large number of applications [2,3]. The uses of maleic copolymers in the medicine or pharmacy were described as drugs per se [4] or drug carriers, supports for enzymes
*
Corresponding author. Tel.: +40-32-260-332; fax: +40-32211- 299. E-mail address: [email protected] (G.C. Chitanu).
or protein modifiers [5–7]. The advantages of these copolymers are their regular alternating reproducible structure, their bicompatibility, their pH-dependent solubility, the possibility to vary the hydrophobicity depending on the comonomer, etc. Another facility is due to the reactivity of the anhydride cycle with nucleophilic agents (OH, NH). It is well known that the phenothiazine derivatives are used in many topics as dyes, semiconductors and photoconductors, charge transfer complexes for solid piles, but especially they are used in the modern pharmacotherapy, due to their antipsychotic properties. Chemical modifications on phenothiazine had led to a great number of derivatives with different activities as: neuroleptic, antihistaminic, antiallergenic, anti-inflammatory, antibacterial, anticancer, etc. [8]. In our paper we present the results regarding the synthesis of new derivatives of phenothiazine with potential pharmacological properties and the obtention of controlled release systems by their reaction with maleic anhydride copolymers. In this view several N-heterocycles with various size and composition were linked to the N-atom of the phenothiazine [9–12]. Such kind of
0014-3057/02/$ - see front matter Ó 2002 Elsevier Science Ltd. All rights reserved. PII: S 0 0 1 4 - 3 0 5 7 ( 0 2 ) 0 0 0 4 0 - X
1510
E. Bacu et al. / European Polymer Journal 38 (2002) 1509–1513
derivatives could possess new pharmacological properties by creating of some favourable synergetic effects.
standard methods. Benzene and toluene were dried over sodium. 2.2. Synthesis
2. Experimental 2.1. Materials Phenothiazine, cyanuric chloride, hydrazine hydrate 98%, b-hydroxyethylpiperazine and 2-amino-2-methyl1-propanol were obtained from Aldrich. Ethanol and acetone p.a. were used as such. Maleic anhydride (MA), N-vinylpyrrolidone (NVP), styrene (St), benzoyl peroxide and azobisisobutyronitrile were carefully purified by
2.2.1. Functionalized phenothiazinyl-S-triazine derivatives 4–6. General procedure Compounds 4–6 were obtained by the heteroarylation of phenothiazine (1) with cyanuric chloride (2) followed by nucleophilic substitution of the two chlorine atoms from 10-(4,6-dichloro-[1,3,5]triazin-2-yl)-10H-phenothiazine (3) [12] (Scheme 1). A solution of 3 (3.4 g, 10 mmol) and appropriate amino compound (hydrazine hydrate 98%, b-hydroxy-
Scheme 1. Synthesis of new phenothiazine derivatives.
E. Bacu et al. / European Polymer Journal 38 (2002) 1509–1513
ethylpiperazine or 2-amino-2-methyl-1-propanol, 46 mmol) in ethanol (40 ml) was refluxed for 2 h. After cooling and dilution with water a white product was separated and washed with water. 10-(4,6-Dihydrazino-[1,3,5]triazin-2-yl)-10H-phenothiazine (4). White solid (72%); m.p.: 276–277 °C. (C15 H14 N8 S) (338.4): Calcd. C, 53.24; H, 4.17; N, 33.11. Found C, 53.46; H, 4.19; N, 32.95. IR (KBr): 3195– 3320 (NH), 3424 (NH2 ), 1527 cm1 (C@N). 1 H NMR (DMSO-d6 ): d ¼ 4:10 (s,NH2 ), 7.20–7.80 (m,aromatic H), 8.10 (s,NH). 13 C NMR (DMSO-d6 ): d ¼ ðCHÞ 125.8, 126.3, 127.4, 129.4; (C) 132.0, 139.4, 163.4, 167.2. 2-(4-{4-[4-(2-Hydroxy-ethyl)-piperazin-1-yl]-6-phenothiazin-10-yl-[1,3,5]triazin-2-yl}-piperazin-1-yl)-ethanol (5). Recrystallization from ethanol–acetone (78%); m.p.: 242–243 °C. (C27 H34 N8 O2 S) (534.7): Calcd. C, 60.65; H, 6.41; N, 20.96. Found C, 60.96; H, 6.52; N, 21.20. IR (KBr): 3250–3550 (OH and NH), 1555 (C@N), 1030 cm1 (C–O). 1 H NMR (DMSO-d6 ): d ¼ 2:35 (m,NCH2 ), 3.48 (m,NCH2 ), 3.62 (m,OCH2 ), 4.43 (OH), 7.16–7.70 (m,aromatic H). 13 C NMR (DMSO-d6 ): d ¼ ðCH2 ) 42.7, 52.9, 58.5, 60.2; (CH) 125.8, 125.9, 127.4, 128.9; (C) 131.8, 139.1, 163.6, 164.3. 2-[4-(2-Hydroxy-1,1-dimethyl-ethylamino)-6-phenothiazin-10-yl-[1,3,5]triazin-2-yl-amino]-2-methyl-propan1-ol (bi 6). White solid (64%); m.p. 185–186 °C. (C23 H28 N6 O2 S) (452.6): Calcd. C, 61.04; H, 6.24; N, 18.57. Found C, 61.33; H, 6.38; N, 18.22. IR (KBr): 3200-3500 (NH and OH), 1450 and 1370 ðCðCH3 Þ2 Þ, 1050 cm1 (C@O). 1 H NMR (DMSO-d6 ): d ¼ 1:01 (s,CH3 ), 3.25 (s,OCH2 ), 4.84 (OH), 7.26–7.67 (m, aromatic H), 8.10 (s,NH). 13 C NMR (DMSO-d6 ): d ¼ ðCH3 Þ 23.6, (CH2 ) 53.7; (CH) 125.9, 126.3, 127.3, 129.6; (C) 68.1, 132.2, 139.4, 164.9. 2.2.2. MA copolymers MA copolymers with NVP and St were obtained by solution–suspension radical polymerization in benzene or toluene, respectively [13,14]. The chemical composition of the copolymers was assessed by conductometric titration with 0.1 N aqueous NaOH in a 1:1 mixture acetone–water [15] and confirmed by FTIR spectra. The molecular weight was estimated from viscometric measurements in acetone at 30 °C for MA–St copolymer [16] or in aqueous solution at pH ¼ 2:1 for MA–NVP copolymer [17]. The chemical structure of MA copolymers is depicted in Scheme 2 and characteristic data are reported in Table 1. 2.3. Conjugates of MA copolymers with phenothiazine derivatives The reactions between MA copolymers and the phenothiazine derivatives are given in Scheme 3. Conjugate 7 of MA–St copolymer with 4. Dihydrazine 4 (0.48 g, 1.42 mmol) was added to a solution of co-
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Scheme 2. Chemical structure of maleic anhydride copolymers.
Table 1 Maleic copolymers used for obtaining conjugates with phenothiazine derivatives Sample code
Copolymer
Ia
Copolymer composition MA:comonomer (mol)
Molecular weight
S P
MA–St MA–NVP
0.396 0.382
1:1 1:1
150,000 28,000
Ia ¼ acid number (g NaOH/g copolymer).
Scheme 3. Reaction between maleic anhydride copolymers and phenothiazine derivatives.
polymer (0.278 g, 1.37 mmol of structural unit) in dioxane (7 ml). The mixture was heated for 4 h at 60 °C. After cooling and precipitation with water the compound 7 was obtained as a white powder. Conjugate 8 of MA–NVP copolymer with 4. From a solution of copolymer (0.252 g, 1.20 mmol) and 4 (0.44 g, 1.30 mmol) in DMSO (8 ml) heated at 80°C for 3 h. Conjugate 9 of MA–St copolymer with 5. From a solution of copolymer (0.14 g, 0.69 mmol) and 5 (0.37 g, 0.69 mmol) in acetone (4.5 ml) refluxed for 4 h.
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Conjugate 10 of MA–NVP copolymer with 5. From a solution of copolymer (0.19 g, 0.91 mmol) and 5 (0.50 g, 0.91 mmol) in acetone (7 ml) refluxed for 4 h. Conjugate 11 of MA–St copolymer with 6. From a solution of copolymer (0.144 g, 0.71 mmol) and 6 (0.35 g, 0.77 mmol) in dioxane (5 ml) heated at 70°C for 5 h. Conjugate 12 of MA–NVP copolymer with 6. From a solution of copolymer (0.144 g, 0.69 mmol) and 6 (0.35 g, 0.77 mmol) in DMSO (5 ml) heated at 80°C for 5 h. 2.4. Measurements
The solubilities of the conjugates are reported in Table 2. It may be observed that the conjugates are insoluble both in DMF and in aqueous diluted alkali solution. However the conjugates having as support MA–NVP copolymers are swellable in alkali solution, due to the hydrophilic character of NVP. This fact can be expected taking into account that all phenothiazine derivatives are bulky and possess a reduced solubility. Consequently, the conjugates have been characterized by means of FTIR spectra (Table 2). In Fig. 1 the spectrum of the conjugate 7 is compared with that of functionalized phenothiazinyl-S-triazine 4 and that of
The melting points were determined on a MELTEMP II apparatus and have not been corrected. The IR spectra were recorded on a FT-IR BOMEM MB 104 spectrometer in KBr pellet from 3 to 4 mg compound and 500 mg KBr in order to facilitate the comparison. The 1 H-NMR and 13 C-NMR spectra were recorded on a Bruker AM-300 spectrometer using DMSO-d6 as solvent.
3. Results and discussion The syntheses of symmetrically functionalized phenothiazinyl-S-triazine were performed by nucleophilic substitution of both halogen atoms from the positions 40 and 60 of triazine cycle with difunctional nucleophilic agents such as an aminoalcohol or hydrazine. The elemental analysis and the NMR and FTIR data confirmed the structure and purity of all phenothiazine derivatives. Two MA copolymers were used as supports for the low molecular phenothiazine derivatives. The copolymer (P) with NVP is rather hydrophilic, while the second (S) with St is hydrophobic. The copolymer (P) is supposed to be more biocompatible, due to the presence of NVP units.
Fig. 1. FTIR spectra of the copolymer S (1), conjugate 7 (2) and phenothiazine derivative 4 (3).
Table 2 Characteristics of conjugates between S or P copolymers and phenothiazine derivatives Conjugate 7 8 9 10 11 12
IR (KBr), m, cm1 1729 (COamide ), 1576 (NHamideII ), 1780 (COcarboxylic ), 3404 (NH2 ), 2900–3350 (NH and OHassociated ) 1732 (CONHcyclic ), 1689 (COamide ), 1570 (NHamideII ), 2850–3550 (NH and OHassociated ) 1727 (COester ), 1700 (COcarboxylic ), 2500–3100 (OHcarboxylic associated ), 3200–3500 (OHalcholic associated ) 1730 (broad band CONHcyclic and COester ), 2700–3000 (OHcarboxylic ), 3100–3500 (strongly H-bonded OH group) 1781 (COcarboxylic ), 1736 (COester ), 2800–3600 (OHcarboxylic and OHalcholic associated ) 1730 (CONHcyclic ), 1682 (COester ), 2500–3350 (OHcarboxylic and OHalcholic associated )
Solubility DMF
NaOH 0.01 N solution
–
Swollen
–
Swollen
–
Swollen
Swollen
–
Swollen
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4. Conclusion Some new functionalized derivatives of phenothiazinyl-S-triazine with potential pharmacological properties were obtained by nucleophilic substitution of halogen atoms with hydrazine or amino alcohols in good yield and purity as confirmed by elemental analysis and NMR or FTIR spectra. They were reacted with maleic anhydride copolymers in mild conditions in order to obtain new conjugates which could be used as controlled release systems. Pharmacological tests of the low molecular compounds and polymeric conjugates are in progress.
References
Fig. 2. FTIR spectra of the copolymer S (1), conjugate 9 (2) and phenothiazine derivative 5 (3).
the parent copolymer S. The spectra of conjugate 9, phenothiazine derivative 5 and S are displayed in Fig. 2. It can be observed that the bands at 1780 and 1850 cm1 assigned to the unreacted maleic anhydride moities have disappeared and that new bands characteristic of the new amide or ester type functions occurred. Indeed the spectra of conjugates 7 and 8 displayed characteristic absorption bands of amide group (an intensive band at 1729 cm1 ) and characteristic absorption bands of the carboxylic group as well (two bands at 1700 and 1780 cm1 for C@O and a broad band at 2500–3100 cm1 corresponding to associated OH). The absorption patterns peculiar for phenothiazinyl-S-triazine hybrid are maintained. In the conjugates 7 and 8 the absorption of the NH2 group appears at 3404 cm1 , but only at a half of intensity, which seems to indicate that the conjugates are not crosslinked by reaction of both functions. The spectra of conjugates 9–12 exhibit new bands characteristic of the new formed ester groups located at 1730 and 1680 cm1 together with the broad bands at 2700–3000 cm1 (associated OH of the COOH group) and 3200–3500 cm1 (associated OH of a free OH group).
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