Thiolated polymers: evidence for the formation of disulphide bonds with mucus glycoproteins

Leitner, Verena M.; Walker, Greg F.; Bernkop‐Schnürch, Andreas

doi:10.1016/s0939-6411(03)00061-4

Cited by 353 publications

(183 citation statements)

References 21 publications

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“…The covalent attachment of cysteine to xyloglucan was achieved by the formation of ester bonds between the hydroxyl group of the xyloglucan and a carboxylic acid group of the cysteine (Leitner et al, 2003;Bilicic et al, 2005). Xyloglucan-cysteine thiomer was prepared by adapting the procedure given in the literature (Constantia et al, 2001).…”

Section: Synthesis Of Xyloglucan-cysteine Conjugatesmentioning

confidence: 99%

Synthesis and characterization of a cysteine xyloglucan conjugate as mucoadhesive polymer

Bhalekar¹,

Sonawane

Shimpi³

2013

Braz. J. Pharm. Sci.

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The aim of this study was to improve the mucoadhesive potential of xyloglucan polymer by the covalent attachment of cysteine as thiol moiety. The parent polymer xyloglucan was chemically modified by introducing sulphydryl bearing compound L-cysteine HCl. Different batches of xyloglucan-cysteine conjugates were prepared at varying reaction pH (2-6) and evaluated for optimum thiol incorporation, disulphide group content, swelling behavior, rheological properties and mucoadhesive properties. The obtained conjugates characterized in vitro by quantification of immobilized thiol groups; showed maximum thiol incorporation on xyloglucan (7.67 ± 0.14 %) at pH 5. The disulphide group content was found maximum (2.83 ± 0.12) at pH 6. The water uptake at end of 4 h was 5.0 for xyloglucan and was found to decrease in thiolated derivatives with increase in thiolation. Mucoadhesion studies revealed that mucoadhesion of xyloglucan-cysteine conjugate increased more than twice compared to the unmodified polymer. The viscosity of thiomer was more than that of xyloglucan because of formation of disulphide bonds.Uniterms: Mucoadhesion. Thiomer. Xyloglucan. L-cysteine HCl.O objetivo deste estudo foi melhorar o potencial mucoadesivo do polímero xiloglicano pela ligação covalente de cisteína como unidade de tiol. O polímero xiloglicano foi quimicamente modificado pela introdução de cloridrato de cisteína como grupo contendo sulfidrila. Prepararam-se diferentes lotes de conjugados cisteína-xiloglicano em pH variando de 2 a 6, avaliando-se a incorporação ótima de tiol, o conteúdo de dissulfeto, o comportamento de inchamento, as propriedades reológicas e mucoadesivas. Os conjugados obtidos foram caracterizados in vitro pela quantificação de grupos tiol, mostrando máxima incorporação na xiloglicana (7.67 ± 0.14 %) em pH 5. O conteúdo de grupos dissulfeto foi máximo (2.83 ± 0.12) em pH 6. O índice de inchamento em % no fim de 4 h foi 83.87 para o xiloglicano e diminuiu para os derivados tiolados. O conteúdo foi mínimo para TH2 (78.26), aumentou pouco até TH5 (83.33) e diminuiu, posteriormente, para TH6 (80.13). Os estudos de mucoadesão revelaram que o conjugado xiloglicano-cisteína aumentou mais que duas vezes comparativamente ao polímero não modificado. A viscosidade do tiômero foi maior do que a do xiloglicano devido à formação das ligações dissulfeto.

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Section: Synthesis Of Xyloglucan-cysteine Conjugatesmentioning

confidence: 99%

Synthesis and characterization of a cysteine xyloglucan conjugate as mucoadhesive polymer

Bhalekar¹,

Sonawane

Shimpi³

2013

Braz. J. Pharm. Sci.

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“…This additional improvement in the mucoadhesive properties of carbo is believed to be based on the formation of disulfide bonds between thiol groups of the thiomer and cysteine-rich subdomains of mucus glycoproteins (Leitner et al, 2003). Due to the covalent attachment of the gel-formed microparticles to the nasal mucus, the residence time of carbocys-based microparticles is longer compared to carbo microparticles.…”

Section: Discussionmentioning

confidence: 99%

Insulin delivery through nasal route using thiolated microspheres

Nema

Jain

et al. 2013

Drug Delivery

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The aim of the present study was to investigate the potential of developed thiolated microspheres for insulin delivery through nasal route. In the present study, cysteine was immobilized on carbopol using EDAC. A total of 269.93 mmol free thiol groups per gram polymer were determined. The prepared nonthiolated and thiolated microspheres were studied for particle shape, size, drug content, swellability, mucoadhesion and in vitro insulin release. The thiolated microspheres exhibited higher mucoadhesion due to formation of covalent bonds via disulfide bridges with the mucus gel layer. Drug permeation through goat nasal mucosa of nonthiolated and thiolated microspheres were found as 52.62 AE 2.4% and 78.85 AE 3.1% in 6 h, respectively. Thiolated microspheres bearing insulin showed better reduction in blood glucose level (BGL) in comparison to nonthiolated microspheres as 31.23 AE 2.12% and 75.25 AE 0.93% blood glucose of initial BGL were observed at 6 h after nasal delivery of thiolated and nonthiolated microspheres in streptozotocin-induced diabetic rabbits.

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“…Thiolation reaction with Traut's reagent (2-iminothiolane) has the advantages of being a one-step reaction and protecting the thiolating agent from oxidation. The degree of thiol substitution in thiolated chitosan can be obtained based on Ellman's method for assaying thiols [33][34][35][36][37][38][39][40][41][42][43]. Thiolated chitosan possesses better mucoadhesiveness and permeation properties as compared to unmodified chitosan [33][34][35][36][37][38][39][40][41][42][43].…”

Section: Thiolationmentioning

confidence: 99%

“…Nanoparticles of thiolated chitosan may be obtained as a result of an ionic cross-linking reaction of thiolated chitosan with TPP [100]. Thiolated chitosan nanoparticles have been studied for applications in drug delivery as well as for permeation enhancement [33][34][35][36][37][38][39][40][41][42][43].…”

Section: Thiolationmentioning

confidence: 99%

“…Thus, in the current chapter, an overview on the drug delivery applications of cross-linked [23] and chemically modified chitosan is given. Important modified and cross-linked derivatives include carboxymethyl-chitosan (CMC), O-carboxymethyl-chitosan (O-CMC), N,O-carboxymethyl-chitosan (N,O-CMC) and N-carboxymethyl-chitosan (N-CMC) [14][15][16][17][18][19], succinylchitosan [24][25][26][27][28][29][30][31][32], thiolated chitosan [33][34][35][36][37][38][39][40][41][42][43], and chitosan grafted with PNIPAAm and PNVCL (chitosang-PNIPAAm and chitosan-g-PNVCL) [44][45][46][47].…”

Section: Introductionmentioning

confidence: 99%

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