Nongnuj Muangsin | Chulalongkorn University (original) (raw)
Papers by Nongnuj Muangsin
The ability to control the morphology of nanoparticles by molecular design and synthesis is gaini... more The ability to control the morphology of nanoparticles by molecular design and synthesis is gaining increasing attention for achieving improved unique properties. In this work, we designed the chemical structure of a stabilizer for controlling the shape of selenium nanoparticles (SeNPs) via a self-assembly process. When folic acid-gallic acid-N,N,N-trimethyl chitosan (FA-GA-TMC) was used as a stabilizer, SeNPs were observed to self-organize into cubic-like structures with an average size of approximately 300 nm. In contrast to the product obtained when unmodified chitosan was used as a stabilizer, this method resulted in spherical shape with an average size of approximately 200 nm. The data suggested that the cubic-like SeNPs were controlled by a combination of electrostatic interaction, π-π stacking and hydrogen bonding between neighboring particles. Furthermore, the cubic-like SeNPs exhibited good anticancer efficacy and cellular uptake against breast cancer cells while exhibiting low toxicity against normal cells. These data demonstrates a simple approach for the shape-controlled synthesis of cubic-like SeNPs for biological applications via the self-assembly method.
![Research paper thumbnail of New azobenzene crown p-tert-butylcalix[4]arenes as switchable receptors for NA+ and K+ ions: Synthesis and isomerization studies](https://attachments.academia-assets.com/46975365/thumbnails/1.jpg)
](Two new azobenzene crown ether calix[4]arenes, 10 and 11, were synthesized by two pathways. In th... more Two new azobenzene crown ether calix[4]arenes, 10 and 11, were synthesized by two pathways. In the first pathway, two ethoxy nitrobenzene groups were attached to t-butylcalix arenes in a 1,3 position. Subsequent reduction of the nitrobenzene groups by metallic zinc in an alkaline solution afforded 10 and 11 in 8% and 12%, respectively. In the second pathway, an azobenzene containing two glycolic units was prepared prior connecting to t-butylcalix arenes. The yields from the second approach (5%, 8% for 10 and 11, respectively) were lower than those from the former approach. Single crystals of 10 suitable for X-ray crystallography was obtained by recrystallization in methanol. Both the X-ray structure and the 1 H-NMR spectrum of 10 indicated that the stereoisomer of the azobenzene moiety was trans and the calixarene platform was in cone conformation.
Acta Crystallographica Section A Foundations of Crystallography, 2011
Chemical biology & drug design, Jan 20, 2016
Human papillomavirus 16 (HPV 16) is a DNA virus that is capable of infecting humans and causing c... more Human papillomavirus 16 (HPV 16) is a DNA virus that is capable of infecting humans and causing cervical cancer. HPV16 E2 plays an important role in viral gene regulation. This work aims to predict the binding conformations and interactions between the dodecapeptides and HPV16 E2 as well as to design novel peptide inhibitors that are capable of binding to HPV16 E2 and disrupt the transcriptional regulator E1-E2 complex formation, using computational protein design techniques. Based on previously reported peptide4 (TWFWPYPYPHLP), novel peptide inhibitors were designed and five peptides that showed lower binding energy to HPV16 E2 than that of peptide4, were selected for in vitro experiments. Enzyme-linked immunosorbent (ELISA) assay showed that Y6R, W4H_Y6R and W4H peptides bound to HPV16 E2 with higher affinity than peptide 4 did. Moreover, Y6R, W4H_Y6R and W4H peptides more effectively inhibited E1-E2 complex formation than peptide 4. This work revealed important interactions betwe...
Journal of the Chemical Society, Dalton Transactions, 1997
A number of manganese() complexes of tetradentate N 2 O 2 Schiff-base ligands have been prepar... more A number of manganese() complexes of tetradentate N 2 O 2 Schiff-base ligands have been prepared with various additional carboxylate anions. Five of these compounds have been crystallographically characterised revealing that a remarkable array of structural chemistry is available. A polymeric species is observed for [{Mn(saltn)(O 2 CEt)} n ] 1, whereas a monomeric species is found in [Mn(saltn)(O 2 CBu t )] 2 [H 2 saltn = N,NЈbis(salicylidene)trimethylenediamine]. The anti-anti bridging of the manganese centres in 1 is in contrast to that in [{Mn(bsaltn)(O 2 CCH 2 Ph)} 2n ] 3 (H 2 bsaltn = 5-bromo derivative of H 2 saltn), which exhibits rare syn-anti bridging; 3 also contains a dimeric repeat unit due to an alternate 180Њ twist in the polymeric chain necessitated by steric constraints. In contrast, the complexes containing the dianion of N,NЈ-bis(3-methoxysalicylidene)ethane-1,2diamine (H 2 msalen) appear to be isostructural, [{Mn(msalen)(O 2 CEt)} 2 ]ؒEtOH 4 and [{Mn(msalen)(O 2 CBu n )} 2 ] 5 being structurally characterised as essentially identical phenoxy-bridged dimers. An insoluble material of stoichiometry Mn 4 (O 2 CR) 3 (saltn) 3 (H 2 O) n (n = 0-3) was isolated from all reactions involving the saltn ligand; attempts to characterise these compounds by X-ray diffraction have been unsuccessful. However, the previously characterised manganese() dimer [{Mn(saltn)O} 2 ]ؒ2dmf 6 (dmf = dimethylformamide) and the monomeric species [Mn(saltn)(O 2 CEt)] 7 were isolated in attempts to crystallise these materials.
Chemical Physics Letters, 2004
The solvation structure of glucosamine in aqueous solution was investigated using Monte Carlo sim... more The solvation structure of glucosamine in aqueous solution was investigated using Monte Carlo simulation at 298 K. The MCY rigid water model and ab initio glucosamine-water fitted potential were applied. The first hydration shell appears at 4.6 Å from the center of glucosamine with a coordination number of seven water molecules where one water lies in the ligandÕs plane while two and four of them are about 2-4 Å above and below the plane, respectively. Furthermore, the mobility distribution and orientation of the water molecules around the ligand have been intensively investigated and reported.
Some physicochemical and rheological properties of jackfruit seed flour and starch, isolated from... more Some physicochemical and rheological properties of jackfruit seed flour and starch, isolated from the flour were investigated. The flour had good capacities for water absorption (205%) and oil absorption (93%). Substitution of wheat flour with the seed flour, at the level of 5, 10 and 20% markedly reduced the gluten strength of the mixed dough. The Brabender amylogram (6% concentration, db) of seed starch showed that its pasting temperature was 81 °C and its viscosity was moderate, remained constant during a heating cycle and retrograded slightly on cooling. The starch showed an A-typed X-ray powder diffraction pattern.
Journal of Microencapsulation, 2015
ABSTRACT
Tetrahedron Letters, 2012
ABSTRACT Using ozonolysis of the acid-catalyzed cyclized products of (-)-nidorellol and air-autox... more ABSTRACT Using ozonolysis of the acid-catalyzed cyclized products of (-)-nidorellol and air-autoxidation as the key steps, (+)-ambrox was obtained in 53% overall yield. In the course of our synthesis, we discovered that (-)-nidorellol provided (+)-ambrox instead of the expected product, (-)-ambrox. Thus the absolute configuration of (-)-nidorellol was proved to be trans-(5R*,7R*,8R*,9S*,10R*)-labda-12,14-diene-7 alpha,8 beta-diol, which is opposite to that illustrated in a previous report. Crown Copyright
Carbohydrate Polymers, 2014
A water-soluble chitosan with improved mucoadhesion was prepared by modifying 19.4% of the amine ... more A water-soluble chitosan with improved mucoadhesion was prepared by modifying 19.4% of the amine groups of chitosan to trimethylammonium and conjugation of gluconolactone (GLU) and homocysteine thiolactone (HT) onto the remaining amine groups of the chitosan backbone. The derived trimethyl-gluconate-HT-chitosan (TM-GN-HT-chitosan) was confirmed by Fourier Transform Infrared spectroscopy, NMR and thermogravimetric analysis. The total thiol and disulfide group level on the TM-GN-HT-chitosan were 17.96 ± 0.03 and 7.36 ± 0.03 μmol/g, respectively. The water solubility of the TM-GN-HT-chitosan conjugate was 79.0 ± 0.15%, more than that of TM-chitosan and chitosan, with an enhanced solubility over a broad pH range ranging from 85.6 ± 10.4% to 58.5±1.1% maximal solubility at pH 2 to 11. Finally, TM-GN-HT-chitosan showed a nearly ∼9.5-, 5.0- and 5.6-fold higher mucoadhesiveness than chitosan at pH 1.2, 4.0 and 6.4, respectively, and was optimal at pH 4.0.
Journal of Chemical Crystallography, 2010
ABSTRACT A 1:1 co-crystal structure of 11-hydroxy-2,3,9-trimethoxy-6H-chromeno[3,4-b]chromen-12-o... more ABSTRACT A 1:1 co-crystal structure of 11-hydroxy-2,3,9-trimethoxy-6H-chromeno[3,4-b]chromen-12-one and 11-hydroxy-2,3,9-trimethoxy-chromeno[3,4-b]chromene-6,12-dione (stemonone) was crystallized from the reaction mixture of 6-deoxyclitoriacetal and methanesulfonyl chloride, and its structure was characterized by X-ray diffraction. This co-crystal crystallizes in a triclinic crystal system, space group P(−1) with unit cell parameters of a = 8.1317(3) Å, b = 9.8224(4) Å, c = 10.7268(3) Å, α = 78.116(1)°, β = 77.463(1)°, γ = 77.140(1)°, Z = 2 and V = 804.11(3) Å3. The crystal structure was solved by direct methods and refined by full-matrix least-squares on F 2 to final values of R 1 = 0.0501 and wR 2 = 0.1520. Graphical Abstract A 1:1 co-crystal structure of 11-hydroxy-2,3,9-trimethoxy-6H-chromeno[3,4-b]chromen-12-one and 11-hydroxy-2,3,9-trimethoxy-chromeno[3,4-b]chromene-6,12-dione (stemonone) is reported.
Zeitschrift für Kristallographie - New Crystal Structures, 2010
Dyes and Pigments, 2008
ABSTRACT
Acta Crystallographica Section E-structure Reports Online, 2010
RSC Adv., 2014
ABSTRACT Here, we proudly present an easy and stability one step to fabricate self-assembled nano... more ABSTRACT Here, we proudly present an easy and stability one step to fabricate self-assembled nanofibers from modified chitosan. To obtain self-assembled, well-ordered nanofibers, we designed and synthesized stearic acid-4-carboxybenzenesulfonamide-N-trimethylchitosan by only re-dispersing the compound in distilled water at a concentration of 3.33 mg/mL. The self-assembled nanofibers had a diameter of 112.23 11.96 nm with a narrow width distribution obtained through the aromatic stacking of 4-carboxybenzenesulfonamide, the hydrophobic effect of the stearic acid and the hydrogen bonding of the chitosan backbone. The intercoronal interaction of N+(CH3)3 provided an elongated axis of nanofibers. Furthermore, the ordered molecular organization of nanofibers led to high thermal stability and enhanced mucoadhesive properties compared to native chitosan, making the fabrication of these nanofibers a promising assembly method for drug delivery in acidic environment.
Natural Product Research, 2010
Biotranformation of ent-kaur-16-en-19-oic acid (1) using Psilocybe cubensis resulted in hydroxyla... more Biotranformation of ent-kaur-16-en-19-oic acid (1) using Psilocybe cubensis resulted in hydroxylated products. After two days of incubation, ent-16beta,17-dihydroxy-kauran-19-oic acid (2) was isolated. After further incubation for nine days, two novel metabolites, ent-12alpha,16beta,17-trihydroxy-kauran-19-oic acid (3) and ent-11alpha,16beta,17-trihydroxy-kauran-19-oic acid (4), were obtained. The metabolites were identified by spectroscopic methods and X-ray crystallography. Compounds 1-4 were evaluated for their cytotoxic properties against the human leukaemia K562 cell line; only compound 1 showed moderate activity.
Zeitschrift für Kristallographie - New Crystal Structures, 2004
ABSTRACT
European Journal of Pharmaceutics and Biopharmaceutics, 2014
Mucoadhesive thiolated chitosan suitable as a carrier for low water soluble drugs was designed an... more Mucoadhesive thiolated chitosan suitable as a carrier for low water soluble drugs was designed and synthesized by conjugating 5-amino-2-mercaptobenzimidazole (MBI) using methylacrylate (MA) as the linking agent. A 14.4% degree of substitution of MA, as determined by (1)H NMR analysis, and 11.86±0.01μmol thiol groups/g of polymer, as determined by Ellman's method, was obtained. The MBI-MA-chitosan had an 11-fold stronger mucoadhesive property compared to unmodified chitosan at pH 1.2, as determined by the periodic acid: Schiff colorimetric method. Chitosan, MA-chitosan and MBI-MA-chitosan were fabricated as well-formed microspheres using electrospray ionization, including an entrapment efficiency of simvastatin (SV) of over 80% for the MBI-MA-chitosan. The mucoadhesiveness of the SV-loaded MBI-MA-CS microspheres was still higher than that for SV-loaded chitosan at pH 1.2 and 6.4. The SV-loaded MBI-MA-CS microspheres revealed a reduced burst effect and an increased release rate (more than fivefold higher than pure SV) of SV over 12h.
ChemInform, 2011
ABSTRACT isolation, characterization and antiinflammatory activity of the new andirobin, thaimolu... more ABSTRACT isolation, characterization and antiinflammatory activity of the new andirobin, thaimoluccensin A (I), the new phragmalin-type limonoids, thaimoluccensins B (II) and C (III) and eight known compounds
The ability to control the morphology of nanoparticles by molecular design and synthesis is gaini... more The ability to control the morphology of nanoparticles by molecular design and synthesis is gaining increasing attention for achieving improved unique properties. In this work, we designed the chemical structure of a stabilizer for controlling the shape of selenium nanoparticles (SeNPs) via a self-assembly process. When folic acid-gallic acid-N,N,N-trimethyl chitosan (FA-GA-TMC) was used as a stabilizer, SeNPs were observed to self-organize into cubic-like structures with an average size of approximately 300 nm. In contrast to the product obtained when unmodified chitosan was used as a stabilizer, this method resulted in spherical shape with an average size of approximately 200 nm. The data suggested that the cubic-like SeNPs were controlled by a combination of electrostatic interaction, π-π stacking and hydrogen bonding between neighboring particles. Furthermore, the cubic-like SeNPs exhibited good anticancer efficacy and cellular uptake against breast cancer cells while exhibiting low toxicity against normal cells. These data demonstrates a simple approach for the shape-controlled synthesis of cubic-like SeNPs for biological applications via the self-assembly method.
Two new azobenzene crown ether calix[4]arenes, 10 and 11, were synthesized by two pathways. In th... more Two new azobenzene crown ether calix[4]arenes, 10 and 11, were synthesized by two pathways. In the first pathway, two ethoxy nitrobenzene groups were attached to t-butylcalix arenes in a 1,3 position. Subsequent reduction of the nitrobenzene groups by metallic zinc in an alkaline solution afforded 10 and 11 in 8% and 12%, respectively. In the second pathway, an azobenzene containing two glycolic units was prepared prior connecting to t-butylcalix arenes. The yields from the second approach (5%, 8% for 10 and 11, respectively) were lower than those from the former approach. Single crystals of 10 suitable for X-ray crystallography was obtained by recrystallization in methanol. Both the X-ray structure and the 1 H-NMR spectrum of 10 indicated that the stereoisomer of the azobenzene moiety was trans and the calixarene platform was in cone conformation.
Acta Crystallographica Section A Foundations of Crystallography, 2011
Chemical biology & drug design, Jan 20, 2016
Human papillomavirus 16 (HPV 16) is a DNA virus that is capable of infecting humans and causing c... more Human papillomavirus 16 (HPV 16) is a DNA virus that is capable of infecting humans and causing cervical cancer. HPV16 E2 plays an important role in viral gene regulation. This work aims to predict the binding conformations and interactions between the dodecapeptides and HPV16 E2 as well as to design novel peptide inhibitors that are capable of binding to HPV16 E2 and disrupt the transcriptional regulator E1-E2 complex formation, using computational protein design techniques. Based on previously reported peptide4 (TWFWPYPYPHLP), novel peptide inhibitors were designed and five peptides that showed lower binding energy to HPV16 E2 than that of peptide4, were selected for in vitro experiments. Enzyme-linked immunosorbent (ELISA) assay showed that Y6R, W4H_Y6R and W4H peptides bound to HPV16 E2 with higher affinity than peptide 4 did. Moreover, Y6R, W4H_Y6R and W4H peptides more effectively inhibited E1-E2 complex formation than peptide 4. This work revealed important interactions betwe...
Journal of the Chemical Society, Dalton Transactions, 1997
A number of manganese() complexes of tetradentate N 2 O 2 Schiff-base ligands have been prepar... more A number of manganese() complexes of tetradentate N 2 O 2 Schiff-base ligands have been prepared with various additional carboxylate anions. Five of these compounds have been crystallographically characterised revealing that a remarkable array of structural chemistry is available. A polymeric species is observed for [{Mn(saltn)(O 2 CEt)} n ] 1, whereas a monomeric species is found in [Mn(saltn)(O 2 CBu t )] 2 [H 2 saltn = N,NЈbis(salicylidene)trimethylenediamine]. The anti-anti bridging of the manganese centres in 1 is in contrast to that in [{Mn(bsaltn)(O 2 CCH 2 Ph)} 2n ] 3 (H 2 bsaltn = 5-bromo derivative of H 2 saltn), which exhibits rare syn-anti bridging; 3 also contains a dimeric repeat unit due to an alternate 180Њ twist in the polymeric chain necessitated by steric constraints. In contrast, the complexes containing the dianion of N,NЈ-bis(3-methoxysalicylidene)ethane-1,2diamine (H 2 msalen) appear to be isostructural, [{Mn(msalen)(O 2 CEt)} 2 ]ؒEtOH 4 and [{Mn(msalen)(O 2 CBu n )} 2 ] 5 being structurally characterised as essentially identical phenoxy-bridged dimers. An insoluble material of stoichiometry Mn 4 (O 2 CR) 3 (saltn) 3 (H 2 O) n (n = 0-3) was isolated from all reactions involving the saltn ligand; attempts to characterise these compounds by X-ray diffraction have been unsuccessful. However, the previously characterised manganese() dimer [{Mn(saltn)O} 2 ]ؒ2dmf 6 (dmf = dimethylformamide) and the monomeric species [Mn(saltn)(O 2 CEt)] 7 were isolated in attempts to crystallise these materials.
Chemical Physics Letters, 2004
The solvation structure of glucosamine in aqueous solution was investigated using Monte Carlo sim... more The solvation structure of glucosamine in aqueous solution was investigated using Monte Carlo simulation at 298 K. The MCY rigid water model and ab initio glucosamine-water fitted potential were applied. The first hydration shell appears at 4.6 Å from the center of glucosamine with a coordination number of seven water molecules where one water lies in the ligandÕs plane while two and four of them are about 2-4 Å above and below the plane, respectively. Furthermore, the mobility distribution and orientation of the water molecules around the ligand have been intensively investigated and reported.
Some physicochemical and rheological properties of jackfruit seed flour and starch, isolated from... more Some physicochemical and rheological properties of jackfruit seed flour and starch, isolated from the flour were investigated. The flour had good capacities for water absorption (205%) and oil absorption (93%). Substitution of wheat flour with the seed flour, at the level of 5, 10 and 20% markedly reduced the gluten strength of the mixed dough. The Brabender amylogram (6% concentration, db) of seed starch showed that its pasting temperature was 81 °C and its viscosity was moderate, remained constant during a heating cycle and retrograded slightly on cooling. The starch showed an A-typed X-ray powder diffraction pattern.
Journal of Microencapsulation, 2015
ABSTRACT
Tetrahedron Letters, 2012
ABSTRACT Using ozonolysis of the acid-catalyzed cyclized products of (-)-nidorellol and air-autox... more ABSTRACT Using ozonolysis of the acid-catalyzed cyclized products of (-)-nidorellol and air-autoxidation as the key steps, (+)-ambrox was obtained in 53% overall yield. In the course of our synthesis, we discovered that (-)-nidorellol provided (+)-ambrox instead of the expected product, (-)-ambrox. Thus the absolute configuration of (-)-nidorellol was proved to be trans-(5R*,7R*,8R*,9S*,10R*)-labda-12,14-diene-7 alpha,8 beta-diol, which is opposite to that illustrated in a previous report. Crown Copyright
Carbohydrate Polymers, 2014
A water-soluble chitosan with improved mucoadhesion was prepared by modifying 19.4% of the amine ... more A water-soluble chitosan with improved mucoadhesion was prepared by modifying 19.4% of the amine groups of chitosan to trimethylammonium and conjugation of gluconolactone (GLU) and homocysteine thiolactone (HT) onto the remaining amine groups of the chitosan backbone. The derived trimethyl-gluconate-HT-chitosan (TM-GN-HT-chitosan) was confirmed by Fourier Transform Infrared spectroscopy, NMR and thermogravimetric analysis. The total thiol and disulfide group level on the TM-GN-HT-chitosan were 17.96 ± 0.03 and 7.36 ± 0.03 μmol/g, respectively. The water solubility of the TM-GN-HT-chitosan conjugate was 79.0 ± 0.15%, more than that of TM-chitosan and chitosan, with an enhanced solubility over a broad pH range ranging from 85.6 ± 10.4% to 58.5±1.1% maximal solubility at pH 2 to 11. Finally, TM-GN-HT-chitosan showed a nearly ∼9.5-, 5.0- and 5.6-fold higher mucoadhesiveness than chitosan at pH 1.2, 4.0 and 6.4, respectively, and was optimal at pH 4.0.
Journal of Chemical Crystallography, 2010
ABSTRACT A 1:1 co-crystal structure of 11-hydroxy-2,3,9-trimethoxy-6H-chromeno[3,4-b]chromen-12-o... more ABSTRACT A 1:1 co-crystal structure of 11-hydroxy-2,3,9-trimethoxy-6H-chromeno[3,4-b]chromen-12-one and 11-hydroxy-2,3,9-trimethoxy-chromeno[3,4-b]chromene-6,12-dione (stemonone) was crystallized from the reaction mixture of 6-deoxyclitoriacetal and methanesulfonyl chloride, and its structure was characterized by X-ray diffraction. This co-crystal crystallizes in a triclinic crystal system, space group P(−1) with unit cell parameters of a = 8.1317(3) Å, b = 9.8224(4) Å, c = 10.7268(3) Å, α = 78.116(1)°, β = 77.463(1)°, γ = 77.140(1)°, Z = 2 and V = 804.11(3) Å3. The crystal structure was solved by direct methods and refined by full-matrix least-squares on F 2 to final values of R 1 = 0.0501 and wR 2 = 0.1520. Graphical Abstract A 1:1 co-crystal structure of 11-hydroxy-2,3,9-trimethoxy-6H-chromeno[3,4-b]chromen-12-one and 11-hydroxy-2,3,9-trimethoxy-chromeno[3,4-b]chromene-6,12-dione (stemonone) is reported.
Zeitschrift für Kristallographie - New Crystal Structures, 2010
Dyes and Pigments, 2008
ABSTRACT
Acta Crystallographica Section E-structure Reports Online, 2010
RSC Adv., 2014
ABSTRACT Here, we proudly present an easy and stability one step to fabricate self-assembled nano... more ABSTRACT Here, we proudly present an easy and stability one step to fabricate self-assembled nanofibers from modified chitosan. To obtain self-assembled, well-ordered nanofibers, we designed and synthesized stearic acid-4-carboxybenzenesulfonamide-N-trimethylchitosan by only re-dispersing the compound in distilled water at a concentration of 3.33 mg/mL. The self-assembled nanofibers had a diameter of 112.23 11.96 nm with a narrow width distribution obtained through the aromatic stacking of 4-carboxybenzenesulfonamide, the hydrophobic effect of the stearic acid and the hydrogen bonding of the chitosan backbone. The intercoronal interaction of N+(CH3)3 provided an elongated axis of nanofibers. Furthermore, the ordered molecular organization of nanofibers led to high thermal stability and enhanced mucoadhesive properties compared to native chitosan, making the fabrication of these nanofibers a promising assembly method for drug delivery in acidic environment.
Natural Product Research, 2010
Biotranformation of ent-kaur-16-en-19-oic acid (1) using Psilocybe cubensis resulted in hydroxyla... more Biotranformation of ent-kaur-16-en-19-oic acid (1) using Psilocybe cubensis resulted in hydroxylated products. After two days of incubation, ent-16beta,17-dihydroxy-kauran-19-oic acid (2) was isolated. After further incubation for nine days, two novel metabolites, ent-12alpha,16beta,17-trihydroxy-kauran-19-oic acid (3) and ent-11alpha,16beta,17-trihydroxy-kauran-19-oic acid (4), were obtained. The metabolites were identified by spectroscopic methods and X-ray crystallography. Compounds 1-4 were evaluated for their cytotoxic properties against the human leukaemia K562 cell line; only compound 1 showed moderate activity.
Zeitschrift für Kristallographie - New Crystal Structures, 2004
ABSTRACT
European Journal of Pharmaceutics and Biopharmaceutics, 2014
Mucoadhesive thiolated chitosan suitable as a carrier for low water soluble drugs was designed an... more Mucoadhesive thiolated chitosan suitable as a carrier for low water soluble drugs was designed and synthesized by conjugating 5-amino-2-mercaptobenzimidazole (MBI) using methylacrylate (MA) as the linking agent. A 14.4% degree of substitution of MA, as determined by (1)H NMR analysis, and 11.86±0.01μmol thiol groups/g of polymer, as determined by Ellman's method, was obtained. The MBI-MA-chitosan had an 11-fold stronger mucoadhesive property compared to unmodified chitosan at pH 1.2, as determined by the periodic acid: Schiff colorimetric method. Chitosan, MA-chitosan and MBI-MA-chitosan were fabricated as well-formed microspheres using electrospray ionization, including an entrapment efficiency of simvastatin (SV) of over 80% for the MBI-MA-chitosan. The mucoadhesiveness of the SV-loaded MBI-MA-CS microspheres was still higher than that for SV-loaded chitosan at pH 1.2 and 6.4. The SV-loaded MBI-MA-CS microspheres revealed a reduced burst effect and an increased release rate (more than fivefold higher than pure SV) of SV over 12h.
ChemInform, 2011
ABSTRACT isolation, characterization and antiinflammatory activity of the new andirobin, thaimolu... more ABSTRACT isolation, characterization and antiinflammatory activity of the new andirobin, thaimoluccensin A (I), the new phragmalin-type limonoids, thaimoluccensins B (II) and C (III) and eight known compounds