Hydroxypropyl Groups Research Articles

Superoxide anion scavenging activity of graft chitosan derivatives

Two kinds of graft chitosan derivatives (CMCTS- g-MAS and HPCTS- g-MAS) were prepared by the graft copolymerization of maleic acid sodium onto etherified chitosans-carboxymethyl chitosan (CMCTS) and hydroxypropyl chitosan (HPCTS), respectively. Superoxide anion scavenging activity of the derivatives was evaluated in a luminal-enhanced autoxidaton of pyrogallol by chemiluminescence techniques. Compared with chitosan, the graft chitosan derivatives have much improved scavenging ability against superoxide anion. They have similar 50% inhibition concentrations (IC 50s) as ascorbic acid and superoxide dismutase (SOD). Graft chitosan derivatives with hydroxypropyl groups have relatively higher superoxide anion scavenging ability owing to the incorporation of hydroxyl groups. The graft chitosan derivatives (HPCTS- g-MAS 1, 2, and 3) with different grafting percentages exhibit IC 50s values ranging from 243 to 308 μg/mL, which could be related to the contents of active hydroxyl and amino groups in the polymer chains.

Swelling Characteristics of Native and Chemically Modified Wheat Starches as a Function of Heating Temperature and Time

AbstractThe effects of hydroxypropylation (molar substitution, MS 0.05, 0.12, and 0.18) and cross‐linking (0.03%, 0.1%, and 0.2%) on swelling properties of wheat starch granules at several temperatures and heating times were investigated by laser diffraction particle size analysis. Starch samples were dispersed in water at temperatures ranging from 30 to 90°C, for 1 to 360 min. All starch granules exhibited distinct bimodal size distributions: small B‐granules with mean diameter of 2.3 μm and large A‐granules with mean diameter of 20.4 μm. As temperature increased, the B‐granules swelled more than A‐granules. Swelling of A‐granules sharply increased at 60°C. Swelling was more pronounced with increasing molar substitution of hydroxypropyl groups, while increased swelling was not observed in cross‐linked starches. The dependence of swelling capacity on heating time was different at 60 and 80°C as well as amongst modified starches. As heating time was prolonged, mean granule sizes for native, control, and hydroxypropylated starches at 80°C decreased after reaching maximum size due to loss of granule integrity, while those at 60°C showed no significant change.

Carboxy Ester Hydrolysis Promoted by a Dicopper(II) Macrocyclic Polyamine Complex with Hydroxypropyl Pendant Groups

AbstractA dinuclear CuII complex containing a hexaaza macrocyclic ligand bearing two 2‐hydroxypropyl pendants, 3,6,9,16,19,22‐hexaaza‐6,19‐bis(2‐hydroxypropyl)tricyclo[22.2.2.211,14]triaconta‐1,11,13,24,27,29‐hexaene (L), was synthesized. The title complex [Cu2(H−2L)Cl2]·6.5H2O was isolated as a blue crystal, orthorhombic, space group Fddd, with a = 16.4581(12), b = 32.248(2), c = 35.830(2) Å, V = 19017(2) Å3, Z = 16, R1 = 0.0690, and wR2 = 0.1546 [I > 2σ(I)]. The protonation constants of Cu2L were determined by potentiometric titration, and it was found that the alcoholic hydroxypropyl group of the complex Cu2L exhibits low pKa values of pKa1 = 7.31, pKa2 = 7.83 at 25 °C. The hydrolysis kinetics of 4‐nitrophenyl acetate (NA) promoted by the title complex have also been studied. The pH‐rate profile for Cu2L gave a sigmoidal curve and showed a second‐order rate constant of 0.39 ± 0.02 M−1 s−1 in 10% CH3CN/H2O(v/v), which is greater than that of the dinuclear CuII complex formed by a hexaaza macrocycle without pendants. The reason for the higher catalytic activity of the title complex is discussed. We found that the volume of nucleophile RO− can effect the hydrolysis of the carboxy ester, the nucleophilicity of RO− and the Lewis acidity of the metal macrocycle also affect the carboxy ester hydrolysis. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

Synthesis, structure and spectroscopy of a copper complex of the chiral pendant-arm macrocycle N,N′,N′′-tris[2S-2-hydroxypropyl]- 1,4,7-triazacyclononane

The preparation, crystal structure and spectroscopy of [Cu(H3L)](ClO4)2] (H3L = N,N′,N′′-tris[2S-hydroxypropyl]-1,4,7-triazacyclononane) is presented. The complex crystallizes in the monoclinic space group P21/c, a = 13.954(5), b = 9.700(4), c = 17.883(7) Å, β = 99.548(8)°, Z = 4; R1 = 0.0665, wR2 = 0.1826. The central copper ion is coordinated to three nitrogen atoms of the macrocycle and three oxygen atoms from the pendant hydroxypropyl groups, forming a distorted octahedral coordination sphere.

Synthese flexibler difluorierter cyclopropanoider Nucleosidanaloga / Synthesis of Flexible Difluorinated Cyclopropanoid Nucleoside Analogues

A novel class of difluorinated cyclopropanoic nucleoside analogues containing a hydroxypropyl group and a methylene spacer between the difluorocyclopropane ring and the heterocycle has been prepared.

Analytical approaches to improved characterization of substitution in hydroxypropyl cellulose.

Chemical characterization of cellulose derivatives is of high importance as it provides information about the often inhomogeneous substitution that may seriously affect the properties of these polymers in various applications. A detailed mapping of the chemical structure of these derivatives requires several advanced techniques to be employed. In this study, the average substitution and the substitution heterogeneity in two hydroxypropyl cellulose (HPC) samples from different suppliers were studied by means of NMR spectroscopy, MALDI-TOF MS, and HPAEC-PAD. (1)H and (13)C NMR provided information on the molar substitution, a parameter that could be analyzed by MALDI-TOF MS as well. In addition, the latter technique was used for determination of the distribution of the number of hydroxypropyl groups per glucose unit present in the two polymers. The heterogeneity of the substitution was studied by determining the amount of unsubstituted glucose units in the HPC samples, which was accomplished by HPAEC-PAD analysis. The results obtained suggest that the two HPC samples differ in both hydroxypropoxy content and distribution of the hydroxypropyl groups. Further, the benefits and importance of employing several analytical methods when investigating the cellulose ether substitution are demonstrated, as each method provides different kinds of information on the chemical content.

Chromatographic Determination of the Association Constants Between Psoralen Derivatives and Modified β‐Cyclodextrin: Effect of Sucrose as a Co‐enhancer Association Agent

The retention of psoralen derivatives, i.e., 8‐methoxypsoralen (8‐MOP), 5‐methoxypsoralen (5‐MOP), and trimethylpsoralen (TMP) in high performance liquid chromatography (HPLC) was investigated using a C18 bond silica column, hydroxypropyl‐β‐cyclodextrin (HP‐β‐CD) as mobile phase additive (0–19 mM) and a wide range of column temperature (−5°C–55°C). Such a study was carried out to demonstrate the potential drug complexing role of this cyclodextrin for a future application in pharmaceutical formulation. Assuming a 1:1 stoichiometry, the association constants (K) were calculated from the chromatographic data. At a column temperature of −5°C, and in a 42% water–58% methanol (v/v) mixture, K was equal to 30, 75, and 40 M−1 for the 8‐MOP/, 5MOP/, and TMP/, HP‐β‐CD associations, respectively. The thermodynamic parameters of the complexes were determined from linear van't Hoff plots for the three complexes. From the enthalpy and entropy changes, it appeared that the recognition mechanism of HP‐β‐CD for 8‐MOP and TMP was temperature dependent, and the hydrophobic effect between TMP and the flexible hydroxypropyl groups of HP‐β‐CD was counterbalanced by its steric hindrance. As well, the role of sucrose on this association was investigated. It was expected, that the sucrose would act on the psoralen derivatives/HP‐β‐CD association process by modifying the surface tension of the bulk solvent and increase the K f values.

Effects of chemical modification of wheat starch on molecular mobility as studied by pulsed 1H NMR

The effects of hydroxypropylation (0.05, 0.12, and 0.18 molar substitution (MS)) and cross-linking (0.03%, 0.1%, and 0.2%) on molecular mobility in low-moisture wheat starch were investigated by pulsed 1H NMR. Starch samples were equilibrated over an a w range of 0–0.93. Transverse relaxation ( T 2) times of the systems were obtained from single-pulse and CPMG experiments and were analysed by distributed exponential fitting. T 2s ∗ values associated with starch molecules increased with increasing MS of hydroxypropyl group, indicating increased mobility of starch chains. Proton relaxation was not significantly affected by cross-linking. The proton relaxation associated with water in control (alkali treated), hydroxypropylated and cross-linked starch showed two distinct populations for samples at a w between 0.43 and 0.93. In general, water mobility in both regions increased as a w or hydroxypropyl MS increased, while cross-linking at 0.03% and 0.1% produced little change in water mobility.

Azanonaboranes [(RNH 2)B 8H 11NHR] as possible new compounds for use in boron neutron capture therapy

The synthesis and biological in vitro and in vivo activities of possible new compounds for Boron Neutron Capture Therapy (BNCT) are reported. The azanonaboranes of the type [(RNH 2)B 8H 11NHR] are water-soluble when hydrophilic groups are introduced. The reaction of B 9H 13SMe 2 with primary amines yields azanonaboranes. Five compounds with different numbers of hydroxypropyl groups have been isolated: [(HO(CH 2) 3NH 2)B 8H 11NHCH 3] ( 4), [(HO(CH 2) 3NH 2)B 8H 11NH(CH 2) 3OH] ( 2), [((HO(CH 2) 3) 2NH)B 8H 11NHCH 3] ( 6), [((HO(CH 2) 3) 2NH)B 8H 11NH(CH 2) 3OCH 3] ( 11) and [((HO(CH 2) 3) 2NH)B 8H 11NH(CH 2) 3OH] ( 8). In vitro experiments as judged by cloning survival tests showed that two of the synthesised compounds are not toxic. The in vivo experiments were carried out with C3H/He mice bearing SCCVII tumours and C57 mice bearing B16 tumours. Compounds 2 and 6 have no particular affinity to any tissue, but are excluded from the brain.

Host-guest complexes of anionic porphyrin sensitizers with cyclodextrins

The photodynamic sensitizers zinc(II)- and palladium(II)-5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrins and 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin form 1:1 and/or 1:2 supramolecular complexes with native cyclodextrins (CD) and 2-hydroxypropyl cyclodextrins (hpCD) in aqueous neutral solutions. The formation of these assemblies causes a bathochromic shift of the porphyrin Soret band in the UV-vis spectra and a red shift of the fluorescence emission bands. The binding constants span over three orders of magnitude, from 8.1 × 102M−1to 5.4 × 105M−1(or 1.1 × 106M−2) depending on the size of the CD cavity and on the functionalization by adding 2-hydroxypropyl groups. The highest binding constants were obtained for hpβCD and hpγCD. The Nuclear Overhauser spectroscopy signals (ROESY) revealed three binding modes: i) inclusion of the porphyrin 4-sulfonatophenyl or 4-carboxyphenyl groups via the secondary face of βCD and hpβCD with sulfonic or carboxylic groups oriented towards the primary hydroxyl groups. ii) inclusion of the porphyrin groups via the primary face of γCD and hpγCD. iii) non-specific binding of the porphyrin monomers or aggregates on the cyclodextrin exterior. The inclusion host-guest complexation via i) or ii) does not influence the inherent photophysical properties of the monomeric porphyrins such as the quantum yields of fluorescence, the triplet states, and the singlet oxygen formation. Due to the deaggregation effect of cyclodextrins, the inclusion complexes remain efficient supramolecular sensitizers of singlet oxygen even under conditions of extensive aggregation in aqueous solutions.

Water mobility and textural properties of native and hydroxypropylated wheat starch gels

The effect of wheat starch concentration and degree of hydroxypropylation on the water dynamics and textural attributes of starch gels was studied using 1H NMR and texture profile analysis. Starches were prepared with molar substitution (MS) of hydroxypropyl groups of 0.05, 0.12, and 0.18. Gels were formed from modified starches at concentrations between 25 and 40%. For all gels, two distinct water fractions were identified using distributed exponential analysis of transverse relaxation results. For the less mobile fraction, T 2a ranged from 2 to 6 ms, while for the more mobile state, T 2b ranged from 20 to 200 ms. Values of both T 2a and T 2b increased with increasing moisture content and hydroxypropyl MS. Control experiments indicated that more mobile states could be associated with both the extragranular amylose gel, as well as intragranular amylopectin-rich gel. The less mobile state was associated only with granule remnants. Gel hardness decreased significantly with increasing moisture content, and with increasing hydroxypropylation. Cohesiveness increased with degree of hydroxypropylation. Results from multi-regression analysis between hardness and NMR parameters showed that the mobility and amount of water in the less mobile state was most related to gel hardness.

Characterization and intermolecular interactions of hydroxypropyl guar solutions.

Aqueous solutions of guar galactomannan and hydroxypropyl guars (HPG) with different molar substitution (MS) levels were studied using dilute solution viscometry and gel permeation chromatography. When guar is modified to HPG, the added hydroxypropyl groups sterically block the hydrogen bonding sites on the guar backbone and reduce the hydrogen bonding attractions between guar molecules. The effects of molar substitution on the intermolecular interactions are inferred from measurements of the Huggins coefficients, which measure intermolecular interactions in dilute solution, and molecular volumes, which reflect intrachain associations. The behavior can be divided into three regimes: (1) at low MS levels (0 < MS < approximately 0.4), there is a sharp decrease in intermolecular interactions as a function of MS; (2) in the intermediate range ( approximately 0.4 < MS < approximately 1.0), interactions become independent of MS; (3) at high substitution levels (MS > approximately 1.0), the temperature dependence of inter- and intramolecular hydrophobic interactions produces a temperature dependence in the Huggins coefficient and molecular volumes that is not seen at lower substitutions. By acid hydrolysis, HPG samples with a range of molecular weights and consistent polydispersities were obtained. On the basis of these samples, the Mark-Houwink-Sakurada parameters and "characteristic ratio" C(infinity) were evaluated for HPG (MS approximately 0.6) and compared to the values for guar. The HPG chain stiffens as the degree of substitution increases.

Chromatographic determination of the association constants between nimesulide and native and modified β-cyclodextrins

The retention of a non-steroidal anti-inflammatory drug (NSAID), i.e. nimesulide, in high performance liquid chromatography (HPLC) was investigated using a phenyl bond silica column and β-cyclodextrin (β-CD) or hydroxypropyl-β-cyclodextrin (HP-β-CD) as mobile phase additive (0–10 mM). Such a study was carried out in order to determine the most efficient cyclodextrin as a potential drug complexing agent for a future application in pharmaceutical formulation. Assuming a 1:1 stoichiometry, the association constants ( K) were calculated from the chromatographic data. At a column temperature of 25 °C and in a highly aqueous medium (98% phosphate buffer-2% methanol (v/v)), K was equal to 523 and 1285 M −1 for the nimesulide-β-CD and nimesulide HP-β-CD complexes, respectively. These results were consistent with the data reported previously using phase solubility studies and UV spectrophotometry. As well, the thermodynamic parameters of the inclusion complexes were determined from linear van't Hoff plots for the two inclusion complexes. From the enthalpy and entropy changes, it appeared that nimesulide interact more strongly with HP-β-CD due to a significant hydrophobic effect between the compound and the flexible hydroxypropyl groups.

Swelling of Zwitterionic Polymer Films Characterized by Spectroscopic Ellipsometry

The swelling of thin biocompatible polymeric films under water has been characterized by spectroscopic ellipsometry. The films were formed by coating a copolymer (PC 100B) onto optically flat silicon oxide surface. PC 100B has a polymethacrylate backbone bearing pendent zwitterionic phosphorylcholine (PC) groups (23 mol %), lauryl chains (47%), 2-hydroxypropyl groups (25%), and trimethoxysilane groups as cross-linker (5%). Film swelling as a result of water sorption was monitored by following the change in two ellipsometric angles (ψ and Δ) with time using dry films of a wide range of thickness. The swelling pattern was characterised by two distinct stages, an initial diffusion-controlled fast swelling, followed by a subsequent slower process controlled by the relaxation of polymer fragments. Although the fast initial stage occurred within the first minute of film immersion in water, some 50% water was absorbed into the films during this period. The rate of swelling in the second stage showed a steady decrease with the increasing annealing temperature. The equilibrated water content (fw,∞) was found to be some 60% for films annealed at 50 °C, 45% at 100 °C, and 30% at 150 °C, thus indicating that as the silyl network is strengthened with temperature its capacity for water uptake is suppressed. The values of fw,∞ calculated from the refractive indices of the films were broadly consistent with those determined separately from the increase in film thickness. This observation suggests that the swelling is almost linear over the period of the experiment and scales with the initial sample volume. The result is consistent with the assumption of homogeneous swelling used in the modeling and rules out any case II type of water distribution within these PC hydrogel films.

Synthesis and characterization of a di- N-hydroxypropylated tetraaza macrocycle and its nickel(II) and copper(II) complexes

The reaction of 5,16-dimethyl-2,6,13,17-tetraazatricyclo[14,4,0 1.18,0 7.12]docosane (L 1) with 3-bromo-1-propanol leads to a new macrocycle 2,13-bis(3-hydroxypropyl)-5,16-dimethyl-2,6,13,17-tetraazatricyclo[14,4,0 1.18,0 7.12]docosane (L 2). [Ni(L 2)]Cl 2·4H 2O ( 1), [Cu(L 2)]Cl 2·H 2O ( 2) and [Cu(L 2)](ClO 4) 2 ( 3) have been synthesized and characterized by X-ray crystallography and electronic absorption as well as by cyclic voltammetry. Crystal structures of 1 and 3 show that the metal ion has a square-planar geometry, coordinated by secondary and tertiary nitrogen donors of the macrocycle; however, these MN bond lengths are about 0.03 Å longer than those of [M(L 1)](ClO 4) 2. Furthermore, 2 reveals a distorted square-pyramidal geometry with an N 4 basal plane and oxygen atom of the pendant arm in the axial position. The electronic spectra, redox potentials and structures of the metal complexes are significantly affected by the presence of the pendant hydroxypropyl groups

Influence of degree of substitution of cyclodextrins on their colligative properties in solution

The purpose of this study was to investigate the effect of the total degree of substitution (TDS) on the colligative properties of substituted cyclodextrins (CDs; i.e., β‐ and γ‐cyclodextrins substituted with sulfobutylether or hydroxypropyl groups) in solution. The osmotic pressure (OP) of aqueous CD solutions was determined over the concentration range 100–350 mmol/kg using vapor pressure osmometry. A chloride ion‐selective electrode was used to help determine the possible mechanism for any CD–water interactions that might occur by measuring the chloride‐ion activity of a sodium chloride solution containing various CDs. Titration microcalorimetry was used to verify that sodium chloride did not interact with the CDs, thereby permitting the chloride ion activity to be utilized as an indicator of any possible CD–water interaction. The results indicate that CDs with different total degrees of substitution (TDS) exhibit different colligative properties in solution. It was observed that increases in the degree of substitution of the CD produced an increased OP. All substituted CDs exhibited an OP above their theoretical values, whereas the OP of the unsubstituted γ‐CD was below its expected value, likely due to self‐association. The results obtained with the chloride‐ion selective electrode did not exhibit a consistent trend; however, it was observed that changes in the TDS caused significant changes in the activity of chloride ions in solution. These findings are of interest in using CDs to formulate parenteral and ophthalmic solutions where the OP of the solutions must be considered. © 2001 Wiley‐Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 90:1086–1090, 2001

High-performance anion-exchange chromatography–electrospray mass spectrometry for investigation of the substituent distribution in hydroxypropylated potato amylopectin starch

The use of high-performance anion-exchange chromatography (HPAEC) with pulsed amperometric detection (PAD) coupled on-line with electrospray mass spectrometry (ESI-MS) for analysis of the substitution pattern in chemically modified starch, has been investigated. In order to characterise the distribution of substitution groups along the polymer chain, hydroxypropylated potato amylopectin starch (HPPAP) was subjected to enzymic hydrolysis, followed by analysis of the degradation products by HPAEC-PAD-MS. When using conventional chromatographic techniques for characterisation of enzymic hydrolysates, standard compounds are required for identification of the hydrolysis products. However, the on-line coupling with ESI-MS allowed identification of all products obtained, substituted as well as unsubstituted, and also of those compounds that co-eluted, without the need for standards. Further, HPAEC-PAD-MS was shown to be useful for analysis of the substitution pattern in modified starch; from results obtained it was suggested that the hydroxypropyl groups were homogeneously distributed in the amylopectin molecule. It was also shown that the starch hydrolysing enzymes were hindered by the hydroxypropyl groups and preferentially cleaved glucosidic linkages between unsubstituted glucose units.

Preparation and structural characterization of water‐soluble O‐hydroxypropyl chitin derivatives

AbstractWater‐soluble hydroxypropyl chitin (HPC) derivatives were prepared by the reaction of chitin with propylene oxide in homogeneous conditions using a dimethylacetamide/5% lithium chloride solvent system. The reaction conditions for a proper substitution of the hydroxypropyl group were an 80°C reaction temperature, 24‐h reaction time, and 48‐h aging time. 1H‐NMR and 13C‐cross‐polarization/magic angle spinning NMR spectroscopy were used for determining the substitution value and reaction site of substitution. It was found that the substitution reaction occurred mainly at the C6OH group in the chitin molecules and water‐soluble chitin derivatives could be obtained at a substitution value higher than 0.35, which is known as a critical substitution value. X‐ray diffraction analysis and FTIR spectroscopy showed that the structural characteristics of HPC derivatives were dependent on the substitution value. As the substitution value of the HPC derivative increased the α‐chitin crystal structure changed to the water‐soluble β‐chitin form in higher substitution values. Differences in the interchenic hydrogen bonding, interplanar spacing of the crystal lattice plane, and crystallinity can explain the structural changes upon substitution. The thermal decomposition temperature was also related to the characteristics of the crystalline structure, depending on a critical substitution value. © 2001 John Wiley &amp; Sons, Inc. J Appl Polym Sci 80: 2624–2632, 2001

Characterisation of the substituent distribution in hydroxypropylated potato amylopectin starch

The distribution of substituents in hydroxypropylated potato amylopectin starch (amylose deficient) modified in a slurry of granular starch (HPPAPg) or in a polymer ‘solution’ of dissolved starch (HPPAPs), was investigated. The molar substitution (MS) was determined by three different methods: proton nuclear magnetic resonance ( 1H NMR) spectroscopy, gas-liquid chromatography (GLC) with mass spectrometry, and a colourimetric method. The MS values obtained by 1H NMR spectroscopy were higher than those obtained by GLC–mass spectrometry analysis and colourimetry. The relative ratio of 2-, 3-, and 6-substitution, as well as un-, mono-, and disubstitution in the anhydroglucose unit (AGU) were determined by GLC–mass spectrometry analysis. Results obtained showed no significant difference in molar distribution of hydroxypropyl groups in the AGU between the two derivatives. For analysis of the distribution pattern along the polymer chain, the starch derivatives were hydrolysed by enzymes with different selectivities. Debranching of the polymers indicated that more substituents were located in close vicinity to branching points in HPPAPg than in HPPAPs. Simultaneous α-amylase and amyloglucosidase hydrolysis of HPPAPg liberated more unsubstituted glucose units than the hydrolysis of HPPAPs, indicating a more heterogeneous distribution of substituents in HPPAPg.

Thermoplastic Xylan Derivatives with Propylene Oxide

Polymeric xylan can be reacted with propylene oxide (PO) in aqueous alkali homogeneously. Since xylan is isolated from biomass in aqueous alkaline solution, an ‘in-line’ modification with PO as part of the isolation protocol, is most practical. Hydroxypropyl xylan (HPX) is a low molecular weight, branched, water-soluble polysaccharide with low intrinsic viscosity and thermoplasticity. Following peracetylation of HPX in formamide solution, water-insoluble acetoxypropyl xylan (APX) is formed that is also thermoplastic but no longer water soluble. The glass transition temperature (T g) of APX varies in relation to degree of substitution with hydroxypropyl groups (DSPO), and this is found to decline from 160 to 70°C as DSPO rises from 0.2 to 2.0. At a temperature above the T g of HPX a molecular reorganization is noted, and a faint transition due to melting (T m) is observed at 205°C. HPX thermally degrades with a weight loss maximum at 317°C, or approximately 60°C below that of a corresponding cellulose derivative. HPX forms clear films when solvent cast from aqueous solution. Films are higher in ultimate tensile strength and lower in toughness than corresponding cellulose derivative films. The properties of HPX and APX derivatives qualify this material as a potential biodegradable and thermoplastic additive to melt-processed plastics. Blend characteristics with polystyrene reveal a shear-thinning effect in melt and a plasticization effect in solid state.