Accelerated synthesis of phthalimide derivatives: Intrinsic reactivity of diamines towards phthalic anhydride evaluated by paper spray ionization mass spectrometry

RATIONALE

Paper spray (PS) is a simple and innovative ambient ionization technique for mass spectrometry (MS) analysis. Under PS-MS conditions, chemical reactions, which usually occur slowly on a bulk scale, are accelerated. Moreover, the formation of products and transient species can be easily monitored. In this manuscript, reactions between phthalic anhydride and diamines were conducted and monitored using a PS-MS platform. The reaction products (phthalimides) have many pharmaceutical applications, but their traditional syntheses can take hours under reflux, requiring laborious purification steps.

METHODS

In situ reactions were performed by dropping methanolic solutions of phthalic anhydride and diamines on a triangular paper. The analyses were achieved by positioning the triangle tip in front of the mass spectrometer entrance, whereas a metal clip was attached to the triangle base. After adding methanol to the paper, a high voltage was applied across the metal clip, and the mass spectra were acquired.

RESULTS

The intrinsic reactivity of alkyl and aromatic diamines was evaluated. The carbon chain remarkably influenced the reactivity of aliphatic diamines. For aryl diamines, the ortho isomer was the most reactive. Moreover, for aryl amines with electron-withdrawing substituents, no reaction was noticed.

CONCLUSIONS

Taking advantage of the unique characteristics of PS-MS, it was possible to investigate the intrinsic reactivity of model alkyl (ethylene versus propylene) and aryl (o-phenylene versus m-phenylene and p-phenylene) diamines towards phthalic anhydride. Some crucial parameters that affect the intrinsic reactivity of organic molecules, such as isomerism, intramolecular interaction, and conformation, were easily explored.

Microbial Synthesis and Evaluation of Fungistatic Activity of 3-Butyl-3-hydroxyphthalide, the Mammalian Metabolite of 3-n-Butylidenephthalide

Phthalides are bioactive compounds that naturally occur in the family Apiaceae. Considering their potentially versatile applications, it is desirable to determine their physical properties, activity and metabolic pathways. This study aimed to examine the utility of whole-cell biocatalysts for obtaining 3-butyl-3-hydroxyphthalide, which is the metabolite formulated during mammalian metabolism of 3-n-butylidenephthalide. We performed transformations using 10 strains of fungi, five of which efficiently produced 3-butyl-3-hydroxyphthalide. The product yield, determined by high-performance liquid chromatography, reached 97.6% when Aspergillus candidus AM 386 was used as the biocatalyst. Increasing the scale of the process resulted in isolation yields of 29–45% after purification via reversed-phase thin layer chromatography, depending on the strain of the microorganism used. We proposed different mechanisms for product formation; however, hydration of 3-n-butylidenephthalide seems to be the most probable. Additionally, all phthalides were tested against clinical strains of Candida albicans using the microdilution method. Two phthalides showed a minimum inhibitory concentration, required to inhibit the growth of 50% of organisms, below 50 µg/mL. The 3-n-butylidenephthalide metabolite was generally inactive, and this feature in combination with its low lipophilicity suggests its involvement in the detoxification pathway. The log P value of tested compounds was in the range of 2.09–3.38.

Phthalic anhydride esterified chicha gum: characterization and antibacterial activity

The objective of this research was to modify chicha gum with phthalic anhydride to obtain a new biologically active material. The chemical modification of the gum structure was proven through FTIR, elemental analysis, XRD, TG, and DSC. The derived materials demonstrated excellent inhibitory effect against P. aeruginosa and K. pneumoniae species (rating 100% inhibition) and could also inhibit Escherichia coli growth. The best antimicrobial activity observed for the derivatives suggests that chicha gum hydrophobization due to the addition of phthalic groups improved the interaction of these derivatives with bacterial cell wall components. On the other hand, the derivatives increased CC₅₀ in macrophages but did not present acute toxicity or hemolytic activity, indicating that they are promising for use in prophylaxis or treatment of infections caused by Gram-negative bacteria.

Antitumor Effects of N-Butylidenephthalide Encapsulated in Lipopolyplexs in Colorectal Cancer Cells

Colorectal cancer (CRC) is the third most common type of cancer and the second most common cause of cancer-related death in the world. N-Butylidenephthalide (BP), a natural compound, inhibits several cancers, such as hepatoma, brain tumor and colon cancer. However, due to the unstable structure, the activity of BP is quickly lost after dissolution in an aqueous solution. A polycationic liposomal polyethylenimine and polyethylene glycol complex (LPPC), a new drug carrier, encapsulates both hydrophobic and hydrophilic compounds, maintains the activity of the compound, and increases uptake of cancer cells. The purpose of this study is to investigate the antitumor effects and protection of BP encapsulated in LPPC in CRC cells. The LPPC encapsulation protected BP activity, increased the cytotoxicity of BP and enhanced cell uptake through clathrin-mediated endocytosis. Moreover, the BP/LPPC-regulated the expression of the p21 protein and cell cycle-related proteins (CDK4, Cyclin B1 and Cyclin D1), resulting in an increase in the population of cells in the G₀/G₁ and subG₁ phases. BP/LPPC induced cell apoptosis by activating the extrinsic (Fas, Fas-L and Caspase-8) and intrinsic (Bax and Caspase-9) apoptosis pathways. Additionally, BP/LPPC combined with 5-FU synergistically inhibited the growth of HT-29 cells. In conclusion, LPPC enhanced the antitumor activity and cellular uptake of BP, and the BP/LPPC complex induced cell cycle arrest and apoptosis, thereby causing death. These findings suggest the putative use of BP/LPPC as an adjuvant cytotoxic agent for colorectal cancer.

Potential of Cellulose Functionalized with Carboxylic Acid as Biosorbent for the Removal of Cationic Dyes in Aqueous Solution

In the last decade, adsorption has been used to minimize the pollution caused by dyes, which represents a serious environmental problem. In this context, this work reports the preparation of phthalic anhydride-modified cellulose (PhCel), through the reaction of cellulose (Cel) with phthalic anhydride (Ph). The efficiency of the reaction was observed by elemental analysis, Fourier Transform Infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and thermogravimetry/derivative thermogravimetry (TG/DTG). The adsorbent matrix (Cel and PhCel) was used in the removal of crystal violet (CV) and methylene blue (MB) dyes in aqueous medium. In the kinetic study, the experimental data obtained had the best fit to the pseudo-first-order model. In general, the isotherms obtained at different temperatures had a best fit to the model proposed by Langmuir, and the CV and MB adsorption process in adsorbent matrixes can be favored strictly by hydrogen bonds and/or electrostatic interactions for Cel and electrostatic interactions for PhCel.

Substituted Phthalic Anhydrides from Biobased Furanics: A New Approach to Renewable Aromatics

A novel route for the production of renewable aromatic chemicals, particularly substituted phthalic acid anhydrides, is presented. The classical two-step approach to furanics-derived aromatics via Diels-Alder (DA) aromatization has been modified into a three-step procedure to address the general issue of the reversible nature of the intermediate DA addition step. The new sequence involves DA addition, followed by a mild hydrogenation step to obtain a stable oxanorbornane intermediate in high yield and purity. Subsequent one-pot, liquid-phase dehydration and dehydrogenation of the hydrogenated adduct using a physical mixture of acidic zeolites or resins in combination with metal on a carbon support then allows aromatization with yields as high as 84 % of total aromatics under relatively mild conditions. The mechanism of the final aromatization reaction step unexpectedly involves a lactone as primary intermediate.

Gas separation performance of carbon molecular sieve membranes based on 6FDA-mPDA/DABA (3:2) polyimide

6FDA-mPDA/DABA (3:2) polyimide was synthesized and characterized for uncross-linked, thermally crosslinked, and carbon molecular sieve (CMS) membranes. The membranes were characterized with thermogravimetric analysis, FTIR spectroscopy, wide-angle X-ray diffraction, and gas permeation tests. Variations in the d spacing, the formation of pore structures, and changes in the pore sizes of the CMS membranes were discussed in relation to pyrolysis protocols. The uncross-linked polymer membranes showed high CO2 /CH4 selectivity, whereas thermally crosslinked membranes exhibited significantly improved CO2 permeability and excellent CO2 plasticization resistance. The CMS membranes showed even higher CO2 permeability and CO2 /CH4 selectivity. An increase in the pyrolysis temperature resulted in CMS membranes with lower gas permeability but higher selectivity. The 550 °C pyrolyzed CMS membranes showed CO2 permeability as high as 14 750 Barrer with CO2 /CH4 selectivity of approximately 52. Even 800 °C pyrolyzed CMS membranes still showed high CO2 permeability of 2610 Barrer with high CO2 /CH4 selectivity of approximately 118. Both polymer membranes and the CMS membranes are very attractive in aggressive natural gas purification applications.

Synthesis and properties of a bio-based epoxy resin with high epoxy value and low viscosity

A bio-based epoxy resin (denoted TEIA) with high epoxy value (1.16) and low viscosity (0.92 Pa s, 258C) was synthesized from itaconic acid and its chemical structure was confirmed by 1H NMR and 13C NMR spectroscopy. Its curing reaction with poly(propylene glycol) bis(2-aminopropyl ether) (D230) and methyl hexahydrophthalic anhydride (MHHPA) was investigated. For comparison, the commonly used diglycidyl ether of bisphenol A (DGEBA) was also cured with the same curing agents. The results demonstrated that TEIA showed higher curing reactivity towards D230/MHHPA and lower viscosity compared with DGEBA, resulting in the better processability. Owing to its high epoxy value and unique structure, comparable or better glass transition temperature as well as mechanical properties could be obtained for the TEIA-based network relative to the DGEBA-based network. The results indicated that itaconic acid is a promising renewable feedstock for the synthesis of bio-based epoxy resin with high performance.

A novel fluorinated polyimide surface with petal effect produced by electrospinning

Superhydrophobic surfaces with strong adhesion to water droplets are drawing great attention due to their unique applications. In this communication, we propose a method to construct such surfaces with considerably strong solid-water adhesion. A novel fluorinated polyimide (FPI), was electrospun into dented nano and/or micro bowl-like particles linked with nanofibers. Surfaces consisting of such structures present robust superhydrophobicity as well as ultra high adhesion. A physical model is built to explain the generation of high adhesion on the revolutionary electrospun structures.

Study of yellow luminescence of binary terbium complexes based on 3,3',4,4'-biphthalic anhydride

Three novel binary Tb(III) complexes (TbL2, TbL, and Tb2L; L=3,3',4,4'-biphenyl tetracarboxylic ligand) were synthesized by changing the molar ratio of Tb(III) to 3,3',4,4'-biphthalic anhydride (BPDA) (1∶2, 1∶1, and 2∶1, respectively). IR spectra indicate that there are two coordination modes of the carboxylate ligands with Tb3+ ions in the complexes. Most of them are in bridging mode; the others are in chelating mode. These complexes all have good thermal stability. The photophysical properties of these complexes are studied in detail using UV absorption spectra, fluorescence spectra, and transient fluorescence spectra. The results indicate that the photoluminescence properties of the complexes depend strongly on the molar ratio of Tb(III) to BPDA. When the molar ratio of Tb(III) to BPDA is 1∶1, complex TbL exhibits the strongest yellow light emission among the three Tb(III) complexes. However, complex Tb2L exhibits a weaker yellowish-green light emission when the molar ratio of Tb(III) to BPDA is 2∶1. The phenomenon of the yellow emission from terbium complexes is rarely reported.

Synthesis of water-dispersible zinc oxide quantum dots with antibacterial activity and low cytotoxicity for cell labeling

Typical photoluminescent semiconductor nanoparticles, called quantum dots (QDs), have potential applications in biological labeling. When used to label stem cells, QDs may impair the differentiation capacity of the stem cells. In this study, we synthesized zinc oxide (ZnO) QDs in methanol with an average size of ∼2 nm. We then employed two different types of polyethylene glycol (PEG) molecules (SH-PEG-NH2 and NH2-PEG-NH2) to conjugate ZnO QDs and made them water-dispersible. Fourier transform infrared spectroscopy spectra indicated the attachment of PEG molecules on ZnO QDs. No obvious size alteration was observed for ZnO QDs after PEG conjugation. The water-dispersible ZnO QDs still retained the antibacterial activity and fluorescence intensity. The cytotoxicity evaluation revealed that ZnO QDs at higher concentrations decreased cell viability but were generally safe at 30 ppm or below. Cell lines of hepatocytes (HepG2), osteoblasts (MC3T3-E1) and mesenchymal stem cells (MSCs) were successfully labeled by the water-dispersible ZnO QDs at 30 ppm. The ZnO QD-labeled MSCs maintained their stemness and differentiation capacity. Therefore, we conclude that the water-dispersible ZnO QDs developed in this study have antibacterial activity, low cytotoxicity, and proper labeling efficiency, and can be used to label a variety of cells including stem cells.

External validation of structure-biodegradation relationship (SBR) models for predicting the biodegradability of xenobiotics

Biodegradation is an important mechanism for eliminating xenobiotics by biotransforming them into simple organic and inorganic products. Faced with the ever growing number of chemicals available on the market, structure-biodegradation relationship (SBR) and quantitative structure-biodegradation relationship (QSBR) models are increasingly used as surrogates of the biodegradation tests. Such models have great potential for a quick and cheap estimation of the biodegradation potential of chemicals. The Estimation Programs Interface (EPI) Suite™ includes different models for predicting the potential aerobic biodegradability of organic substances. They are based on different endpoints, methodologies and/or statistical approaches. Among them, Biowin 5 and 6 appeared the most robust, being derived from the largest biodegradation database with results obtained only from the Ministry of International Trade and Industry (MITI) test. The aim of this study was to assess the predictive performances of these two models from a set of 356 chemicals extracted from notification dossiers including compatible biodegradation data. Another set of molecules with no more than four carbon atoms and substituted by various heteroatoms and/or functional groups was also embodied in the validation exercise. Comparisons were made with the predictions obtained with START (Structural Alerts for Reactivity in Toxtree). Biowin 5 and Biowin 6 gave satisfactorily prediction results except for the prediction of readily degradable chemicals. A consensus model built with Biowin 1 allowed the diminution of this tendency.

Plasma protein adsorption to nanofabricated fluorinated polyimide surface

In this article, a series of fluorinated polyimides rubbed at different pressures was prepared, and the plasma protein adsorption on the rubbed polyimide films was evaluated using a micro-bicinchoninic acid protein assay. Interestingly, the amount of plasma protein adsorbed on the polyimide surface strongly depended on the rubbing pressure. The amounts of BSA and Fbg adsorbed on the rubbed polyimide film significantly decreased with an increase in the rubbing pressure. In contrast, the amounts of IgG adsorbed on the rubbed film dramatically increased with an increase in the rubbing pressure. In particular, it is interesting to note that a specific adsorption surface for IgG is formed by the rubbing process. We proposed that the nano-ordered hydrophilic and hydrophobic patternings formed on the top and bottom surfaces on the rubbed fluorinated polyimide film might have a significant influence on the plasma protein adsorption.

[Antiviral activity of 3-hydroxyphthalic anhydride-modified ovalbumin against herpes simplex virus 2 in vitro]

OBJECTIVE

To investigate the antiviral activity of 3-hydroxyphthalic anhydride-modified ovalbumin (HP-OVA) against herpes simplex virus 2 (HSV-2) in vitro.

METHODS

By chemical modification, ovalbumin (OVA) was treated with 3-hydroxyphthalic anhydride (HP) to prepare HP-OVA. The anti-HSV-2 activity against HSV-2 333 virus in vitro and the cytotoxicity of HP-OVA in African green monkey kidney cells (Vero cells) were detected by MTT colorimetric assay. The inhibitory effects of HP-OVA on 17 strains of vaginal lactobacilli were observed by microscopy.

RESULTS

Anhydride-modified ovalbumin significantly inhibited the infection by HSV-2 with an IC(50) of 23.56±8.33 µg/ml. HP-OVA showed only low cytotoxicity to the host cells with a CC(50) over 1 mg/ml. HP-OVA did not produce significant inhibitory effect on the 17 strains of vaginal lactobacilli (MIC>1 mg/ml).

CONCLUSION

Anhydride-modified protein HP-OVA exhibits potent anti-HSV-2 activity in vitro and can be a good microbicide candidate for prevention of sexually transmitted diseases.

(Z)-3-butylidenephthalide from Ligusticum porteri , an α-glucosidase inhibitor

An extract from the roots of Ligusticum porteri, orally administered to groups of normal and diabetic mice, showed significant hypoglycemic and antihyperglycemic effects. Experimental type-II DM was achieved by treating mice with streptozotocin 15 min after an injection of β-nicotinamide adenine dinucleotide. (Z)-6,6',7,3'α-diligustilide (1), (Z)-ligustilide (2), 3-(Z)-butylidenephthalide (3), myristicin (4), and ferulic acid (5) were isolated from the active extract. When tested In Vivo, compounds 1-3 showed antihyperglycemic activity, with 3 being the most active. Compound 3 (56.2 mg/kg) decreased blood glucose levels in NAD-STZ-diabetic mice after an oral sucrose load, suggesting that its antihyperglycemic effect is due to inhibition of α-glucosidase at the intestinal level. Furthermore, 3 inhibited the activity of yeast-α-glucosidase (IC(50) 2.35 mM) in a noncompetitive fashion with a K(i) of 4.86 mM. Docking analysis predicted that 3 binds to the enzyme in a pocket close to the catalytic site, but different from that for acarbose, with a K(i) of 11.48 mM. Compounds 1 and 2 did not affect α-glucosidase In Vivo, but altered glucose absorption by a mechanism yet to be determined. The stimulatory effect of 5 on insulin secretion, present in high amounts in the extract, has been demonstrated in previous investigations. The present study provides scientific support of the use of L. porteri in Mexican folk medicine for the treatment of diabetes.

In vitro evaluation of ketoprofen controlled release from various formulations

The aim of this study is to investigate the potential utility of some hydrogels, based on chitosan, chitosan modified with phthalic anhydride and 75/25 poly(N-isopropyl acrylamide)/alginate, for preparing drug release systems containing ketoprofen, as model drug.

MATERIAL AND METHOD

The in vitro release profiles and swelling studies were done in ethanol medium, where the studied drug presents high solubility, at 25 degrees C (room temperature). The ketoprofen release was observed by monitoring the absorbance at max = 254 nm as a function of time.

RESULTS

The experimental results indicated that the smallest amount of drug was released from chitosan matrices, appreciatively 31%.

CONCLUSIONS

The composition of hydrogels had an important effect on ketoprofen release.

Shear horizontal guided wave modes to infer the shear stiffness of adhesive bond layers

This paper presents a non-destructive, ultrasonic technique to evaluate the quality of bonds between substrates. Shear-horizontally polarized (SH) wave modes are investigated to infer the shear stiffness of bonds, which is necessarily linked to the shear resistance that is a critical parameter for bonded structures. Numerical simulations are run for selecting the most appropriate SH wave modes, i.e., with higher sensitivity to the bond than to other components, and experiments are made for generating-detecting pre-selected SH wave modes and for measuring their phase velocities. An inverse problem is finally solved, consisting of the evaluation of the shear stiffness modulus of a bond layer at different curing times between a metallic plate and a composite patch, such assembly being investigated in the context of repair of aeronautical structures.

Dynamic nature of the ligustilide complex

Monomeric phthalides such as Z-ligustilide (1) and Z-butylidenephthalide (2) are major constituents of medicinal plants of the Apiaceae family. While 1 has been associated with a variety of observed biological effects, it is also known for its instability and rapid chemical degradation. For the purpose of isolating pure 1 and 2, a gentle and rapid two-step countercurrent isolation procedure was developed. From a supercritical CO2 fluid extract of Angelica sinensis roots, the phthalides were isolated with high GC-MS purities of 99.4% for 1 and 98.9% for 2 and consistently lower qHNMR purities of 98.1% and 96.4%, respectively. Taking advantage of molarity-based qHNMR methodology, a time-resolved study of the dynamic changes and residual complexity of pure 1 was conducted. GC-MS and (qH)NMR analysis of artificially degraded 1 provided evidence for the phthalide degradation pathways and optimized storing conditions. Parallel qHNMR analysis led to the recognition of variations in time- and process-dependent sample purity and has impact on the overall assessment of time-dependent changes in complex natural products systems. The study underscores the importance of independent quantitative monitoring as a prerequisite for the biological evaluation of labile natural products such as monomeric phthalides.

Improvement of activity and stability of chloroperoxidase by chemical modification

Background

Enzymes show relative instability in solvents or at elevated temperature and lower activity in organic solvent than in water. These limit the industrial applications of enzymes.

Results

In order to improve the activity and stability of chloroperoxidase, chloroperoxidase was modified by citraconic anhydride, maleic anhydride or phthalic anhydride. The catalytic activities, thermostabilities and organic solvent tolerances of native and modified enzymes were compared. In aqueous buffer, modified chloroperoxidases showed similar K_m values and greater catalytic efficiencies k_cat/K_m for both sulfoxidation and oxidation of phenol compared to native chloroperoxidase. Of these modified chloroperoxidases, citraconic anhydride-modified chloroperoxidase showed the greatest catalytic efficiency in aqueous buffer. These modifications of chloroperoxidase increased their catalytic efficiencies for sulfoxidation by 12%~26% and catalytic efficiencies for phenol oxidation by 7%~53% in aqueous buffer. However, in organic solvent (DMF), modified chloroperoxidases had lower K_m values and higher catalytic efficiencies k_cat/K_m than native chloroperoxidase. These modifications also improved their thermostabilities by 1~2-fold and solvent tolerances of DMF. CD studies show that these modifications did not change the secondary structure of chloroperoxidase. Fluorescence spectra proved that these modifications changed the environment of tryptophan.

Conclusion

Chemical modification of epsilon-amino groups of lysine residues of chloroperoxidase using citraconic anhydride, maleic anhydride or phthalic anhydride is a simple and powerful method to enhance catalytic properties of enzyme. The improvements of the activity and stability of chloroperoxidase are related to side chain reorientations of aromatics upon both modifications.

Preparation and characterization of phthalated cellulose derivatives in room-temperature ionic liquid without catalysts

Homogeneous modification of cellulose, isolated with 10% KOH from delignified sugarcane bagasse, was performed in room-temperature ionic liquid 1-allyl-3-methylinidazolium chloride with phthalic anhydride in the absence of catalyst. The results showed the degree of substitution of phthalated cellulosic derivatives, ranging from 0.10 to 0.73, increased with the increment of reaction temperature, reaction time, and the molar ratio of phthalic anhydride/anhydroglucose units in cellulose under the conditions given. The products were characterized by FT-IR and solid-state CP/MAS 13C NMR spectroscopy as well as thermal analysis, and the results revealed that the phthalation reaction at C-6, C-2, and C-3 positions of the cellulose all occurred. The thermal stability of the phthalated cellulose was found to decrease upon chemical modification. However, this thermal stability of the phthalated cellulose over 200 degrees C is rather satisfactory.

Thalidomide Analogs from Diamines: Synthesis and Evaluation as Inhibitors of TNF-.ALPHA. Production

Fourteen thalidomide analogs bearing two phthalimido units were prepared in high yields (83-94%) by condensation of different diamines with phthalic or 3-nitrophthalic anhydride. An in vitro investigation of the compounds as inhibitors of the TNF-alpha production was performed. The inhibition was higher for compounds bearing amino and nitro groups and was modulated by increasing the size of the spacers between the phthalimide groups.

[High performance liquid chromatography-mass spectrometry analysis of radix Angelica sciensis]

AIM

To analyze the chemical components in Danggui (the roots of Angelica sinensis (Oliv.) Diel).

METHODS

HPLC-MS/MS was used to identify the main components in Danggui. Furthermore, the MS fragmentation regularity of the phthalides was proposed. The mobile phase of HPLC consisted of 0.5% acetic acid in water and 0.5% acetic acid in acetonitrile, analytical column was Hypersil ODS2 (250 mm x 4.6 mm, 5 microm), flow rate 1.0 mL x min(-1), injected volume 2 microL. The ionization source was ESI in positive ion mode.

RESULTS

Ferulic acid, nine known phthalides and one unknown phthalide derivative were tentatively identified in chromatograms based on their MS data and the comparison of their UV spectra with those published in the literatures.

CONCLUSION

The structural information of phthalides was obtained via HPLC-MS/MS, which provides an accurate and fast method to identify the phthalides and provides more scientific information for quality control of Danggui.

Synthesis of 15N-labeled phthalimide

A new method for preparing 15N-labeled phthalimide from the reaction between phthalic anhydride and 15N-urea (99.34% 15N) in the presence of ortho-xylene is described in this work. Reaction conditions were the mole ratio of phthalic anhydride to 15N-urea (99.34% 15N) of 3-1 at 140 degrees C and under atmospheric pressure. Excessive phthalic anhydride reacted with ethanol for 90 min. The by-product of diethyl phthalate dissolving in ethanol was separated by filtration. The high yield of 96% of 15N-labeled phthalimide was obtained and the purity and abundance was 99.5% and 99.04%, respectively.

Dimeric progestins from rhizomes of Ligusticum chuanxiong

Five dimeric phthalides were isolated from rhizomes of Ligusticum chuanxiong and their structures deduced based on spectral data. All compounds and their parent extracts were assessed for progesterone-like activity using a progesterone receptor driven reporter-gene bioassay. Among all the compounds, riligustilide, displayed weak progesterone-like activity (EC50 approximately 81 microM), whereas, (3Z')-(3a'R,6'R,3R,6R,7R)-3,8-dihydro-6.6',7.3a'-diligustilide (Mr: 382, EC50 approximately 90 nM), was found to be a potent and specific activator of the progesterone receptor. Levistolide A, although having a very similar plenary structure, was inactive indicating the importance of stereochemistry of chiral centers and flexibility of butylidene side chain for progestogenic activity. These bioactive phthalides and their parent extracts (EC50 approximately 8 microg/ml) may have utility for treatment of conditions requiring progesterone action.

Adducts between nucleophilic amino acids and hexahydrophthalic anhydride, a structure inducing both types I and IV allergy

Haptens causing type I allergy have been shown to predominantly form lysine adducts in the carrier protein, while many haptens giving rise to type IV allergy preferentially form adducts with cysteine residues. Hexahydrophthalic anhydride derivatives are strong sensitizers capable of inducing allergic rhinitis, asthma and urticaria (type I allergy) and allergic contact dermatitis (type IV allergy). The ability of hexahydrophthalic anhydride (HHPA) to form adducts with nucleophilic amino acids and a model peptide in vitro is presented. Adduct formation was monitored by high-performance liquid chromatography with ultraviolet light/vis detection (LC-UV/vis) and high-performance liquid chromatography with mass spectrometric detection (LC/MS). The characterization was obtained by nuclear magnetic resonance spectroscopy (NMR) and mass spectrometry (MS and MS/MS). It was found that HHPA formed adducts with N(alpha)-acetylated lysine and cysteine and the non-acetylated alpha-amino group of proline and, to some extent, also with other nucleophilic amino acids. The adducts with lysine and proline were chemically stable. Addition of one HHPA to a model carrier peptide with all important nucleophilic amino acid residues showed N-terminal proline to be the major site of reaction. The addition of a second hapten gave a lysine adduct, but a minor cysteine adduct was also found. The cysteine-HHPA adducts were shown to be chemically unstable and participated in further reactions with lysine forming lysine-HHPA adducts. The results will be useful for understanding the formation of HHPA-protein adducts with the capability of being markers of exposure, and also to a deeper understanding of the chemical structures causing types I and IV allergy.

Synthesis and antimicrobial activity of N-analogous corollosporines

Corollosporine is an antimicrobial metabolite, which was isolated from the marine fungus Corollospora maritima. Owing to its basic 4-hydroxyphthalic acid anhydride structure, it has become an attractive target for a structure/activity relationship modelling of derived compounds with potential antibiotic activity. In this regard we report on the straightforward synthesis of hetero analogous corollosporines, which were easily prepared by a three-step reaction sequence, taking advantage of a novel multicomponent reaction (AAD-reaction) and a subsequent aromatization/Grignard reaction protocol. Furthermore, the obtained products were tested in several biological assays to evaluate their antimicrobial activity.

Comparison of Larvicidal, Adulticidal and Acaricidal Activity of Two Geometrical Butylidenephthalide Isomers

Insecticidal and acaricidal activities of two geometrical isomers, (E)- and (Z)-butylidenephthalide isolated from Angelica acutiloba, against larvae and adults of fruit fly (Drosophila melanogaster), cat fleas (Ctenocephalides felis) and house dust mites (Dermatophagoides farinae and Tyrophagus putrescentiae) were investigated and compared with that of positive controls. (E)- and (Z)-Butylidenephthalide exhibited 50% lethal concentration (LC50) values of 2.07 and 0.94 micromol/ml of diet concentration against larvae of D. melanogaster, respectively. This indicated that two isomers of butylidenephthalide have geometrical stereoselectivity for larvicidal effect. Even though both (E)- and (Z)-butylidenephthalide also showed potent adulticidal and acaricidal activity against adults of D. melanogaster and two mites, there was no significant difference between two isomers. Insecticidal activity of both (E)- and (Z)-butylidenephthalide toward adults of C. felis was not detected even at the maximum concentration of 200 microg/cm2.

SPE/LC/ESI/MS with phthalic anhydride derivatisation for the determination of alcohol ethoxylate surfactants in sewage influent and effluent samples

A new method for the analysis of alcohol ethoxylates (AEs) using electrospray ionisation liquid chromatography/mass spectrometry (ESI LC/MS) is described. The procedure incorporates a novel derivatisation step with phthalic anhydride for the analysis of EO0-20 ethoxylates in a single analysis. The derivatives obtained have proved to be very stable and the negative ion spectra show reduced background ions and competing adduct formation as compared to positive ion spectra. An automated solid phase extraction (SPE) step is used to allow both pre-concentration and clean-up of the environmental samples. The method provides more efficient recovery of AEs across the C12-C18 range than previously reported in the literature. Recoveries from final effluent spiked at 100 microg/L total AE, for the 126 species analysed, were found to be in the range 55-117%, with approximately 100 of the individual analytes having recoveries of 90-105%. An LOD of 0.02 microg/L for individual ethoxylate components is reported with the instrument operated in scan mode over the range m/z 300-1300. The method was applied to sewage effluent and influent samples, with AEs determined at approximately 7 and 5000 microg/L, respectively.

Pyrolysis of flame retardant brominated polyester composites

A series of three flame retardant, thermoset polyester/styrene composite wastes were pyrolysed in a static-bed reactor. The wastes contained different proportions of brominated polyester resin. Higher char and gas yields were observed on the pyrolysis of the brominated samples than for a similar non-brominated sample. The pyrolysis gas composition showed a small, but significant influence of pyrolysis temperature and by the use of brominated resin. In all cases, over 95wt % of the bromine originally present in the composite ended up in the condensable products. Thermo-gravimetric analysis indicated that the presence of brominated polyester resins decreased the temperatures at which the main decomposition region started and the maximum rate of weight loss was observed. The global apparent activation energy of decomposition was between 83 and 97kJ mol(-1).

Identification of contact and respiratory sensitizers using flow cytometry

Identification of the chemicals responsible for respiratory and contact allergies in the industrial area is an important occupational safety issue. This study was conducted in mice to determine whether flow cytometry is an appropriate method to analyze and differentiate the specific immune responses to the respiratory sensitizer trimellitic anhydride (TMA) and to the contact sensitizer dinitrochlorobenzene (DNCB) used at concentrations with comparable immunogenic potential. Mice were exposed twice on the flanks (days 0, 5) to 10% TMA or 1% DNCB and challenged three times on the ears (days 10, 11, 12) with 2.5% TMA or 0.25% DNCB. Flow cytometry analyses were conducted on draining lymph node cells harvested on days 13 and 18. Comparing TMA and DNCB immune responses on day 13, we found obvious differences that persisted for most of them on day 18. An increased proportion of IgE+ cells correlated to total serum IgE level and an enhancement of MHC II molecule expression were observed in the lymph node B lymphocytes from TMA-treated mice. The percentage of IL-4-producing CD4+ lymphocytes and the IL-4 receptor expression were clearly higher following TMA exposure. In contrast, higher proportions of IL-2-producing cells were detected in CD4+ and CD8+ cells from DNCB-treated mice. Both chemicals induced a significant increase in the percentage of IFN-gamma-producing cells among CD8+ lymphocytes but to a greater proportion following TMA treatment. In conclusion, this study encourages the use of flow cytometry to discriminate between contact and respiratory sensitizers by identifying divergent expression of immune response parameters.

Full wave modeling of therapeutic ultrasound: efficient time-domain implementation of the frequency power-law attenuation

For the simulation of therapeutic ultrasound applications, a method including frequency-dependent attenuation effects directly in the time domain is highly desirable. This paper describes an efficient numerical time-domain implementation of the power-law attenuation model presented by Szabo [Szabo, J. Acoust. Soc. Am. 96, 491-500 (1994)]. Simulations of therapeutic ultrasound applications are feasible in conjunction with a previously presented finite differences time-domain (FDTD) algorithm for nonlinear ultrasound propagation [Ginter et al., J. Acoust. Soc. Am. 111, 2049-2059 (2002)]. Szabo implemented the empirical frequency power-law attenuation using a causal convolutional operator directly in the time-domain equation. Though a variety of time-domain models has been published in recent years, no efficient numerical implementation has been presented so far for frequency power-law attenuation models. Solving a convolutional integral with standard time-domain techniques requires enormous computational effort and therefore often limits the application of such models to 1D problems. In contrast, the presented method is based on a recursive algorithm and requires only three time levels and a few auxiliary data to approximate the convolutional integral with high accuracy. The simulation results are validated by comparison with analytical solutions and measurements.

Mild and effective N-phthaloylation of amino acids

In the present work various free amino acids, including tryptophan and tyrosine, were effectively N-phthaloylated under reduced pressure and at lower temperature. Moreover, under these conditions, the presence of phthalic acid in phthalic anhydride did not hinder the N-phthaloylation of amino acids. This simple process is economic, environmentally friendly, and suitable for large-scale production.

Determination of hexahydrophthalic anhydride adducts to human serum albumin

Hexahydrophthalic anhydride (HHPA) is a highly sensitizing industrial chemical that is known to covalently bind to endogenous proteins. The aim of this study was to determine the binding sites of HHPA to human serum albumin (HSA). Conjugates between HSA and HHPA, at two different molar ratios, were synthesized under physiological conditions. The conjugates were digested with trypsin and Pronase E to obtain specific peptides and amino acids, which were separated by liquid chromatography (LC). Fractions containing modified peptides were detected through quantification of hydrolysable HHPA using LC coupled to a triple quadrupole mass spectrometer with electrospray ionization. Modified residues in albumin were identified by sequence analyses using nanoelectrospray quadrupole time-of-flight mass spectrometry. A total of 36 HHPA adducts were found in the HSA-HHPA conjugate with 10 times molar excess of added HHPA. In the conjugate with a molar ratio of 1:0.1 of added HHPA, seven HHPA adducts were found bound to Lys(137) (domain IB), Lys(190), Lys(199) and Lys(212) (domain IIA), Lys(351) (domain IIB), and Lys(432) and Lys(436) (domain IIIA). Moreover, several of these adducted albumin peptides were detected in nasal lavage fluid from one volunteer exposed to HHPA. The binding sites of HHPA to HSA have been determined, thus identifying potential allergenic chemical structures. This knowledge generates the possibility of developing methods for the biological monitoring of HHPA exposure by analysing tryptic peptides including these binding sites.

Synthesis of N-sugar-substituted phthalimides and their derivatives from sugar azides and phthalic anhydride

N-Sugar-substituted phthalimides and tetrachlorophthalimide derivatives can be prepared in good yields under essentially neutral conditions. Mixing a sugar azide, NaI, Me3SiCl, phthalic or substituted phthalic anhydride and tetrabutylammonium iodide as catalyst in acetonitrile at rt or 60 degrees C, afforded 12 imides in 83-95% yields.

A murine model for low molecular weight chemicals: differentiation of respiratory sensitizers (TMA) from contact sensitizers (DNFB)

Exposure to low molecular weight (LMW) chemicals contributes to both dermal and respiratory sensitization and is an important occupational health problem. Our goal was to establish an in vivo murine model for hazard identification of LMW chemicals that have the potential to induce respiratory hypersensitivity (RH). We used a dermal sensitization protocol followed by a respiratory challenge with the evaluation of endpoints typically associated with RH in human disease. Trimellitic anhydride (TMA) was used as a prototype respiratory sensitizer and was compared to the dermal sensitizer; 2,4-dinitrofluorobenzene (DNFB), along with vehicle controls. BALB/c mice were dermally sensitized using two exposure protocols. Mice in both protocols were dermally exposed on experimental days; D-18 and D-17 (abdomen), and D-13 (ear). On D 0 mice received an intratracheal (IT) challenge. The mice in Protocol 2 were abdominally exposed twice with the addition of exposures on D-25 and D-24. Results indicate that mice required the additional dermal sensitization and the IT challenge (Protocol 2) to significantly elevate total IgE in serum and bronchoalveolar lavage fluid (BALF). Additional responses suggestive of RH were seen following Protocol 2, including increases in BALF cell numbers and neutrophils post IT with TMA (but not DNFB). These data suggest that the dermal sensitization and IT challenge followed by evaluation of serum antibodies and lung parameters are a reasonable and logistically feasible approach towards the development of a model for RH responses to LMW chemicals.

Exposure-response relationships for hexahydrophthalic and methylhexahydrophthalic anhydrides with total plasma protein adducts as biomarkers

OBJECTIVES

This study investigated the exposure-response relationships of hexahydrophthalic anhydride (HHPA) and methylhexahydrophthalic anhydride (MHHPA) and evaluated the applicability of the total plasma protein adducts (TPPA) of these anhydrides as biomarkers of exposure and risk.

METHODS

In a cross-sectional study of 139 workers in a plant manufacturing electrical capacitors, the long-term exposure to HHPA and MHHPA was assessed through the quantification of TPPA using gas chromatography-mass spectrometry. Smoking and medical histories were obtained through questionnaires. Work-related symptoms of the eyes and airways were recorded. Specific immunoglobulin (Ig) E (radioallergosorbent test) and IgG (enzyme-linked immunosorbent assay) were determined in serum.

RESULTS

The mean level of the TPPA of HHPA was 840 fmol/ml and that of the TPPA of MHHPA was 1700 fmol/ml. There was no correlation between the TPPA of HHPA and the TPPA of MHHPA. Of all the workers, 19% were found to be positive for specific IgE and 17-19% for IgG. Positive associations were observed between HHPA exposure and specific IgE and IgG and between MHHPA exposure and specific IgG. Regarding work-related symptoms, 27% of the workers had symptoms of the nose, 21% had symptoms of the eyes, 11% had symptoms of the lower airways, and 8% had nose bleeding. There were significant exposure-response relationships for symptoms of the eyes and nose for HHPA exposure.

CONCLUSIONS

The results show that there is an exposure-response relationship for HHPA both with specific antibodies and with work-related symptoms and down to adduct levels of 40 fmol/ml plasma. In addition, the results elucidate the potential power of TPPA as a relevant index of exposure and risk.

The antiviral activity of naturally occurring proteins and their peptide fragments after chemical modification

Chemical modification of the proteins bovine serum albumin, alpha-lactalbumin, beta-lactoglobulin and chicken lysozyme by 3-hydroxyphthalic anhydride (3-HP) yielded compounds which exerted antiviral activity in vitro as compared with the native unmodified proteins. Of the three enveloped viruses tested, human herpes simplex virus type 1 (HSV-1), bovine parainfluenza virus type 3 and porcine respiratory corona virus, only HSV-1 proved sensitive to the 3-HP-proteins. All of the chemically modified proteins presented antiviral activity against HSV-1 when assayed before, during or after infection. However, to achieve HSV-1 inhibition, significantly higher concentrations of the modified proteins were required if present before infection as compared to during or after infection. Our results suggest that multiple mechanisms are involved in the inhibition of HSV-1 infection. Proteolytical digestion of albumin, alpha-lactalbumin, beta-lactoglobulin and lysozyme by trypsin, chymotrypsin and pepsin yielded several peptide fragments with antiherpetic activity. Chemical modification of these peptide fragments by 3-HP generated peptides with antiviral activity, however, this was almost always combined with a cytotoxic effect on the Vero cells. Overall, our results suggest that targeted chemical modification of some natural products might provide compounds effective against HSV-1 infection.

Acaricidal activity of Cnidium officinale rhizome-derived butylidenephthalide against Tyrophagus putrescentiae (Acari: Acaridae)

The acaricidal activity of materials derived from the rhizome of Cnidium officinale Makino against Tyrophagus putrescentiae Schrank adults was examined using direct contact application and fumigation methods, and compared with that of benzyl benzoate and N,N-diethyl-m-toluamide (DEET). The biologically active constituent of the Cnidium rhizome was identified as butylidenephthalide by spectroscopic analyses. On the basis of 24-h LD50 values, acaricidal activity was more pronounced with butylidenephthalide (5.80 microg cm(-2)) than with benzyl benzoate (9.75 microg cm(-2)) and DEET (16.26 microg cm(-2)). In typical poisoning symptoms, butylidenephthalide resulted in lethargy of treated mites, leading to death without knockdown, whereas benzyl benzoate and DEET caused death associated with uncoordinated behaviour. In a fumigation test with T. putrescentiae adults, butylidenephthalide was much more effective in closed containers than in open ones, indicating that the effects of this compound were largely due to action in the vapour phase. Naturally occurring C. officinale rhizome-derived materials merit further study as potential T. putrescentiae control agents or as lead compounds.

A biomimetic pH-responsive polymer directs endosomal release and intracellular delivery of an endocytosed antibody complex

Poly(propylacrylic acid) (PPAAc) is a synthetic pH-responsive polymer that has been shown to disrupt cell membranes at low pH values typical of the endosome, but not at physiological pH, suggesting its use as an endosomal-releasing agent [Murthy et al. J. Controlled Release 61, 137-43]. We have constructed an antibody-targeted biotherapeutic model to investigate whether PPAAc can enhance intracellular trafficking of proteins to the cytoplasm. A ternary complex composed of a biotinylated anti-CD3 antibody, streptavidin, and biotinylated PPAAc was fluorescently labeled, and its intracellular fate was analyzed by confocal microscopy, flow cytometry, and quantitative western blotting of cell fractionates. The 64.1 anti-CD3 antibody was previously shown to direct receptor-mediated endocytosis in the Jurkat T-cell lymphoma cell line and was rapidly trafficked from the endosome to the lysosomal compartment. The antibody-streptavidin complex was also rapidly internalized to the endosomal/lysosomal compartment and retained there, as evidenced by punctate regions of fluorescence observed by confocal fluorescence microscopy. In samples containing the ternary complex of antibody, streptavidin, and PPAAc-biotin, diffuse fluorescence in the cytoplasm was observed, indicating that PPAAc enhanced translocation to the cytoplasm. This was confirmed by western blotting analysis of the isolated cytoplasm. Flow cytometry results demonstrated that neither streptavidin nor PPAAc caused nonspecific uptake of the complex, nor did they inhibit antibody-mediated endocytosis. The striking enhancement of protein delivery to the cytoplasm by complexed PPAAc suggests that this polymer could provide a new delivery agent for therapeutic, vaccine, and diagnostics development.

Biomedical properties of nanofabricated fluorinated polyimide surface

Cell adhesion, proliferation, and their orientation on the surface of fluorinated polyimide, 6FDA-6FAP, which was fabricated by curing treatment and the rubbing method, were investigated using a continuous cell line of human epithelial cells (adherent HeLa). The surface free energy of the fabricated 6FDA-6FAP was analyzed by the contact angle measurement and the topographic change of the surface was observed using atomic force microscopy. These properties were changed drastically by the treatment, and it was found that the adhesion and proliferation of the cells increased with the curing temperature. The noticeable finding was that the cells on the rubbed 6FDA-6FAP surface were modulated and aligned along with the rubbing direction, where nano-ordered grooves were formed, while the cells proliferated randomly on the unrubbed surface without such a nano-ordered structure.

Separation and identification of the phthalic anhydride derivatives of Liqusticum Chuanxiong Hort by GC-MS, TLC, HPLC-DAD, and HPLC-MS

A simple, sensitive, and rapid method using gas chromatography (GC)-mass spectrometry (MS) is developed for the simultaneous separation and identification of the active ingredients of Liqusticum Chuanxiong Hort (Chuanxiong). Ten phthalic anhydride derivatives (PADs) are identified in Chuanxiong as 3-butylphthalide, 3-butylidenephthalide, 3-butylidene-4-hydroxyphthalide, senkyunolide A, neocnidilide, Z-ligustilide, E-ligustilide, senkyunolide F, senkyunolide-H, and senkyunolide-I. The existence of ferulic acid and vanillin in Chuanxiong extract is also demonstrated. Further identification of these compounds is performed by thin-layer chromatography, high-performance liquid chromatography (HPLC), and HPLC-MS analysis. This is the first report of the separation and determination of the PADs in Chuanxiong by GC-MS.

Kinetic study of the hydrolysis of phthalic anhydride and aryl hydrogen phthalates

The kinetics of the hydrolysis of phthalic anhydride and X-phenyl hydrogen phthalate (X = H, p-Me, m-Cl, and p-Cl) were studied. Several bases accelerate the reaction of phthalic anhydride: acetate, phosphate, N-methyl imidazole, 1,4-diazabicyclo[2,2,2]octane (DABCO), and carbonate. Phosphate, DABCO, and N-methyl imidazole react as nucleophiles, whereas the data do not allow the determination of whether the other bases react in the same way or as general bases catalyzing the water reaction. The rate constants for all of them including water and HO- define a Brönsted plot with beta = 0.46. The kinetics of the hydrolysis of the esters were studied below pH 6.20, and the mechanism involves the formation of phthalic anhydride, which then is hydrolyzed to the phthalic acid. Phenoxide ion has a very high rate constant for the reaction with phthalic anhydride, so above pH 6.20 it competes significantly with the hydrolysis of the anhydride. The reactions of the esters as a function of pH allow the determination of the kinetic pK(a) which are 3.06, 3.02, 2.95, and 2.93 for X = H, p-Me, m-Cl, and p-Cl, respectively. The data also show that the catalysis by the neighboring carboxy group takes place only when it is ionized (i.e., as carboxylate).

Synthesis of corollosporine, an antibacterial metabolite of the marine fungus Corollospora maritima

Corollosporine [(+/-)-3-hexyl-3,7-dihydroxy-1(3H)-isobenzofuran-1-one], an antibacterial metabolite of the marine fungus, Corollospora maritima, was synthesized by four different routes from 3-hydroxyphthalic anhydride or 2-methoxybenzoic acid as the starting material to verify its proposed structure.

Corollosporine, a new phthalide derivative from the marine fungus Corollospora maritima Werderm. 1069

Extracts of the culture medium from the marine fungus Corollospora maritima exhibited concentration dependent antibacterial activity against Staphylococcus aureus and other microorganisms. Bioactivity-guided fractionation and purification afforded the new isobenzofuranone or phthalid type compound corollosporine.

[Chemical constituents of radix Angelicae Sinensis]

Six compounds were isolated from Radix Angelicae Sinensis and identified as (E)-ligustilide, (Z)-ligustilide, (Z)-n-butylidene phthalide, palmitic acid, beta-sitosterol and ferulic acid.

Trimellitic anhydride-sensitive mouse as an animal model for contact urticaria

The respiratory allergen trimellitic anhydride (TMA) has been shown to induce IgE production and immediate ear swelling in mice sensitized to it. We studied whether TMA sensitivity could be used as an animal model for immunological contact urticaria. BALB/C mice were sensitized to TMA by topical applications. Groups of animals were pretreated on the ears with the glucocorticosteroid (GCS) betamethasone-17,21-dipropionate, the antihistamine (AH) diphenhydramine hydrochloride, the non-steroidal anti-inflammatory drug (NSAID) indomethacin or vehicle (VEH). Ears were challenged with TMA and ear thickness was measured at baseline and 1, 2, 4, 8 and 24 h after challenge. Trimellitic anhydride caused a significant biphasic ear swelling response with an early peak at 1-2 h, a plateau at 4 h and a late peak at 24 h. However, there was also an early swelling by TMA in non-sensitized mice, suggesting that non-immunological as well as immunological mechanisms contribute to early swelling by TMA. Glucocorticosteroid suppressed significantly the early and to some extent the late TMA responses, while AH suppressed only early and NSAID only late TMA responses. Ear swelling in TMA-sensitive BALB/C mice may represent a combination of immunological and non-immunological contact urticaria and allergic contact dermatitis. Mice sensitive to TMA may be helpful in defining pharmacological agents affecting contact urticaria and the model is perhaps suitable for identification of some immunologically mediated contact urticants.

Structural and functional analysis of negatively charged milk proteins with anti-HIV activity

Several polyanionic reagents such as dextran sulfates, heparin sulfates, and negatively charged proteins have been reported to exhibit anti-HIV activity in vitro. Particularly potent inhibition has been reported for the milk protein beta-lactoglobulin (betaLG) on modification by 3-hydroxyphthalic anhydride (3HP). The introduction of multiple negatively charged carboxyl groups along the polypeptide backbone obviously leads to repulsion within the protein molecule and this is likely to affect the specific tertiary, and perhaps also secondary, structure of the protein. We used several biophysical techniques to probe the structural changes that occur on 3HP modification of betaLG. The results suggest that the protein becomes largely unstructured on chemical modification. Although a profound anti-HIV activity was measured for 3HP-betaLG, similar antiviral effects were observed with two other 3HP-modified milk proteins, alpha-lactalbumin and alpha(S2)-casein, but not with the unmodified proteins. Most potent inhibition of HIV-1 replication was obtained with 3HP-modified alpha-lactalbumin, which also demonstrated the least cytotoxicity. These combined results indicate that HIV inhibition is a general property of negatively charged polypeptides and do not support a model in which the negatively charged 3HP-betaLG protein interacts in a structure-specific manner with the CD4 cell surface receptor for HIV-1 entry.

Determination of Z-butylidenephthalide in plasma by high-performance liquid chromatography

An HPLC assay is described for the determination of Z-butylidenephthalide (Z-Bdph) in plasma. Plasma samples were cleaned up by extraction with 2% chloroform in n-hexane. Z-Bdph was separated on a normal-phase silica column with a mobile phase of chloroform-n-hexane (1:1). The limit of quantitation with UV detection at 254 nm for Z-Bdph in plasma was 0.01 microgram/ml. The recovery of Z-Bdph by organic solvent extraction of plasma was 99.5%. The intra-day and inter-day coefficients of variation and relative errors for Z-Bdph determination in plasma were both less than 10%. The present method was applied to pharmacokinetic studies of Z-Bdph in plasma after intravenous administration to rabbits.

Lysine adducts between methyltetrahydrophthalic anhydride and collagen in guinea pig lung

The formation of adducts between methyltetrahydrophthalic anhydride (MTHPA), an important industrial chemical and potent allergen, and collagen from guinea pig lung tissue was investigated. Collagen peptides were obtained from the lung tissue by homogenization, defatting, washing, and digestion with collagenase. In experiments in vitro, lung tissue was exposed to 8.4 mumol (50 microCi) of 14C MTHPA. The amount of adducts was 97 nmol MTHPA/g of wet tissue as determined from the bound radioactivity. In a study in vivo, four guinea pigs were injected intratracheally with 8.4 mumol of 14C MTHPA each. The amount of adducts was 0-1.2 nmol MTHPA/g of wet tissue (determined by bound radioactivity). N epsilon-methyltetrahydrophthaloyl-L-lysine (MTHPL) was synthesized and characterized by NMR, UV, and mass spectrometry (MS). A method to analyze MTHPL, after derivatization with methanol and pentafluorobenzoyl chloride, using gas chromatography-MS was developed. Analysis of Pronase-digested MTHPA-exposed lung tissue showed a concentration of 19 nmol MTHPL/g wet lung in vitro and between 0 and 0.15 nmol MTHPL/g wet lung in vivo. Thus, 20% in vitro and 12-15% in vivo of the bound radioactivity was found as adducts with lysine. These results are a first step toward studies of allergenic epitopes in proteins and methods for biological monitoring of exposure to acid anhydrides.

Preparative and analytical separations by high-performance liquid chromatography and capillary electrophoresis of the products from the reaction of insulin with exo-3,6-epoxy-1,2,3,6-tetrahydrophthalic anhydride

An anion-exchange high-performance liquid chromatographic method using a TSKgel DEAE-2SW column and zone electrophoresis using a fused-silica capillary are described for the preparative and analytical separations of the products of the reaction between insulin and exo-3,6- epoxy-1,2,3,6-tetrahydrophthalic anhydride (ETPA), an amino protective reagent. Four stable products were identified having exo-3,6-epoxy-1,2,3,6-tetrahydrophthalic group(s) on insulin at the i) Gly(A1), ii) Gly(A1) and Phe(B1), iii) Gly(A1) and Lys(B29), and iv) Gly(A1), Phe(B1) and Lys(B29) sites, together with four labile products produced by the reaction of ETPA with the non-amino groups of the stable products. The usefulness of capillary electrophoresis was demonstrated in the evaluation of the effect of the molar ratios of anhydride to insulin on the production of the insulin derivatives.