PEGylation strategy to the development of analytical and therapeutic proteins / Potencial da PEGuilação para o desenvolvimento de proteínas para fins terapêuticos e analíticos

Protein PEGylation is the covalent bonding of polyethylene glycol (PEG) polymers to amino acid residues of the protein and it is one of the most promising techniques for improving the therapeutic effect of biopharmaceuticals and long-term stability of protein-based biosensors. This chemical modification brings advantages to biopharmaceuticals, such as an increased half-life, enhanced stability, and reduced immunogenicity. Moreover, in the analytical field, PEGylation improves the multiple properties of protein-based biosensors including biocompatibility, thermal and long-term stability, and solubility in organic solvents. However, the use of PEGylated conjugates in the analytical and therapeutic fields has not been widely explored. The limited industrial application of PEGylated bioconjugates can be attributed to the fact that the reaction and separation steps are currently a challenge. The correct selection of the PEGylation reaction design and the purification process are important challenges in the field of bioconjugation. In this sense, the design and optimization of site-specific PEGylation reactions and application of aqueous biphasic systems (ABS) as purification platforms for PEGylated conjugates are the two main objectives of this thesis. Regarding the purification step, the efficient fractionation (i) of the PEGylated conjugates from the native protein and (ii) of the PEGylated conjugates based on their degree of PEGylation was studied. Centrifugal partition chromatography (CPC) was applied as a continuous regime platform based on ABS technology to efficiently purify the PEGylated proteins. The two proteins under study are L-asparaginase, an important biopharmaceutical applied in the treatment of acute lymphoblastic leukemia and cytochrome c, a promising biosensor. The current work developed in this thesis demonstrates the great potential of ABS in the fractionation of PEGylated proteins, under batch and continuous regime. In addition, in situ recovery of the PEGylated products through one-pot bioconjugation and ABS purification was successfully demonstrated for both enzymes studied. Although further research on scale-up is still required, the results presented show the relevance of ABS platforms for the development of separation processes of PEGylated proteins

A PEGuilação de proteínas é a ligação covalente de polímeros de polietilenoglicol (PEG) a resíduos de aminoácidos da proteína e é uma das técnicas mais promissoras para melhorar o efeito terapêutico dos biofármacos e a estabilidade a longo prazo de biossensores proteícos. Esta modificação química traz vantagens aos produtos biofarmacêuticos, como um aumento da meia-vida, maior estabilidade e imunogenicidade reduzida. Além disso, no campo analítico, a PEGuilação melhora as múltiplas propriedades dos biossensores baseados em proteínas, incluindo biocompatibilidade, estabilidade térmica e a longo prazo, e solubilidade em solventes orgânicos. No entanto, o uso de conjugados PEGuilados em campos analíticos e terapêuticos não tem sido amplamente explorado. A aplicação industrial limitada dos bioconjugados PEGuilados pode ser atribuída ao facto de as etapas de reacção e separação serem atualmente um desafio. A seleção correcta do design da reacção de PEGuilação e do processo de purificação são importantes desafios no campo da bioconjugação. Neste sentido, a concepção e otimização de reações de PEGuilação sítio-específicas e aplicação de sistemas aquosos bifásicos (ABS) como plataformas de purificação de conjugados PEGuilados são os dois principais objetivos desta tese. No que concerne à etapa de purificação foi estudado o eficiente fracionamento (i) dos conjugados PEGuilados, da proteína nativa e (ii) dos conjugados PEGuilados baseados no seu grau de PEGuilação. A cromatografia por partição centrífuga (CPC) foi aplicada como uma plataforma de regime contínuo baseada na tecnologia de ABS para purificar eficientemente as proteínas PEGuiladas. As duas proteínas em estudo são a L-asparaginase, importante biofármaco aplicado no tratamento da leucemia linfoblástica aguda e o citocromo c, um potencial biossensor. A partir dos trabalhos desenvolvidos, é possível confirmar o grande potencial dos ABS no fracionamento de proteínas PEGuiladas, em regime contínuo e descontínuo. Além disso, a recuperação in situ dos produtos PEGuilados através da integração em uma única etapa de bioconjugação e purificação por ABS foi comprovada com sucesso para ambas as enzimas estudadas. Embora ainda sejam necessários estudos adicionais sobre a viabilidade destes sistemas em larga escala, os resultados aqui apresentados demonstram a relevância dos ABS para o desenvolvimento de processos de separação de proteínas PEGuiladas

Identification and partial purification of antibacterial compounds against Streptococcus mutans from Galla Rhois / 대한구강보건학회지

OBJECTIVES: This study aims to identify and partially purify antibacterial compounds against Streptococcus mutans from Galla Rhois extract. METHODS: Galla Rhois was extracted with n-hexane or ethanol and concentrated in a rotary evaporator. The antibacterial effect of the Galla Rhois extract against S. mutans was determined by the paper discdiffusion method with n-hexane, ethanol, methanol, ethyl acetate, dimethyl sulfoxide (DMSO), acetone, and distilled water as the solvents. The active compounds were purified by partition chromatography, thin-layer chromatography (TLC), and high-performance liquid chromatography (HPLC). RESULTS: The antibacterial effect of the n-hexane extract was more effective against S. mutans than the ethanol extract (P<0.05). The antibacterial component of Galla Rhois was partially purified using partition chromatography and HPLC, and the antibacterial activity was confirmed. CONCLUSIONS: The partially purified component of Galla Rhois showed strong antibacterial effect against S. mutans. These results confirm that the antibacterial compounds of Galla Rhois can be used for the prevention of dental caries.

Content Determination of Aciclovir Cream by Centrifugal Partition Chromatography / 中国药房

OBJECTIVE:To establish a method for the content determination of Aciclovir cream. METHODS:Centrifugal parti-tion chromatography(CPC)was conducted. The solvent system was hexane-acetonitrile-water(2∶1∶1,V/V/V),the injection vehicle was an aqueous solution of 5%Tween 80 and the volume was 1.0 ml;the flow rate was 5 ml/min;the wavelength was 254 nm. RE-SULTS:There was a good linear relationship between quality concentration and peak area in the range of 0.012 7-0.126 7 mg/ml (r=0.998 7). The RSD of precision,stability and reproducibility tests was all no more than 2.0% and the average recovery was 97.34%(RSD=0.90%,n=9). CONCLUSIONS:The method is with high precision and accuracy,and can be used for the content determination of principal components of Aciclovir cream.

Purification of Puerarin from Pueraria lobata by FCPC versus HSCCC Using Small-volume Columns / 中草药·英文版

Objective: To develop an efficient method for separating and purifying puerarin from the roots of Pueraria lobata. Methods: Separation by fast centrifugal partition chromatography (FCPC) was processed with a biphasic solvent system composed of ethyl acetate- n-butanol-water (2:1:3). The separation conditions were determined as follows: sample loading of 10 mg, flow rate of 2 mL/min, rotation speed of 2200 r/min, ascending mode, and detection wavelength of 254 nm. High speed countercurrent chromatography (HSCCC) was used as a comparative method with the rotation speed of 800 r/min, flow rate of 2.0 mL/min, and sample loading of 10 mg in tail-to-head mode. Results: Puerarin was obtained by FCPC with a resolution of 0.90 and a purity above 99%, while a resolution below 0.50 and a purity below 90% by HSCCC. Compared with HSCCC, FCPC has the advantages with higher purity and better resolution. Conclusion: FCPC is a powerful method to separate and purify puerarin. © 2014 Tianjin Press of Chinese Herbal Medicines.

Study on removing (-)-bicuculline from Corydalis Decumbentis Rhizoma total alkaloids by fast centrifugal partition chromatography / 中草药

Objective: Using fast centrifugal partition chromatography (FCPC) to remove (-)-bicuculline from Corydalis Decumbentis Rhizoma total alkaloids. Methods: The technological parameters of orthogonal experiment of FCPC was optimized by flow rate, rotation speed, and loading sample size. The optimized process was compared with the solvent extraction method, and the linear amplification experiments were carried out using the optimal process. Results: The optimized parameters were as follows: rotation speed was 1200 r/min, flow rate was 4 mL/min, and loading sample size was 80 mg/mL. The new prepared alkaloids fraction of Corydalis Decumbentis Rhizoma using amplification experiments has > 94.0% removed rate of BI and >85.0% recovery of the other alkaloids, which were higher than those of the solvent extraction method. This simple method with good repeatability could be completed in a short time. Conclusion: The simple and fast method could improve the safety of Corydalis Decumbens Rhizoma total alkaloids, and provide the industrialization of non-toxic total alkaloids.