Optimized Separation of Carthamin from Safflower by Macroporous Adsorption Resins and Its Protective Effects on PC12 Cells Injured by OGD/R via Nrf2 Signaling Pathway

The growing demand for safe natural products has reignited people's interest in natural food pigments. Here, we proposed the use of macroporous adsorption resins (MARs) to separate and purify carthamin from safflower. The optimal parameters for carthamin purification with HPD400 MAR were determined as follows: a mass ratio of crude carthamin in sample solution to wet resin of 0.3, a crude carthamin solution concentration of 0.125 g·mL-1, a pH of 6.00, a sample volume flow rate of 0.5 mL·min-1, an ethanol volume fraction of 58%, an elution volume of 4 BV, and an elution volume flow rate of 1.0 mL·min-1. Under the above purification conditions, the recovery rate of carthamin was above 96%. Carthamin dramatically improved the survival rate of PC12 cells damaged by oxygen-glucose deprivation/reoxygenation and protected them from oxidative stress by inhibiting the generation of reactive oxygen species and increasing the total antioxidant capacity and glutathione (GSH) levels. Carthamin promoted extracellularly regulated protein kinase phosphorylation into the nucleus, permitting Nrf2 nuclear translocation and upregulating the gene expression of the rate-limiting enzymes glutamate-cysteine ligase catalytic subunit and glutamate-cysteine ligase regulatory subunit of GSH synthesis to obliterate free radicals and exert antioxidant effects. This study revealed the purification method of carthamin and its antioxidant protective effects, providing important insights into the application of carthamin in functional foods.

Measurement of high protein concentrations by optical rotation: a case study for monitoring of monoclonal antibody drug downstream processes

BACKGROUND

Recent advancements in cell engineering and bioreactor engineering have enabled high monoclonal antibody (mAb) concentrations in harvested solutions for the downstream process (DSP).

METHODS

As many unit operations such as capture chromatography, polish chromatography, membrane filtration, virus inactivation, virus filtration, and concentration by ultrafiltration are involved in DSP, it is crucial to monitor the process carefully in order to perform reliable and stable DSP operations. One of the most important signals (process parameter) to be monitored is the protein concentration C_P. Although various methods are available, most of them are not suited for measuring high C_P. In this paper, we have developed a method for measuring very high C_P by optical rotation (OR).

RESULT

Linear correlations were confirmed between OR and C_P in the range C_P = 0 to 80 g/L for mAbs with high repeatability and small variation coefficients. This method was applied to the monitoring of C_P in the opaque (colored) solution during the cell culture. The C_P by OR was in good agreement with those by the standard Protein A HPLC method.

CONCLUSION

Monitoring of high C_P by OR is expected to be an efficient process analytical tool (PAT) for DSP.

Critical Assessment of Purification and Analytical Technologies for Enveloped Viral Vector and Vaccine Processing and Their Current Limitations in Resolving Co-Expressed Extracellular Vesicles

Viral vectors and viral vaccines are invaluable tools in prevention and treatment of diseases. Many infectious diseases are controlled using vaccines designed from subunits or whole viral structures, whereas other genetic diseases and cancers are being treated by viruses used as vehicles for delivering genetic material in gene therapy or as therapeutic agents in virotherapy protocols. Viral vectors and vaccines are produced in different platforms, from traditional embryonated chicken eggs to more advanced cell cultures. All these expression systems, like most cells and cellular tissues, are known to spontaneously release extracellular vesicles (EVs). EVs share similar sizes, biophysical characteristics and even biogenesis pathways with enveloped viruses, which are currently used as key ingredients in a number of viral vectors and licensed vaccine products. Herein, we review distinctive features and similarities between EVs and enveloped viruses as we revisit the downstream processing steps and analytical technologies currently implemented to produce and document viral vector and vaccine products. Within a context of well-established viral vector and vaccine safety profiles, this review provides insights on the likely presence of EVs in the final formulation of enveloped virus products and discusses the potential to further resolve and document these components.

Extractive fermentation for process integration of protease production by Aspergillus tamarii Kita UCP1279 and purification by PEG-Citrate Aqueous Two-Phase System

The present study evaluated the influence of the variables polyethylene glycol (PEG) molar mass, pH, PEG concentration and sodium citrate concentration in the integrated production of the protease from Aspergillus tamarii Kita UCP1279 by extractive fermentation, obtaining as a response the partition coefficient (K), activity yield (Y) and concentration factor (CF). The enzyme preferably partitioned to the top phase and obtained in the system formed by variables M_PEG = 400 g mol^-1, C_PEG = 20% (w w^-1), and C_CIT = 20% (w w^-1) and pH 6, in this condition were obtained CF = 1.90 and Y = 79.90%. The protease showed stability at a temperature of 60 °C for 180 min, with optimum temperature 40 °C and pH 8.0. For the ions and inhibitors effects, the protease activity increased when exposed to Fe²⁺, Ca²⁺ and Zn^{2 +} and inhibited by EDTA, being classified as metalloprotease. The kinetic parameters K_m (35.63 mg mL^-1) and V_max (1.205 mg mL^-1min^-1) were also estimated. Thus, the protease showed desirable characteristics that enable future industrial applications, especially, for beer industry.

Laboratory-Scale Lentiviral Vector Production and Purification for Enhanced Ex Vivo and In Vivo Genetic Engineering

Lentiviral vectors (LVs) are increasingly employed in gene and cell therapy. Standard laboratory production of LVs is not easily scalable, and research-grade LVs often contain contaminants that can interfere with downstream applications. Moreover, purified LV production pipelines have been developed mainly for costly, large-scale, clinical-grade settings. Therefore, a standardized and cost-effective process is still needed to obtain efficient, reproducible, and properly executed experimental studies and preclinical development of ex vivo and in vivo gene therapies, as high infectivity and limited adverse reactions are important factors potentially influencing experimental outcomes also in preclinical settings. We describe here an optimized laboratory-scale workflow whereby an LV-containing supernatant is purified and concentrated by sequential chromatographic steps, obtaining biologically active LVs with an infectious titer and specific activity in the order of 10⁹ transducing unit (TU)/mL and 5 × 10⁴ TU/ng of HIV Gag p24, respectively. The purification workflow removes >99% of the starting plasmid, DNA, and protein impurities, resulting in higher gene transfer and editing efficiency in severe combined immunodeficiency (SCID)-repopulating hematopoietic stem and progenitor cells (HSPCs) ex vivo, as well as reduced activation of inflammatory responses ex vivo and in vivo as compared to TU-matched, laboratory-grade vectors. Our results highlight the value of accessible purified LV production for experimental studies and preclinical testing.

An Integrated Approach to Aggregate Control for Therapeutic Bispecific Antibodies Using an Improved Three Column Mab Platform-Like Purification Process

Single chain variable fragment‐IgGs (scFv‐IgG) are a class of bispecific antibodies consisting of two single chain variable fragments (scFv) that are fused to an intact IgG molecule. A common trend observed for expression of scFv‐IgGs in mammalian cell culture is a higher level of aggregates (10%–30%) compared to mAbs, which results in lower purification yields in order to meet product quality targets. Furthermore, the high aggregate levels also pose robustness risks to a conventional mAb three column platform purification process which uses only the polishing steps (e.g., cation exchange chromatography [CEX]) for aggregate removal. Protein A chromatography with pH gradient elution, high performance tangential flow filtration (HP‐TFF) and calcium phosphate precipitation were evaluated at the bench scale as means of introducing orthogonal aggregate removal capabilities into other aspects of the purification process. The two most promising process variants, namely Protein A pH gradient elution followed by calcium phosphate precipitation were evaluated at pilot scale, demonstrating comparable performance. Implementing Protein A chromatography with gradient elution and/or calcium phosphate precipitation removed a sufficient portion of the aggregate burden prior to the CEX polishing step, enabling CEX to be operated robustly under conditions favoring higher monomer yield. From starting aggregate levels ranging from 15% to 23% in the condition media, levels were reduced to between 2% and 3% at the end of the CEX step. The overall yield for the optimal process was 71%. Results of this work suggest an improved three‐column mAb platform‐like purification process for purification of high aggregate scFv‐IgG bispecific antibodies is feasible. © 2018 The Authors. Biotechnology Progress published by Wiley Periodicals, Inc. on behalf of American Institute of Chemical Engineers. Biotechnol. Prog., 35: e2720, 2019

The Effect of Phenazine-1-Carboxylic Acid on Mycelial Growth of Botrytis cinerea Produced by Pseudomonas aeruginosa LV Strain

One of the most important postharvest plant pathogens that affect strawberries, grapes and tomatoes is Botrytis cinerea, known as gray mold. The fungus remains in latent form until spore germination conditions are good, making infection control difficult, causing great losses in the whole production chain. This study aimed to purify and identify phenazine-1-carboxylic acid (PCA) produced by the Pseudomonas aeruginosa LV strain and to determine its antifungal activity against B. cinerea. The compounds produced were extracted with dichloromethane and passed through a chromatographic process. The purity level of PCA was determined by reversed-phase high-performance liquid chromatography semi-preparative. The structure of PCA was confirmed by nuclear magnetic resonance and electrospray ionization mass spectrometry. Antifungal activity was determined by the dry paper disk and minimum inhibitory concentration (MIC) methods and identified by scanning electron microscopy and confocal microscopy. The results showed that PCA inhibited mycelial growth, where MIC was 25 μg mL-1. Microscopic analysis revealed a reduction in exopolysaccharide (EPS) formation, showing distorted and damaged hyphae of B. cinerea. The results suggested that PCA has a high potential in the control of B. cinerea and inhibition of EPS (important virulence factor). This natural compound is a potential alternative to postharvest control of gray mold disease.

Large-scale purification and characterization of recombinant human stem cell factor in Escherichia coli

The pharmacological importance of recombinant human stem cell factor (rhSCF) has increased the demand to establish effective and large-scale production and purification processes. A good source of bioactive recombinant protein with capability of being scaled-up without losing activity has always been a challenge. The objectives of the study were the rapid and efficient pilot-scale expression and purification of rhSCF. The gene encoding stem cell factor (SCF) was cloned into pBV220 and transformed into Escherichia coli. The recombinant SCF was expressed and isolated using a procedure consisting of isolation of inclusion bodies (IBs), denaturation, and refolding followed by chromatographic steps toward purification. The yield of rhSCF reached 835.6 g/20 L, and the expression levels of rhSCF were about 33.9% of the total E. coli protein content. rhSCF was purified by isolation of IBs, denaturation, and refolding, followed by SP-Sepharose chromatography, Source 30 reversed-phase chromatography, and Q-Sepharose chromatography. This procedure was developed to isolate 5.5 g of rhSCF (99.5% purity) with specific activity at 0.96 × 10⁶  IU/mg, endotoxin levels of pyrogen at 1.0 EU/mg, and bacterial DNA at 10 ng/mg. Pilot-scale fermentations and purifications were set up for the production of rhSCF that can be upscaled for industry.

Acid-induced aggregation propensity of nivolumab is dependent on the Fc

Nivolumab, an anti-programmed death (PD)1 IgG4 antibody, has shown notable success as a cancer treatment. Here, we report that nivolumab was susceptible to aggregation during manufacturing, particularly in routine purification steps. Our experimental results showed that exposure to low pH caused aggregation of nivolumab, and the Fc was primarily responsible for an acid-induced unfolding phenomenon. To compare the intrinsic propensity of acid-induced aggregation for other IgGs subclasses, tocilizumab (IgG1), panitumumab (IgG2) and atezolizumab (aglyco-IgG1) were also investigated. The accurate pH threshold of acid-induced aggregation for individual IgG Fc subclasses was identified and ranked as: IgG1 < aglyco-IgG1 < IgG2 < IgG4. This result was cross-validated by thermostability and conformation analysis. We also assessed the effect of several protein stabilizers on nivolumab, and found mannitol ameliorated the acid-induced aggregation of the molecule. Our results provide valuable insight into downstream manufacturing process development, especially for immune checkpoint modulating molecules with a human IgG4 backbone.

Bioactive Organocopper Compound from Pseudomonas aeruginosa Inhibits the Growth of Xanthomonas citri subsp. citri

Citrus canker is a very destructive disease of citrus species. The challenge is to find new compounds that show strong antibiotic activity and low toxicity to plants and the environment. The objectives of the present study were (1) to extract, purify and evaluate the secondary metabolites with antibiotic activity produced by Pseudomonas aeruginosa LV strain in vitro against Xanthomonas citri subsp. citri (strain 306), (2) to determine the potential of semi-purified secondary metabolites in foliar application to control citrus canker under greenhouse conditions, and (3) to identify antibiotic activity in orange leaf mesophyll infected with strain 306, by electron microscopy. Two pure bioactive compounds were isolated, an organocopper antibiotic compound (OAC) and phenazine-1-carboxamide. Phenazine-1-carboxamide did not show any antibiotic activity under the experimental conditions used in this study. The OAC showed a high level of antibiotic activity with a minimum inhibitory concentration of 0.12 μg mL(-1). In greenhouse tests for control of citrus canker in orange trees, the semi-purified fraction F3d reduced lesion formation by about 97%. The concentration used was 500 times lower than that for the recommended commercial copper-based product. Electron microscopy showed that F3d altered the exopolysaccharide matrix and caused cell lysis of the pathogen inside the citrus canker lesions. These results suggest that secondary metabolites produced by inducing P. aeruginosa LV strain have a high potential to be used as a bioproduct to control citrus canker.

TiO₂ Nanosols Applied Directly on Textiles Using Different Purification Treatments

Self-cleaning applications using TiO₂ coatings on various supporting media have been attracting increasing interest in recent years. This work discusses the issue of self-cleaning textile production on an industrial scale. A method for producing self-cleaning textiles starting from a commercial colloidal nanosuspension (nanosol) of TiO₂ is described. Three different treatments were developed for purifying and neutralizing the commercial TiO₂ nanosol: washing by ultrafiltration; purifying with an anion exchange resin; and neutralizing in an aqueous solution of ammonium bicarbonate. The different purified TiO₂ nanosols were characterized in terms of particle size distribution (using dynamic light scattering), electrical conductivity, and ζ potential (using electrophoretic light scattering). The TiO₂-coated textiles’ functional properties were judged on their photodegradation of rhodamine B (RhB), used as a stain model. The photocatalytic performance of the differently treated TiO₂-coated textiles was compared, revealing the advantages of purification with an anion exchange resin. The study demonstrated the feasibility of applying commercial TiO₂ nanosol directly on textile surfaces, overcoming problems of existing methods that limit the industrial scalability of the process.

Purification and characterization of broccoli (Brassica oleracea var. italica) myrosinase (β-thioglucosidase glucohydrolase)

Myrosinase (β-thioglucosidase glucohydrolase, EC 3.2.1.147) from broccoli (Brassica oleracea var. italica) was purified by ammonium sulfate precipitation followed by concanavalin A affinity chromatography, with an intermediate dialysis step, resulting in 88% recovery and 1318-fold purification. These are the highest values reported for the purification of any myrosinase. The subunits of broccoli myrosinase have a molecular mass of 50-55 kDa. The native molecular mass of myrosinase was 157 kDa, and accordingly, it is composed of three subunits. The maximum activity was observed at 40 °C and at pH below 5.0. Kinetic assays demonstrated that broccoli myrosinase is subjected to substrate (sinigrin) inhibition. The Michaelis-Menten model, considering substrate inhibition, gave Vmax equal to 0.246 μmol min(-1), Km equal to 0.086 mM, and K(I) equal to 0.368 mM. This is the first study about purification and characterization of broccoli myrosinase.