An Efficient Method for Endotoxin Removal from Snake Antivenoms

Advanced approaches for endotoxin detection and removal from snake antivenoms

A comprehensive assessment of the literature on strategies for the detection and removing endotoxin from biotechnological preparations was conducted. This study highlighted the brief history of endotoxin. After that, a review of endotoxin's chemical and physical features, as well as its pathophysiological consequences when the body is exposed to LPS excessively or systemically, is presented. The procedures for determining endotoxin and the interaction of endotoxin with proteins are also discussed, considering both known approaches and cutting-edge technology in this sector. This review presented the endotoxin detection and removal approaches from antisera with an economical approach using several processes documented in the literature (e.g., adsorption, ultrafiltration, and chromatography). Different methods with relatively high protein recoveries are mentioned. This review concludes that heat activation at 70 °C-80 °C for 10 min and rehydration of the LAL reagent with endotoxin-specific buffer solution is the best technique to control the enhancement problem when testing polyvalent snake venom antiserum samples by the LAL method. The most efficient method for eliminating endotoxins has proven to be affinity resin-based chromatography.

Sub/supercritical Fluid Chromatography Purification and Desalting of a Cyclic Dinucleotide STING Agonist

An efficient and "endotoxin-free" purification of a cyclic dinucleotide (CDN) STING agonist was achieved to produce multigram quantities of pure BMT-390025, an active pharmaceutical ingredient (API), for toxicological studies. A two-step sub/supercritical fluid chromatography (SFC) procedure was developed for the achiral purification and desalting of the polar ionic CDN. A robust SFC process employing methanol-acetonitrile-water with ammonium acetate as co-solvent in CO₂ on BEH 2-ethylpyridine was established and scaled up as the first step to achieve a successful purification. The desalting/salt-switching (i.e. removing acetate and acetamide) was conducted using methanol-water with ammonium hydroxide as co-solvent on the same column in the second step to convert the final API to the ammonium salt. Water with additive was essential to eliminating salt precipitation and improving the peak shape and resolution. Due to the extreme hydrophilicity of BMT-390025, 65% of co-solvent was needed to adequately elute the target in both steps. More than 40 g of crude API was purified and desalted producing >20 g of pure BMT-390025 as the ammonium salt which was obtained with a chemical purity of >98.5% and met the endotoxin requirement of <0.1 EU/mg. In addition, >80 g of its penultimate prior to the deprotection of the silyl group was purified at a high throughput of 6.3 g/h (0.42 g/day/g SP).

Combinatorial ethanol treatment increases the overall productivity of recombinant hG-CSF in E. coli: a comparative study

Human granulocyte colony-stimulating factor (hG-CSF) is a cytokine that regulates the proliferation, maturation, and differentiation of precursor cells to neutrophils. In the present study, we report the feasibility of inducing recombinant hG-CSF expression (rhG-CSF) in a pET vector system by combinatorial induction using low-concentration ethanol, IPTG, and lactose and auto-induction media (AIM). The coding sequence of hG-CSF transcript variant 2 was expressed in pET14 vector, and the effect of combinatorial induction was analyzed on inclusion body (IB) formation, biomass, protein purification, and bioactivity. Results showed that there was an inverse relationship between the temperature and soluble expression of rhG-CSF. Three-step washing with Triton-X, 2 M, and 5 M urea resulted in the maximum recovery of IBs. Combinatorial single-spike induction with IPTG, ethanol, and lactose in a batch culture led to a 3-fold increase in the expression of rhG-CSF. It was also observed that low concentration of ethanol (1-3% v/v) could be used in lieu of IPTG for inducing the rhG-CSF protein expression without adversely affecting biomass production. A 2.4-fold increase in productivity was obtained in LB-AIM media with combinatorial ethanol induction, and the overall yield of 2.8 g/L rhG-CSF was found. The purified rhG-CSF was bioactive and increased the cellular proliferation of umbilical cord blood-derived mesenchymal stem cells (U-MSC) by 29%. In conclusion, our study shows that combined ethanol induction can enhance the expression of rhG-CSF with three-step washing for recovery of the proteins from IBs and a single-step purification of rhG-CSF by affinity chromatography. KEY POINTS: • Low concentration of ethanol (1-3%) could be used in lieu of IPTG for inducing rhG-CSF expression. • Combinatorial single-spike induction with IPTG, ethanol, and lactose improved rhG-CSF expression. • Purified rhG-CSF was bioactive and increased the proliferation of U-MSC.