Amino acid-mPEGs: Promising excipients to stabilize human growth hormone against aggregation.

Objectives: Today, the non-covalent PEGylation methods of protein pharmaceuticals attract more attention and possess several advantages over the covalent approach. In the present study, Amino Acid-mPEGs (aa-mPEGs) were synthesized, and the human Growth Hormone (hGH) stability profile was assessed in their presence and absence. Materials and Methods: aa-mPEGs were synthesized with different amino acids (Trp, Glu, Arg, Cys, and Leu) and molecular weights of polymers (2 and 5 KDa). The aa-mPEGs were analyzed with different methods. The physical and structural stabilities of hGH were analyzed by SEC and CD spectroscopy methods. Physical stability was assayed at different temperatures within certain intervals. Molecular dynamics (MD) simulation was used to realize the possible mode of interaction between protein and aa-mPEGs. The cell-based method was used to evaluate the cytotoxicity. Results: HNMR and FTIR spectroscopy indicated that aa-mPEGs were successfully synthesized. hGH as a control group is known to be stable at 4 °C; a pronounced change in monomer degradation is observed when stored at 25 °C and 37 °C. hGH:Glu-mPEG 2 kDa with a molar ratio of 1:1 to the protein solution can significantly increase the physical stability. The CD spectroscopy method showed that the secondary structure of the protein was preserved during storage. aa-mPEGs did not show any cytotoxicity activities. The results of MD simulations were in line with experimental results. Conclusion: This paper showed that aa-mPEGs are potent excipients in decreasing the aggregation of hGH. Glu-mPEG exhibited the best-stabilizing properties in a harsh environment among other aa-mPEGs.

Polyethylenimine Grafted onto Nano-NiFe2O4@SiO2 for the Removal of CrO42-, Ni2+, and Pb2+ Ions from Aqueous Solutions.

Polyethyleneimine (PEI) has been reported to have good potential for the adsorption of metal ions. In this work, PEI was covalently bound to NiFe2O4@SiO2 nanoparticles to form the new adsorbent NiFe2O4@SiO2-PEI. The material allowed for magnetic separation and was characterized via powder X-ray diffraction (PXRD), showing the pattern of the NiFe2O4 core and an amorphous shell. Field emission scanning electron microscopy (FE-SEM) showed irregular shaped particles with sizes ranging from 50 to 100 nm, and energy-dispersive X-ray spectroscopy (EDX) showed high C and N contents of 36 and 39%, respectively. This large amount of PEI in the materials was confirmed by thermogravimetry-differential thermal analysis (TGA-DTA), showing a mass loss of about 80%. Fourier-transform IR spectroscopy (FT-IR) showed characteristic resonances of PEI dominating the spectrum. The adsorption of CrO42-, Ni2+, and Pb2+ ions from aqueous solutions was studied at different pH, temperatures, metal ion concentrations, and adsorbent dosages. The maximum adsorption capacities of 149.3, 156.7, and 161.3 mg/g were obtained for CrO42-, Ni2+, and Pb2+, respectively, under optimum conditions using 0.075 g of the adsorbent material at a 250 mg/L ion concentration, pH = 6.5, and room temperature.

Plant Extract and Herbal Products as Potential Source of Sorbent for Analytical Purpose: An Experimental Study of Morphine and Codeine Determination Using HPLC and LC-MSMS.

Solid-phase microextraction (SPME) is an analytical method for microextraction of analytes, in which the analytes bind to the sorbent on the surface of the SPME fiber. Many types of chemical agents are used as sorbent; however, many of these sorbents cause secondary contamination or are not cost-effective. Here, aqueous extract of Ferula gummosa was evaluated as potential source of sorbent for simultaneous microextraction of morphine and codeine. For this purpose, multiwalled carbon nanotubes were carboxylated with H2SO4/HNO3 (3:1) and then functionalized with aqueous extract of F. gummosa. Functionalization was confirmed by Fourier transform infrared and Raman spectroscopy measurements as well as scanning electron microscopy analysis. Porous polypropylene hollow fibers were filled with the functionalized carbon nanotubes (CNTs) and used for analyte extraction in urine sample at 40°C and pH 6 for 2 min. Reversed-phase high-performance liquid chromatography (RP-HPLC) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis showed that the fiber could preconcentrate 1 ng/mL of morphine and 0.75 ng/mL codeine in urine sample and was successfully used for 30 times with no significant loss in the extraction efficiency. Limit of detection (LOD) and limit of quantification (LOQ) for morphine were 1 and 3.3 ng/mL, respectively. LOD and LOQ for codeine were determined 0.75 and 2.47 ng/mL, respectively. Recovery of the fiber was 80% and 93% for morphine and codeine, respectively. SPME fiber using extract of F. gummosa plant was used for the detection of a small amount of morphine in urine sample. Therefore, plants can be considered as abundant and cheap sources of sorbent for various analytical purposes.

Acute and sub-acute toxicity evaluation of the root extract of Rheum turkestanicum Janisch.

Despite the widespread use of Rheum turkestanicum in herbal medicine, no study has yet examined its in vivo toxicity. The aim of this study is to evaluate the acute and sub-acute toxicity of hydroalcoholic extract of R. turkestanicum root. In acute toxicity experiment, female and male mice (n = 5/group/sex) were orally administrated with the extract at single doses of 300, 2000 and 3000 mg/kg and observed for 14 days. In the sub-acute study, the extract was orally administered daily at doses of 100 and 400 mg/kg to male rats (n = 8) for 4 weeks. During the acute toxicity test, there were no deaths or any signs of toxicity observed after administration of the R. turkestanicum extract at 300 mg/kg, which was the no-observed-adverse-effect level (NOAEL). The extract at a dose of 3000 mg/kg led to the death of one female and one male mouse (LD50 > 3000 mg/kg). In sub-acute toxicity experiment, the extract induced no mortality or significant changes in body weight, general behaviors, hematological parameters, serum biochemical factors (related to the kidney and liver function), and histopathology of the heart, liver, kidney, and brain up to the highest dose tested of 400 mg/kg (NOAEL). High-performance liquid chromatography-mass spectrometry revealed the presence of phenolic compounds, flavonoids, alkanes, and anthraquinones in the extract. In conclusion, short-term use of R. turkestanicum root does not appear to produce significant toxicity up to a dose of 400 mg/kg.