Ultrafiltration Method Research Articles

A low-molecular-weight ascophyllan prepared from Ascophyllum nodosum: Optimization, analysis and biological activities

In this study, a low-molecular-weight saccharide fragment (LMWAs-L) was prepared from alginate lyase (EC 4.2.2.3) hydrolyzed ascophyllan by ultra-filtration separation method. LMWAs-L was a homogeneous saccharide fraction with an average molecular weight of 6.96 kDa. Enzymolysis process optimization experiments revealed that the optimum process parameters for preparing LMWAs-L were the enzyme concentration 0.02 U/mL, initial pH 6.8, and enzymolysis temperature 43 °C. After optimization, the yield of LMWAs-L was increased to 9.74% higher than that without optimization. Interestingly, LMWAs-L exhibited stronger enhancing activities on the proliferation and migration of human skin fibroblasts cells in vitro and better antibacterial activities as compared to native ascophyllan at the same mass concentration. Our study establishes a simple way to prepare low-molecular-weight saccharide with beneficial bioactivities from ascophyllan efficiently. This is the first report to reveal that ascophyllan and its low-molecular-weight saccharide have the potentials to be developed as natural biological dressing and antibacterial agents.

Bacteriostatic effect of lipopeptides from Bacillus subtilis N-2 on Pseudomonas putida using soybean meal by solid-state fermentation

Bacillus subtilis N-2 which was isolated from natto, produced lipopeptides using soybean meal as a substrate. This work aimed to purify, identify, and determine the antibacterial mechanism of lipopeptides produced by B. subtilis N-2. The fermented product obtained by solid-state fermentation was subjected to water extraction, acid precipitation, and methanol extraction. Fractions were separated and collected using a two-step ultrafiltration method and then identified by LC–MS/MS. Mass spectrometry characterization revealed the presence of four variants of iturin A that differed according to the β-amino fatty acid chain from C14 to C17 as well as the amino acid positions. A new lipopeptide (m/z 1070.3) was identified and its structure was different from the previously reported lipopeptides. The lipopeptides were shown to inhibit the growth of an isolate of Pseudomonas putida, a common pathogen in decaying fish, by changing membrane permeability. These results suggest that the lipopeptides from B. subtilis N-2 could be used as a biocontrol agent in aquaculture.

Mediated pathways of exosomes uptake by stem cells of apical papilla

To evaluate the uptake of exosomes by stem cells from apical papilla (SCAP), thus to provide experimental basis for mechanism of the exosomes endocytosis by SCAP. (1) Exosomes of dental pulp stem cells (DPSCs) were isolated by hypercentrifugation combined with ultrafiltration method. The exosomes were identified by transmission electron microscopy, nanoparticle tracking analysis and western blot. (2) PKH-26 membrane labeling technology was used to mark the DPSCs derived exosomes. The labeled exosomes were co-cultured with SCAP at 37 °C as positive control group, and co-cultured with SCAP at 4 °C as the low-temperature treatment group, while the negative control group was set up. (3) Using clathrin-mediated endocytosis inhibitor chlorpromazine (CPZ, 10 μmol /L) as CPZ group, caveolae-mediated endocytosis Genistein (200 μmol/L) as Genistein group, and macropinocytosis inhibitor LY294002 (50 μmol/L) as LY294002 group to treat the SCAP respectively. Solvent control group (DMSO group) was set. Immunofluorescence staining was used to detect the red fluorescence SCAP and flow cytometry was used to analyze the proportion of SCAP labeled with red fluorescence. (1) The bilayer membrane and cup-shaped appearance of representative exosomes were observed. The peak of the size of DPSCs-derived exosomes was at 144 nm. The exosomes expressed exosomal marker proteins TSG101 and CD63, but not GAPDH which was the cellular internal control protein. (2) Immunofluorescence staining showed that after being co-cultured at 37 °C for 6 hours, red fluorescence could be detected in SCAP but it could not be detected after being co-cultured at 4 °C for 6 hours. After endocytosis inhibition, the red fluorescence in SCAP was reduced. Flow cytometry showed that the proportion of SCAP labeled with red fluorescence in positive group was 35.0%, in negative control group was 0.5%, and in solvent control group was 29.7%, in CPZ group, Genistein group and Genistein group were reduced to 13.7%, 16.6%, and 20.9%, respectively. SCAP could uptake the DPSCs derived exosomes, and low temperature could inhibit this process. The exosomes uptake of SCAP was mediated by the clathrin endocytosis pathway, caveolae-mediated endocytosis and macropinocytosis pathway.

Perspectives of coagulation/flocculation for the removal of pharmaceuticals from domestic wastewater: A critical view at experimental procedures

Literature frequently reports that colloids in aqueous matrices sorb a large fraction of pharmaceuticals. Since coagulation/flocculation removes colloids, it is expected that coagulation/flocculation in principle should be useful in concentrating pharmaceuticals in wastewater treatment, which would facilitate the treatment of these refractory compounds. In our present work, we researched the potential of coagulation/flocculation for removing pharmaceuticals from raw sewage. Results from jar tests showed that pharmaceuticals are hardly removed from sewage with coagulation/flocculation. To investigate the discrepancy between reported colloidal sorption and the lack of removal when removing colloids, we tested a commonly applied experimental setup, which makes use of ultra-filtration (UF), for determining the colloidal sorption of pharmaceuticals. The UF method under research was compared with an assessment making use of flocculation. Both methods, UF and flocculation, showed similar removal of colloids. However, during UF, the retention of pharmaceuticals reached values up to 93 ± 4 %. In contrast, when removing the colloids with flocculation, no pharmaceutical removal was observed. These results confirm that it is very likely to introduce an analysis bias in using UF membranes in the determination of colloidal sorption of pharmaceuticals. In fact, results predict an over-estimation caused by a direct retention of pharmaceuticals without any binding to colloidal matter. Overall results of the current work show that pharmaceuticals hardly sorb to colloids and herewith the absence of removal of pharmaceuticals during coagulation/flocculation is explained.

A comparative study of the bacteriotropic effect of metabiotics

Objective of the study:comparative evaluation of the bacteriotropic activity of Actoflor-S metabiotic and the exometabolic bifidobacteria complex.Materials and methods:in our work we used Actoflor-S dietary supplement as oral solution in 2 ml drop tubes (Solopharm). As a comparator drug, we used an exometabolite complex from the culture fluid of strain Bifidobacterium bifidum 1 obtained by method of ultrafiltration using separation apparatus with HOMM 15 kDa. We studied the stimulating effect of metabolite compositions on the acid forming activity and dynamics of the accumulation of lactobacilli Lactobacillus plantarum 8P-A3. Antagonistic activity against enterobacteria was determined in the test of inhibition of bioluminescence of the indicator strain Escherichia coli lum+ and quantified as an index of antibacterial activityResults and discussions.A comparative study of the effects of metabiotics on the acid forming activity of lactobacilli showed that both drugs have a pronounced stimulating effect on the probiotic strain L. plantarum. A comparative study of the effects of metabiotics on the model test strain of enterobacteria showed that whole preparations quickly and significantly (by more than 90%) inhibit the bioluminescence of E.coli lum+. Preparation dilutions 1:10 and 1:100 discovered significant differences in their activity. Given equal pH values (5.8 ± 0.1), Actoflor-S (dilution 1:10) inhibited the luminescence of E. coli lum + to a greater degree, exceeding almost 2 times the indicators of the metabolite bifidobacteria complex. It is revealing that Actoflor-S diluted 1:10 is not inferior to the whole preparation in terms of the level of effect on the test strain culture. What calls attention to itself is that large dilutions of UFLC of bifidobacteria after a short period of inhibition of luminescence of E. coli lum + have a stimulating effect. There is evidence that effect of inhibition of the luminescence of the control culture is dose-dependent.Conclusion.The results of a comparative examination of the bacterial action profile of the native exometabolites complex and Actoflor-S preparation confirm the presence of combination of the necessary inhibitory and stimulating activity against various agents of the microbiota. Creation of the metabiotics line based on Actoflor-S preparation with variability of biological properties and specialized for the management of various dysbiotic conditions show promise. An additional inclusion of native exometabolites of bifidobacteria and/or lactobacilli into the formula of artificial compositions will make it possible to expand the spectrum of the positive effect of probiotic preparations on the microorganism.

Bioaffinity Fishing Procedure Using Secretory Phospholipase A2 for Screening for Bioactive Components: Modulation of Pharmacological Effect Induced by sPLA2 from Crotalus durissus terrificus by Hispidulin from Moquiniastrum floribundum.

Bioaffinity capturing of molecules allows the discovery of bioactive compounds and decreases the need for various stages in the natural compound isolation process. Despite the high selectivity of this technique, the screening and identification methodology depends on the presence of a protein to capture potential ligands. However, some proteins, such as snake secretory phospholipase A2 (sPLA2), have never been investigated using this approach. The purpose of this study was to evaluate the use of a new method for screening natural compounds using a bioaffinity-guided ultrafiltration method on Crotalus durissus terrificus sPLA2 followed by HPLC-MS to identify the compounds, and this method could be used to discover new anti-inflammatory compounds from the various organisms originating from biodiversity. Different extracts were selected to evaluate their ability to inhibit sPLA2 activity. The extracts were incubated with sPLA2 and the resulting mixture was ultrafiltrated to elute unbound components. The resulting compounds were identified by HPLC-MS. We identified hispidulin as one of the components present in the Moquiniastrum floribundum leaf and evaluated the ability of this isolated compound to neutralize the inflammatory activity of sPLA2 from Crotalus durissus terrificus.

Is Zero-Balance Ultrafiltration an Effective Clinical Method for SIRS Prevention During Extracorporeal Circulation in Adults Heart Diseases Correction?

Background: Ultrafiltration, which is currently considered as a standard method to remove the excess water administered during cardiopulmonary bypass (CPB), aims to minimize the adverse effects of hemodilution, such as tissue edema and blood transfusion. Three ultrafiltration techniques can be used before, during and after CPB procedure, including conventional ultrafiltration (CUF), zero-balance ultrafiltration (Z-BUF), and modified ultrafiltration (MUF) at the end of CPB. The aim of study: The present research attempts to revise the efficiency of Z-BUF ultrafiltration method, laboratory results, and clinical impacts. Material and methods: 94 adults (54 men and 40 women) with acquired heart diseases undergoing a single cardiac surgical procedure in condition of cardiopulmonary bypass (clamp aortic 89, 9± 38, 8 min. and pump 135,14 ± 45,17 min.) were divided into 3 groups. 1st group (no ultrafiltration) - 34 patients with classic cardiac surgery, 2nd with the use of zero-balance ultrafiltration (ZBUF) group - 37 patients with classic cardiac surgery, and 3rd group ZBUF with mini invasive cardiac surgery - 23 patients.

Allometric Scaling Approaches for Predicting Human Pharmacokinetic of a Locked Nucleic Acid Oligonucleotide Targeting Cancer-Associated miR-221.

LNA-i-miR-221 is a novel phosphorothioate backbone 13-mer locked nucleic acid oligonucleotide-targeting microRNA-221 designed for the treatment of human malignancies. To understand the pharmacokinetic properties of this new agent, including unbound/total clearance, we investigated the LNA-i-miR-221 protein binding in three different species, including rat (Sprague–Dawley), monkey (Cynomolgus), and human. To this end, we generated a suitable ultrafiltration method to study the binding of LNA-i-miR-221 to plasma proteins. We identified that the fraction of LNA-i-miR-221 (at concentration of 1 and 10 µM) bound to rat, monkey, and human plasma proteins was high and ranged from 98.2 to 99.05%. This high protein binding of LNA-i-miR-221 to plasma proteins in all the species tested translates into a pharmacokinetic advantage by preventing rapid renal clearance. The integration of these results into multiple allometric interspecies scaling methods was then used to draw inferences about LNA-i-miR-221 pharmacokinetics in humans, thereby providing a framework for definition of safe starting and escalation doses and moving towards a first human clinical trial of LNA-i-miR-221.

Colloidal toxic trace metals in urban riverine and estuarine waters of Yantai City, southern coast of North Yellow Sea

The environmental characteristics of colloidal toxic trace metals Cd, Cu and Pb in riverine and estuarine waters collected from two urban rivers of Yantai City in eastern China, the Guangdang and Xin'an Rivers, were investigated using a modified centrifugal ultrafiltration (CUF) method in conjunction with acid extraction and inductively coupled plasma mass spectrometry. The target metals in dissolved pool were divided into four CUF fractions, i.e. <1 kDa, 1–3 kDa, 3–10 kDa and 10 kDa–0.2 μm, and the results showed that colloidal Cd, Cu and Pb were dominated by 1–10 kDa (1–3 and 3–10 kDa), 1–3 kDa and 10 kDa–0.2 μm fractions, respectively. The coagulation/flocculation of low-molecular-weight (1–10 kDa) colloidal Cd and Cu in the estuaries was obvious and strong, while the enrichment of dissolved Pb in the 10 kDa–0.2 μm fraction may be mainly related to its biogeochemical interactions with Fe-oxides, which is easy to occur in macromolecular colloids. In addition, the actual molecular weight cutoffs (MWCOs) of the three used CUF units with nominal MWCOs of 1, 3 and 10 kDa were determined to be 4.9, 8.5 and 33.9 kDa, respectively, indicating that membrane calibration is essential for explaining the actual fraction of dissolved trace metals and verifying the integrity of ultrafiltration membrane. Overall, the results in this study provide a further understanding of the heterogeneity in biogeochemical features, migration and fate of toxic trace metals in aquatic ecosystems, especially that of the river-sea mixing zone.

Biomedical copper speciation in relation to Wilson’s disease using strong anion exchange chromatography coupled to triple quadrupole inductively coupled plasma mass spectrometry

Biomedical analytical methods often rely on indirect measurements, such as immunoassays, which can lack effective metrological traceability. In the nephelometric determination of ceruloplasmin (Cp), an important protein whose circulating level is altered in Wilson’s disease (WD), the anti-Cp antibody used is not specific for the biologically active holoprotein so the assay can overestimate the concentration of Cp due to the presence of the apoprotein. By providing quantitation using elemental standards, the use of strong anion exchange chromatography (SAX) coupled to triple quadrupole inductively coupled plasma mass spectrometry (ICP-MS-MS) can overcome the drawbacks of methods for the measurement of metalloproteins reliant on immunoassays. In the current study, a SAX-ICP-MS-MS method for Cp quantification was designed and tested in samples of blood serum of WD patients and healthy controls. Using standards based on a copper-EDTA complex for calibration, the method provides relatively simple quantification of Cp with the limit of detection of 0.1 μg L−1 (limit of quantification 0.4 μg L−1). The method was also used to investigate the copper species separated by using a 30 kDa cut-off ultrafiltration device. The so-called "exchangeable" copper fraction is considered as an alternative clinical biomarker of WD. Using the designed speciation approach, it was shown that the ultrafiltration method can overestimate the "exchangeable" copper fraction due to a removal of copper from Cp. This was confirmed by comparing the enzymatic activity of the fractions. Thus, the specificity of the "exchangeable" copper test can be ensured only under strict maintenance of ultrafiltration conditions.

Routine and novel methods for isolation of extracellular vesicles

Extracellular vesicles (EV) play an important role in many physiological and pathological processes. Three main classes of EV are recognized, based on their biogenesis: exosomes, microvesicles and apoptotic bodies. Exosomes are extracellular-vesicles of 30 to 150 nm found in many bodily fluids (blood, urine, milk, cerebrospinal fluid, etc.). Due to their cellular origin and role in physiological and pathological processes, exosomes present in body fluids are considered a unique source of non-invasive and clinically relevant biomarkers. Analysis of exosomes can provide insight into the state of the parent-cell from which they originated. However, there is great heterogeneity in the methodologies used for exosome purification affecting the results of downstream analysis. The most commonly used methods for purification are based on ultracentrifugation (UC), ultrafiltration (UF) and precipitation. However, these are hard to standardize, leading to confounding and misleading results during downstream analyses, especially when highly-sensitive techniques such as mass spectrometry are used. Furthermore, loss of certain fractions or damage of EVs can lead to loss in obtained protein and RNA profile. Consequently, there is an emerging need to obtain consensus protocols for exosome isolation and identification of specific sub-populations. This manuscript will critically review the most commonly used techniques for EV purification such as UC, UF, size-exclusion, precipitation and immunoaffinity (IA) methods. We will also review the use of nano-antibodies for the development of novel IA protocols and identification of new EV biomarkers.

Development of a method to screen and isolate bioactive constituents from Stellera chamaejasme by ultrafiltration and liquid chromatography combined with semi‐preparative high‐performance liquid chromatography and high‐speed counter current chromatography

A simple and efficient method based on ultrafiltration with liquid chromatography and mass spectrometry was used for the rapid screening and identification of ligands in the extracts of Stellera chamaejasme. The bound ligands, i.e. daphnoretin, isopimpinellin, chamaechromone, neochamaejasmin A, and chamaejasmine (purity of 96.8, 90.75, 91.41, 93.98, and 98.91%, respectively), were separated by semi-preparative high-performance liquid chromatography combined with high-speed counter-current chromatography. To the best of our knowledge, this is the first study to report the detection of potent lipoxidase and lactate dehydrogenase inhibitors in Stellera chamaejasme extracts. The results demonstrate that our method of ultrafiltration with liquid chromatography and mass spectrometry combined with mixed chromatography can be used to screen and confirm the bioactivity of all isolated compounds. This method also eliminates the need for separation of inactive compounds, thereby improving efficiency when studying bioactive substances. For some complex mixtures, neither semi-preparative high-performance liquid chromatography nor high-speed counter-current chromatography can purify all the target active compounds with high purity in a one-step separation. The combination of the two methods allow for efficient purification of target bioactive compounds with different polarities and physicochemical properties based on their complementary properties.

Association of Hepatic Nuclear Factor 4 Alpha Gene Polymorphisms With Free Imatinib Plasma Levels and Adverse Reactions in Chinese Gastrointestinal Stromal Tumor Patients.

As the first-line treatment of gastrointestinal stromal tumor (GIST), the pharmacokinetic and pharmacodynamic of imatinib (IM) were characterized by marked interindividual variability. Pharmacogenetics of IM involved metabolic enzymes and transporters have been extensively reported, but the results remained inconsistent. This study investigated the effect of genetic variants in hepatocyte nuclear factor 4 alpha (HNF4α, encoded by gene NR2A1), a pivotal transcriptional regulator of drug disposition genes, on dose-adjusted IM-free plasma levels and related adverse reactions in Chinese GIST patients. Five common polymorphisms of NR2A1 (rs3818247, rs1884613, rs2071197, rs2425640, and rs736824) were genotyped in 70 Chinese GIST patients who had been administered IM 300-600 mg/d. The free IM trough plasma levels were determined based on a method of ultrafiltration coupled with high performance liquid chromatography-tandem mass spectrometry. There were wide interpatient variations in free plasma levels of IM (range, 9.50-67.50 ng/mL), in which significant sex differences were observed (P < 0.01). The dose-adjusted IM-free plasma levels showed a significant negative correlation with body surface area (r = -0.302, P = 0.012). Although there were no significant effects of NR2A1 polymorphisms on dose-adjusted IM-free plasma levels among the study population, polymorphism in rs736824 was found to be significantly associated with dose-adjusted IM-free plasma levels in male subjects (P = 0.031). For the IM-related adverse reaction, polymorphisms in rs3818247 were found to be significantly associated with periorbital edema (P = 0.032). In addition, no significant correlations were found between IM-free plasma levels and IM-related adverse reactions, except for the correlation of IM-free plasma levels with periorbital edema among male patients (P = 0.013). The research demonstrated that NR2A1 polymorphisms may act as contributors of IM pharmacokinetics and responses in Chinese GIST patients. This represents an attractive opportunity for IM therapy optimization, worth testing in clinical trials.

Antioxidant Peptides from the Protein Hydrolysate of Spanish Mackerel (Scomberomorous niphonius) Muscle by in Vitro Gastrointestinal Digestion and Their In Vitro Activities.

For the full use of Spanish mackerel (Scomberomorous niphonius) muscle to produce antioxidant peptides, the proteins of Spanish mackerel muscle were separately hydrolyzed under five kinds of enzymes and in vitro gastrointestinal digestion, and antioxidant peptides were isolated from the protein hydrolysate using ultrafiltration and multiple chromatography methods. The results showed that the hydrolysate (SMPH) prepared using in vitro GI digestion showed the highest degree of hydrolysis (27.45 ± 1.76%) and DPPH radical scavenging activity (52.58 ± 2.68%) at the concentration of 10 mg protein/mL among the six protein hydrolysates, and 12 peptides (SMP-1 to SMP-12) were prepared from SMPH. Among them, SMP-3, SMP-7, SMP-10, and SMP-11 showed the higher DPPH radical scavenging activities and were identified as Pro-Glu-Leu-Asp-Trp (PELDW), Trp-Pro-Asp-His-Trp (WPDHW), and Phe-Gly-Tyr-Asp-Trp-Trp (FGYDWW), and Tyr-Leu-His-Phe-Trp (YLHFW), respectively. PELDW, WPDHW, FGYDWW, and YLHFW showed high scavenging activities on DPPH radical (EC50 1.53, 0.70, 0.53, and 0.97 mg/mL, respectively), hydroxyl radical (EC50 1.12, 0.38, 0.26, and 0.67 mg/mL, respectively), and superoxide anion radical (EC50 0.85, 0.49, 0.34, and 1.37 mg/mL, respectively). Moreover, PELDW, WPDHW, FGYDWW, and YLHFW could dose-dependently inhibit lipid peroxidation in the linoleic acid model system and protect plasmid DNA (pBR322DNA) against oxidative damage induced by H2O2 in the tested model systems. In addition, PELDW, WPDHW, FGYDWW, and YLHFW could retain their high activities when they were treated under a low temperature (<60 °C) and a moderate pH environment (pH 5–9). These present results indicate that the protein hydrolysate, fractions, and isolated peptides from Spanish mackerel muscle have strong antioxidant activity and might have the potential to be used in health food products.

Searching for diagnostic properties of novel fluorine-18-labeled D-allose.

Two fluorine-18-labeled analogues, 3-deoxy-3-[18F]fluoro-D-allose (3-[18F]FDA) and 6-deoxy-6-[18F]fluoro-D-allose (6-[18F]FDA), were synthesized and their potentials of diagnostic property were characterized. In vitro rat red blood cell (RBC) transport and phosphorylation by yeast hexokinase were evaluated in comparison with 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG). The rate of protein binding in pooled human serum was measured by an ultrafiltration method. In vivo metabolite analysis in mice was also performed. Biodistribution, urine excretion, and in vivo renal kinetics in mice were compared with 2-deoxy-2-[18F]fluorosorbitol ([18F]FDS). Rat RBC uptake of 3- and 6-[18F]FDA (7.8 ± 2.5%ID and 10.2 ± 4.8%ID, respectively) was significantly lower than that of [18F]FDG (44.7 ± 8.7%ID). RBC uptake of 3-[18F]FDA was inhibited by D-glucose (30%) and cytochalasin B (40%), indicating the involvement of GLUT1-dependent transport. In contrast, 6-[18F]FDA transport was not inhibited by D-glucose and cytochalasin B. 3- and 6-[18F]FDA were not phosphorylated by yeast hexokinase under the conditions that result in 60% conversion of [18F]FDG into [18F]FDG-6-phosphate within 30min. Serum protein binding of 3- and 6-[18F]FDA was negligible. Metabolic transformation of both tracers was not detected in plasma and urine at 30min after injection. The highest tissue uptake of both tracers was observed in kidneys. Heart and brain uptake of both tracers was below blood levels throughout the biodistribution studies (until 120min after injection). No significant uptake in the bone was observed, indicating the absence of de-fluorination in mice. In vivo PET imaging visualized rapid excretion of the administered 3- and 6-[18F]FDA from the kidneys, with minimal tracer accumulation in other organs. The urine excretion rate of 3-[18F]FDA was much lower than that of 6-[18F]FDA and [18F]FDS. 3- and 6-[18F]FDA might be unsatisfactory for tumor imaging. In contrast, these tracers demonstrated high levels of kidney uptake and excretion, low serum protein binding, and high metabolic stability as preferable properties for renal imaging. Notably, the urine excretion rate and kidney uptake kinetics of 6-[18F]FDA were comparable with those of the potential renal imaging agent [18F]FDS. Further validation studies in animal models are required to confirm the feasibility of 6-[18F]FDA as a functional renal imaging agent.

Identification and Active Evaluation of Antioxidant Peptides from Protein Hydrolysates of Skipjack Tuna (Katsuwonus pelamis) Head.

For the full use of fish by-products to produce antioxidant peptides, skipjack tuna (Katsuwonus pelamis) heads generated during can processing were defatted and hydrolyzed using the in vitro gastrointestinal (GI) digestion (pepsin–trypsin system) method and six antioxidant peptides (P1 to P6) were purified from the head hydrolysate (KPH) using ultrafiltration and serial chromatography methods. Six isolated peptides (P1 to P6) were identified as Val-Glu-Glu (VEE, P1), Trp-Met-Phe-Asp-Trp (WMFDW, P2), Asp-Ala-Gly-Pro-Tyr-Gly-Pro-Ile (DAGPYGPI, P3), Trp-Met-Gly-Pro-Tyr (WMGPY, P4), Glu-Arg-Gly-Pro-Leu-Gly-Pro-His (ERGPLGPH, P5), and Glu-Met- Gly-Pro-Ala (EMGPA, P6), respectively, using a protein sequencer and electrospray ionization-mass spectrometer. Among skipjack tuna head hydrolysates, fractions, and six isolated peptides (P1 to P6), WMFDW (P2), WMGPY (P4), and EMGPA (P6) showed the highest radical scavenging activities on 2,2-diphenyl-1-picrylhydrazyl (DPPH) (EC50 values of 0.31, 0.33, and 0.46 mg/mL for WMFDW, WMGPY, and EMGPA, respectively), hydroxyl (EC50 values of 0.30, 0.43, and 0.52 mg/mL for WMFDW, WMGPY, and EMGPA, respectively), and superoxide anion (EC50 values of 0.56, 0.38, and 0.71 mg/mL for WMFDW, WMGPY, and EMGPA, respectively). Moreover, WMFDW, WMGPY, and EMGPA showed strong capability in reducing power and lipd peroxidation inhibition in the linoleic acid system. In addition, WMFDW, WMGPY, and EMGPA can retain strong antioxidant activity at temperatures lower than 60 °C and pH values ranged from 5 to 9. The results showed that six isolated peptides (P1 to P6) from skipjack tuna heads, especially WMFDW, WMGPY, and EMGPA, might be applied in health care products acting as powerful antioxidant agents.

Angiotensin Converting Enzyme (ACE) Inhibitory Activity of Peptide Fraction of Germinated Pigeon Pea (&lt;i&gt;Cajanus cajan&lt;/i&gt; (L.) Millsp.)

During the germination process, seeds can release various types of peptides due to the degradation of storage proteins. Some of these peptides can have biological activity (bioactive peptides). The objective of this study was to determine the ACE inhibitory activity of germinated pigeon pea peptide extract at various germination times and to carry out the fractionation to the extract to get the most active peptide fraction. The results showed that the highest activity of peptide extract was found on the 4th-day germination of pigeon pea with an IC50 value of 63.46 μg/mL. The peptide extract was further fractionated by centrifugal ultrafiltration method and it was found that the peptide fraction &lt; 3 kDa had the highest ACE inhibitory activity with an IC50 value of 57.79 μg/mL. The result of identification with the LCMS method to the fraction was able to detect 4 types of the peptide with a molecular weight of 230.304, 294.303, 441.436, and 570.591 Da. These results suggested that the peptide fraction of germinated pigeon pea has the potency as an ACE inhibitory nutraceutical.

500-P: The Performance of Four Different Exosome Isolation Methods for Urinary Exosomal microRNA Profiling in Patients with Diabetic Kidney Disease

Both exosome and microRNAs (miRNAs) in biological fluids can be good biomarkers for pathologic conditions. Thus, urinary exosome miRNAs would be reasonable non-invasive tools for biomarker development for diabetic kidney disease. To be eligible for exosome miRNA biomarker development, the performance of exosome isolation methods for miRNA profiling need to be tested. In the present study, using urine samples from patients with type 2 diabetes, we compared four different exosome isolation methods for their performance in urine exosome isolation and detectable urinary exosome miRNA profiles. Four methods compared in the present study were ultracentrifugation (UC), size exclusion chromatography using qEV column (qEV), ExoQuick-TC (ExoQuick), and Amicon tube 100K (Amicon). Isolated exosomes were subjected to next generation sequencing (NGS) to profile miRNAs. The counts, RNA concentrations, and protein marker expressions of isolated urine exosome were variable between the extraction methods, with the highest exosome count with the qEV method. The number of miRNAs detected (read count ≥1) in 100 mL urine each were 314, 174, 91, and 130 from UC, qEV, ExoQuicK, and Amiconmethods, respectivley. And, 57 miRNAs were detected with all 4 methods concordantly. There were correlations in the levels of exosomal miRNAs between samples from UC, qEV, and ExoQuick methods, whereas exosome miRNA profiles from Amicon sample showed only a weak correlation with those from other methods. Our results suggest that exosome isolation by using UC or qEV method may be a better option among different isolation methods to profile urinary exosome miRNAs in diabetic kidney disease. However, ultrafiltration method using Amicon tube produced a different profile of miRNAs with other methods. Further studies are needed to characterize both exosome and their genetic materials from different extraction sources. Disclosure K. Lee: None. D. Lee: None. I. Park: None.

Spectroscopic methodologies and molecular docking studies on the interaction of antimalarial drug piperaquine and its metabolites with human serum albumin.

Artemisinin-based combination therapy is widely used for the treatment of uncomplicated Plasmodium falciparum malaria, and piperaquine (PQ) is one of the important partner drugs. During the biotransformation of PQ, M1 (N-oxidation product), M2 (N-oxidation product), M3 (carboxylic acid product), M4 (N-dealkylation product), and M5 (N-oxidated product of M4) are formed by cytochrome P450 pathways. Despite decades of clinical use, the interactions between PQ and its main metabolites (PQs) with human serum albumin (HSA) have not been reported. In the present study, the binding of PQs with HSA under physiological conditions was investigated systematically through fluorescence, circular dichroism (CD) spectroscopy, and molecular docking methods. The experimental results show that the intrinsic fluorescence quenching of HSA was induced by those compounds resulting from the formation of stable HSA-compound complexes. The main forces involved in the interactions between PQ, M1, and M2 which bind to HSA were hydrogen s and van der Waals forces, while the interactions of M3, M4, and M5 were driven by hydrophobic forces. The main binding sites of the compounds to HSA were also examined by classical fluorescent marker experiments and molecular docking studies. Binding constants (Kb) revealed that the affinities of the PQ, M1, M2, M3, and M4 to HSA were stronger than that of M5. Additionally, the binding rates of PQs with HSA were determined by ultrafiltration methods. Consistent with the binding constant results, the binding rate of M5 was lower than the binding rates of PQ, M1, M2, M3, and M4. Furthermore, PQs binding to HSA led to conformational and structural alterations of HSA, as revealed by multi-spectroscopic studies. In order to investigate one possible mechanism by which PQs inhibit the growth of malaria-causing Plasmodium parasites, 1H NMR spectroscopy was performed to investigate the interaction of the PQs with heme. This study is beneficial to enhance our understanding of the ecotoxicology and environmental behaviors of PQ and its metabolites.

Ultrafiltration isolation, hypoglycemic activity analysis and structural characterization of polysaccharides from Brasenia schreberi

Brasenia schreberi (B. schreberi) is a rare and precious vegetable, which coat with a gelatinous mucilage. This study is aiming to investigate the relationship between structural characteristics and hypoglycemic activities of polysaccharides with different molecular weight (Mw) range. Three polysaccharides fractions, namely BSP-U100 (50–100 kDa), BSP-U50 (10–50 kDa) and BSP-U10 (<10 kDa), were isolated from B. schreberi mucilage using ultrafiltration method. Compared to other polysaccharide samples, only BSP-U100 had a triple helix structure and existed as the ordered structure in aqueous solution. Furthermore, BSP-U100 exhibited higher α-amylase (IC50 = 0.4414 mg/mL) and α-glucosidase (IC50 = 0.5993 mg/mL) inhibitory activity. A heteropolysaccharide BSP-1a, which average Mw was 83.98 kDa, was purified from BSP-U100 by DEAE Sepharose Fast Flow and Sephadex G-75 column. D-galactose (66.85%), d-glucose (2.05%) and D-mannose (1.65%) were three main monosaccharides of BSP-1a. Structural characterization of BSP-1a showed that BSP-1a might be a kind of L-D-pyranose type galactose and mainly composed of α-1 → 6-linked Galp, α-1 → 3-linked Manp and α-1 → 4-linked Glcp. This study provided a theoretical basis for the development and application of B. schreberi polysaccharides as a potential anti-diabetic supplement.