Investigating the migration hypothesis: Effects of trypsin-like protease on the quality of muscle proteins of red shrimp (Solenocera crassicornis) during cold storage

This study aimed to investigate the effect of trypsin-like protease (TLP) on the quality of muscle proteins in red shrimp (Solenocera crassicornis) during cold storage. The results indicated that the activity of TLP decreased significantly in the head of shrimp but increased significantly in the muscle tissues during the cold storage. The myofibril fragmentation index (MFI) value of intact shrimp was significantly higher than that of beheaded shrimp, while the Ca2+-ATPase activity of intact shrimp was significantly lower than that of beheaded shrimp. SDS-PAGE analysis showed that the molecular weight of purified TLP from the shrimp head was about 24 kDa, and the TLP showed high activity at 50 °C and pH 8, indicating that the TLP belongs to the trypsin family. Results from in vitro simulation experiments indicated that the process of TLP incubation significantly reduced the particle size and enlarged the distribution of myofibrillar proteins (MPs) in shrimp muscle tissues. The comparisons were made with respect to the control samples. It can be inferred that TLP migrated from the shrimp head to the muscle tissues during storage and thus promoted the degradation of MPs in red shrimp. The beheading treatment could be an effective mean to maintain better quality and extend the commercialization of shrimp products.

Elaboration and characterization of curcumin-loaded soy soluble polysaccharide (SSPS)-based nanocarriers mediated by antimicrobial peptide nisin

Curcumin was recently attracted great interest owing to its multiple bioactivities; however, the use of curcumin was hindered by its poor solubility and stability. In this study, curcumin-nisin-soy soluble polysaccharide nanoparticles (Cur-Nisin-SSPS-NPs, size = 118.76 nm) have been successfully elaborated to improve the application of curcumin. The formation of Cur-Nisin-SSPS-NPs was mediated by amphiphilic and positively charged nisin: SSPS encapsulated nisin, which was mainly driven by electrostatic attraction. And nisin-SSPS complex encapsulated curcumin mainly through hydrophobic interactions between nisin and curcumin. The encapsulation efficiency of curcumin (91.66%) in this novel nanocarriers was significantly higher than that in nanoparticles prepared by a single SSPS (31.82%) or nisin (41.69%), most likely because more hydrophobic regions of nisin were exposed after interacting with SSPS through electrostatic interaction. Consequently, this facile and green nanocarriers improved the solubility/dispersibility and stability of curcumin and nisin, as well as endowed SSPS-based nanoparticles with antioxidant and antimicrobial activities.

BabaoDan cures hepatic encephalopathy by decreasing ammonia levels and alleviating inflammation in rats

ETHNOPHARMACOLOGICAL RELEVANCE

BabaoDan (BBD) is a famous traditional Chinese formula frequently used in TCM clinics to eliminate jaundice and treat infectious viral hepatitis. This paper assesses BBD's preventive and therapeutic effects on hepatic encephalopathy after liver cirrhosis (CHE) and acute liver failure (AHE) in rats and explains its possible mechanism of action.

METHODS

CHE rat model was established by injection of carbon tetrachloride (CCl4) twice a week for a total of 9 weeks and then by injection of thioacetamide (TAA) to induce hepatic encephalopathy. AHE rat model was established by injection of TAA once a day for a total of 3 days. In CHE rat model, BBD was gavaged once a day at the end of the 6th week until the experiment ended. In AHE rat model,BBD was gavaged once a day 3 days before TAA injection until the experiment ended. The preventive and therapeutic effects of BBD on brain dysfunction, as well as liver injury, pathology and fibrosis were evaluated in vivo. The role of BBD in the regulation of inflammatory factors and myeloid differentiation factor 88/Toll-like receptor 4/nuclear factor kappa-B (TLR4/MyD88/NK-κ B) pathway was detected in both liver and brain in vivo. The rat bone marrow derived macrophages (BMDMs) were activated by Lipopolysaccharide (LPS), and the role of BBD in the regulation of inflammatory factors and NK-κ B pathway were detected in vitro.

RESULTS

In CHE rat model: BBD significantly improved the total distance as well as the activity rate of rats. BBD also improved the learning and memory abilities of rats compared with the control group. In addition, BBD effectively decreased ammonia levels and significantly decreased the levels of alanine aminotransferase (ALT), aspartate transaminase (AST), total bilirubin (TBil) and total bile acid (TBA), as well as improved the levels of total protein (TP) and albumin (Alb). In the liver, BBD not only inhibited the gene expressions of tumor necrosis factor alpha (TNF-α), interleukini-6 (IL-6), TLR4, MyD88, and NF-κ B but also inhibited the protein expressions of TLR4, MyD88, NK-κ B and TNF-α. In the brain, BBD inhibited the gene expressions of iNOS, IL-6, TNF-α, TLR-4, MyD88, and NF-κ B, as well as inhibited the protein expressions of TLR4, MyD88, P65 TNF-α and ionized calcium binding adapter molecule 1 (Iba-1). BBD also decreased NO and TNF-α in the blood.

IN AHE RAT MODEL

BBD improved neurological scores, blood ammonia levels and the brain inflammatory gene expressions of iNOS, TNF-α and IL-1β. BBD also improved liver function biomarkers such as ALT, TBil, TBA, TP, ALB and inflammatory and apoptotic gene expressions of TNF-α, IL-1β, IL-6, Bax, Bcl-2, caspase-9, caspase-3 and NF-κ B. In LPS-activated rat BMDMs, BBD decreased NO and TNF-α production in BMDM culture supernatant. In addition, BBD inhibited the gene expressions of TNF-α, IL-1 β and IL-6 as well as the phosphorylation of P65.

CONCLUSION

BBD can prevent and cure hepatic encephalopathy (HE) derived from both chronic and acute liver diseases. BBD can reduce hyperammonemia as well as the systematic and neurological inflammation. Inflammation is likely an important target of BBD to treat HE. The anti-inflammatory role of BBD may lie in its regulation of the TLR4/MyD88/NF-κ B pathways.

Aroma binding and stability in brewed coffee: A case study of 2-furfurylthiol

The aroma stability of fresh coffee brew was investigated during storage over 60 min, there was a substantial reduction in available 2-furfurylthiol (2-FFT) (84%), methanethiol (72%), 3-methyl-1H-pyrole (68%) and an increase of 2-pentylfuran (65%). It is proposed that 2-FFT was reduced through reversible chemical binding and irreversible losses. Bound 2-FFT was released after cysteine addition, thereby demonstrating that a reversible binding reaction was the dominant mechanism of 2-FFT loss in natural coffee brew. The reduction in available 2-FFT was investigated at different pH and temperatures. At high pH, the reversible binding of 2-FFT was shown to protect 2-FFT from irreversible losses, while irreversible losses led to the reduction of total 2-FFT at low pH. A model reaction system was developed and a potential conjugate, hydroxyhydroquinone, was reacted with 2-FFT. Hydroxyhydroquinone also showed 2-FFT was released after cysteine addition at high pH.

Citric acid can force Staphylococcus aureus into viable but nonculturable state and its characteristics

Pathogens in viable but nonculturable (VBNC) state can escape traditional detection methods based on culturable ability, thus bringing risks to food safety and human health. Considering Staphylococcus aureus as a kind of primary foodborne pathogen, this study attempted to investigate whether citric acid, a food additive commonly used, can force S. aureus into VBNC state along with low temperature. Treated with citric acid solution (pH 4.0) at 4 °C, S. aureus was confirmed to enter into VBNC state after induction for 18 days. Meanwhile, resuscitation was achieved in culture medium rather than in nutrition-free saline solution. In VBNC cells, ATP concentration still maintained at a high level, as about two-thirds of exponential-phase cells. For survival, intracellular structure of VBNC cells changed remarkably, including irregular cell shape, denser cytoplasm, space between cell wall and cell membrane, and decreased density of nuclear region. Notably, resistance of VBNC cells to simulated gastric fluid improved when compared with exponential-phase cells. What are noted above suggests that VBNC state adopted by S. aureus might be a survival strategy to the adverse environment (acidity stress and low temperature). In conclusion, our study sounds an alarm for the safety of citric acid-containing foods.

In vitro and ex vivo studies on diltiazem hydrochloride-loaded microsponges in rectal gels for chronic anal fissures treatment

Diltiazem hydrochloride, topically applied at 2% concentration, is considered effective for the treatment of chronic anal fissures, although it involves several side effects among which anal pruritus and postural hypotension. To test the hypothesis that a sustained delivery system of diltiazem hydrochloride may be helpful for the treatment of chronic anal fissures, in the present study we evaluated the potential of gels containing diltiazem hydrochloride entrapped in microsponges. Such microsponges were based on Eudragit RS 100 and the effect of some formulation variables was assessed by a 2³ full factorial screening design. An optimized formulation of diltiazem hydrochloride microsponges was dispersed in Methylcellulose 2% or Poloxamer 407 20% and the resulting gels (micro-l-diltiazem hydrochloride 2%) were subjected to in vitro drug release, ex vivo permeability and drug deposition after application on porcine rectal mucosa. The results showed a prolonged release up to 24 h from micro-l-diltiazem hydrochloride at 2% in the gels. The permeation tests revealed up to 18% higher drug retention on the mucosal tissue after 24 h by the micro-l-diltiazem hydrochloride 2% gels compared to conventional diltiazem hydrochloride gels at 2%. These results suggest that diltiazem hydrochloride-loaded microsponges dispersed in rectal gels may be useful to overcome some limitations of conventional local chronic anal fissure therapy.

Sodium sulfite pH-buffering effect for improved xylose-phenylalanine conversion to N-(1-deoxy-d-xylulos-1-yl)-phenylalanine during an aqueous Maillard reaction

The yield of the Maillard reaction intermediate (MRI), prepared in aqueous medium, is usually unsatisfactory. However, the addition of sodium sulfite could improve the conversion of xylose-phenylalanine (Xyl-Phe) to the MRI (N-(1-deoxy-d-xylulos-1-yl)-phenylalanine) in aqueous medium. Sodium sulfite (Na₂SO₃) showed a significant pH-buffering effect during the Maillard reaction, which accounted for its facilitation of the N-(1-deoxy-d-xylulos-1-yl)-phenylalanine yield. The results revealed that the pH could be maintained at a relatively high level (above 7.0) for an optimized pH-buffering effect when Na₂SO₃ (4.0%) was added before the reaction of Xyl-Phe. Thus, the conversion of Xyl-Phe to N-(1-deoxy-d-xylulos-1-yl)-phenylalanine increased from 47.23% to 74.86%. Furthermore, the addition moment of Na₂SO₃ and corresponding solution pH were crucial factors in regulating the pH-buffering effect of Na₂SO₃ on N-(1-deoxy-d-xylulos-1-yl)-phenylalanine yield. Based on the pH-buffering effect of Na₂SO₃ and maintaining the optimal pH 7.4 relatively stable, the conversion of Xyl-Phe to N-(1-deoxy-d-xylulos-1-yl)-phenylalanine was successfully improved.

Interactions of two food colourants with BSA: Analysis by Debye-Hückel theory

We have focused on exploring pH- and ionic strength-modulated binding of acid red 1 (AR1) and acid green 50 (AG50) with bovine serum albumin (BSA) by fluorescence, UV-vis absorption and FTIR spectra. The results implied that the quenching mechanism of BSA-AR1/AG50 system was a static quenching, electrostatic force dominated the formation of BSA-AR1/AG50 complex, and the binding affinity of AR1 was greater than that of AG50 on the subdomain IIA of BSA. Moreover, their true thermodynamic binding constant (Keq), true free energy change (ΔG(0)I→0), and effective charge (ZP) in the anion receptor pocket of BSA were calculated using Debye-Hückel limiting law. The local charge bound by AR1/AG50 rather than the overall or surface charge of BSA played a key role in determining their interaction strength. Besides, the thermal and structural stabilization of BSA was discussed by analyzing the changes of Tm and Hurea without/with the addition of AR1/AG50, respectively.

Production of nano bacterial cellulose from beverage industrial waste of citrus peel and pomace using Komagataeibacter xylinus

Bacterial cellulose (BC) is a high-purity and robust cellulose that is utilised in medicine, consumer goods, and industrial practices. The present study aimed to investigate the suitability of beverage industrial waste for the production of BC by Komagataeibacter xylinus CICC No. 10529 and to study the structural properties of BC films in both citrus peel and pomace enzymolysis (CPPE) and Hestrin-Schramm (HS, Hestrin & Schramm, 1954) media. Under similar experimental conditions, the yield of BC from CPPE medium was 5.7±0.7g/L, which was higher than from HS medium (3.9±0.6g/L). To evaluate the structure of BC, fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and colour evaluation using a chroma meter were utilised. The average diameters of BC, obtained from CPPE and HS mediums, were 50nm and 60nm, respectively. The crystallinity index of BC from the CPPE medium was approximately 63%, which was lower than BC produced from the HS medium (65%). The two varieties of BC showed no significant differences in relation to their colour parameters. Therefore, BC production from CPPE medium had similar properties to BC from HS medium, but it is more environmentally friendly and cheaper to produce.

A novel extraction method for β-carotene and other carotenoids in fruit juices using air-assisted, low-density solvent-based liquid-liquid microextraction and solidified floating organic droplets

Green extraction using air-assisted, low-density solvent-based liquid-liquid microextraction and solidified floating organic droplets (AA-LDS-LLME-SFOD) prior to spectrophotometry was successfully applied for quantitation of carotenoids in fruit juices. Under optimal conditions, β-carotene could be quantified with a linear response up to a concentration of 60 μg mL(-1). The procedure was performed in a microcentrifuge tube with 40 μL of 1-dodecanol as the extraction solvent and a 1.0 mL juice sample containing 8% NaCl under seven extraction cycles of air pumping by syringe. This method was validated based on linearity (0.2-30 μg mL(-1), R(2) 0.998), limit of detection (0.04 μg mL(-1)) and limit of quantification (0.13 μg mL(-1)). The precision, expressed as the relative standard deviation (RSD) of the calibration curve slope (n=12), for inter-day and intra-day analysis was 4.85% and 7.92%, respectively. Recovery of β-carotene was in the range of 93.6-101.5%. The newly proposed method is simple, rapid and environmentally friendly, particularly as a useful screening test for food analysis.

Heat-pretreatment and enzymolysis behavior of the lotus seed protein

Lotus seed protein (LSP) was heat-pretreated before enzymolysis in order to seek a greater degree of hydrolysis (DH) during enzymatic hydrolysis. The parameters including substrate concentration, temperature, pH, and papain concentration were optimized by response surface methodology in the enzymolysis of the heat-pretreated LSP. The influence of substrate concentration on the non-pretreated LSP enzymolysis was assessed, and the enzymolysis was found to obey the Haldane model with inhibition by LSP substrate. The initial concentration of non-pretreated LSP was inferred theoretically to be 11.07 g/L in order to avoid substrate inhibition. On the other hand, Chrastil model was fitted and the diffusion resistance constant values were in the range of 0.5-0.6 for the diffusion-controlled encounter of enzyme and substrate, implying that diffusion was a rate-limiting step. The heat-pretreatment at 60 °C for 60 min could increase the DH of the LSP, which enhanced the efficiency of the enzymolysis by papain.

Hyperbranched-hyperbranched polymeric nanoassembly to mediate controllable co-delivery of siRNA and drug for synergistic tumor therapy

This study reported a flexible nanoplatform constructed on the pH-dependent self-assembly of two kinds of hyperbranched polymers, and then validated its potency as the controllable siRNA/drug co-delivery vehicle for the combination of chemotherapy with RNA interfering (RNAi) therapy. By virtue of pH-reversible phenylboronate linking, phenylboronic acid-tethered hyperbranched oligoethylenimine (OEI600-PBA) and 1,3-diol-rich hyperbranched polyglycerol (HBPO) can be spontaneously interlinked together into a core-corona nanoconstruction. The special buildup of compactly clustering OEI600-PBA units around hydrophobic HBPO aggregate offered significant advantages over parent OEI600-PBA, including strengthened affinity to siRNA, ability of further loading anticancer drug, easier cellular transport, and acidity-responsive release of payloads. To evaluate the co-delivery capability, Beclin1 siRNA and antitumor DOX were used as the therapeutic models in order to suppress the post-chemotherapy survival of tumor cells caused by drug-induced autophagy. The nanoassembly-mediated single delivery of DOX displayed even better anticancer effects than free DOX, demonstrating the superiority of our pH-responsive nano-design. The nanoassembly-mediated co-delivery of siRNA together with DOX can effectively silence Beclin1 gene, suppress DOX-induced autophagy, and consequently provide strong synergism with a significant enhancement of cell-killing effects in cultured cancerous cells. The in vivo combinational treatment was shown to make the tumor more sensitive to DOX chemotherapy while displaying substantially improved safety as compared with the monochemotherapy.

Micelle formulation of hexadecyloxypropyl-cidofovir (HDP-CDV) as an intravitreal long-lasting delivery system

There still is an unmet need for a safe and sustained intravitreal drug delivery system. In this study we are proposing and characterizing a micelle based, clear-media intravitreal drug delivery system using the lipid derivatized nucleoside analog, hexadecyloxypropyl-cidofovir (HDP-CDV, CMX 001). HDP-CDV forms micelles in water and in vitreous supernatant with the critical micelle concentration of 19 μg/mL and 9 μg/mL, respectively at 37 °C. The formed micelles had the average size of 274.7 nm and the Zeta potential of -47.1 mV. Drug release study in the excised rabbit vitreous showed a sustained release profile with a half-life of 2.7 days. The micelle formulation of HDP-CDV demonstrated a good safety profile in two animal species (rabbit and guinea pig) following intravitreal injection. The sustained efficacy was tested in a pretreatment study design and the drug potency was tested in an ongoing herpes simplex virus (HSV-1) retinitis model. The pretreatment studies using single intravitreal injection and later HSV-1 infection revealed at least 9 weeks of vitreous presence and therapeutic level of HDP-CDV, with 71% eyes protection from infection. The treatment study demonstrated that intravitreal administration halted active HSV-1 retinitis in 80% of the infected eyes while cidofovir (CDV) treatment failed to suppress active HSV-1 retinitis. In summary, lipid derivatized nucleoside analogs can be formulated as a micelle intravitreal injection and provides a sustained drug release in vitreous for chronic retinal diseases.

Improved solubility and stability of 7-hydroxy-4-methylcoumarin at different temperatures and pH values through complexation with sulfobutyl ether-β-cyclodextrin

The inclusion complex of 7-hydroxy-4-methylcoumarin (7H4MC) with sulfobutyl ether-β-cyclodextrin (SBE-β-CD) was investigated by means of UV-vis, circular dichroism and (1)H NMR spectroscopy in phosphate buffer solutions at different temperatures and pH values. The stoichiometric ratio of the complexation was found to be 1:1 and the stability constants (KC) were estimated from phase solubility analysis. The thermodynamic parameters of standard Gibbs free energy change, ΔG(o), enthalpy change, ΔH(o), and entropy change, ΔS(o), for the complexation process were obtained by using the van't Hoff equation and Gibbs-Helmholtz equation. The large negative ΔH(o) and the small negative or positive ΔS(o) (|ΔH(o)|>|TΔS(o)|) demonstrated that the inclusion interaction was an enthalpy-driven process. The positive signal of circular dichroism indicated that 7H4MC penetrated the cavity in such a way that the transition moment of the guest chromophore was parallel to the long axis of SBE-β-CD cavity. Moreover, the (1)H NMR spectrum showed that the entire 7H4MC molecule, except the hydroxyl group, was included in the SBE-β-CD cavity.