Curcumin encapsulated zein/caseinate-alginate nanoparticles: Release and antioxidant activity under in vitro simulated gastrointestinal digestion.

Curcumin-loaded zein/sodium caseinate-alginate nanoparticles were successfully fabricated using a pH-shift method/electrostatic deposition method. These nanoparticles produced were spheroids with a mean diameter of 177 nm and a zeta-potential of -39.9 mV at pH 7.3. The curcumin was an amorphous, and the content in the nanoparticles was around 4.9% (w/w) and the encapsulation efficiency was around 83.1%. Aqueous dispersions of the curcumin-loaded nanoparticles were resistant to aggregation when subjected to pH changes (pH 7.3 to 2.0) and sodium chloride addition (1.6 M), which was mainly attributed to the strong steric and electrostatic repulsion provided by the outer alginate layer. An in vitro simulated digestion study showed that the curcumin was mainly released during the small intestine phase and that its bioaccessibility was relatively high (80.3%), which was around 5.7-fold higher than that of non-encapsulated curcumin mixed with curcumin-free nanoparticles. In the cell culture assay, the curcumin reduced reactive oxygen species (ROS), increased superoxide dismutase (SOD) and catalase (CAT) activity, and reduced malondialdehyde (MDA) accumulation in hydrogen peroxide-treated HepG2 cells. The results suggested that nanoparticles prepared by pH shift/electrostatic deposition method are effective at delivering curcumin and may be utilized as nutraceutical delivery systems in food and drug industry.

Co-Encapsulation of Tannic Acid and Resveratrol in Zein/Pectin Nanoparticles: Stability, Antioxidant Activity, and Bioaccessibility.

Hydrophilic tannic acid and hydrophobic resveratrol were successfully co-encapsulated in zein nanoparticles prepared using antisolvent precipitation and then coated with pectin by electrostatic deposition. The encapsulation efficiencies of the tannic acid and resveratrol were 51.5 ± 1.9% and 77.2 ± 3.2%, respectively. The co-encapsulated nanoparticles were stable against aggregation at the investigated pH range of 2.0 to 8.0 when heated at 80 °C for 2 h and when the NaCl concentration was below 50 mM. The co-encapsulated tannic acid and resveratrol exhibited stronger in vitro antioxidant activity than ascorbic acid, as determined by 1,1-diphenyl-2-picrylhydrazyl free radical (DPPH·) and 2,2'-azinobis (3-ethylberizothiazoline-6-sulfonic acid) radical cation (ABTS+·) scavenging assays. The polyphenols-loaded nanoparticles significantly decreased the malondialdehyde (MDA) concentration and increased the superoxide dismutase (SOD) and catalase (CAT) activities in peroxide-treated human hepatoma cells (HepG2). An in vitro digestion model was used to study the gastrointestinal fate of the nanoparticles. In the stomach, encapsulation inhibited tannic acid release, but promoted resveratrol release. However, in the small intestine, it led to a relatively high bioaccessibility of 76% and 100% for resveratrol and tannic acid, respectively. These results suggest that pectin-coated zein nanoparticles have the potential for the co-encapsulation of both polar and nonpolar nutraceuticals or drugs.

A Bacillus thuringiensis Chitin-Binding Protein is Involved in Insect Peritrophic Matrix Adhesion and Takes Part in the Infection Process.

Bacillus thuringiensis (Bt) is used for insect pest control, and its larvicidal activity is primarily attributed to Cry toxins. Other factors participate in infection, and limited information is available regarding factors acting on the peritrophic matrix (PM). This study aimed to investigate the role of a Bt chitin-binding protein (CBPA) that had been previously shown to be expressed at pH 9 in vitro and could therefore be expressed in the alkaline gut of lepidopteron larvae. A ∆cbpA mutant was generated that was 10-fold less virulent than wild-type Bt HD73 towards Ostrinia furnacalis neonate larvae, indicating its important role in infection. Purified recombinant Escherichia coli CBPA was shown to have a chitin affinity, thus indicating a possible interaction with the chitin-rich PM. A translational GFP-CBPA fusion elucidated the localization of CBPA on the bacterial surface, and the transcriptional activity of the promoter PcbpA was immediately induced and confirmed at pH 9. Next, in order to connect surface expression and possible in vivo gut activity, last instar Galleriamellonella (Gm) larvae (not susceptible to Bt HD-73) were used as a model to follow CBPA in gut expression, bacterial transit, and PM adhesion. CBPA-GFP was quickly expressed in the Gm gut lumen, and more Bt HD73 strain bacteria adhered to the PM than those of the ∆cbpA mutant strain. Therefore, CBPA may help to retain the bacteria, via the PM binding, close to the gut surface and thus takes part in the early steps of Bt gut interactions.

Three-dimensional (3D) structure prediction and function analysis of the chitin-binding domain 3 protein HD73_3189 from Bacillus thuringiensis HD73.

Bacillus thuringiensis (Bt) is capable of producing a chitin-binding protein believed to be functionally important to bacteria during the stationary phase of its growth cycle. In this paper, the chitin-binding domain 3 protein HD73_3189 from B. thuringiensis has been analyzed by computer technology. Primary and secondary structural analyses demonstrated that HD73_3189 is negatively charged and contains several α-helices, aperiodical coils and ß-strands. Domain and motif analyses revealed that HD73_3189 contains a signal peptide, an N-terminal chitin binding 3 domains, two copies of a fibronectin-like domain 3 and a C-terminal carbohydrate binding domain classified as CBM_5_12. Moreover, analysis predicted the protein's associated localization site to be the cell wall. Ligand site prediction determined that amino acid residues GLU-312, TRP-334, ILE-341 and VAL-382 exposed on the surface of the target protein exhibit polar interactions with the substrate.

Perforation of the transverse colon by a fish bone: a case report.

The inadvertent swallowing of foreign bodies is common, but rarely results in perforation of the gastrointestinal tract. Because any site of the gastrointestinal tract may be perforated by a foreign body, the clinical presentation may vary and mimic diverse medical conditions. We report the case of a 60-year-old man who experienced left upper quadrant pain of 4 weeks duration before the onset of peritoneal signs. The symptoms were shown to result from perforation of the transverse colon by a fish bone (35 mm in length) with a developing abscess.