Screening and Identification of Peptides that Bind Specifically to the X gene Promoter of Hepatitis B Virus Using a Combinatorial Peptide Library Approach

Hepatitis B virus (HBV) X protein (HBx) plays a key role in the development of hepatocellular carcinoma (HCC) in HBV carriers. A drug that can bind to the promoter region of HBV may shut down the expression of HBx and subsequently prevent the development of HCC in the HBV carrier. We have constructed a seven amino acid residue peptide library on a TentaGel resin using a combinatorial one‐bead one‐sequence peptide synthesis method. The fluorescently labeled eicosanucleotide (5′‐(6‐FAM) CTTTTGGGCT TTGCTGCCCC‐3′) of the HBx promoter region was used as a monitor to screen for peptides that have high binding affinity to the HBx promoter. Two heptapeptides, KAPLFSI and SRVRMTW, were identified, and synthesized. The binding affinities of the peptides to the HBx promoter oligonucleotide were determined using Surface Plasmon Resonance (SPR). The peptide KAPLFSI had a greater binding affinity constant (k_a) and equilibrium constant (K_D) than SRVRMTW. The k_a and K_D values with the full X‐promoter sequence were found to be 1.425 E+5 (1/Ms) and 1.186 E‐8 (M), respectively. The peptide may open a new route for tumor suppression in HBV carriers.     

Effects of 2′,4′-Dihydroxy-6′-methoxy-3′,5′-dimethylchalcone from Syzygium nervosum Seeds on Antiproliferative,DNA Damage,Cell Cycle Arrest,and Apoptosis in Human Cervical Cancer Cell Lines

2′,4′-Dihydroxy-6′-methoxy-3′,5′-dimethylchalcone (DMC), a natural product derived from Syzygium nervosum A. Cunn. ex DC., was investigated for its inhibitory activities against various cancer cell lines. In this work, we investigated the effects of DMC and available anticervical cancer drugs (5-fluorouracil, cisplatin, and doxorubicin) on three human cervical cancer cell lines (C-33A, HeLa, and SiHa). DMC displayed antiproliferative cervical cancer activity in C-33A, HeLa, and SiHa cells, with IC₅₀ values of 15.76 ± 1.49, 10.05 ± 0.22, and 18.31 ± 3.10 µM, respectively. DMC presented higher antiproliferative cancer activity in HeLa cells; therefore, we further investigated DMC-induced apoptosis in this cell line, including DNA damage, cell cycle arrest, and apoptosis assays. As a potential anticancer agent, DMC treatment increased DNA damage in cancer cells, observed through fluorescence inverted microscopy and a comet assay. The cell cycle assay showed an increased number of cells in the G₀/G₁ phase following DMC treatment. Furthermore, DMC treatment-induced apoptosis cell death was approximately three- to four-fold higher compared to the untreated group. Here, DMC represented a compound-induced apoptosis for cell death in the HeLa cervical cancer cell line. Our findings suggest that DMC, a phytochemical agent, is a potential candidate for antiproliferative cervical cancer drug development.     

Activity of Propolis Nanoparticles against HSV-2: Promising Approach to Inhibiting Infection and Replication

Herpes simplex type 2 (HSV-2) infection causes a significant life-long disease. Long-term side effects of antiviral drugs can lead to the emergence of drug resistance. Thus, propolis, a natural product derived from beehives, has been proposed to prevent or treat HSV-2 infections. Unfortunately, therapeutic applications of propolis are still limited due its poor solubility. To overcome this, a nanoparticle-based drug delivery system was employed. An ethanolic extract of propolis (EEP) was encapsulated in nanoparticles composed of poly(lactic-co-glycolic acid) and chitosan using a modified oil-in-water single emulsion by using the solvent evaporation method. The produced nanoparticles (EEP-NPs) had a spherical shape with a size of ~450 nm and presented satisfactory physicochemical properties, including positively charged surface (38.05 ± 7.65 mV), high entrapment efficiency (79.89 ± 13.92%), and sustained release profile. Moreover, EEP-NPs were less cytotoxic on Vero cells and exhibited anti-HSV-2 activity. EEP-NPs had a direct effect on the inactivation of viral particles, and also disrupted the virion entry and release from the host cells. A significant decrease in the expression levels of the HSV-2 replication-related genes (ICP4, ICP27, and gB) was also observed. Our study suggests that EEP-NPs provide a strong anti-HSV-2 activity and serve as a promising platform for the treatment of HSV-2 infections.     

Positive solutions of three-point fractional sum boundary value problem for Caputo fractional difference equations via an argument with a shift

In this paper, we study a new class of three-point boundary value problem of nonlinear Caputo fractional difference equation. Our problem contain an argument with a shift. The existence of at least one positive solution is proved by using the Guo-Krasnoselskii’s fixed point theorem. Some illustrative examples are given.     

Gel strength and swelling of acrylamide‐protic acid superabsorbent copolymers

The viscoelastic and swelling properties of polyacrylamide‐based superabsorbent copolymers were investigated as a function of the ionic comonomer structure. Superabsorbent copolymers were synthesized by free‐radical crosslinking copolymerization of acrylamide and one of the monoprotic acids (acrylic acid and crotonic acid) or the diprotic acids (maleic acid and itaconic acid) as the investigated ionic comonomer. The reaction composition of all components, i.e. monomer, comonomer, initiator, co‐initiator, and crosslinker, was fixed to be the same for the synthesis of all four superabsorbent copolymer systems. Viscoelastic measurements were performed in all systems where the particles were closely packed. The network structures of all systems were evaluated via viscoelastic and swelling measurements. The results indicated that superabsorbent polymers (SAPs) with high water absorbency were accompanied by low gel strength and the calculated high value of molecular weight between crosslinks ($\bar {M}{}_c$ ) and low value of effective crosslinking density (ν_e). Diprotic acid‐containing SAPs showed higher water absorbency over monoprotic acid‐containing and non‐ionic ones. The differences in $\bar {M}{}_c$ and ν_e values of each system were explained with respect to the differences in the monomer reactivity ratio and hydrophilicity of the comonomers. Copyright © 2010 John Wiley & Sons, Ltd.     

Total synthesis and cytotoxic activity of dechlorogreensporones A and D

The first and convergent total syntheses of polyketide natural products dechlorogreensporones A and D have been accomplished in 17 longest linear steps with 2.8% and 5.4% overall yields, respectively, starting from known methyl 2-(2-formyl-3,5-dihydroxyphenyl)acetate and commercially available R-(+)-propylene oxide and 1,2-epoxy-5-hexene. Our synthesis exploited key Mitsunobu esterification and (E)-selective ring-closing metathesis (RCM) to assemble the macrocycles as well as a Jacobsen hydrolytic kinetic resolution to install the stereogenic centers. Both synthetic compounds were found to display significant cytotoxic activity against seven human cancer cell lines with the IC₅₀ ranges of 6.66–17.25?μM.     

Expression of Low Endotoxin 3-O-Sulfotransferase in Bacillus subtilis and Bacillus megaterium

A key enzyme for the biosynthesis and bioengineering of heparin, 3-O-sulfotransferase-1 (3-OST-1), was expressed and purified in Gram-positive Bacillus subtilis and Bacillus megaterium. Western blotting, protein sequence analysis, and enzyme activity measurement confirmed the expression. The enzymatic activity of 3-OST-1 expressed in Bacillus species were found to be similar to those found when expressed in Escherichia coli. The endotoxin level in 3-OST-1 from B. subtilis and B. megaterium were 10⁴–10⁵-fold lower than that of the E. coli-expressed 3-OST-1, which makes the Bacillus expression system of particular interest for the generation of pharmaceutical grade raw heparin from nonanimal sources.     

Metabolites from the endophytic fungi Botryosphaeria rhodina PSU-M35 and PSU-M114

Three dimeric γ-lactones (1-3), one dihydronaphthalene-2,6-dione (4), one hexahydroindenofuran (5), one cyclopentanone (6), and one lasiodiplodin (7) were isolated from the endophytic fungi Botryosphaeria rhodina PSU-M35 and PSU-M114 along with twelve known metabolites. The structures and the proposed stereochemistry of the new metabolites were established by spectral data analysis. The isolated compounds were submitted for evaluation of the antibacterial activity against Staphylococcus aureus, both standard and methicillin-resistant strains.     

On positive solutions to fractional sum boundary value problems for nonlinear fractional difference equations

In this paper, we study a new class of 3‐point boundary value problems of nonlinear fractional difference equations. Our problems contain difference and fractional sum boundary conditions. Existence and uniqueness of solutions are proved by using the Banach fixed‐point theorem, and existence of the positive solutions is proved by using the Krasnoselskii's fixed‐point theorem. Copyright © 2015 John Wiley & Sons, Ltd.