Design and synthesis of strong root gravitropism inhibitors with no concomitant growth inhibition.

Herein, we describe a highly potent gravitropic bending inhibitor with no concomitant growth inhibition. Previously, we reported that (2Z,4E)-5-phenylpenta-2,4-dienoic acid (ku-76) selectively inhibits root gravitropic bending of lettuce radicles at 5 μM. Based on the structure-activity relationship study of ku-76 as a lead compound, we designed and synthesized various C4-substituted analogs of ku-76.

Design and chemical synthesis of root gravitropism inhibitors: Bridged analogues of ku-76 have more potent activity.

Previously, we found (2Z,4E)-5-phenylpenta-2,4-dienoic acid (ku-76) to be a selective inhibitor of root gravitropic bending of lettuce radicles at 5 μM, with no concomitant growth inhibition, and revealed the structure-activity relationship in this inhibitory activity. The conformation of ku-76 is flexible owing to the open-chain structure of pentan-2,4-dienoic acid with freely rotating single bonds, and the (2Z)-alkene moiety may be isomerized by external factors. To develop more potent inhibitors and obtain insight into the target biomolecules, various analogues of ku-76, fixed through conformation and/or configuration, were synthesized and evaluated.

Essential structural features of (2Z,4E)-5-phenylpenta-2,4-dienoic acid for inhibition of root gravitropism.

Previously, we found (2Z,4E)-5-phenylpenta-2,4-dienoic acid (ku-76) to be a selective inhibitor of root gravitropic bending of lettuce radicles at 5 μM, with no concomitant growth inhibition. Here, we describe a structure-activity relationship study of ku-76 to determine the essential structural features for the inhibitory activity. A series of ku-76 analogues was synthesized and the key features of ku-76 that are necessary for inhibition of lettuce root gravitropic bending were determined.

Bongkrekic acid facilitates glycolysis in cultured cells and induces cell death under low glucose conditions.

Bongkrekic acid (BKA) inhibits adenine nucleotide translocator (ANT) and suppresses ADP/ATP exchange in the mitochondrial inner membrane. Previously, we demonstrated that BKA exhibited cytotoxic effects on 4T1 tumor cells, depending on the cell number in the culture, but not on NIH3T3 cells. However, the cause of this differential sensitivity was unelucidated.

Efficient Total Synthesis of Bongkrekic Acid and Apoptosis Inhibitory Activity of Its Analogues.

Bongkrekic acid (BKA), isolated from the bacterium Burkholderia cocovenenans, is an inhibitor of adenine nucleotide translocator, which inhibits apoptosis, and is thus an important tool for the mechanistic investigation of apoptosis. An efficient total synthesis of BKA has been achieved by employing a three-component convergent strategy based on Kocienski-Julia olefination and Suzuki-Miyaura coupling. It is noteworthy that segment B has been prepared as a new doubly functionalized coupling partner, which contributes to shortening of the number of steps.

Tumor cell secretion of soluble factor(s) for specific immunosuppression.

Studies of tumor models using syngeneic transplantation have advanced our understanding of tumor immunity, including both immune surveillance and evasion. Murine mammary carcinoma 4T1 cells secrete immunosuppressive soluble factors as demonstrated in splenocyte culture. Cultured primary splenocytes secrete IFN-γ, which was strikingly elevated when the cells were isolated from 4T1 tumor-bearing mice.

Effective tumor treatment by VEGF siRNA complexed with hydrophobic poly(amino acid)-modified polyethylenimine.

Two copolymers are designed and synthesised for siRNA delivery based on polyethylenimine by grafting hydrophilic acrylamide segments and hydrophobic poly(γ-benzyl L-glutamate). The amphiphilic PEI-PBLG/siRNA complex demonstrates high gene silencing efficiency in the absence or presence of 10 vol% and 50 vol% sera in vitro. The anti-tumor effects in vivo are evaluated in luciferase-bearing mice expressing CT26 tumors.

Design of UCST polymers for chilling capture of proteins.

Ureido-derivatized polymers, such as poly(allylurea) (PU) and poly(L-citrulline) derivatives, exhibited upper critical solution temperature (UCST) behavior under physiological buffer conditions as we previously reported. The PU derivatives having amino groups (PU-Am) also showed UCST behavior. In this study, we modified the amino groups of the polymer with succinyl anhydride (PU-Su) or acetyl anhydride (PU-Ac) to determine the effects of these ionic groups on the UCST behavior and to control interactions between the PU derivatives and biocomponents such as proteins and cells.

Tumor delivery of Photofrin® by PLL-g-PEG for photodynamic therapy.

Photofrin® (porfimer sodium) is a photosensitive reagent used for photodynamic therapy (PDT) of tumors and dysplasias. Because only photo-irradiated sites are damaged, PDT is less invasive than systemic treatments. However, a photosensitive reaction is a major side effect of systemically delivered Photofrin.

Polyelectrolyte-assisted transconformation of a stem-loop DNA.

A cationic copolymer triggered dimerization of a self-complementary stem-loop DNA. The dimerization was faster than spontaneous dissociation of the dimer. Reversible transformation between stem-loop and dimer structures was driven by switching on/off copolymer activity.

Dual crosslinked hydrogel nanoparticles by nanogel bottom-up method for sustained-release delivery.

Polysaccharide-PEG hybrid nanogels (CHPOA-PEGSH) crosslinked by both covalent ester bonds and physical interactions were prepared by the reaction of a thiol-modified poly(ethylene glycol) (PEGSH) with acryloyl-modified cholesterol-bearing pullulan (CHPOA). Experimental parameters, including CHPOA concentration, the degree of acryloyl substitution of CHPOA, and the initial amounts of CHPOA and PEGSH, were modified in order to assess their effect on the size of the nanogels (50-150 nm) and on their degradation kinetics, monitored by dynamic light scattering (DLS) and asymmetrical flow field-flow fractionation (AF4) chromatography. Rhodamine-labeled nanogels were injected intravenously into mice and their concentration in blood was determined by a fluorescence assay as a function of post-injection time.

Enhanced cell uptake via non-covalent decollation of a single-walled carbon nanotube-DNA hybrid with polyethylene glycol-grafted poly(l-lysine) labeled with an Alexa-dye and its efficient uptake in a cancer cell.

The use of single-walled carbon nanotubes (SWNTs) for biomedical applications is a promising approach due to their unique outer optical stimuli response properties, such as a photothermal response triggered by near-IR laser irradiation. The challenging task in order to realize such applications is to render the SWNTs biocompatible. For this purpose, the stable and homogeneous functionalization of the SWNTs with a molecule carrying a biocompatible group is very important.

Ureido-derivatized polymers based on both poly(allylurea) and poly(L-citrulline) exhibit UCST-type phase transition behavior under physiologically relevant conditions.

There are few examples of polymers that exhibit upper critical solution temperature (UCST) behavior under physiological conditions of temperature, pH, and ionic strength. In this study, we demonstrated that polymers with ureido groups undergo UCST-type phase transitions under physiologically relevant conditions. Poly(allylurea) copolymers showed UCST behavior at pH 7.

The role of cationic comb-type copolymers in chaperoning DNA annealing.

G-rich oligonucleotides tend to fall into kinetically trapped unstable structures because of their conformational polymorphism. Nucleic acid chaperones accelerate association of nucleic acids assemblies into the thermodynamically most stable conformations by decreasing the energy barrier for breakage or re-assembly of base pairings. Here, we report that an artificial nucleic acid chaperone, a cationic comb-type copolymer, promotes tetramolecular quadruplex assembly from mixtures of two different G-rich sequences, 5'-TGGGGT-3' (TG(4)T) and 5'-TGGGGGT-3' (TG(5)T).

DNA assembly and re-assembly activated by cationic comb-type copolymer.

Guanine-rich oligonucleotides, such as TG(4)T and TG(5)T, assemble into a tetramolecular quadruplexes with layers of G-quartets stabilized by coordination to monovalent cations. Association rates of the quadruplexes are extremely slow, likely owing to electrostatic repulsion among the four strands. We have shown that comb-type copolymers with a polycation backbone and abundant hydrophilic graft chains form water-soluble polyelectrolyte complexes with DNA and promote DNA hybridization.

Evaluation of polyanion-coated biodegradable polymeric micelles as drug delivery vehicles.

Polymeric micelles, as drug delivery vehicles, must achieve specific targeting and high stability in the body for efficient drug delivery. We recently reported the preparation of polyanion-coated biodegradable polymeric micelles by coating positively charged polymeric micelles consisting of poly(L-lysine)-block-poly(L-lactide) (PLys-b-PLLA) AB diblock copolymers with anionic hyaluronic acid (HA) by polyion complex (PIC) formation. The obtained HA-coated micelles showed significantly higher stability in aqueous solution.

Nuclear localization and antisense effect of PNA internalized by ASGP-R-mediated endocytosis with protein/DNA conjugates.

In order for peptide nucleic acids (PNAs) to be effective as therapeutic agents, methods for cellular delivery must be developed. Here we demonstrate spontaneous nuclear localization and antisense effects of peptide nucleic acids (PNAs) delivered to hepatic cells through asialoglycoprotein receptor-mediated endocytosis. Asialofetuin conjugates with DNA oligonucleotides (AF/DNA) complementary to the PNA of interest were designed as cell-specific delivery vectors.

Cationic graft copolymer as a DNA B-z transition inducer: effect of copolymer structure.

The biological importance of left-handed Z-DNA was supported by the identification of Z-DNA binding proteins. We previously reported that poly(l-lysine)-graft-dextran copolymers composed of a poly(l-lysine) main chain and dextran graft chains induced the B-Z transition under low salt conditions. Not only the cationic main chain but also the dextran grafts play an important role in induction of the B-Z transition.

Synthesis, characterization and drug release of biocompatible/biodegradable non-toxic poly(urethane urea)s based on poly(epsilon-caprolactone)s and lysine-based diisocyanate.

Segmented poly(urethane urea)s (SPUUs) based on aliphatic diisocyanato (2,6-diisocyanato methyl caproate (lysine-based diisocyanate, LDI)), poly(epsilon-caprolactone diol)s (PCLs) with molecular weights 530, 1250 and 2000, and 1,4-butanediamine were synthesized in absence of catalyst. The resulting SPUUs, with different soft segment length, were characterized by suitable analytical techniques. The synthesized SPUUs had high molecular weights, low glass-transition temperatures ( View Article and Find Full Text PDF

Grafting of poly(ethylene glycol) to poly-lysine augments its lifetime in blood circulation and accumulation in tumors without loss of the ability to associate with siRNA.

Poly-lysine has been studied as a carrier for the delivery of drugs and nucleic acids for at least a decade. It is an especially attractive carrier for DNA and RNA, because of its condensed cationic charges. In our previous study, we showed that poly(ethylene glycol) (PEG) grafted to poly-L-lysine (PLL) remarkably increased the life time of a small interfering RNA (siRNA) in blood circulation.

A highly efficient siRNA carrier of PBLG modified hyperbranched PEI.

In search for effective non-viral gene vectors for the delivery of siRNA, a copolymer was designed and synthesized by grafting hydrophobic poly(gamma-benzyl L-glutamate) segment (PBLG) to hyperbranched polyethylenimine (PEI-PBLG). PEI-PBLG could efficiently deliver siRNA to cells to silence the targeted gene. Markedly, PEI-PBLG caused lower cytotoxicity in comparison to unmodified PEI.

Design of cationic graft copolymers as a potential inducer of B-Z transition.

Biological roles of transition from B form to Z form of DNA (B-Z transition) have recently received attention. The B-Z transition was also employed as driving machinery of a nano-mechanical DNA device. However, there are little reports of effective inducer of the B-Z transition.

Cationic comb-type copolymer as a nucleic acid chaperone for DNA quadruplex.

The intermolecular DNA quadruplex is attractive materials for design of nanomolecular constructs and machines. This folding kinetics is, however, slow, hampering its application to these materials. We have reported that the cationic comb-type copolymer accelerated duplex and triplex formation.

Uptake of enzymatically-digested hyaluronan by liver endothelial cells in vivo and in vitro.

Intravenously-injected hyaluronan (HA) is distributed into liver in which endothelium is a site of uptake and degradation of HA. The role and fate of HA have been widely investigated; however, effects of size and dose of HA on its metabolism have not been well documented yet. To investigate these effects, we prepared fluorescein-labeled HAs, according to the modified methods described by de Belder and Wik, which were enzymatically digested.