Thiol-modified chitosan sulfate nanoparticles for protection and release of basic fibroblast growth factor.

A series of chitosan (CS) derivatives, the 6-O-carboxymethylchitosan (6-O-CC), 2-N sulfated 6-O-carboxymethylchitosan (N-SOCC) and the 2-N and 3,6-O sulfated 6-O-carboxymethyl chitosan (N,O-SOCC) were synthesized in this study. The chemical structures and the degrees of substituted carboxymethyl and sulfate groups of the synthesized compounds were respectively determined by FT-IR spectra and elemental analysis. N,O-SOCC displayed the highest protective efficiency for basic fibroblast growth factor (bFGF) as examined by the L929 fibroblast culture test and docking simulation. N,O-SOCC-4-thio-butylamidine (TBA) conjugates prepared by modification of N,O-SOCC with 2-iminothiolane were in situ cross-linkable. The degrees of thiol substitution of the 2-iminothiolane modified N,O-SOCC polymers were determined to be in the ranges of 45.9 +/- 3.7 and 415.6 +/- 12.5 micromol SH/g SOCC by quantifying the amount of thiol groups on the thiolated polymers with Ellman's reagent. The 2-iminothiolane modified N,O-SOCC and CS complex could be used for preparing nanoparticles by a polyelectrolyte self-assembly method, and the release of bFGF from the nanoparticles was successfully controlled. L929 fibroblast culture tests showed that the thiol modified N,O-SOCC/CS nanoparticles could effectively protect bFGF from inactivation over a 120 h period. The results of this study suggest that the thiol modified N,O-SOCC/CS nanoparticles may be useful as novel materials for specific delivery of bFGF with mitogenic activity.

Woodfordia fruticosa: traditional uses and recent findings.

Woodfordia fruticosa Kurz of the family Lythraceae is a plant of tropical and subtropical region with a long history of medicinal use. A wide range of chemical compounds including tannins (especially those of macrocyclic hydrolysable class), flavonoids, anthraquinone glycosides, and polyphenols have been isolated from this species in recent times. Extracts and metabolites of this plant, particularly those from flowers and leaves, possess useful pharmacological activities. A comprehensive account of the chemical constituents and the biological activities is presented and a critical appraisal of the ethnopharmacological issues is included in view of the many recent findings of importance on this plant.

A triterpenoid saponin possessing antileishmanial activity from the leaves of Careya arborea.

Bioguided-fractionation of the methanol extract of the leaves of Careya arborea led to isolation of a triterpenoid saponin, designated arborenin, and characterized as 3-O-beta-D-glucopyranosyl(1-->2)-beta-D-glucopyranosyl-2 alpha,3beta-dihydroxy-taraxast-20-en-28-oic acid (1), together with desacylescin III (2). The structures were determined on the basis of extensive 2D NMR spectroscopic analysis. The saponin showed in vitro antileishmanial activity against Leishmania donovani (strain AG 83).

Polyoxypregnane glycosides from the flowers of Dregea volubilis.

Three novel polyoxypregnane glycosides, volubiloside A, B and C (1-3), were isolated from the flowers of Dregea volubilis Linn., and their structures were elucidated as drevogenin D-3-O-beta-D-glucopyranosyl (1-->4)-6-deoxy-3-O-methyl-beta-D-allopyranosyl (1-->4)-beta-D-cymaropyranosyl (1-->4)-beta-D-cymaropyranoside, drevogenin D-3-O-beta-D-glucopyranosyl (1-->4)-6-deoxy-3-O-methyl-beta-D-allopyranosyl (1-->4)-beta-D-cymaropyranosyl (1-->4)-beta-D-digitoxopyranoside and drevogenin P-3-O-beta-D-glucopyranosyl (1-->4)-6-deoxy-3-O-methyl-beta-D-allopyranosyl (1-->4)-beta-D-cymaropyranosyl (1-->4)-beta-D-cymaropyranoside, respectively, on the basis of extensive NMR experiments, MALDI-TOF MS, and some chemical strategies.

Calcium depletion-mediated protease inhibition and apical-junctional-complex disassembly via an EGTA-conjugated carrier for oral insulin delivery.

Calcium (Ca(2+)) has a crucial role in maintaining the intestinal protease activity and in forming the apical junctional complex (AJC) that preserves epithelial barrier function. Ethylene glycol tetraacetic acid (EGTA) is a Ca(2+)-specific chelating agent. To maintain the concentration of this chelator in areas where enzyme inhibition and paracellular permeation enhancement are needed, this study synthesized a poly(γ-glutamic acid)-EGTA conjugate (γPGA-EGTA) to form nanoparticles (NPs) with chitosan (CS) for oral insulin delivery. The results of our molecular dynamic (MD) simulations indicate that Ca(2+) ions could be specifically chelated to the nitrogen atoms, ether oxygen atoms, and carboxylate oxygen atoms in [Ca(EGTA)](2-) anions. By chelating Ca(2+), γPGA-EGTA conferred a significant insulin protection effect against proteases in intestinal tracts isolated from rats. Additionally, calcium depletion by γPGA-EGTA could stimulate the endocytosis of AJC components in Caco-2 cell monolayers, which led to a reversible opening of AJCs and thus increased their paracellular permeability. Single-photon emission computed tomography images performed in the biodistribution study clearly show the (123)I-insulin orally delivered by CS/γPGA-EGTA NPs in the heart, aorta, renal cortex, renal pelvis and liver, which ultimately produced a significant and prolonged hypoglycemic effect in diabetic rats. The above results confirm that this γPGA-EGTA conjugate is a promising candidate for oral insulin delivery.

Protease inhibition and absorption enhancement by functional nanoparticles for effective oral insulin delivery.

Complexing agents such as diethylene triamine pentaacetic acid (DTPA) are known to disrupt intestinal tight junctions and inhibit intestinal proteases by chelating divalent metal ions. This study attempts to incorporate these benefits of DTPA in functional nanoparticles (NPs) for oral insulin delivery. To maintain the complexing agent concentrated on the intestinal mucosal surface, where the paracellular permeation enhancement and enzyme inhibition are required, DTPA was covalently conjugated on poly(γ-glutamic acid) (γPGA). The functional NPs were prepared by mixing cationic chitosan (CS) with anionic γPGA-DTPA conjugate. The γPGA-DTPA conjugate inhibited the intestinal proteases substantially, and produced a transient and reversible enhancement of paracellular permeability. The prepared NPs were pH-responsive; with an increasing pH, CS/γPGA-DTPA NPs swelled gradually and disintegrated at a pH value above 7.0. Additionally, the biodistribution of insulin orally delivered by CS/γPGA-DTPA NPs in rats was examined by confocal microscopy and scintigraphy. Experimental results indicate that CS/γPGA-DTPA NPs can promote the insulin absorption throughout the entire small intestine; the absorbed insulin was clearly identified in the kidney and bladder. In addition to producing a prolonged reduction in blood glucose levels, the oral intake of the enteric-coated capsule containing CS/γPGA-DTPA NPs showed a maximum insulin concentration at 4 h after treatment. The relative oral bioavailability of insulin was approximately 20%. Results of this study demonstrate the potential role for the proposed formulation in delivering therapeutic proteins by oral route.