ABSTRACT
A natural compound, aglycone geniposidic acid (aGSA), originated from the fruits of Gardenia jasminoides ELLIS was used for the fixation of collagenous tissues. The presumed crosslinking reaction mechanism of collagenous tissues with aGSA was inferred by reacting aGSA with a bifunctional amine, 1,6-hexanediamine, using a series of (1)H NMR, FT-IR, and UV/Vis spectra analyses. aGSA reacted with 1,6-hexanediamine by a nucleophilic attack on the olefinic carbon atom at C-2 of deoxyloganin aglycone, followed by opening the dihydropyran ring to form heterocyclic amine compounds. It is inferred that aGSA may form intramolecular and intermolecular crosslinks with a heterocyclic structure within collagen fibers in tissues. The degrees of tissue fixation by aGSA at different pH values were investigated by examining the fixation indices and denaturation temperatures of test samples. It was found that the fixation indices and denaturation temperatures of test samples fixed at neutral or basic pH (pH 7.4 or pH 8.5) were significantly greater than at acidic pH (pH 4.0). The results obtained in this study may be used to elucidate the crosslinking mechanism and optimize the fixation process for developing bioprostheses fixed by aGSA.
Subject(s)
Bioprosthesis , Collagen/chemistry , Cross-Linking Reagents/chemistry , Gardenia/chemistry , Glucosides/chemistry , Iridoids/chemistry , Tissue Adhesives/chemistry , Glucosides/chemical synthesis , Hydrogen-Ion Concentration , Iridoid Glucosides , Iridoids/chemical synthesisABSTRACT
The purpose of this study was to evaluate the characteristics of a chitosan film cross-linked by a naturally occurring compound, aglycone geniposidic acid (aGSA). This newly developed aGSA-cross-linked chitosan film may be used as an edible film. The chitosan film without cross-linking (fresh) and the glutaraldehyde-cross-linked chitosan film were used as controls. The characteristics of test chitosan films evaluated were their degree of cross-linking, swelling ratio, mechanical properties, water vapor permeability, antimicrobial capability, cytotoxicity, and enzymatic degradability. It was found that cross-linking of chitosan films by aGSA (at a concentration up to 0.8 mM) significantly increased its ultimate tensile strength but reduced its strain at fracture and swelling ratio. There was no significant difference in the antimicrobial capability between the cross-linked chitosan films and their fresh counterpart. However, the aGSA-cross-linked chitosan film had a lower cytotoxicity, a slower degradation rate, and a relatively lower water vapor permeability as compared to the glutaraldehyde-cross-linked film. These results suggested that the aGSA-cross-linked chitosan film may be a promising material as an edible film.
Subject(s)
Anti-Infective Agents/pharmacology , Cell Death/drug effects , Chitosan/chemistry , Chitosan/pharmacology , Cross-Linking Reagents/chemistry , Glucosides/chemistry , Iridoids/chemistry , Chemical Phenomena , Chemistry, Physical , Chitosan/metabolism , Fibroblasts/drug effects , Humans , Iridoid Glucosides , Mechanics , Muramidase/metabolism , Permeability , WaterABSTRACT
In the study, poly(gamma-glutamic acid) (gamma-PGA) and poly(lactide) (PLA) were used to synthesize block copolymers via a simple coupling reaction between gamma-PGA and PLA to prepare self-assembled nanoparticles. For the potential of targeting liver cancer cells, galactosamine was further conjugated on the prepared nanoparticles as a targeting moiety. gamma-PGA, a water-soluble, biodegradable, and non-toxic compound, was produced by microbial fermentation (Bacillus licheniformis, ATCC 9945a) and then was hydrolyzed. The hydrolyzed gamma-PGA with a molecular weight of 4 kDa and a polydispersity of 1.3 was used, together with PLA (10 kDa, polydispersity 1.1), to synthesize block copolymers. The prepared nanoparticles had a mean particle size of about 140 nm with a zeta potential of about -20 mV. The results obtained by the TEM and AFM examinations showed that the morphology of the prepared nanoparticles was spherical in shape with a smooth surface. In the stability study, no aggregation or precipitation of nanoparticles was observed during storage for up to 1 month, as a result of the electrostatic repulsion between the negatively charged nanoparticles. With increasing the galactosamine content conjugated on the rhodamine-123-containing nanoparticles, the intensity of fluorescence observed in HepG2 cells increased significantly. Additionally, the intensity of fluorescence observed in HepG2 cells incubated with the nanoparticles with or without galactosamine conjugated increased approximately linearly with increasing the duration of incubation. In contrast, there was no fluorescence observed in Hs68 cells (without ASGP receptors) incubated with the nanoparticles with galactosamine conjugated. The aforementioned results indicated that the galactosylated nanoparticles prepared in the study had a specific interaction with HepG2 cells via ligand-receptor recognition.
