Self-assembly of mucoadhesive nanofibers

Here, we present an easy and stable one-step procedure to fabricate self-assembled nanofibers from modified chitosan.

Mucoadhesive 4-carboxybenzenesulfonamide-chitosan with antibacterial properties

The mucoadhesive property of chitosan, especially in an acidic (<pH 6.0) environment, was increased by conjugating an aromatic sulfonamide group at the C2-N position of chitosan. Four different feeding ratios of 4-carboxybenzensulfonamide (4-CBS) to chitosan in the presence of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride as a coupling agent were investigated. The 0.2:1 (w/w) ratio 4-CBS:chitosan revealed a 20-fold stronger mucoadhesion to mucin type II than the native chitosan in the simulated gastric fluid (SGF; pH 1.2), and a swelling ratio after 1 h in water, SGF and simulated intestinal fluid (pH 7.4) of about 2.9-, 3.0- and 3.4-fold higher than that of chitosan, respectively. In tissue culture, the 4-CBS-chitosan, like chitosan, were found to be non-cytotoxic to the Vero, KB, MCF-7 and NCI-H187 cell lines but showed potential antibacterial activity against Escherichia coli and Staphlyococcus aureus as model gram-negative and gram-positive bacteria, respectively.

Andirobin from X. moluccensis

The title compound (systematic name: methyl 2-{(1R,2R)-2-[(1aS,4S,4aS,8aS)-4-(furan-3-yl)-4a-methyl-8-methyl­ene-2-oxoocta­hydro­oxireno[2,3-d]isochromen-7-yl]-2,6,6-trimethyl-5-oxocyclo­hex-3-en-1-yl}acetate), C₂₇H₃₂O₇, was isolated from X. moluccensis seeds from Thailand. The conformations of the six-membered rings are distorted half-chair, chair and half-chair for the isolated cyclo­hexane, fused cyclo­hexane and lactone rings, respectively. In addition, the lactone ring bears in an equatorial orientation an essentially planar furan ring (r.m.s. deviation = 0.004 Å), which forms an angle of 63.87 (13)° with the mean plane defined by the ten atoms of the two fused six-membered rings (r.m.s. deviation = 0.213 Å). The absolute configuration was fixed on the basis of literature data.

Bis(acetato-κ(2)O,O')(4,4'-dimethyl-2,2'-bipyridine-κ(2)N,N')copper(II) monohydrate

In the title compound, [Cu(C₂H₃O₂)₂(C₁₂H₁₂N₂)₂]·H₂O, the Cu^II atom exhibits a distorted octa­hedral coordination geometry, defined by two N atoms from one 4,4′-dimethyl-2,2′-bipyridine ligand and four O atoms from two acetate ligands. In the crystal, O—H⋯O hydrogen bonds are observed between the coordinated carboxyl­ate O atoms and the solvent water mol­ecule.

9,10-Dioxoanthracene-1,4-diyl bis-(4-methyl-benzene-sulfonate)

The title mol­ecule, C₂₈H₂₀O₈S₂, has a T-shaped conformation. The central 9,10-anthraquinone moiety is bow-shaped with the two outer aromatic rings being inclined to one another by 13.99 (11)°. The benzenesulfonate rings are inclined to one another by 47.35 (12)°, and by 34.51 (11) and 17.88 (11)° to the bridging aromatic ring of the 9,10-anthraquinone moiety. In the crystal, C—H⋯O interactions link the mol­ecules into ribbons in [100].

Synthesis of rotenoid derivatives with cytotoxic and topoisomerase II inhibitory activities

6-Deoxyclitoriacetal (1) and a series of 11 further derivatives of it (2-12) were synthesized and evaluated for their cytotoxic and topoisomerase IIα inhibitory activities. Compounds bearing epoxide (2), morpholine (6) and benzylamine (10) moieties showed promising in vitro cytotoxic activities against four cancer cell lines, with IC(50) values ranging from 0.38 to 0.73 μM. These three compounds also strongly inhibited topoisomerase II activity at 68.3-93.5% and showed a moderately high DNA intercalating property.

Electrospray fabrication of doxorubicin-chitosan-tripolyphosphate nanoparticles for delivery of doxorubicin

This work focused on a new technique for the preparation of doxorubicin (DOX) loaded chitosan (CS) nanoparticles (DOX-CS) - formation by electrospray ionization in the presence of tripolyphosphate (TPP) as the stabilizer. The working distance, needle gauge, flow rate, stirring rate, electrospraying voltage and DOX to CS molar ratio were sequentially and individually optimized and found to be a 26 gauge needle, an applied voltage of 13 kV, a flow rate of 0.5 mL/h, a working distance of 8 cm and a stirring rate of 400 rpm. The incorporation of chemically unchanged DOX with the CS into the particles was ascertained by Fourier transformed infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Under these optimized conditions, the DOX-CS particles were found to be nanoparticles of approximately 300-570 (dry particles) or 530-870 nm diameter (hydrated particles), with a PDI and SPAN polydispersity indices of 0.97-0.82 and 0.62-0.64, respectively, for initial DOX loading levels of 0.25-1%, as determined by SEM and particle size analyzer, respectively. Moreover, a high encapsulation efficiency (EE) of DOX into the nanoparticles was attained, ranging from 63.4 to 67.9% EE at 1 to 0.25% DOX loading. Finally, the in vitro DOX release behaviors of the DOX-CS particles revealed a prolonged release of DOX over at least seven hours.

Sustained release of amoxicillin from ethyl cellulose-coated amoxicillin/chitosan-cyclodextrin-based tablets

Sustained release mucoadhesive amoxicillin tablets with tolerance to acid degradation in the stomach were studied. The sustained-release tablets of amoxicillin were prepared from amoxicillin coated with ethyl cellulose (EC) and then formulated into tablets using chitosan (CS) or a mixture of CS and beta-cyclodextrin (CD) as the retard polymer. The effects of various (w/w) ratios of EC/amoxicillin, the particle sized of EC coated amoxicillin and the different (w/w) ratios of CS/CD for the retard polymer, on the amoxicillin release profile were investigated. The physicochemical properties of the EC coated amoxicillin particles and tablets were determined by scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, and differential scanning calorimetry. The result showed that the release profiles of amoxicillin were greatly improved upon coating with EC, while the inclusion of CD to the CS retardant additionally prolonged the release of the drug slightly. Overall, a sustained release of amoxicillin was achieved using amoxicillin coated with EC at a (w/w) ratio of 1:1 and a particle size of 75-100 μm. Therefore, the tablet formulation of amoxicillin may be an advantageous alternative as an orally administered sustained-release formulation for the treatment of peptic ulcers.

7-Deacetyl-gedunin

The title compound [systematic name: (1S,3aS,4aR,4bS,5R,6aR,10aR,10bR,12aS)-1-(furan-3-yl)-5-hy­droxy-4b,7,7,10a,12a-penta­methyl-4b,5,6,6a,7,10a,10b,11,12,12a-deca­hydro­naphtho­[2,1-f]oxireno[2,3-d]isochromene-3,8(1H,3aH)-dione], C₂₆H₃₂O₆, which is a limonoid-type triterpene isolated from the seeds of X. moluccensis, crystallizes with three independent mol­ecules with very similar geometries in the asymmetric unit. In each mol­ecule, the four fused six-membered rings of the genudin core adopt distorted half-chair, chair, twist-boat and twisted half-chair conformations. In the crystal, inter­molecular O—H⋯O hydrogen bonds link the mol­ecules into helical chains propagated in [100]. Weak non-classical C—H⋯O contacts further consolidate the crystal packing.

2-[(4-Methoxybenzyl)iminomethyl]phenol

In the title Schiff base compound, C₁₅H₁₅NO₂, prepared from 4-meth­oxy­benzyl­amine and salicyl­aldehyde, an intra­molecular O—H⋯N hydrogen bonds influences the mol­ecular conformation; the two aromatic rings form a dihedral angle of 73.5 (1)°. In the crystal, weak inter­molecular C—H⋯O inter­actions link the mol­ecules into chains propagating in [010].

2-[(4-Chlorobenzyl)iminomethyl]phenol

The title Schiff base compound, C₁₄H₁₂ClNO, was prepared from 4-chloro­benzyl­amine and salicyl­aldehyde. The mol­ecule is V-shaped: the dihedral angle between the aromatic rings is 67.51 (5)°. The rings are located on the opposite side of the C=N bond, giving an E configuration. An intra­molecular N—H⋯O hydrogen bond generates a S(6) ring. In the crystal structure, only weak non-classical C—H⋯O contacts are observed.

Chitosan/polyethylene glycol beads crosslinked with tripolyphosphate and glutaraldehyde for gastrointestinal drug delivery

This study reports on the preparation of chitosan (CS)/polyethylene glycol (PEG) hydrogel beads using sodium diclofenac (DFNa) as a model drug. Following the optimization of the polymer to drug ratio, the chitosan beads were modified by ionic crosslinking with sodium tripolyphosphate (TPP). The CS/PEG/DFNa beads obtained from a (w/w/w) ratio of 1/0.5/0.5 with crosslinking in 10% (w/v) TPP at pH 6.0 for 30 min yielded excellent DFNa encapsulation levels with over 90% loading efficiency. The dissolution profile of DFNa from CS/PEG/DFNa beads demonstrated that this formulation was able to maintain a prolonged drug release for approximately 8 h. Among the formulations tested, the CS/PEG/DFNa (1/0.5/1 (w/w/w)) beads crosslinked with a combination of TPP (10% (w/v) for 30 min) and glutaraldehyde (GD) (5% (w/v)) were able to provide minimal DFNa release in the gastric and duodenal simulated fluids (pH 1.2 and 6.8, respectively) allowing for a principally gradual drug release over 24 h in the intestinal (jejunum and ileum) simulated fluid (pH 7.4). Thus, overall the CS/PEG beads crosslinked with TPP and GD look to be a promising and novel alternative gastrointestinal drug release system.

Salicyl-aldehyde-4-(dimethyl-amino)-pyridine (1/1)

In the title compound, C₇H₁₀N₂·C₇H₆O₂, the components are linked by an O—H⋯N hydrogen bond. The mean planes of two mol­ecules form a dihedral angle of 78.68 (5)°. The crystal packing exhibits weak non-classical C—H⋯O contacts.

Xylorumphiins A-D, mexicanolide limonoids from the seed kernels of Xylocarpus rumphii

Four new mexicanolide limonoids, named xylorumphiins A-D (1-4), were isolated from the seed kernels of Xylocarpus rumphii, together with three known limonoids. Their structures and configurations were established on the basis of spectroscopic data.