Novel in situ mucoadhesive gels based on Pluronic F127 and xyloglucan containing metronidazole for treatment of periodontal disease

Novel thermoresponsive in situ-forming hydrogels were prepared from co-solutions of Pluronic F127 (PF; triblock-copolymer of polyethylene oxide, polypropylene oxide and polyethylene oxide) and 0.1 wt% tamarind seed xyloglucan (0.1TSX). Based on test tube inversion method, co-solutions comprising 18 or 20 wt% PF and 0.1TSX (18PF/0.1TSX or 20PF/0.1TSX) gelled at 29 and 26 °C compared with 28 and 25 °C for equivalent concentration of PF solutions. DSC analyses indicated that 18PF/0.1TSX and 20PF/0.1TSX exhibited micellization temperatures of 15.5 and 14.9 °C, respectively, compared with 16.2 and 15.7 °C, respectively, for 18PF and 20PF. The lower micellization temperature but higher gel formation temperature suggests that 0.1TSX assists micelle formation but may interrupt order pack structure of micelle that is necessary for gelling. SEM revealed the cylindrical pore structure of lyophilized gels with diameters around 35 μm for 18PF, 20PF and 42 μm for 18PF/0.1TSX and approximately 78 μm for 20PF/0.1TSX. Extractables, released from PF/0.1TSX gels in phosphate buffered saline, did not reduce the viability of mouse osteoblast-like (MC3T3-E1) cells compared with the control, whereas those from PF gels were very cytotoxic with cell viability of 54–60% compared with the control. Therefore, the addition of 0.1TSX resulted in a significant decrease in cytotoxicity of PF. PF/0.1TSX gels exhibited improved mucoadhesive strength compared with PF gels and sustained the release of incorporated metronidazole antibacterial. These biocompatible systems which are in the liquid state before administration and undergo gelation in situ to form a gel at body temperature may, therefore, be injected into periodontal pockets to achieve sustained local delivery of antibacterials for the treatment of periodontitis.     

Characterization of freeze-dried gallic acid/xyloglucan

Background: Tamarind seed xyloglucan (TSX) is generally used for drug delivery systems. Gallic acid (GA) possesses various pharmacological activities. It has a good solubility and bioavailability but short half-life.

Purpose: To prepare a sustained-release of GA to overcome its relatively short half-life. GA was blended with TSX and freeze-dried. The physicochemical properties of freeze-dried GA and freeze-dried GA/TSX were characterized, and the release profiles of GA from these freeze-dried samples were investigated.

Method: All freeze-dried samples were characterized by PXRD, spectroscopic and thermal analyses. The dissolution studies were performed according to the United States Pharmacopeia (USP) XXX.

Results: According to FTIR, FT-Raman and ¹³C CP/MAS NMR, the spectra of freeze-dried GA were similar to that of the anhydrous form. Nevertheless, DRIFTS and DSC were able to differentiate these two forms. The crystallinity of GA in the freeze-dried GA/TSX was the same as that of the freeze-dried GA. DSC indicates that there were interactions between GA and TSX. It was of interest that a freeze-dried sample with low amount of GA, 0.2% GA/1% TSX was mostly in an amorphous form. Moreover, all freeze-dried GA/TSX preparations demonstrated a sustained-release of GA compared to GA alone. The freeze-dried 1% GA/1% TSX provided the best sustained-release of GA of up to 240?min.

Conclusions: TSX could change a crystal form of a small molecule to a mostly amorphous form. It was of importance that the freeze-dried GA/TSX could effectively retard the release of GA. These samples may be able to overcome the limitation for the therapeutic use of GA due to its short biological half-life.     

Aflatoxin B1-degrading activity from Bacillus subtilis BCC 42005 isolated from fermented cereal products

ABSTRACT

Aflatoxin B₁ is a naturally occurring mycotoxin that is produced as secondary metabolite by Aspergillus spp., especially A. flavus and A. parasiticus. This is the most severe toxin due to its carcinogenic, mutagenic, and teratogenic properties. Hence, methods for toxin degradation have been received increasing interest from both scientific communities and industries. In this study, 32 isolates of Bacillus spp. from various fermented cereal products were screened for their aflatoxin B₁ degradation ability. The results indicated the extracellular fraction of Bacillus subtilis BCC 42005 isolated from Iru (African locust bean) potentially possessed aflatoxin B₁-degrading ability. The maximum activity of the active fraction was at 50°C and pH 8.0. The activity was stable in a wide range of pH (5.0–8.0) and temperature (25–60°C). The aflatoxin B₁-degrading mechanisms of this strain may be possibly involved by enzyme(s). This extracellular fraction was not toxic at IC₅₀ 4 mg/ml and it can be combined with water as a soaking agent for maize, which results in 54% of aflatoxin B₁ reduction after contact time 120 min. Hence, the extracellular fraction of Bacillus subtilis BCC 42005 can be further applied as an effective soaking agent in a pretreatment process with a practical and easy-to-implement condition and also probably used to reduce the aflatoxin B₁ contamination in other foods and feeds commodities.