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Abstract
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.
Declaration of interest
The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this paper.
This work was supported by the Thailand Research Fund through the Royal Golden Jubilee Ph.D. Program through Grant Nos PHD/0259/2549 and PHD/0045/2552 and the Nanotechnology Center (NANOTEC), NSTDA, Ministry of Science and Technology, Thailand, through its program of Center of Excellence Network.