Isolation and Characterization of Native Cellulose and Microcrystalline Cellulose from Teff Straw, and Evaluation of Microcrystalline Cellulose as Directly Compressible Pharmaceutical Excipient
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Date
2019-07
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Addis Ababa University
Abstract
Cellulose is one of the major components of agricultural byproducts. Teff is the most widely cultivated cereal crop in Ethiopia covering 22.95% of the cultivated land from which about 7.46 million tons of Teff straw is produced as a byproduct each year. The aim of this study was to isolate and characterize native cellulose and microcrystalline cellulose (MCC) from Teff straw, and evaluate MCC as directly compressible pharmaceutical excipient. Cellulose was isolated from Teff straw with formic/ acetic acid-based treatments and MCC was prepared through HCl catalyzed hydrolysis of cellulose. The isolated cellulose and MCC were characterized through scanning electron microscope (SEM), infrared spectroscopy (FTIR), differential thermal analysis (DTA), thermogravimetric analysis (TGA) and x-ray diffraction (XRD). Powder property, compressibility and tablet properties of MCC were also studied.
Yields of cellulose and MCC powder from the raw material were 35.2% and 27.2%, respectively. Cellulose displayed rod-shaped fibers whereas MCC showed irregularly shaped aggregated particles. The IR spectra of both cellulose and MCC, and thermogram of MCC showed similarity with that of Avicel PH-101. The degree of polymerization (DP) and crystallinity index of cellulose were 594.51 and 72.26%, respectively. Whereas, MCC powders showed DP of 241.09–257.38 and crystallinity index of 76.45–84.52%. Spray dried MCC (MCC-SD) exhibited poor flow while oven dried MCC (MCC-OD) showed passable flow property. Both MCC-SD and MCC-OD displayed lower mean particle size and wider particle size distribution than Avicel PH-101. At all compression forces studied, MCC-SD showed superior compactibility than MCC-OD. Both MCC-OD & MCC-SD showed lower lubricant sensitivity and compressibility than Avicel PH-101. Paracetamol loaded tablets of MCC-SD and Avicel PH-101 powders exhibited comparable tensile strength. Disintegration and dissolution profiles of all tablets fall within acceptable limits set for conventional tablets.
Based on the results of this study, MCC powder could be prepared from locally available alternative source (Teff straw) for pharmaceutical applications. But, critical variables of MCC preparation should be optimized in order to improve its powder and compaction properties.
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Keywords
Cellulose, Microcrystalline cellulose, Oven dried Microcrystalline cellulose, Spray dried Microcrystalline cellulose, Teff straw