Extraction and Characterization of Cellulose and Microcrystalline Cellulose from Teff Straw and Evaluation of the Microcrystalline Cellulose as Tablet Excipient

Abstract

ABSTRACT Teff (Eragrostis tef), a grass which belongs to the Family Poaceae, is widely cultivated for its starch-rich grains in Ethiopia, generating large amounts of agricultural byproduct, teff straw. The aim of this study was to isolate and characterize cellulose and microcrystalline cellulose (MCC) from teff straw and evaluate MCC as directly compressible tablet excipient. Cellulose was extracted from teff straw and partially depolymerized to obtain MCC. The physicochemical properties of cellulose and MCC powders were characterized. Yields of cellulose and MCC powder from the raw material were 35.2% and 27.2%, respectively. The samples exhibited type-I crystal lattice and similar infrared spectra 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 indexes of 76.45–84.52%. Spray dried MCC was found to be more porous and poorly flowable and had higher moisture content when compared with the oven-dried MCC powder. Tablets prepared from both MCC powders fulfil most of the pharmacopoeial requirements. The spray-dried MCC powder also showed superior compactibility to oven-dried MCC. Teff straw can, therefore, be considered to be an alternative source of cellulose and MCC.