Solid state characterization of two novel gums from Cedrela odorata and Enterolobium cyclocarpum

Abstract

Functional and physicochemical properties of two novel polymers from plants were characterized with a view of determining suitability for use in pharmaceutical dosage forms. Cedrela gum (CD) and Enterolobium gum (ET) were extracted from the incised trunk of Cedrela odorata (Meliaceae) and Enterolobium cyclocarpum (Mimosoideae) trees respectively. The gums were characterized using particle size and distribution analysis, density measurements, swelling index, angle of repose, Carrs’ compressibility index and Hausner’s ratio. Other physicochemical properties were determined by pH measurement, powder X-ray diffractometry (PXRD), scanning electron microscopy (SEM) differential scanning calorimetry (DSC) and viscometry. Hydroxypropylmethyl cellulose (HPMC) was the reference polymer. The polymers generally had particle size range of 145–436 µm and the particles were normally distributed. The gums had comparable particle density, Carr’s index and Hausner’s ratio with HPMC, indicating similar packing properties between the gums and HPMC. All polymers had angle of repose values in the range for excellent flow properties. The polymers were of alkaline pH, thereby suggesting compatibility with basic drugs. Hydration capacity of the polymers was generally high. The ranking order for viscosity was ET > CD > HPMC (p < 0.05). Similar thermal behaviour was recorded by DSC for the gums and HPMC. SEM revealed irregularly shaped and aggregating surface morphology while broad halo diffraction patterns were obtained by the PXRD. CD and ET gums showed comparable functional and physicochemical properties with HPMC, a standard polymer. These gums could be used as pharmaceutical excipients in bioadhesive formulations and other drug delivery systems.