PHYSICOCHEMICAL AND MORPHOLOGICAL PROPERTIES OF THERMALLY MODULATED CARBOXYMETHYLATED ENTANDOPHRAGMA ANGOLENSE GUM

*Oladapo A. Adetunji, Olubunmi M. Ajakore and Oludele A. Itiola

ABSTRACT

Modification and subsequent use of natural polymers as excipients in drug delivery is due majorly to their affordability, low toxicity, biocompatibity, physiological inertness and bio-degradability, and also to eliminate poor cohesive and dynamic properties that are characteristic of the natural polymers. In this study, Entandophragma angolense gum (ENTA) was modified by carboxymethylation at different reaction conditions and comparatively investigated for physicochemical and morphological properties. The ENTA was carboxymethylated at different reaction conditions (450C and 600C at 30 min and 60 min) to yield CENTA45/30, CENTA45/60, CENTA60/30 and CENTA60/60 granules, which were characterized using morphology, crystallinity, swelling index, rheology measurements, FTIR spectra, flow properties and density measurements. Results were analyzed using mean and standard deviation. CENTA45/30 and CENTA45/60 granules were spherically shaped discrete structures with smooth surfaces, while ENTA, CENTA60/30 and CENTA60/60 granules were round to oval shaped clumped structures. All granules exhibited some degree of crystallinity, while swelling indices at 270±0.60C and 800±0.30C ranked CENTA45/60CENTA45/60>CENTA45/30>CENTA60/60 >CENTA60/30, while for the trough and final viscosities, the order was the reverse. FTIR spectra for CENTA batches showed similar absorption peaks, with strong absorption bands at 2358.47cm-1 and 2358.56cm-1. Modification enhanced flowability, while density measurements show that CENTA45/60 was the most compressible. Carboxymethylation improved the physiochemical properties of ENTA due to introduction of functional groups to its crystalline structure. The carboxymethylation carried out at 450C for 60 mins produced granules with the highest pasting temperature and most compressibility profile.

Keywords: Natural polymers, Entandophragma angolense gum, Carboxymethylation, Reaction conditions, Physicochemical properties.