Isolation and Characterization of Cola acuminata Gum as a Potential Pharmaceutical Excipient

Abstract

Aim: Gums are polysaccharides composed of varying chemical compositions and a wide range of molecular weights. Appropriate evaluation of their physicochemical properties assists in determining their suitability as pharmaceutical excipients in the preparation of various dosage forms and drug delivery systems. The present study focused on characterization of a novel natural polymeric gum extracted from the pods of Cola acuminata plant for its possible application as pharmaceutical excipients.  Methodology: The novel Cola acuminata gum (CAG) was extracted by soaking the sliced Cola acuminata pods in water and precipitated using acetone. Phytochemical screening and characterization of physicochemical properties such as particle size distribution and densification, organoleptic and flow properties, solubility in various solvents, pH, moisture sorption, swelling index and apparent viscosity were carried out on the extracted gum using standard and official methods. Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC) and Wide angle X Ray Diffractometry (WAXD) were also employed to further characterize the gum. Acute toxicity and in vivo skin irritation of the gum on rats were determined using standard methods.  Results: The results revealed that CAG is tasteless, odorless and brown in colour. The dry CAG powder is a hydrophillic polysaccharide gum containing mixture of monosaccharides and possesses good compressibility and flow properties. It is slightly acidic with pH of 5.37 and exhibited pH dependent swelling in water to produce viscous mucilage with pseudoplastic flow. LD50 of the gum in rat is greater than 5000 mg/Kg and Primary Irritation Index (PII) is zero. DSC revealed a glass transition  temperature of 224.5°C ; WAXD showed predominantly diffused diffractogram with only two sharp peaks at 2θ = 20.9° and 2θ = 26.6° while FTIR spectrum showed characteristic bands at 3427 cm-1, 2935 cm-1, 1625 cm-1, 1230 cm-1, 1045 cm-1, 870 cm-1 and 770 cm-1   which indicate the amorphous nature of the gum. Conclusion: CAG obtained from a waste product exhibited good physicochemical properties, it can be considered as a novel pharmaceutical excipient with a great potential for wide range of applications in varieties of pharmaceutical formulations from simple dosage forms to advance drug delivery systems. Its safety for both oral and topical applications was also established.