Scientific African (Sep 2021)
Physicochemical characterisation of Piptadeniastrum africana (Hook. F.) gum, a potential pharmaceutical excipient
Abstract
Modern advances in dosage forms require innovative excipients that make them more efficient than conventional dosage forms. Natural excipients like gums are known to be cheap, biodegradable, and readily available. However several natural gums are yet to be fully characterized and utilized. This study sought to determine the physicochemical properties of Piptadiniastrum africana (Hook. F.) gum to establish a basis for its pharmaceutical application. The crude Piptadiniastrum africana gum (CPAG) was collected as the natural exudates from the tree bark and observed for its macroscopic features. Physicochemical characteristics such as the moisture content, insoluble matter, and ions as well as pH, swelling index, hydration capacity, solubility, viscosity, flow properties, and rheological behaviour were determined. To assess the chemical and morphological nature of the purified gum, scanning electron microscopy (SEM), nuclear magnetic resonance (NMR) imaging, X-ray diffractogram (XRD), and Fourier Transform Infrared (FT-IR) spectroscopy were employed. CPAG was a pale-dark brown color with an ammoniac smell and a biting taste while the purified Piptadeniastrum africana gum (PPAG) (yield 33.19%w/v) was off white-light brown color with a characteristic smell and bland taste. The moisture content of CPAG and PPAG was determined to be 13% and 8% respectively while the insoluble matter level was 0.31% and 0.12% respectively. Both CPAG and PPAG contained monovalent and divalent metal ions in the order Ca2+>Mg2+>Fe2+>Na+>Cu2+>K+>Zn2+. The swelling and hydration capacities of CPAG were found to be 1.35 and 4.24 respectively while values for PPAG were determined as 0.22 and 3.8 respectively. PPAG was soluble in both hot and cold water, HCl and chloroform. The gum was determined morphologically to be an amorphous carbohydrate with β-D-mannopyranosyl units attached to repeated units of α-D-galactopyranosyl. This study reveals that the purified gum possesses physicochemical features suitable as an excipient for pharmaceutical use.
