Results and discussion
Various physiochemical and microbial characteristics of the extracted mucilage from A. barbadensis were investigated. The presence of mucilage in extracted material was confirmed using Molisch's test and by treatment with
ruthenium red. Both tests were positive for the presence of mucilage. The results of other investigations (percentage yield,
particle size, pH of solution, density, and charring) are shown in Table II. The weight loss on drying indicates the amount
of moisture present in the material available to interact with other material. For dried mucilage, the loss on drying was
4.89%. The result of microbial testing of the mucilage was within official limits [less than 100 colony-forming units (cfg)/g].
The swelling ratio of mucilage, determined in distilled water, was 40. There was a significant change in swelling by the end
of the study, which indicated that the mucilage had excellent swelling properties.
Table II: Physicochemical and microbial properties of dried powdered mucilage.
The viscosity of the extracted dried mucilage was compared with a semisynthetic polymer (sodium CMC). The range of viscosities
over the concentration range studied was 5.03 to 9.96 mPa s for dried mucilage and 2.79 to 12.15 mPa s for sodium CMC (see
Table III). It can be concluded that the dried mucilage has viscosity comparable with sodium CMC.
Table III: Rheological data of Aloe barbadensis mucilage and sodium carboxymethylcellulose (CMC).
The flow properties and compressibility of the dried mucilage, including bulk and tapped density, Carr's index, the Hausner
ratio, and the angle of repose, were assessed. Comparison was made with guar gum and ispaghula, two other natural materials
(see Table IV). The dried mucilage has excellent flow properties compared with guar gum and ispaghula. It can be concluded
that the dried mucilage has flow properties suitable for a direct-compression formulation.
Table IV: Flow properties of dried Aloe barbadensis mucilage and other gums.
The physical tests (hardness test, friability, and weight variation) were performed for all formulations. Mean hardness for
all formulations was about 4 kg/cm2 , friability was less than 1%, and the weight-variation results for the matrix tablets complied with pharmacopeial limits.
From this work, it was shown that dried mucilage possesses good tablet-forming properties.