This work was part of a pure research project on the functionalization of three families of hydrocolloids: cellulose derivatives, carrageenates, and alginates. Principal component analysis (PCA), a powerful statistical method, was used to demonstrate the relations existing among these different parameters that describe the consistency of hydrogels and their spreadability. This approach therefore provides a basis for modeling hydrogel consistency. PCA also afforded a classification of hydrogels that demonstrated the remarkable adhesiveness of very stiff gels based on cellulose derivatives and sodium or potassium alginates. The corresponding semi-fluid gels and all the gels based on carrageenates and mixed sodium-calcium alginates, whatever their spreadability, were found to be very poorly adhesive. Generalized to all the many colloids currently marketed, this approach can be used to set up a databank for the formulation of mucoadhesive excipients.
The tannins in leaf, bark, and stem extracts of HAMAMELIS VIRGINIANA were analyzed. Four proanthocyanidins were isolated by HPLC. One was a procyanidin polymer containing only one type of flavanol unit; the other three were polymers of procyanidin and prodelphinidin containing two types of flavanol units. A method of assay of hamamelitannin showed the bark extract to be 31 times richer in hamamelitannin than the leaf extract and 87 times richer than the stem extract.
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