The phrase "most demulcent" refers to something that has a soothing or calming effect, particularly on mucous membranes. There are several synonyms that could be used to suggest a similar idea, such as "emollient", "palliative", "curative", "nourishing", or "healing". These words all imply a sense of gentleness and the ability to relieve discomfort or pain in some way. Other options might include "mild", "mellow", "soothing", or "calming", which convey a similar sense of ease and relief. Ultimately, the choice of synonym will depend on the context of the sentence and the exact connotation that the writer wishes to convey.