Alternative sulfur trioxide complexes involving Py•SO3 and DMF•SO3 were used for the sulfation of polysaccharides and polyphenolic flavonoids. For instance, Cellulose sulfate is an example of sulfated polysaccharide which has been studied for its potential biological and pharmaceutical applications such as anticoagulant, antimicrobial, antioxidant, and used in drug delivery system. Richter and co-workers have described the regioselective sulfation of the trimethylsilyl cellulose (TMSC) using sulfur trioxide complexes such as Py•SO3, DMF•SO3, and Et3N•SO3. The synthesis of sodium cellulose sulfates were carried out by dissolving TMSC in tetrahydrofuran (THF) followed by the addition of sulfur trioxide complexes at room temperature for 24 h. The resulting intermediate was treated with sodium hydroxide yielding the final desired sodium cellulose sulfates (Scheme 12). Scheme 12. The regioselective sulfation of trimethylsilyl cellulose (TMSC) using sulfur trioxide complexes.