Enhancing antioxidant and antimicrobial activity of carnosic acid in rosemary (Rosmarinus officinalis L.) extract by complexation with cyclic glucans

Of all the active compounds in rosemary extract, carnosic acid (CaA) has the most potent antimicrobial and antioxidant activity; however, its low solubility limits its applications. We developed complexing systems using cycloamylose (CA), branched dextrin (BD), and beta-cyclodextrin (beta CD) to improve the solubility of CaA and compared it to the use of maltodextrin (MD). The complexes formed with CA, BD, beta CD, and MD improved the water solubility of CaA by as much as 2.8-fold, 2.1-fold, 1.75-fold, and 2.06-fold, respectively. The antioxidant capacity of CaA in aqueous solutions was also enhanced in the complexes due to the increased water solubility. Interestingly, the antimicrobial activity was improved more dramatically upon complexation with CA (7.27-fold) compared to the improvement when complexed with BD (4.82-fold), beta CD (2.87-fold), and MD (3.83-fold). This may be due to the improvement of the antimicrobial potential of the functional groups of CaA by complexation with flexible cyclic glucans.