# Formulation Strategies to Improve Oral Bioavailability of Ellagic Acid
## 4 Formulation Strategies for Improving EA Oral Bioavailability
### EA Encapsulated in Polymeric Carriers
#### 4.4.3 Chitosan Micro/Nanospheres  
CS is a polysaccharide obtained by partial deacetylation of chitin, endowed by important features from the biomedical point of view. It is mucoadhesive, non-toxic, biocompatible, biodegradable and exerts slight antimicrobial properties. CS is a weak base (pKa value \(\sim\)6.5) positively charged at physiologic pH. In a study by [PERSON] et al., EA-CS NP were prepared by ionic gelation method using sodium tripolyphosphate (TPP) as gelating agent, with CS to TPP ratio of 4:1. CS was dissolved in 1% _v/v_ acetic acid under magnetic stirring overnight and the final pH was adjusted to 5.0 [76]. Different EA amounts (25, 50, 100 mg) dissolved in DMSO (0.5% _v/v_) were added to the CS solution, and finally an equal volume of 1 mg/mL TPP solution was added dropwise under mild stirring. The mixture was kept under stirring till NPs formation. The lowest EA amount added led to the highest EE and DL, of 94% and 33% respectively. Spherical NP were obtained with a mean diameter of 176 nm and a slightly positive zeta potential (\(\zeta\) = +4 mV), which could be due to the adsorption of EA on the particle surface, thus masking CS positive groups. As usually, the EA release showed a two-step profile, where 55% of loaded EA was rapidly released during the first 8 h and the remaining 20% was released more slowly until 48 h. Finally, EA-CS NPs were investigated as anticancer agents and proved higher cytotoxicity than free EA on KB human oral cancer cell line at almost all the tested doses. Successively, in another study by [PERSON] et al., EA-CS NPs were been investigated as anti-hemorrhagic agents [77]. Also in this case, the NPs were prepared by ionic gelation procedure with 1:12 EA:CS ratio. They sized around 80 nm, being 50% their maximum EE. Release studies showed an EA fast dissolution (84% in 12 h), suitable for clotting purposes. In fact, EA-CS NPs yielded a significantly faster clotting time when compared to free EA, void CS NPs, and an EA:CS physical mixture.  
A recent study by [PERSON] et al. focused on the preparation of EA microspheres based on CS and sodium alginate as coating materials [78]. CS-alginate microparticles (MPs) were prepared by ionotropic gelation. The polycationic CS and Ca\({}^{2+}\) were added to the EA alginate solution, thus a polyelectrolyte complex coating formed; MPs were further stabilized with 2% glutaraldehyde solution. SEM images revealed a mean size of 4.36 \(\upmu\)m, with some EA crystals on the surface, while EE was around 30%. Regarding dissolution profiles, they reflected the structure of the MPs, because EA was quickly released at 0-3 h and 6-24 h, while it was slowly released from 3 to 6 h because of the necessary deconstruction of the strong coating, suggesting the effective dispersion of EA inside the MPs. Therefore, this formulation seems to be more suitable if a sustained release is desired. Finally, in vitro experiments on 3T3-L1 adipocytes showed a consistent inhibition of adipogenic differentiation by entrapped EA vs. EA alone, suggesting its possible use in obesity treatment.