Scopoletin release modulation in alginate-gums beads analysed by a novel spectrophotometric technique in radiofrequency spectra

Gastro-oesophageal reflux disease (GORD) is a current global clinical problem, which negatively affects patients’ quality of life, causing symptoms like heartburn, acid regurgitation and/or mucosal damage. The administration of scopoletin represents a promising alternative therapy against GORD, due to its antisecretory and prokinetic activities. Encapsulation in a calcium alginate matrix enables the sustained release of bioactive compounds, especially when secondary excipients are incorporated. The release kinetic of encapsulated substances can be studied through permittivity measurements in radiofrequency range, serving as a novel, continuous, and quantitative method for measuring the release of active compounds in the digestive media.

In this work, three systems of scopoletin beads were prepared, using an alginate (AS); alginate and guar gum (ASGG); and alginate and arabic gum (ASAG) matrix, respectively. The swelling of each system in simulated gastric medium (SGM) was evaluated by optical microscopy, and the release kinetic of scopoletin was obtained through radiofrequency spectroscopy. Eventually, an irreversible thermodynamic model was developed to determine the driving forces of scopoletin release in each case. The results showed that the addition of gums, especially guar gum, provokes an increased expansion of the system in SGM and a reduction of the flux of scopoletin within the gastric phase. Gums provide more elasticity to the beads, which store mechanical energy during the drying process and release it when rehydrated in SGM. As consequence, a hydrodynamic flux against the diffusion of scopoletin is generated, and the release is prolonged over time. The present study provides the basis for the design and development of encapsulations to treat gastrointestinal diseases.