Release study of polyphenols in different mediums from Euphorbia serpens extract encapsulated

MOSCHEN, MATÍAS; PÉREZ ZAMORA, CRISTINA MARISEL; NUÑEZ, MARÍA BEATRIZ

Rosario

Congreso; 7ma Reunión Internacional de Ciencias Farmacéuticas; 2023

Universidad Nacional de Rosario y Universidad Nacional de Córdoba

Polyphenols are natural compounds of interest because they are associated with benefits for human health. Euphorbia species have medicinal properties due to the presence of several secondary metabolites, mainly terpenoids, flavonoids, and polyphenols. Previously, our group studied the biological activities of the species Euphorbia serpens and encapsulated the extract to study its stability. In this work, our objective was to determine if the release of polyphenols from the encapsulated E. serpens extract is affected by the pH conditions of the medium. The extract was obtained by macerating of leaves (20 g) in 100 ml of ethanol (70% v/v). Encapsulation was carried out by ionic gelation with sodium alginate and calcium chloride. For the release study, exactly 0.1 g of particles were weighed to be dissolved in 5 ml of medium. Three different media were used in triplicate: distilled water (pH=7), acid buffer (pH=2.2), and slightly acid buffer (pH=5.4), all of them at 37 °C. At specific time periods, 200 µl of sample were extracted and used to determine the released polyphenols, using the colorimetric method that uses the Folin-Ciocalteau reagent. The volume extracted in each intake was replaced by the same amount of medium used, to keep the total volume constant. The concentration of polyphenols released at each time was calculated from the absorbances obtained at 765nm, by interpolation in the corresponding calibration curve for each medium worked. To describe the release kinetics, the data obtained in this assay were analyzed with the Excel add-in, DDsolver. The mathematical models to which the data were fitted were: order zero, order one, Higuchi, Korsmeyer-Peppas, Peppas-Sahlin, Weibull. In neutral medium, after 210 minutes the release reaches an average value of 1,032 mg of polyphenols per 100 g of sample. In the acidic and slightly acidic media, the values reached 4.044 mg and 3.951 mg per 100 g of sample, respectively. The Peppas-Sahlin model best fits the data for all the media used, with R2 values between 0.93 and 0.98. In all cases, the relationship between the parameters k1 and k2 is greater than one, so the release mechanism is based mainly on diffusion. Furthermore, for the parameter n, the values are between 0.23 and 0.35, so it is considered that the release kinetics are affected by two additive transport mechanisms, release by Fick diffusion and relaxation of the case II associated with the relaxation of hydrophilic polymers that undergo swelling in water. Based on the results, we conclude that pH influences the quantities of polyphenols released from calcium alginate particles and that the greatest release occurs in an acidic medium.