Polyphenol content and antiradical activity of Euphorbia serpens extract stored in different forms and under different conditions

MOSCHEN, MATÍAS; MARTÍNEZ MEDINA, JUAN JOSÉ; 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

Euphorbia species have medicinal properties due to the presence of several secondary metabolites, mainly terpenoids, flavonoids, and polyphenols. These phytochemicals usually present a variety of biological activities associated with an antioxidant action mechanism. Nevertheless, natural compounds are unstable under different environmental factors (light, oxygen, or temperature), losing their antioxidant capacity, and consequently, their beneficial health activities. The encapsulation of the extracts is a strategy to achieve the stability of these compounds. The aim of this work was to evaluate the polyphenol content and the antiradical activity of different forms of Euphorbia serpens Kunth extract (fluid, dry, and encapsulated extract) stored under different conditions. E. serpens plants were harvested and allowed to dry at room temperature, protected from direct light, for 7 days. Then, the extract was obtained by macerating 20g of leaves in 100 ml of 70% (v/v) ethanol. One part was used as it was obtained (fluid extract), another part was dried to constant weight (dry extract), and a third part was used to prepare capsules with sodium alginate (1% w/v) and calcium chloride (5% w/v) by using the ionic gelation technique. Each extract was stored in glass vials protected from light. Storage conditions were: 1) 40 °C and 75% relative humidity (RH); 2) 25 °C and 58% RH; 3) 8 °C and 58% RH. The extracts were analyzed to determine the content of phenolic compounds by the reaction with the Folin-Ciocalteau reagent, and their antiradical activity by using the DPPH radical at 0, 30, 90, and 180 days. For these assays, the dry extract was reconstituted at its initial concentration and the particles were dissolved in a 2% (w/v) citric acid solution. The initial content of polyphenols was 2.04 ± 0.17 mg equivalents of acid gallic per ml (mg EAG/ml) of fluid extract, 2.30 ± 0.18 mg EAG/ml of reconstituted dry extract, and 2.19 ± 0.22mg EAG per gram of capsules. There were fluctuations in the polyphenol content throughout the time, but at 180 days, the values were close to the initial value for all samples. Regarding the antiradical activity, the initial values were 72 ± 2%, 80 ± 3, and 23 ± 2%, for fluid, dry, and encapsulated extracts, respectively. Fewer fluctuations were detected throughout the time, thus increasing the antiradical activity after 180 days. Previous reports described that the polyphenol content can decrease with time, while the antioxidant activity increases.1,2 This could happen because new antioxidants are formed by reactions between oxidized phenolic compounds or hydrolysis. These results suggest that regardless of the form of the extracts of E. serpens and the storage conditions evaluated, their antioxidant properties are preserved for at least 180 days.