Recherche d'activités biologiques dans les graines de Cucurbita pepo

Abstract

The seeds of Cucurbita pepo serve as plant storage structures that function as a genuine natural bioactive complex. These seeds are distinguished by a rich chemical composition, that confers several biological properties, notably antioxidant, enzymatic, anti-inflammatory, and antimicrobial activities. In this study, two biological activities (antioxidant and enzymatic activities) were investigated within aqueous solution of Cucurbita pepo seeds. Antioxidant activities were evaluated by monitoring the degradation of H2O2 (catalase activity) and by the DPPH radical-scavenging assay, whereas amylase and phytase activities were assessed, respectively, by determining the amount of degraded starch and the amount of released inorganic phosphate as a function of pH, temperature, and salinity. The results showed the presence of a catalase activity (complete degradation of the initial H2O2 concentration, 5 mM) and a DPPH radical-scavenging activity with an IC50 value of 8.36 mg/mL. Furthermore, the aqueous extract of these seeds exhibited, after 5 min of incubation at 30 °C, an amylase activity (degradation of 18.18 μg starch/mg protein) and a phytase activity (release of 0.6 mM phosphate/mg protein), with optima at 30 °C and pH 9 for amylases, and 50 °C and pH 5 for phytases. In the presence of salt, both enzymes were affected, with phytases being more sensitive. Stability studies showed that amylases retained little activity after thermal treatment (about 9%) and were sensitive to both acidic and alkaline media (25% and 31.81% residual activity, respectively), while remaining highly stable in saline medium (72.72%). Conversely, phytases withstand thermal treatment (25% residual activity) and acidic pH (55%), but completely lost their activity under alkaline and saline conditions. The results obtained confirm that Cucurbita pepo seeds can constitute an exploitable source of antioxidant and enzymatic activities that could be valorized in industrial and biotechnological sectors.