Nanoencapsulated Aqueous Extract of <i>Catharanthus Roseus</i> L. Improves the Biological Activities In Vitro

Abstract Encapsulating plant extracts into an alginate matrix is a propitious approach for developing novel antidiabetic agents. This study focused on preparing, characterizing, assessing release kinetics, and determining biological activities of aqueous extract of Catharanthus roseus L. encapsulated alginate nanoparticles (AqCR‐ANs). The AqCR‐ANs were prepared by the ionic gelation technique and were characterized. In vitro polyphenol release from the alginate matrix was determined at both pH 1.2 and pH 6.8. Antidiabetic, anti‐inflammatory, and antioxidant activities were assessed. The AqCR‐ANs had satisfactory encapsulation efficiency (62.02%), loading capacity (1.12%), and mean particle diameter (152 ± 33 nm). Notably, the release of polyphenols from AqCR‐ANs was low at pH 1.2 (50%–74%), compared to the release at pH 6.8 (50%–100%). AqCR‐ANs exhibited enhanced antidiabetic activity with low IC 50 values of 0.60 ± 0.09, 9.35 ± 1.65, and 1.16 ± 0.07 mg/mL in the α‐amylase, α‐glucosidase inhibitory activities, and antiglycation activity, respectively (p &lt; 0.05). AqCR‐ANs were more active against hypotonicity and heat‐induced hemolysis at IC 50 values of 0.91 ± 0.04 and 0.09 ±0.01 mg/mL, respectively, compared to AqCR. In conclusion, the antidiabetic and ant‐inflammatory activities of AqCR‐ANs were improved upon encapsulation, while their antioxidant activity was preserved. AqCR‐ANs show promising potential to be developed as a nanoencapsulated antidiabetic drug lead with controlled release.