Preparation and characterization of Haematococcus pluvialis carotenoid-loaded PLGA nanocapsules in a gel system with antioxidant properties for topical application

Abstract Haematococcus pluvialis is a green microalga that produces a considerable amount of carotenoids, mainly astaxanthin (ASTX), which is a powerful antioxidant compound. However, carotenoid compounds exhibit poor water solubility and high instability, which restrain their application in pharmaceutical products. Considering that, here we describe the encapsulation of Haematococcus pluvialis carotenoids into poly-lactide-co-glycolide nanocapsules (NC-ESHp), aiming to obtain an innovative topical product with antioxidant properties. Nanocapsules were prepared by the solvent displacement method and characterized according to size, zeta potential, total carotenoid content, and ASTX content. Poloxamer 407 was added to the colloidal dispersion to form a thermosensitive hydrogel (HG-NC-ESHp). Release studies demonstrated that the carotenoids were released from the gel system in a sustained way. In the DPPH scavenging assay, NC-ESHp15 exhibited an antioxidant activity 9-fold higher than ascorbic acid. These results indicated that the hydrogel developed may be a promising formulation to provide prolonged protection of the skin against the photo-oxidation process.