Lyotropic Liquid Crystal System for Drug Delivery of Astaxanthin: Physical Characterization and Enhanced Antioxidant Potential

Abstract

Astaxanthin is a xanthophyll carotenoid, well known for its potent anti-inflammatory and antioxidant properties, owing to its unsaturated molecular structure. Aquatic plants and animals contain the hydrophobic carotenoid astaxanthin, which is thought to possess a number of advantageous biological traits. However, due to its weak bioavailability and low water solubility, its use as a nutraceutical in food is currently restricted. Cubosomal encapsulation has been considered an effective alternative for improving the bioavailability and solubility of hydrophobic bioactives. The current paper aimed to conquer these issues by encapsulating astaxanthin in lyotropic liquid crystal nano-formulations prepared via the fabrication method. The physicochemical properties of astaxanthin-loaded cubosomes (AST-LC) have also been analyzed, in order to know the morphology of the prepared formulations and their bioavailability in the biological system. The formulation has been tested for particle size, thermal behavior, zeta potential, crystallinity, encapsulation efficiency, and drug-polymer interactions. The observed experimental results showed the particle size and zeta potential of astaxanthin-loaded cubosomes (AST-LC) as 199 ± 0.23 nm −27.4 ± 4.67 mV, with a small polydispersity index (0.283 ± 1.01). The cubic structure and nano-range size of the ideal formulation were verified by a field emission scanning electron microscope (FESEM) and (HRTEM) high-resolution transmission electron microscopic examination. The formulation exhibits a higher encapsulation efficiency with good yield. Results from X-ray diffraction and diffraction scanning calorimetry demonstrated an amorphous state of astaxanthin incorporated into the formulation. Fourier transform infrared spectroscopy (FTIR) analysis of AST-LC showed the absence of astaxanthin main peaks, indicating its complete encapsulation inside the formulation. The drug–excipient interaction was carried out with diffraction scanning calorimetry DSC and FTIR, resulting in no interaction between them. These results offered important details about increasing astaxanthin bioavailability by incorporating it into cubosomes. Furthermore, the astaxanthin loaded into cubosomes has been evaluated for antioxidant potency, compared with astaxanthin extract using 2,2-diphenylpicrylhydrazylassay (DPPH assay).