Preparation and in vitro characterization studies of astaxanthin-loaded nanostructured lipid carriers with antioxidant properties

Astaxanthin-loaded alginate-chitosan gel beads activate Nrf2 and pro-apoptotic signalling pathways against oxidative stress

Oxidative stress (OS) plays a crucial role in disease development. Astaxanthin (ATX), a valuable natural compound, may reduce OS and serve as a treatment for diseases like neurodegenerative disorders and cancer. Nuclear factor-erythroid 2-related factor 2 (Nrf2) regulates antioxidant enzymes and OS management. We evaluated ATX's antioxidant activity via Alg-CS/ATX gel beads in vitro. ATX-encapsulated alginate-chitosan (Alg-CS/ATX) gel beads were synthesized and structurally/morphologically characterized by SEM, FT-IR, and XRD. Their biological effects were examined in human umbilical vein endothelial cells (HUVECs) treated with H2O2 through MTT assay, Annexin V/PI, cell cycle studies, and western blotting. Alg-CS effectively carried ATX, with high capacity and reduced pore size. Alg-CS/ATX displayed an 84% encapsulation efficiency, maintaining stability for 30 days. In vitro studies showed a 1.4-fold faster release at pH 5.4 than at neutral pH, improving ATX's therapeutic potential. HUVECs treated with Alg-CS/ATX showed enhanced viability via increased Nrf2 expression. Alg-CS gel beads exhibit significant potential as a biocompatible vehicle for delivering ATX to combat OS with considerable opportunity for clinical applications.

Effects of Four Organic Carbon Sources on the Growth and Astaxanthin Accumulation of Haematococcus lacustris

The microalga Haematococcus lacustris has a complex life cycle and a slow growth rate, hampering its mass cultivation. Culture of microalgae with organic carbon sources can increase the growth rate. Few studies have evaluated the effects of organic carbon sources on H. lacustris. We compared the vegetative and inductive stages of H. lacustris under autotrophic and mixotrophic conditions using four organic carbon sources: sodium acetate, glycerol, sodium gluconate, and ribose, each at various concentrations (0.325, 0.65, 1.3, and 2.6 g/L). The cell density was increased by 1.3 g/L of glycerol in the vegetative stage. The rapid transition to the inductive stage under nitrogen-depletion conditions caused by 1.3 or 2.6 g/L sodium acetate promoted the accumulation of astaxanthin. The production of astaxanthin by H. lacustris in mass culture using organic carbon sources could increase profitability.

Astaxanthin-loaded polylactic acid-glycolic acid nanoparticles ameliorate ulcerative colitis through antioxidant effects

Introduction

Astaxanthin (AST) is a type of carotenoid with strong antioxidant effects. However, the development and use of AST are limited by its water insolubility and low bioavailability. This study aims to investigate whether AST@PLGA can inhibit UC and reveal its possible mechanism.

Methods

We tested the particle size, polydispersity index, and zeta potential of AST@PLGA. Then, the in vitro release and antioxidant capacity of AST@PLGA were tested. Finally, the mouse model of colitis was established and SOD, MDA, TNF-α, IL-1β, IL-6 and P38 as well as ERK were detected from mice.

Results

Particle size, polydispersity index and zeta potential of AST @PLGA were 66.78 ± 0.64 nm, 0.247 and -9.8 ± 0.53 mV, respectively, and were stable within 14 days. Then, it was observed that the AST@PLGA nanoparticles not only maintained the effect of AST but also had a sustained release effect. Experiments in mice showed that AST@PLGA effectively reduced MDA, TNF-α, IL-1β and IL-6 levels and increased SOD levels. AST@PLGA also downregulated the protein expression of P38 and ERK. The results showed the positive protective effect of AST@PLGA in inhibiting acute colitis.

Discussion

AST@PLGA nanoparticles have good stability and alleviating effect in colitis, which could be functional foods in the future.