ABSTRACT
Fucoxanthin (FUCO), a marine carotenoid is photo-, and thermo-labile and poorly bioavailable due to its lipophilicity. Hence, we developed a chitosan (CS)â¯+â¯glycolipid (GL) nanogels (NGs) to increase cellular uptake and anticancer efficacy of FUCO (10⯵M) in human colon cells (Caco-2). Effect of FUCO loaded in NGs with/with no GL was studied in comparison with micellar FUCO. Results showed that the cell viability was lower (pâ¯<â¯0.05) in NGsâ¯+â¯GL (50.5%) compared to NGs (-GL) (66.5%) and the mixed micelles (72.5%) groups over 48â¯h exposure. An enhanced reactive oxygen species (ROS) generation was evident in NGsâ¯+â¯GL (379.2%) group compared to NGs (-GL) and mixed micelles groups. Further, induction of apoptosis with an increased chromatin condensation and DNA fragmentation as evidenced in DAPI staining and DNA ladder assay were higher in NGsâ¯+â¯GL group than other groups. Down-regulation of Bcl-2 (6.6 folds) was higher in NGsâ¯+â¯GL group compared to NGs (-GL) (1.94 fold) and mixed micelles (1.19 fold) groups. Higher Bax up-regulation in NGsâ¯+â¯GL compared to other groups supports the Bcl-2 down regulation. Mitochondrial membrane polarisation (ΔΨm) was higher in NGsâ¯+â¯GL group (2.46 fold) compared to NGs (-GL) (1.91 fold) and mixed micelles (1.26 fold) groups. The cellular FUCO uptake illustrated a positive correlation between its level (pmol/106 cells) in NGsâ¯+â¯GL (758.3) and enhanced caspase-3 activity (25.8 folds). This could be the reason for an increased apoptotic activity in NGsâ¯+â¯GL group than other groups. Results demonstrate that delivery of FUCO in NGsâ¯+â¯GL carrier aids cellular uptake and chemotherapeutic potential of FUCO. Results further demonstrate, for the first time, higher anti-cancer activity of FUCO loaded in NGsâ¯+â¯GL and the effect was through ROS generation via a caspase dependent mechanism in Caco-2 cells.
Subject(s)
Apoptosis/drug effects , Chitosan/chemistry , Colonic Neoplasms/pathology , Drug Carriers/chemistry , Drug Delivery Systems , Glycolipids/chemistry , Nanoparticles/chemistry , Xanthophylls/pharmacology , Caco-2 Cells , Carotenoids/chemistry , Carotenoids/pharmacology , Caspases/metabolism , Cell Survival/drug effects , DNA Fragmentation/drug effects , Endocytosis/drug effects , Enzyme Activation/drug effects , Humans , Kinetics , Membrane Potential, Mitochondrial/drug effects , Muramidase/metabolism , Nanogels , Polyethylene Glycols , Polyethyleneimine , Reactive Oxygen Species/metabolism , Xanthophylls/chemistry , bcl-2-Associated X Protein/metabolismABSTRACT
Fucoxanthin (FUCO) is a light- and heat-sensitive marine xanthophyll carotenoid, present in brown algae that render physiological properties as anti-oxidants. In this study, nanoencapsulation is an approach adopted to improve bioavailability of FUCO by using ionic-gelation method with polymeric chitosan (CS) dispersed in glycolipid (GL), as a carrier. Further, the aim was to investigate adverse effect of acute and sub-acute toxicity of chitosan nanogels (CS-NGs) loaded with FUCO+GL in rats. In the acute toxicity study, FUCO was fed to rats at doses of 0.1, 1, 10 and 100 mg/kg body weight (BW). In the sub-acute toxicity study, FUCO was fed at doses of 1 and 10 mg/kg BW for 28 days. In both the studies, no mortality and abnormalities in gross morphology were observed. Acute toxicity study revealed that the LD50 of FUCO in CS-NGs is higher than 100 mg/kg BW. No postprandial plasma levels of FUCO were detected. However, fucoxanthinol (FUOH), a hydrolytic metabolite of FUCO was detected in a dose dependent manner (P < 0.01). Compared to the control group(s), no dose-related toxic effects of CS-NGs with FUCO + GL were found in haematological, histopathological, plasma biochemical indices, etc. The no-observed-adverse-effect level (NOAEL) for CS-NGs with FUCO + GL in rats was 10 mg/kg/day. To conclude, no apparent adverse effect of CS-NGs with FUCO + GL demonstrating CS could be a promising polymer matrix for safe delivery of FUCO. This is the first study to demonstrate the safety assessment of CS-NGs with FUCO + GL.