Table 2.

In vivo antioxidant activities of COS.

Sample	Assay	Effect	Reference
COS	High-fat diet (HFD) mouse model; superoxide radical scavenging activity; hydroxyl radical scavenging and DPPH assay	Reduction of the oxidative damage resulted from the HFD.	[39]
Chitooligomers with degrees of polymerization	Measurement of reducing power; hydroxyl radical scavenging assay	Increase of SOR scavenging potential of chitooligomers accompanying several degrees of polymerization.	[42]
COS	Estimation of O2 and H2O2; flow cytometric analysis to assess neutrophil apoptosis	Neutrophils' proapoptotic capacity from glycogen-mediated peritonitis in mice model; inhibition of SOR generation; reduction of the myeloperoxidase liberation.	[43]
COS	Histological study and retinal cell count; estimation of NeuN-positive ganglion cell layer neurons; terminal deoxynucleotidyl transferase-induced dUTP biotinide end labeling (TUNEL); cell culturing of RGC-5 and in vitro oxidative damage	Preventing ischemia of retina through decreasing oxidative and inflammatory conditions.	[44]
COS	Determination of GSH, MDA contents, and SOD activity; evaluation of neuronal apoptosis through TUNEL assay; immunohistochemical analysis of 8-OHdG, IL-1b, and TNF-α	Amyloid-1–42-induced rat model of Alzheimer's disease; antioxidant activity in hippocampus, effects on apoptosis (TUNEL assay); inhibition of neuroinflammatory responses.	[45]
Chitin, chitosan, COS and N-acetyl-D-glucosamine	Measurement of antioxidant defense parameters; determination of antioxidant enzyme activity; MDA and carbonyl protein assays	Dietary intake containing COS could enhance the growth performance of P. monodon and improve its resistance to DO stress on shrimp, Penaeus monodon.	[46]
COS	Measurement of antibacterial activities of COS; measurement for the resistance to COS after long-term culture; biochemical analysis; RT-PCR and western blot analysis	Reduction of antibiotics dose; prevention of antibiotics-caused side effects in adolescent idiopathic scoliosis (AIS) patients with spinal fusion surgery.	[47]
COS	Measurements of antioxidant-related indices; analyses of cytokines and immunoglobulins; duodenal, jejunal, and ileal histomorphological studies; intestinal mucosal digestive enzymes assay and sIgA; extraction of total RNA and reverse transcription reactions; PCR and microbial population determination	Enhancing growth performance, antioxidant capacity, immunity, and intestinal development of weaned pigs.	[48]
N-acetyl COS	DPPH assay and production of N-acetyl COS; measurement of enzyme activity	Production of antioxidants and N-acetyl COS by Serratia sp.; TKU020 fermentation.	[49]
COS	Drug-metabolizing enzyme activity; estimation of lipid peroxide and GSH levels and GSH S-transferase and NQO1 activity; western blot analysis	Suppression of hepatic CYP enzymes and enhancement of phase II detoxifying reactions of hepato and renal cells in vivo.	[50]
COS	Cell culture; nitrite assay; measurement of TNF-α; spectrofluorometric assay of RDPase; protein and creatinine assay; SOD and MDA assay	COS stimulated the production of TNF-α, NO, and RDPase.	[51]
COS	Measurement of antioxidant enzyme's activities or oxidant injury product; RNA isolation and real-time polymerase chain reaction	Increase of antioxidant defense capacity and placental amino acid transport of sows.	[52]