Chitin is a natural polysaccharide of major importance. This biopolymer is synthesized by an enormous number of living organisms; considering the amount of chitin produced annually in the world, it is the most abundant polymer after cellulose. The most important derivative of chitin is chitosan, obtained by partial deacetylation of chitin under alkaline conditions or by enzymatic hydrolysis. Chitin and chitosan are known to have important functional activities but poor solubility makes them difficult to use in food and biomedicinal applications. Chitooligosaccharides (COS) are the degraded products of chitosan or chitin prepared by enzymatic or chemical hydrolysis of chitosan. The greater solubility and low viscosity of COS have attracted the interest of many researchers to utilize COS and their derivatives for various biomedical applications. In light of the recent interest in the biomedical applications of chitin, chitosan, and their derivatives, this review focuses on the preparation and biological activities of chitin, chitosan, COS, and their derivatives.

Numerous plants have been documented to contain phenolic compounds. Thymol is one among these phenolic compounds that possess a repertoire of pharmacological activities, including anti-inflammatory, anticancer, antioxidant, antibacterial, and antimicrobial effects. Despite of the plethora of affects elicited by thymol, its activity profile on gastric cancer cells is not explored. In this study, we discovered that thymol exerts anticancer effects by suppressing cell growth, inducing apoptosis, producing intracellular reactive oxygen species, depolarizing mitochondrial membrane potential, and activating the proapoptotic mitochondrial proteins Bax, cysteine aspartases (caspases), and poly ADP ribose polymerase in human gastric AGS cells. The outcomes of this study displayed that thymol, via an intrinsic mitochondrial pathway, was responsible for inducing apoptosis in gastric AGS cells. Hence, thymol might serve as a tentative agent in the future to treat cancer.

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Recent reports have shown the antidiabetic effect of Moringa oleifera from various parts of the world. However, M. oleifera from Cambodia has never determined. Therefore, the aim of this study was to assess the antidiabetic effect of M. oleifera extract from Cambodia. The leaf ethanolic extract contained flavonoids (31.90 mg/mL), polyphenols (53.03 mg/mL), lycopene (0.042 mg/mL), and ß-carotene (0.170 mg/mL), and possessed 2,2-diphenyl-1-picrylhydrazyl, hydrogen peroxide, and hydroxyl radical scavenging activities of 92.40, 99.25, and 83.57 TE/μM at 1 mg/mL, respectively. Db/db mice were orally administered the leaf extract (150 mg/kg/day) for 5 weeks. M. oleifera treatment significantly ameliorated the altered fasting plasma glucose (from 483 to 312 mg/dL), triglyceride (from 42.12 to 23.00 mg/dL), and low-density lipoprotein cholesterol (from 107.21 to 64.25 mg/dL) compared to control group, and increased the insulin levels from 946 ± 92 to 1678 ± 268 pg/mL. The histopathological damage and expression levels of tumor necrosis factor-alpha, interleukin (IL)-1β, IL-6, cyclooxygenase-2, and inducible nitric oxide synthase in renal tissue decreased. These results indicate the potential antidiabetic benefits of M. oleifera ethanolic leaf extract.

Food protein-derived peptides are important components for nutraceuticals, with many biological functions as well as substantial nutritional benefits. The aim of this study was to investigate the antioxidant effects of ovotransferrin (OTF) derived from egg white and its hydrolysates (OH) prepared by hydrolyzing either with acid or enzymes (protamex, alkalase, trypsin, neutrase, flavorzyme, maxazyme, collupulin, protex, promod 278, and α-chymotrypsin). All OH showed approximately 3.2 to 13.5 times higher superoxide anion scavenging activity than OTF, with the maximum activity found in the OH-protamex. Similar results were obtained for oxygen radical absorbance capacity assay, with the highest value in OH-α-chymotrypsin [1.6 μM trolox equivalents (TE)] and the lowest value in OTF (0.2 μM TE). However, OTF showed the most powerful 2,2-diphenyl-2-picrylhydrazyl radical scavenging activity, which reached 78.2% after 36 h of reaction. Both OTF and OH showed protective effects against the oxidative stress-induced DNA damages in human leukocytes. Overall, OTF possessed antioxidant abilities and hydrolyzation of OTF with acid or enzymes improved these abilities.