*2.6.1 Bioactive compounds*

The major phytochemical in cinnamon bark is cinnamaldehyde. Some other bioactive compounds of essential oils in cinnamon bark are cinnamic acid, coumarin, cinnamyl alcohol, and 2-methoxycinnamaldehyde [130]. Cinnamon bark also contain terpenoids such as oxygenated sesquiterpenes, oxygenated monoterpenes, sesquiterpene hydrocarbon [130–132]. In addition to essential oils and terpenoids cinnamon bark consist of guaiacol, benzenepropanal, cis-cinnamaldehyde, bornyl acetate, acetophenone, geranyl acetate, tetradecanal. Oxygenated monoterpenes are eucalyptol, linalool, borneol, L-α-terpineol, benzaldehyde, anethole, and eugenol. Some of the sesquiterpene hydrocarbons are *α*-cubebene, copaene, *β*-caryophyllene, *α*-muurolene, trans-α-bergamotene, *α*-humulene, *α*-amorphene, 1 s-cis-calamenene, calarene, cedrene, and *β*-cadinene [130–132].

#### *2.6.2 Antioxidant activity*

Cinnamon is considered as one of the most important flavored spices with strong antioxidant activity [133]. Different extraction method has been applied to investigate the antioxidant activities of cinnamon bark extract. For example Yang et al. [134]

#### *Bioaccessibility, Bioavailability, Antioxidant Activities and Health Beneficial Properties of Some… DOI: http://dx.doi.org/10.5772/intechopen.109774*

investigated the antioxidant activity of ethanol and aqueous extracts of cassia bark to evaluate its antioxidant activity by the DPPH and ABTS radical scavenging activity. Both extracts reported to possess strong antioxidant activities however ethanolic extract possessed higher than the aqueous extract [134]. The polyphenolic extracts of cinnamon bark reduced oxidative stress in a dose-dependent manner through inhibition of 5-lipooxygenase enzyme [135].

#### *2.6.3 Anti-inflammatory activities*

Numerous research studies reported that cinnamon essential oil possess antiinflammatory activities and have been used in soothing and numbing for joint aches and pain [136, 137]. On human dermal fibroblast system, a model of chronic inflammation and fibrosis, cinnamon (*Cinnamomum zeylanicum*) bark essential oil (CBEO) significantly inhibited the production of several inflammatory biomarkers such as vascular cell adhesion molecule-1, intercellular cell adhesion molecule-1, monocyte chemoattractant protein-1, interferon gamma induced protein 10 [138]. Cinnamon extract also showed significant reduction in both IL-6 and TNF-*α* level on Lipopolysaccharide (LPS)-induced Interlukin-6 (IL-6) and Tumor Necrosis Factor-*α* (TNF-*α*) which indicates anti-inflammatory effect [136–138].

#### *2.6.4 Antidiabetic effect*

Available *in vitro* and *in vivo* evidence demonstrated that cinnamon confers health benefits in relation to hypoglycaemic activity [139, 140]. Consumption of cinnamon bark reported to have antidiabetic activities as it showed improvements in fasting blood glucose and lipid profile after consumption [139]. *In vivo* studies on cinnamon extract showed that it could improve insulin action via enhancing glucose uptake [141]. The cinnamon bark extract could reduce the blood glucose level by decreasing the carbohydrate absorption in the small intestine [142]. Another *in vivo* study demonstrated that administration of cassia bark extracts the intestinal glycosidase activity was reduced, whereas the serum insulin level and HDL-cholesterol level are increased [142]. Compiling the human studies of 2003–2018 concerning the glycemic profiles of individuals with type II diabetes mellitus showed that fasting blood glucose reduced from 12.9 to 52.2 mg/dL and HbA1c from 0.27 to 0.83%, after moderate consumption of cinnamon extract [143]. Some meta-analysis also indicated that cinnamon powder intake decreased fasting blood glucose and HbA1c [144]. Methylhydroxychalcone polymer (MHCP) in cinnamon bark reported as effective mimetic of insulin which could activate glycogen synthase and inhibit actions of glycogen synthase kinase-3b as well as insulin receptor phosphorylation homologous [145].

### *2.6.5 Cardiovascular health*

Previous research studies reported that cinnamon could reduce the risk of cardiovascular diseases and its complications such as cardiac ischemia, cardiac hypertrophy, and myocardial infarction [130]. Cinnamaldehyde and cinnamic acid are among the main cinnamon compounds with protective effects on cardiovascular diseases through different molecular mechanisms [130]. Cinnamaldehyde played crucial role in the cardiovascular system like vasorelaxation and reduction in blood pressure [146]. Cinnamaldehyde could protect human umbilical vein endothelial cells from the oxidative stress via stimulation of the nuclear factor erythroid

2-related factor signaling pathway [147]. Cinnamaldehyde prevents the progression of hypertension in insulin deficiency and insulin resistance due to its insulinotropic properties [148]. Using Wistar rats of induced metabolic syndrome it was found that cinnamon altered the body composition in association with improved insulin sensitivity [149].
