**3. Cinnamon**

Cinnamon has a sweet, warm taste and is derived from dried central part of bark of *Cinnamomum zeylanicum* Blume (family Lauraceae). It is native to the Caribbean, South America, and Southeast Asia and is used throughout the world for its astounding properties such as anti-inflammatory, antidiabetic, antimicrobial, anticarcinogenic effects (**Figure 2**) [55]. Biochemical investigation of cinnamon revealed presence of camphor, linalool, cinnamaldehyde (major constituent), terpinen-4-ol, 1,8-cineole, α-cadiene, safrole, α-cadinol, germacrene D, γ-muurolene, α- terpineol, eugenol, 1,6-octadien-3-ol, 3,7-dimethyl,1-phenyl-propanr-2,2-diol diethanoate, etc. [56].

Cinnamon has been reported to exhibit antioxidant effects. In vitro studies showed free radical scavenging activity of methanolic extracts of cinnamon against 2,20 -azinobis- 3-ethylbenzothiazoline-6-sulphonic acid (ABTS) radical and Diphenylpicrylhydrazyl (DPPH) radical cations [57]. Intake of 100 mg/30 ml of cinnamon tea for 2 weeks showed reduction in the levels of 2-thiobarbituric acid reactive substances (TBARS) in plasma by 38% and increase in total antioxidant power 21% in a clinical study [58].

Antidiabetic and cholesterol lowering effects of aqueous extracts of cinnamon (AEC) have also been reported where it reduced fasting glucose levels (at 250 mg) from 1.14 mg/ml to 1.02 mg/ml in patients with impaired fasting glucose [59]; at a dose of 500 mg/kg for two months decreased glucose levels (p < 0.005) along with increasing in insulin sensitivity [60] and at 200 mg/kg reduced levels of LDL cholesterol, triglycerides and total cholesterol and increased levels of HDL-cholesterol in diabetic rats and hyper-lipidemic albino rabbits [61]. Further, decline in gastric acid secretion by 60% and reduction in gastric hemorrhagic lesions in rats was observed on pre-treatment with 250 mg/kg and 500 mg/kg of AEC [62].

Peterson et al., reported cinnamon as a potent anti-alzheimer agent as AEC inhibited tau aggregation (aggregation destabilizes microtubules causing Alzheimer's disease) [63].

In addition, cinnamon possesses antimicrobial and anticancer activities. Ethanolic extracts of cinnamon exhibited anti-microbial properties against

**Figure 2.** *Biological properties of Cinnamon.*

#### *Spices-Reservoir of Health Benefits DOI: http://dx.doi.org/10.5772/intechopen.96471*

*Listeria monocytogenes* (MIC 0.4 mg/ml other MICs) [64]. Further, essential oil of cinnamon also showed inhibitory effects against *Candida albicans* (MIC 7.81 μl/ ml) [65]; nosocomial *P. aeruginosa* isolate (MIC- 1.9 μl/ml) [66]; *Anopheles tessellatus* (LD50: 0.33 μg/mL) and *Culex quinquefasciatus* (LD50: 0.66 μg/mL) [67]. Furthermore, AEC inhibited vascular endothelial growth factor (VEGF) and induced growth of vessels in aortic ring of rat ex vivo at a dose of 25 and 50 μg/ ml suppressing angiogenesis [68]. Constituents of cinnamon essential oil, transcinnamaldehyde and its analogue - 4-hydroxy-3-methoxy-trans-cinnamaldehyde are effective inhibitors of bacterial acetyl-CoA carboxylase [69].

Cinnamon is considered as a strong immunity booster. At a dosage of 10 mg/kg, it significantly increased serum immunoglobulin levels whereas at 100 mg/kg dosage, along with boosting humoral immunity, cinnamon increased antibody titer and phagocytic index too thereby increasing cell-mediated immunity [70]. Cinnamon reportedly exhibits immunomodulatory properties as well. Studies have suggested that cinnamon decreased fibrotic symptoms and pro-inflammatory cytokines on treatment with 4.5 ml/kg dose [71] and 0.8 g/kg dose for 12 weeks [72] respectively in colitis infected mice models. Suppression of pro-inflammatory cytokines such as TNF-a, IL-1b, and IL-6 along with inhibition of nitric oxide secretion were also observed in BV 2 microglial cells on treatment with 50 μg/ml of ethanolic cinnamon extract [73]. Further, cinnamon bark is capable of decreasing in IFN-γ levels, enhancing of IL2 secretion thereby inhibiting cell death [74]. Studies have also suggested that cinnamaldehyde inhibits PI3K, NF-B activation and PDK1 thereby regulating monocyte\macrophage-mediated immune responses [74].

Recent bioinformatic analysis showed the possible effectiveness of molecules isolated from cinnamon against COVID-19 [75]. The ability to reduce pro-inflammatory cytokines and strong in silico investigation suggests the probable potential of cinnamon in fight against COVID-19.

Though cinnamon exhibits a wide range of health benefits, it is important to keep a check on the quantity of cinnamon consumed. A large amount can cause a dramatic drop in the blood sugar levels. In addition, high levels of cinnamon can cause rapid increase in heart rate, liver toxicity [76, 77].
