*2.3.3 Anticancer activities*

Ginger possessed promising potential for inhibiting the proliferation of multiple cancer cells, such as cancers of the colon, liver, lung, and cervix [62, 69, 70]. Treatment of the human colorectal cancers such as HCT-116, H-1299, and LoVo cells with 6-gingerol and 10-gingerol reduced the cell viability and induced apoptosis in a dose-dependent manner [71, 72]. Ginger extract was responsible for the activating transcription factor 3 (ATF3)-mediated apoptosis induction in human colorectal cancer cells [73]. 6-shogaol and 10-shogaol displayed anti-cancer potentials against human promyelocytic leukemia of HL-60 cells [51]. The anticancer effects of 6-gingerol, 10-gingerol, 6-shogaol, and 10-shogaol acted as prominent bioactive

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

compounds for anticancer activities that used multiple molecular targets such as NF-κB, TNF-*α*, PI3K, Caspase-3 [62, 69–72].

#### *2.3.4 Antidiabetic activity*

Ginger has been examined for blood glucose lowering effect and improvement in metabolic disorders in diabetic animals and humans. Streptozotocin (STZ) is considered as a diabetogenic agent due to its ability to selectively destroy the *β*-cells of the pancreatic islets. When STZ rat were administered by ginger extract their blood glucose levels were decreased and the body weights was improved [52]. Oral administration of aqueous ginger extract increased the serum insulin levels and insulin sensitivity in the alloxan-induced and insulin-resistant diabetic rats [53]. Wei et al. demonstrated that 6-shogaol, 6-paradol, and 8-paradol showed antidiabetic activities by improving glucose utilization in both the adipocytes and muscle cells in high-fat diet (HFD) fed rats [74].

#### *2.3.5 Gastrointestinal activity*

After oral administration of 6-gingerol in rats it showed high tissue partitioning and distribution in the brain, heart, lung, spleen, liver, kidney, stomach, and small intestinal tissue. However, the highest concentration were detected in the gastrointestinal tract [75]. That is why ginger is commonly used to treating gastrointestinal diseases since ancient times and 6-gingerol and its analogues compounds are reported to be responsible for the gastro-intestinal pharmacological activity [62].

#### **2.4 Onion (***Allium cepa* **L.)**

#### *2.4.1 Bioactive compounds*

Quercetin and its glucoside are major compounds found in onions [76]. Other secondary metabolites are saponins, flavonoids, and phytosterols, polysaccharides, organosulfur compounds-onionin A and cysteine sulfoxides and various phenolic compounds [76, 77]. Anthocyanins are also found in onion. Onion contains three types of alkyl cysteine sulfoxides (ACSO), 1 trans- (±S-1-propenyl-L-cysteine sulfOxide (PECSO), 2(±S-methyl-L-cysteine sulfoxide (MCSO), and 3(±S-propyl-L-cysteine sulfoxide (PCS) [76, 78].

#### *2.4.2 Antioxidant activity*

Onion is one of the great sources of natural antioxidant comprising quercetin, kaempferol, and anthocyinns, and some other polyphenolic compounds [76, 77]. Numerous in vitro studies adopting DPPH, ABTS, ORAC and TEAC assay suggested the strong antioxidant potential of onion [78]. Several human trial and other animal model studies demonstrated that the antioxidant role against oxidative stress and lipid peroxidation in various body organs [79, 80]. Due to their antioxidant activities onion and its extract compounds reduced risk of neurodegenerative disorders [81]. Onion decreased lipid peroxidation and enhanced activities of antioxidant enzymes such as SOD, (superoxide dismutase), CAT (catalase), GSH (glutathione), GPx(glutathione peroxidase), TrxR (Thioredoxin reductase), SDH, GST and GR [80].

#### *2.4.3 Anti-inflammatory activity*

Presence of polyphenolic compounds in onion such as tannin, flavonoids, anthocyanin, saponin contributed to anti-inflammatory activities [76, 81]. Onion exhibited anti-inflammatory activities due to presence of high level of quercetin and some organosulfur compounds [76, 81]. Quercetin exhibited anti-inflammatory activities by reducing the production of inflammatory cytokines such as IL-1, IL-4, and TNF-*α* and inhibited the proliferation and activity of lymphocytes [82, 83]. Moreover Umoh et al. showed that quercetin enriched red onion decreased inflammation by inhibition of NF-κB, MARK and STAT-1 [83]. Organosulfur compounds such as thiosulfinates and cepaenes exhibited anti-inflammatory properties by inhibiting the actions of COX and LOX enzymes in arachidonic acid metabolic pathways [84].

#### *2.4.4 Anticancer activities*

Earlier research studies indicated that moderate consumption of onions may have a role in the prevention of a wide range of different cancers, including colorectal, breast, lung, stomach, liver, brain, renal, bladder, ovarian, esophagus, and laryngeal cancer [61, 85–87]. Several epidemiological studies reported that due to the high level of flavonoids in onion it protect from developing lung cancers [85]. Numerous research studies demonstrated that the organosulfur compounds in onions are responsible for their anticarcinogenic properties in cell experiments, animals and human trials [86]. Another class of anticarcinogenic compounds of highly abundant is organoselenium compounds [76].

#### *2.4.5 Antimicrobial activity*

It has been evident form the earlier research that onion extract possesses antibacterial and antifungal properties [87–90]. *In vitro* studies indicated that aqueous extract of onion inhibited growth of *E. coli*, *Serratia marcescens, Steptococcus species, Acetobacillus odontolyticus, Pseudomonas aeruginosa and Salmonella Typhosa, Streptococcus mutans, Streptococcus sobrinus, Porphyromonas gingivalis and Prevotella intermedia* [87–92]. A petroleum ether extract of onion inhibited the in vitro growth of *Clotridium paraputrificum and S. aureus* [76].

#### *2.4.6 Anti-diabetic activity*

Several research studies reported that onion and its extract are strongly associated with managing diabetes and reducing diabetic complications [93–95]. Several animal model studies also reported that onions play significant role in lowering blood sugar levels in fasting diabetic rats [94]. Quercetin from onion inhibited the action of digestive enzymes *α*-glucosidase and induce hypoglycemia [96]. It also reduced insulin resistance by increasing adiponectin which is responsible for carbohydrate digestion [96]. Quercetin also protected pancreatic islets against oxidative damage by acting through phosphorylation of extracellular signal-regulated kinase (ERK) [97]. Quercetin showed a significant increase in protection against DNA damage from hydrogen peroxide on human diabetic lymphocytes [98]. Sulfur containing compounds such as S-methly cysteine sulpoxide and S-allyl cysteine sulpoxide controlled the blood glucose and lipids in serum and tissues and normalized the activities of liver hexokinase, glucose 6-phosphatase and HMG CoA reductase and increase the level of

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

insulin in blood [99]. Earlier study indicated that administration of onion extract to human reduced LDL-C, waist circumference, and total cholesterol in blood [100–102].

#### **2.5 Chili (***Capsicum annuum* **L.)**

#### *2.5.1 Bioactive compounds*

Capsaicinoids, an acid amide of vanillylamine with C9-C12 branched fatty acid chain is the major compound of chili that confers the characteristic pungency [103]. Other major isomers of capsacins are dihydrocapsaicin, nordihydrocapsaicin, homocapsaicin, and homodihydrocapsaicin [103–105]. Other bioactive valuable bioactive compounds such as polyphenols (phenolic acids, apigenin, luteolin, quercetin, catechins, anthocyanins and proanthocyanidins), steroids, saponins, anthroquinones, carotenoids, terpenoids and alkaloids are highly abundant in chili peppers [103–106].

#### *2.5.2 Antioxidant activity*

As chili pepper contains high level of vitamin C, E, anthocyanin, and phenolic compounds it showed strong antioxidant activities *in vitro, in vivo,* and clinical studies [103–107]. From earlier research studies it was demonstrated a positive correlation between phenolic content and antioxidant potential with strong radical scavenging activities in ABTS, DPPH, and FRAP assays [103]. Various *in vivo* studies indicated antioxidant activities by mitigating oxidative stress in various tissues or organs [104–106].

#### *2.5.3 Anti-inflammatory activity*

It has been shown that capsaicin could reduce inflammations in different animal models and human trials. Capsacin has been reported to have anti-inflammatory activities by inhibiting the NO, IL-6, and TNF-*α* in LPS-induced in RAW 264.7 cells [107, 108]. Capsaicin reduced the inflammatory responses by inhibiting the pro-inflammatory cytokines such as interleukin 1*β* (IL-1*β*) and tumor nuclear factor-kappa (NF-κ) [109]. Capsaicin could be used as analgesic since it could induce inflammatory effects in adipose tissues [110].

#### *2.5.4 Anticancer properties*

Chili phytochemicals has been reported to trigger apoptosis of various cancerous cell lines including skin cancer, colon cancer, bladder cancer, breast cancer, prostate cancer and lung cancer in human and some other experimental animal models [111–120]. Capsaicin exhibited inhibitory effects against cancer initiation, promotion, progression, and metastasis. It has been found that capsaicin could inhibit nuclear factor-kappa (NF-κ) activation in prostate cancer cells. In some cases, capsaicin could alter the expression of several genes involved in cancer growth process. For example, capsaicin down-regulated Bcl-2 (B-cell lymphoma 2) expression during the growth of skin cancer in mouse [113, 115]. Capsaicin induced p53 phosphorylation at the Ser-15 residue and activated the apoptosis of cancer cells [119]. In vitro studies revealed that capsaicin could inhibit the growth of blood cancer by inhibiting human T-cell leukemia virus type 1 [120].

#### *2.5.5 Antimicrobial activity*

It has been demonstrated that capsaicinoids and other phenolic compounds inhibited growth of microorganism like bacteria, yeasts, and fungi [121]. Capsaicin could inactivate the virus binding proteins and prevent their replication [121]. Previous reports supported that capsaicin showed strong antimicrobial activities against *Streptococcus pyogenes, E. coli, S. aureus, Proteus mirabilis, Proteus vulgaris, P. aeruginosa, Enterobacter aerogenes and S. mutans*. Bell pepper extract inhibited the *Listeria monocytogenes, Salmonella typhimurium, S. aureus,* and *Bacillus cereus* including few foodborne bacteria *Salmonella typgimurium* [122].

#### *2.5.6 Anti-diabetic activity*

Chili pepper imparted antidiabetic activity by their potential inhibition capacities of *α*-amylase and *α*-glucosidase activities which has a significant effect in carbohydrate metabolism [123]. It has been reported that consumption of chili pepper reduces the glucose absorption in the intestine and controls post-prandial rise of glucose [124]. Administration of capsaicin to rats lowered blood glucose levels and increased blood insulin level [125].

#### *2.5.7 Cardiovascular activity*

Capsaicin promoted vascular health by increasing nitric oxide (NO) production and reducing inflammatory responses. It also reduced low-density lipoprotein (LDL) levels, increased high-density lipoprotein (HDL) levels, and reduced oxidative stress levels in various tissues [126]. Capsaicin could lower low-density lipoprotein cholesterol (LDL-C), plasma cholesterol, and inhibits LPS-induced IL-1*β*, IL-6 and TNF-*α* production in a time- and dose-dependent [127–129].

#### **2.6 Cinnamon bark (***Cinnamomum cassia***)**
