**3. Phytochemical composition**

*Z. diploperennis*, *Z. luxurians*, *Z. nicaraguensis*, *Z. perennis*, *and Z. mays. Zea mays* is the only

Various parts of corn such as grains, leaves, corn silk, stalk, and inflorescence are commonly used as food for humans, feedstuff for animals, fuel for small industries, and potential ingredient of homemade remedies [3, 5]. Corn seeds are served as food in Asian countries including China, Korea, Taiwan, Vietnam, Laos, Myanmar, Thailand, India, and Pakistan [6]. The unripe seeds of sweet corn are eaten raw or cooked, while the mature seeds are dried and ground to make flour that is used in various food preparations. The major products of wet and dry milling of corn seeds are used to make breakfast cereals, snacks, and tortillas, while the coproducts are used as animal feed. The maize flour has been found to enhance the nutritional and functional quality of food materials when used in the form of blend with other cereal flours [7, 8]. Corn kernel is also used to obtain ethanol as a fuel [9]. Oil obtained from seeds is edible and is used in the preparation of various food products. A semidrying oil obtained from seeds has many industrial uses like manufacturing of linoleum, paints, varnishes, and soaps.

The edible part of corn is covered by long, silky, and colored (yellowish to reddish) hairlike structures known as corn silk. Corn silk, due to its high medicinal value, has been traditionally used as herbal remedies for the treatment of various diseases [6]. It has been reported to be used in the treatment of hypercholesterolemia, urinary infections, and associated diseases [10]. Corn silk is also used as an important ingredient in development of various drugs [11]. It has been found to be nontoxic and is safe for human consumption [12, 13]. In Asia, it is used in tea as a healthy and medical drink [14]. Corn silk powder can also be used as food additive and flavoring agent as it does not change the taste; rather, it enhances the content and physical characteristics of meals like beef patties [15, 16]. Pith of the stem of corn plant is used to make corn syrup [17], the spathes are

Corn, due to its high nutritional quality, is a permanent global crop used to fulfill the nutritional requirements of humans and cattle [3]. Corn is rich in nutritional compounds

used in making papers, straw hats, and baskets, and dried cobs are used as fuel [3].

cultivated species, while others are wild grasses [1–4].

Synonyms Maize, corn, mealie

Kingdom Plantae Family Poaceae Subfamily Panicoideae

50 Corn - Production and Human Health in Changing Climate

Genus *Zea* Species *mays*

The corn plant is classified as:

**2. Nutritional composition**

Phytochemicals are the non-nutritional bioactive compounds found in various parts of plants. In plants these compounds perform vital functions particularly protection from predators and harsh environmental conditions. These compounds are also important in pharmaceutical and medicinal field due to their antioxidant, antimicrobial, and other biological properties. Flavonoids are the bioactive phytochemical compounds which make the plant resistant to the attack of microbes and insects and also protect the animals against various diseases [22–24]. Flavonoids possess strong antioxidant activity and free radical-scavenging capacity and inhibit protein glycation [23, 25, 26]. The anthocyanins have been found to protect against ischemic reperfusion injury in rats [27]. These have been also found to show antioxidant and antiradical activities which are further associated with certain health-promoting activities such as anticancer, anti-inflammatory, anti-obesity, antidiabetic, cardioprotective, and hepatoprotective activities [28–30]. Tannins are polyphenolic compounds which show several biological activities such as anti-inflammatory, antioxidant, free radical-scavenging, and antimutagenic activities [31, 32].

Various parts of corn plant such as silk, seed, stem, leaves, and roots are good sources of bioactive phytochemical compounds such as phenolic acids, flavonoids, steroids, alkaloids, carotenoids, tannins, saponins, anthocyanins, and other phenolic compounds [6, 28, 33, 34]. Corn seeds contain polyphenols, phenolic acids, flavonoids, anthocyanins, carotenoids, vitamins, sugars, polysaccharides, and other phytochemicals of medicinal importance [35, 36]. Corn silk contains a number of bioactive phytochemical compounds including phenols, polyphenols, phenolic acids, flavonoids, flavone glycosides, anthocyanins, carotenoids, terpenoids, alkaloids, steroids, luteins, tannins, saponins, volatile oils, vitamins, some sugars, and polysaccharides (**Table 1**) [6, 11, 22]. The corn silk flavonoids have been also reported to reduce the oxidative stress and show anti-fatigue activity in mice [37, 38]. The content of the major phytochemical compounds found in various parts of corn are summarized in **Table 2**.


**Corn part**

Corn stem

Corn root and shoot

**Corn part**

Corn silk

**Class of phytochemicals**

Phenolic compounds

Polyphenols, flavonoids, and others

**Extracting solvent**

Methanol acidified with 1% citric acid

Aqueous acetone

**Phytochemical components Reference**

Phytochemical Composition: Antioxidant Potential and Biological Activities of Corn

Flavonoids, terpenoids, alkaloids, tannins, phlobatannins, saponins [85]

**TPC TFC TAC TCC References**

[84]

53

http://dx.doi.org/10.5772/intechopen.79648

[81]

[79, 87]

[87, 89],

[87, 90]

[18, 88]

[91]

[92]

[79, 93]

[57, 41]

[94]

[20],

11.3 mg/ kg dw

Methyl (E)-p-cumarate, methyl (Z)-p-cumarate, methyl ferulate, and

Flavonoids Tricin, salcolin A, and salcolin B [81] Anthocyanins Cyanidin-3-glucoside, pelargonidin-3-glucoside, and peonidin-3-glucoside [27, 29, 67]

Water 1.5 mg GAE/g extract 2–7 μg/ml extract [86]

extract

dw

g dw

40.38 μg TAE/g extract 0.017–0.023 g

2.31–7.55 mg CE/g

4.1–38.01 mg CE/g

Hot water 68.61 mg GAE/g 72.74 mg QE/g 0.02 mg CGE/g [21]

0.66–9.26 mg CE/

Ethanol 164.1 μg GAE/g dw 69.4 μg RE/g dw [34]

14.66–26.63 mg CAE/g extract

RE/g dw

1840– 3644 mg CE/100

g dw

211.05 ± 3.73 mg/kg dw

Ethyl acetate 6.70 mg GAE/g extract 8.40 mg CE/g extract [90]

42.71 μg TAE/g extract [88]

272.81 mg GAE/100 g dw [89]

93.43 mg GAE/g dw 65.58 mg RE/g dw [87, 90],

CGE/100 g dw.

78.90– 408.54 mg CGE/100 g fw

1779 mg CGE/100 g dw.

0.4–72.9 μg CGE/g dw

1.49 mg CGE/100 g dw

1,3-O-diferuloyl glycerol

**Table 1.** Bioactive phytochemical components in various parts of corn.

35.34–64.22 mg GAE/g

extract

Methanol 101.99–175.8 mg GAE/ g dw

extract

256.36–272 mg GAE/100 g dw

69.01–85.49 mg GAE/100 g of fw

1756 mg chlorogenic acid/100 g dw

34029.37 ± 1926.61 mg /kg dw

2093–4447 81 mg GAE/100 g dw

86.26–143.58 mg GAE/g

80.8–117.1 μg GAE/g dw 30.1–88.8 μg

Lignan Tetrahydro-4,6-bis(4-hydroxy-3-methoxyphenyl)- 1H,3H-furo[3,4-c]furan-1-one


**Table 1.** Bioactive phytochemical components in various parts of corn.

**Corn part**

Corn silk

**Class of phytochemicals**

52 Corn - Production and Human Health in Changing Climate

Volatile compounds

Miscellaneous compounds

Miscellaneous compounds

Corn seeds

**Phytochemical components Reference**

[19]

[20]

[11, 36, 73–76] [20, 34, 77]

[78]

[6, 23, 25, 34–36, 49, 55, 70, 74, 75, 78, 80]

[35]

[82]

[36]

[83]

[28, 30, 35, 78, 82]

Polyphenols Tannins, saponins, flavonoids, alkaloids, steroids, cardiac glycosides, allantoins, anthocyanins, hesperidin, and resins

Flavonoids Catechin, protocatechin, quercetin, rutin, flavone, 3-hydroxyl,

6,4-dihydroxy-3-methoxyflavone-7-O-glucoside. Isoorientin-2-2-*O*-α-L-rhamnoside, cardiac glycosides

6,4′-dihydroxy-3′-methoxyflavone-7-O-glucosides,

Carotenoids β-Carotene, zeaxanthin

Sugars Dextrose, xylose

Tannins Gallotannins, phlobatannins

citronellol,

hordenine, xanthoproteins,

naringenin, kaempferol

β-carotene, α and β-cryptoxanthin

glucoside, and peonidin-3-glucoside

Sterols Phytosterols like stigmasterol, beta-sitosterol

*cis*-R-terpineol, and neo-iso-3-thujanol

Polyphenols Tannins, saponins, rutin, allantoins, quercetin, isoquercetin, morin,

Anthocyanins Cyanogenic glycosides including pelargonidin-3-glucoside, cyanidin-3-

acid, niacin, pyridoxine, thiamine), vitamin C

Vitamins Vitamin E (tocopherols), vitamin B (biotin, riboflavin, pantothenic acid, folic

Polysaccharide, sugars, proteins, inositols, resins, hexaphosphoric and maizenic acid, esters of indole-3-acetic acid, d-glucose hydroxyl-2 indolinone-3-acetic acid, N-coumaryltryptamine, N-feruloyltryptamine, 6-methoxybenzoazoline, oxalic acids, essential fatty acids, and choline

Phenolic acids Gallic acid, chlorogenic acid, syringic acid, hydroxycinnamic acid derivatives, ferulic acid, 7-hydroxy-2-indolinone-3-acetic acid, caffeic acid

Flavonoids Anthocyanins, quercetin, and catechin [81] Carotenoids Carotenes including lutein, cyclosadol, β-cryptoxanthin, zeaxanthin, α- and

Phenolic acids Para-aminobenzoic acid (PABA), vanillic acid, p-coumaric acid, chlorogenic acid, protocatechuic acid, caffeic acid, ferulic acid, maizenic acid, hydroxycinnamic acid ester, and 3-O-caffeoylquinic acid

> 4-hydroxy, 5-hydroxy, and 7-hydroxy flavones and isoflavones. 2-O-α-L-rhamnosyl-6-C-3-deoxyglucosyle-3-methoxy luteolin and

Luteolins: 2"-O-α-L-rhamnosyl-6-C-quinovosylluteolin, 2"-O-α-L-rhamnosyl-6-C-fucosylluteolin, and 2"-O-α-L-rhamnosyl-6-C-fucosyl-3′-methoxyluteolin, 2"-O-α-L-rhamnosyl-6-C-3″-deoxyglucosyl-3′ methoxyluteolin, 2′′-O-α-Lrhamnosyl-6-C-(6-deoxyxylo-hexos-4-ulosyl)-luteolin, 2′′-O-α -L-rhamnosyl-6-C-(6-deoxy-xylo-hexos-4-ulosyl)-luteolin-3′-methylether, kaempferol Maysins: Rhamnosyl-6-C-(4-ketofucosyl)-5, 7, 3′4′-tetrahydroxyflavone, ax-5′-methane-3′-methoxymaysin, ax-4"-OH-3′-methoxymaysin,

7,4′-dihydroxy-3′-methoxyflavone-2"-O-α-L-rhamnosyl-6-C-fucoside

Vitamins Vitamin C, vitamin K, vitamin E [79]

Polysaccharides (galactan), geraniol, limonene, terpenoids, α-terpineol,

trans-pinocamphone, formononetin, apigenin, pelargonidin, anthraquinones,

Menthol, carvacrol, thymol, eugenol, neo-iso-3-thujanol, *cis*-sabinene hydrate, 6,11-oxidoacor-4-ene, citronellol, *trans*-pinocamphone, *cis*-sabinene hydrate,



**4. Antioxidant potential**

affecting the activity of antioxidant enzymes [38].

Ethanol 5.61–9.98 mg FeSO<sup>4</sup>

17.9–32.19%

equivalent; AAE, ascorbic acid equivalent; fw, fresh weight; dw, dry weight.

Methanol acidified with citric acid

Methanol acidified with HCl

Methanol acidified with citric acid

Methanol acidified with citric acid

citric acid

Ethanol acidified with

**Corn part**

Corn silk

Corn seed

Corn cob

Corn husk

The pharmaceutical and medicinal significance of medicinal plants is usually based on their antioxidant phytochemical composition. Antioxidants are the substances which have the ability to prevent the oxidation reactions in living and nonliving systems. They possess hydrogendonating ability due to which they reduce other species and are themselves oxidized. These substances perform their action by reducing the reactive oxygen or nitrogen species or metals in their oxidized forms. These substances have the ability to terminate the free radical chain reactions occurring in the living system. Owing to their antiradical and reducing properties, the antioxidant phytochemicals play a key role in the preparation of pharmaceutical formulations against various diseases. The diversity in the phytochemical quality and high content of bioactive antioxidant phytochemicals make corn a valuable candidate for pharmaceutical application. Among various parts of corn, the corn silk is a rich source of antioxidant compounds and possesses strong antioxidant potential. The antioxidant properties of various parts of corn studied in terms of total antioxidant activity, ferric reducing, iron chelating, copperreducing properties, and free radical-scavenging capacities are presented in **Tables 3–5**. The corn extracts have been also reported to improve the antioxidant status of various organs by

Phytochemical Composition: Antioxidant Potential and Biological Activities of Corn

http://dx.doi.org/10.5772/intechopen.79648

55

**Extracting solvent TAOA β-CABC References**

/g dw 52.92% [87]

18–100 μmol AAE/100 g [95]

22.95% TE [41]

31.10% [91]

11.85% [91]

26.33%

[87, 89]

[61, 82, 91]

Water 73–44.19% [87]

Methanol 66.05% [87]

Ethyl acetate 2.15–2.735 mg GAE/g dw 38.65%,

1827.5–2429.3 μmol TE/100 g dw, 61.15%, 3.1 μmol TE/g fw, 3.8 μmol TE/g dw,

Methanol 0.3–10.2 μmol/g dw [67]

TAOA, total antioxidant activity; β-CABC, β-carotene-bleaching capacity; GAE, gallic acid equivalent; TE, Trolox

**Table 3.** Total antioxidant activity and β-carotene-bleaching capacity of extracts from various parts of corn.

GAE, gallic acid equivalent; RE, rutin equivalent; TFC, total flavonoid content; TPC, total phenolic content; TAC, total anthocyanin content; CGE, cyanidin-3-glucoside equivalents; fw, fresh weight; CE, catechin equivalent; TCC, total carotenoid contents; QE, quercetin equivalent; BCE, β-carotene equivalent; dw, dry weight; NE, naringin equivalent; TAE, tannic acid equivalent.

**Table 2.** Phytochemical composition of extracts from various parts of corn.
