Phytochemical Composition and Antioxidant Potential of Brassica Phytochemical Composition and Antioxidant Potential of Brassica

The edible parts of Brassica plants are a rich source of phytochemical compounds which possess strong antioxidant potential. These plants contain a variety of phytochemical compound including phenolics, polyphenols, phenolic acids, flavonoids, carotenoids (zeaxanthin, lutein, β-carotene), alkaloids, phytosterols chlorophyll, glucosinolates, ter- penoids, and glycosides. These plants possess strong antioxidant potential in terms of metal reducing, metal chelating, lipid reducing and free radical scavenging activities. These also have a positive effect on the activity of antioxidant enzymes such as glutathione peroxidase, superoxide dismutase, catalase, and ascorbate peroxidase. Among various species of genus Brassica studied for their phytochemical composition and anti oxidant activity, Brassica oleracea leaves, florets and seeds have better phytochemical and antioxidant profile. Brassica juncea, Brassica napus, Brassica rapa and Brassica nigra are also the phytochemical and antioxidant rich species of genus Brassica. The phytochemical pro file and antioxidant potential of Brassica plants make them the preferable candidates for nutritional and pharmaceutical applications. glucosinolates, volatiles, reducing sugars and vitamin C. The aqueous and ethanolic extracts of root and leaves show antioxidant activity in terms of Fe reducing, Cu reducing, and Fe 2+ chelating activity, ORAC, and DPPH, ABTS, and SOA radical scavenging activity. Florets possess antioxidant enzymes including POD, SOD, and CAT. It inhibits DNA methylation, prevent DNA damage and threats of cancer and cardiovascular diseases. It also possesses thrombolytic and cytotoxic activities.


Introduction
Brassica is a genus of plants family Cruciferae also called Brassicaceae which consists of about 350 genera and almost 3500 species. Brassica is the most important of all the genera of this family. Most of the species this genus have worldwide importance due to their economic, nutritional, medicinal, and pharmaceutical value. These species are cultivated as vegetables, B. oleracea is the most important species of genus Brassica due to its cultivation, consumption and nutritional and medicinal value. The members of this species are commonly called as cabbage, kale, broccoli, cauliflower and Brussels sprouts. These are equally used as vegetables for human and forage for animals. B. juncea, B. napus, B. nigra, B. napus, B. carinata and B. rapa are the other commonly used species of this genus which are used as vegetables and a source of vegetable oil. The parts of Brassica plants used as food and medicine include root, shoot, stem, leaves, leaf buds, flower buds, florets, landraces, sprouts, inflorescence, seeds, seed oil, and callus. The Brassica plants are very rich and economical source of a variety of nutritional (carbohydrates, lipids, protein, vitamins, and minerals) and phytochemical components of medicinal value.

Gemmifera
Leaves are rich in phytochemicals including phenolic acids, phenols, flavonoids, glucosinolates, thiocyanates, carotenoids (zeaxanthin, lutein, β-carotene), phytosterols and chlorophyll. It possesses antioxidant activity in terms of free radical scavenging capacity and antioxidant enzymes activity (POD, SOD, and CAT). It inhibits DNA methylation, prevent DNA damage and threats of cancer and cardiovascular diseases. [35,40] B. oleracea Sabellica L.

Gongylodes
The extracts of knobs in various solvents have been found to improve the antioxidant status of liver and kidneys of diabetic animals by increasing the SOD and CAT activities. [21]
It enhances the activity of antioxidant enzymes including GPx, CAT, and APx. Seeds contain sinigrin, quercetin, catechin, sophoroside-glucosides and vitamin E and seed oil possesses antioxidant activity in terms of FRAP, Fe chelating and DPPH and SOA radical scavenging activity. It also possesses cytotoxic activity. [5,12,13,15,28,54,58,59] B. juncea L. Coss It contains phenolic compounds with antioxidant activity in terms of FRAP and DPPH radical scavenging activity. [58]

Phytochemical content
The major phytochemical compounds quantitatively estimated in various species of Brassica include phenolics, flavonoids, ascorbic acid (Vit. C) glucosinolates, carotenoids, and tocopherols. Tables 2 and 3 present the phytochemical content (total phenolic content: TPC, total flavonoid content: TFC, ascorbic acid content: AAC, total glucosinolate content: TGC, total

Antioxidant potential
Antioxidants are the compounds which prevent the oxidation of the biomolecules by reducing the oxidizing agents and being self-oxidized. These compounds have the ability to scavenge the free radicals produced during the redox reactions occurring in the living and nonliving systems and prevent the free radical chain reactions. In this way, the antioxidant compounds minimize the oxidative stress and prevent the oxidative damage to food materials and living organisms. Brassica plants are known to possess antioxidant properties due to the presence of antioxidant phytochemicals mainly the polyphenols, flavonoids and ascorbic acid. Most of these phytochemical compounds act as antioxidants due to their hydrogen donating and reducing abilities. Polyphenols are the phytochemicals which act as metal ion chelators and interfere with oxidation reactions including lipid peroxidation by donating the proton to free radicals. Phenoxy radicals are relatively stable to stop the oxidation chain reaction. Therefore, they stop the initiation of new oxidation chain reaction and terminate the propagation routs by capturing free radicals [26]. Polyphenols are used for the treatment of hypertension, vascular fragility, allergies and hypercholesterolemia due to their antimicrobials, antiulcer, antidiarrheal, and anti-inflammatory activities. Flavonoids possess metal ion chelating and free radical scavenging potential [27]. These phytochemicals comprise a vast antioxidant, antiproliferative and inhibitory action on inflammatory cells especially mast cells. Ascorbic acid is a water-soluble vitamin which possesses strong antioxidant potential and protects against oxidative damage.    reducing, metal chelating, lipid reducing and free radical scavenging activities [24,[28][29][30]. These also possess antioxidant enzyme activities as these have been found to enhance the activities of some antioxidant enzymes including glutathione peroxidase, superoxide dismutase, catalase, heme oxygenase and ascorbate peroxidase [21,[31][32][33] (Table 6). B. oleracea plants have been studied most for their antioxidant activities among the Brassica species and found to possess strong antioxidant potential in terms of reducing power and free radical scavenging capacity. The strong antioxidant potential of Brassica plants highlights their medicinal and therapeutic importance.

Factors affecting the antioxidant activity of Brassica plants
Antioxidant activity of Brassica plants has been studied to be effected by various factors including solvent polarity, extraction time, temperature, cooking methods and nutritional and environment stress ( Table 7). The increase in the polarity of the extracting solvent, extraction time and salinity stress has resulted in an increase in the antioxidant activity of Brassica plants.
However, an increase in the temperature results in a reduction in the antioxidant potential of these plants. APx: ascorbate peroxidase, CAT: Catalase, GPx: Glutathione peroxidase, GSH: Glutathione, HO: Heme oxygenase, SOD: Superoxide dismutase.

Conclusion
The edible of Brassica plants have been found to be a rich source of phytochemical compounds which possess strong antioxidant potential. These plants possess strong antioxidant potential in terms of metal reducing, metal chelating, lipid reducing and free radical scavenging and antioxidant enzymes activities. Brassica oleracea has been found to possess better phytochemical and antioxidant profile among Brassica plants. Brassica  Temperature High temperature resulted in a rapid decrease in flavonoid content of B. oleracea var. Italica. [73] Cooking method Steam boiling and microwave cooking showed a time-dependent decrease in phytochemical content and antioxidant activity of green broccoli.
Water boiling, water blanching, steam boiling, steam blanching, microwave heating and stir-frying resulted in the reduction of antioxidant potential of cauliflower.
[ 46,69] Salinity stress Extracts of B. juncea L. under salinity stress have been found to be helpful in decreasing the oxidative stress by increasing the activity of activity of antioxidant enzymes.
[33] Table 7. Factors affecting the phytochemical composition and antioxidant activity of some commonly used Brassica species.