General features: The plant is an edible green; botanical name is Brassica oleracea colloquially named Broccoli which has been accepted in the English language also. The word Broccoli is originated from Italian language. The plant belongs to the Brassicaceae family of Brassica genus like mustard, cabbage, kale, or cauliflower. About fifteen of them are presently known. Broccoli grows with large flower heads with dark green appearance which seems arranged in tree like fashion splitting from the thick stalk having light green shade. Broccoli resembles cauliflower which also belongs to Brassica species. It is enriched with vitamin C and K. Along with the others it synthesizes unique phytocomponents like glucosinolates, isothiocyanates and sulforaphane which enforce large beneficial effects on health. There is another variety of the Broccoli family, called Rapini. Although distinctly different but it possesses almost identical characteristics.
In nature, there are more edible varieties of Broccoli eg, Calabria which has large green heads and thick stalks whereas Sprouting Broccoli possesses thin stalks, appears white or purple in color having multiple heads. On the other hand, Purple Cauliflower which also belongs to Broccoli family grows mostly in Europe and North America. There are several more cultivars and all of them are edible belonging to the Brassica oleracea family. The family name was originally, Cruciferae. So, cabbage, cauliflower, broccoli, rapini, mustard and others of the same family are commonly termed cruciferous vegetables. The name originated misnomerly by the Europeans of medieval age imagining resembling it as Crucifix, from the flower petal pattern of ‘cabbage’.
History of Broccoli: The vegetable has been known for almost two millennia. It is speculated that it was created from cabbage by the ancient Etruscans of Mediterranean regions. Broccoli arrived in England and acquired the name “Italian asparagus” at about 1500 AD. It reached to the US with the help of Italian immigrants around 1920. To the Italians, since Roman Empire Broccoli is a valuable food. The illustrious Roman naturalist and philosopher, Pliny the Elder (23 – 79 AD) described this vegetable in his “Naturalis Historia”. Later Marcus Gavius Apicius, the eminent Roman gourmet cook of first century AD during Emperor Tiberius included the art of cooking Broccoli in his cookbook “API CAE”. He recognized this vegetable for popular consumption. Afterward, it emerged in France in 1560 AD. Even appearing around 1500 AD, Broccoli was fully unfamiliar in England for an extended period as pointed out in Gardner’s Dictionary by Philip Morris in 1724. The vegetable was mentioned as “Italian Asparagus” or “Sprout of cauliflower”. In the US, Broccoli was introduced at first by President Thomas Jefferson, the illustrious 3rd President and an avid gardener who planted Broccoli in his highly creative own home Monticello, Virginia after receiving seeds from his Europeans correspondents in 1767. In 1775, loyalist / Tory (loyal to the British Crown), attorney General John Randolph described it in his book “A Treatise on Gardening by a Citizen of Virginia” about this exotic vegetable, Broccoli. He explained in a unique manner that “The stems will eat like asparagus and the heads like cauliflower.” It has always been that Broccoli remains an exotic vegetable in the US. Its commercial cultivation was started in the US by D’Arrigo brothers, immigrants from Messina, Italy whose company planted it in San Jose, California in 1900. In later years they started advertising about Broccoli in radio that eventually caught up the popularity also found ways of cooking too.
Nutrition and health benefits: Broccoli is a rich source of vitamins and minerals especially Vit C and K. One cup (~ 100 gm) of Broccoli provides ~ 30 calories energy which has 6.0 gm carbohydrate, 2.5 gm protein, 2.0 gm fiber, 81 mg vitamin C, 93µg vitamin K, 567 IU vitamin A, 57 µg folate, 288 mg Potassium (K), 19 mg Magnesium (Mg), 67 mg Phosphorous (P), 0.7 mg Iron (Fe), 43 mg Calcium (Ca), Selenium 2.0µg (Se) and 0.37 mg zinc (Zn). Uniquely, this vegetable is extraordinarily enriched with sulfur containing compounds like glucosinolate, isothiocyanate, and sulforaphane.
Those compounds Glucosinolates, Sulforaphane and isothiocyanates break down / hydrolyze if the vegetable is boiled too long in water but stay stable if steamed, microwaved, or even stir-fried. The compounds exhibit a considerable beneficial role on health, particularly sulforaphane. Broccoli is frequently eaten raw added to salad that provides all the beneficial ingredients intact. Besides eating raw, steamed Broccoli sprinkled with cheese is a dish preferable to many westerners. Indians cook it delectably adding grinded poppy seeds along with prodigious spicy mixture even adding with fried shrimps, keeping the vegetable crunchy in texture. The health benefits of Broccoli are too many. It has potent anti-diabetic role enabling to lower the blood glucose level particularly in the case of type-2 diabetes or obesity. The compound sulforaphane is also good for preventing osteoarthritis, helping cartilage stay unharmed and healthy. Sulforaphane convincingly inhibits generation of cancers / tumors inside the body as indicated by many epidemiological studies. It is further claimed that at higher concentrations it might swing the levels of neurochemicals in brain which may help manage schizophrenia. Sulforaphane can also act as an antibiotic helping eradicate resistant strains of Helicobacter pylori. Recent studies convince that sulforaphane might have beneficial role on autistic children enhancing social interaction as well as their verbal communication skills. The compound has a strong protective role against UV skin damage caused by the sun. Studies on animals indicate that sulforaphane can improve memory and reduce mental decline in the case of brain injury. Broccoli improves the symptoms of constipation when tested in adults. The presence of appreciable quantity of carotenoids and other related components is expected to reduce cardiac problems and simultaneously boost immunity. The elevated level of vitamin K in Broccoli helps the blood clot expediting wound healing. Another essential element, selenium (Se) is seen at an elevated level which is known to have beneficial impact on health. Selenium (Se) is an important and necessary micronutrient for maintaining good health, but the excessive amount can impose toxicity also. Plants, particularly members of Brassicaceae family are the good provider of Se. At low doses it protects from abiotic stresses like cold, drought etc. In animals / humans it is a good antioxidant helping reproduction, immune responses, and thyroid hormone metabolism. According to the periodic table Se falls in the same category / group as sulfur (S) thus bears similar chemical identity. It is taken up by the plant using sulfur transporter inside plasma membrane of roots afterward metabolized via sulfur assimilatory pathway. Se and vitamin E act as synergistic antioxidants. Selenium supports the actions of Vitamin E lowering the oxidation of fats. It works along with vitamin C, glutathione, and vitamin B3 (niacin) to prevent oxygen molecules from becoming too reactive. In that way, it prevents oxidation of LDL or bad “cholesterol” thus lowering the risk of cardiovascular diseases, stroke, cataracts, and aging. All the problems are caused by the damaging effects of free radicals or reactive oxygen (ROS) or nitrogen species. Interestingly, evidence indicates a great correlation between Selenium uptake and the incidences of cancers. Epidemiological studies provide the fact that skin cancer incidences are higher in the regions where selenium content in soil is low. The element reduces the cancer risk by protecting from the free radicals enabling to prevent tumor / cancerous growth. It is further proven that individuals having higher levels of Se in the body show reduced rates of cancer death particularly, concerning lung, colon, and prostate. Mysteriously, Se has significant role in men than women. Further, in patients with rheumatoid arthritis, eczema, and psoriasis the level of Se and glutathione peroxidase are seen to be low. Selenium lowers oxidative stress preventing the generation of proinflammatory molecules which leads to inflammatory diseases. Its adequate supplementation stimulates blood cells and thymus function. Besides having immense beneficial role, Broccoli can exert hypothyroidism. Compounds thiocyanates are the real culprit. They are goitrogens which have the potential to develop the conditions for hypothyroidism. Isothiocyanates interfere with the iodine uptake by the thyroid gland. Iodine is the key element to synthesize the thyroid hormone. Interfering iodine uptake causes enlargement of the thyroid gland that in turn results finally to goitre, a dysfunctional thyroid can exert serious health problems.
Chemistry of Glucosinolates (GL): Like most members of the Brassica family, Broccoli synthesizes large quantity of versatile glucosinolate (GL) compounds, almost 120 components are identified. GLs are not straight way becoming bioactive inside the animal bodies even after consumption until they are hydrolyzed to isothiocyanates with the help of endogenously produced enzymes, myrosinase residing within the plant cells which undergoes release due to cellular disruption during mastication or by any subsequent processing steps. All GLs characteristically hold basic structures consisting of β – D – thioglucose, a sulfonated oxime and a side chain which is derived from methionine, phenylalanine, tryptophane, or any branched chain amino acids. The molecules are highly acidic. They are synthesized and stored in vacuoles as potassium salts (K). They are the metabolic products acting as potent modulators of xenobiotic- metabolizing enzymes enabling to protect any DNA damages. Overall statistics convince that larger intake of Broccoli reduces the risk of cancers especially for colon, gastrointestinal tract, and lung. Epidemiological surveys indicate that routine consumption of Broccoli tends to lower the risk of prostate cancer also. Considering additional measures, Broccoli exerts therapeutic role on skin diseases. Juices prepared from the leaves of Broccoli plant reduce several skin diseases and can act against warts. The breakdown products of GLs are previously known for their bactericidal, nematocidal, fungicidal and allelopathic activities. Recent research indicates that GLs have potential chemoprotective properties. Although GLs occur at elevated levels in Broccoli, mustard, cabbage or cauliflowers or members of any Brassicaceae family, they also exist among the other crucifier vegetables like Capparaceae (Caper) and Caricaceae (Papaya) families also. Ample of studies suggest that isothiocyanates released by the hydrolysis of GLs enable numerous steps during cancer development which includes modulation of phase I and II detoxification enzymes. They act as direct antioxidants and help phase II enzyme induction modulating cell signaling, inducing apoptosis, controlling cell cycle, and additionally reducing Helicobacter pylori infection. Among the predominant isothiocyanate components are sulforaphane, phenyl isothiocyanate, and allyl isothiocyanates. The most intriguing product generated from the breakdown of sulfoglucobrassicin and few other isothiocyanates is indole – 3-crabinol. But there are more isothiocyanates and associated compounds which exist in much less concentrations. Collectively they all contribute to anticarcinogenic activities which are major characteristics of the crucifiers.
The compound, indole-3-carbinol has several beneficial roles. It is cleaved from the glucosinolate naming sulfoglucobrassicin available within Brassica family members like Broccoli. It can prevent breast cancer. It has strong antioxidant and chemopreventive properties. It scavenges free radicals and induces hepatic cytochrome p450 monooxygenases resulting in increased 2- hydroxylation of estrogens thereby increasing the production of chemopreventive estrogen, 2 – hydroxyestrone.
2-hydroxyestrone is a potent inhibitor of angiogenesis and prevents tumor cell proliferation. Benzyl isothiocyanate is protective against pancreatic carcinogenesis. It also has the ability to lower obesity, control fatty liver and prevent insulin resistant diet induced diabetes. Phenyl isothiocyanate is a strong antiinflammatory compound. It downregulates TNF-α and inducible nitic oxide synthase (iNOS) preventing NO production and angiogenesis too. Allyl isothiocyanate has potent antiinflammatory properties that acts by downregulating the gene expression of proinflammatory mediators like IL-1β and iNOS. It is slightly less potent than sulforaphane.
The chemoprotective ability of Broccoli and other cruciferous vegetables along with its active metabolites like isothiocyanates and indole-3- carbinol or others are extensively studied using both animal and cellular models. It is established that chemoprotective components originated from cruciferous families significantly influence carcinogenesis during initiation and promotional phases while developing cancers. Both epidemiological and clinical studies support the fact.
Other chemical components: Besides the large reserve of glucosinolates, other majorly available chemical components are tocopherols (δ-, γ, α enantiomers), and carotenoids (lutein, zeaxanthin, β – carotene), flavonoids (rutin and quercitin) and phenolic components (chlorogenic acid, neochlorogenic acid, sinapic acid, caffeoyl acid, and quinic acid derivatives). Carotenoids, besides acting as antioxidants, protect bodies from numerous diseases by boosting the immune system. It is provitamin A which is converted to vitamin A necessary for growth, immune function, and wellbeing of eye. Flavonoids show strong antiinflammatory effects, beneficial for health. It protects cells from any oxidative damage, and prevents cardiovascular problems, diabetes, cancers, and Alzheimer’s or other forms of dementia. Phenolic acids are necessary factors for defense responses like anti-aging, antiinflammatory, antiproliferative, and antioxidant properties. It prevents chronic diseases like diabetes, cancers, cardiovascular problems by regulating oxidative stress. It is also effective to control type-2 diabetes.
Pharmacological effects: Broccoli is an edible green. Its constituents have significant therapeutic potential enabling it to prevent a great number of metabolic disorders.
Effect on diabetes – Animal experiments support the hypoglycemic actions of Broccoli on humans. It helps improve insulin resistance in type-2 diabetic patients and reduces the associated complications. The vegetable is highly enriched with flavonoids, which can exert antioxidant and antiinflammatory effects enabling it to protect against diabetes. Besides flavonoids, glucosinolates / sulforaphane can induce peroxisome proliferators-activated receptors contributing to glucose homeostasis in hyperglycemic and oxidative conditions. Additionally, this vegetable green prevents nephropathy, diabetes induced fibrosis as well the vascular complications. In fact, sulforaphane can be ascribed as an excellent selection as a supplementary treatment for type-2 diabetes.
Antioxidant effect – Besides having flavonoids, carotenoids, vitamin C, A, and others, the presence of glucosinolates are more involved to exert antioxidant behavior. Glucoraphin or sulforaphane has an intense antioxidant effect that leads to anticarcinogenic role of Broccoli. It has been noticed that oxidative stress plays a major role in the pathophysiology of cardiac problems. The overproduction of reactive oxygen or nitrogen species indicates a primal role regarding ischemic myocardial damage and subsequent cardiac dysfunction. Recent studies have pointed out that isothiocyanates like sulforaphane have beneficial impact on cardiovascular diseases owing to its antioxidant and antiinflammatory actions. It activates nuclear regulatory factor-2 (Nrf2), leucine zipper transcriptional factor that acts as defensive mechanism against oxidative stress and electrophilic toxicants while inducing several hundreds of cytoprotective proteins that includes antioxidants and phase II detoxifying enzymes.
Anticancer effect – The national library of medicine provides innumerable evidence regarding the anticancer role of Broccoli. The major focus relies on various derivatives of glucosinolates. Obviously, other antioxidants like flavonoids, carotenoids, vitamin C, A and others exert antineoplastic activities but glucosinolates exert more forceful impacts in preventing or regulating the tumors. Among all the thiol of Broccoli, sulforaphane demonstrates to be the most effective. The compound works follows various ways. It is suggested that sulforaphane controls several key genes which influences initiation and progression of cancers. This observation provides the basis for its clinical use for chemoprevention, also allowing design of any preventive strategies for cancer management intending to reduce recurrence, development and concomitantly improving survival of the patients. It is observed that micro RNAs are genetic materials engaged in many biological events like cell cycle regulation, proliferation, apoptosis, and differentiation. Impairment in the expression and function of micro RNAs is noticed to be associated with the risk of cancers. But sulforaphane helps regulate micro RNAs in a way that would interfere with their survival mechanism, deliberately used by the cancer cells to escape from death.
Antiinflammatory effect – Extract by 80 % methanol followed further by ethyl acetate / n-hexane / n-butanol, and water fractionations are utilized for studying antiinflammatory activities in the case of lipopolysaccharide (LPS) stimulated macrophage cell lines, RAW 264.7. In ethyl acetate fractionation the sulforaphane content are noticed to be 620.2 µg / ml and phenolic content is 35 mg / ml. The Oxygen radical absorbance of that fraction is ~ 11 times higher than the aqueous. This fraction inhibits nitric oxide release from the LPS stimulated RAW264.7 cells dosedependently, also prevents IκB- α degradation and subsequently NF-κβ activation within them. So provenly, broccoli exerts potent antiinflammatory effect along with antioxidant actions.
Effect on blood clotting – For high vitamin K content, often a suspicion arises if Broccoli could enhance the blood clotting event in a normal person. So far, no evidence supports any such alteration. Notably Vitamin K, a fat-soluble vitamin, is one of the necessary factors required for proper blood clotting incident. The deficiency leads to heavy bleeding by not letting clot formation at the wound site thus delaying the healing process. Further, excessive bleeding can result in fatality. Vitamin K is actually a cofactor for the action of enzyme γ-glutamylcarboxylase that catalyzes the carboxylation of glutamic acid forming γ-carboxyglutamic acid. Vitamin K dependent γ- carboxylation takes place only on a specific glutamic acid residue within vitamin K dependent proteins which is very crucial for their ability to bind Calcium. The calcium binding helps activate Vitamin K dependent clotting factors of the coagulation / clotting cascade. Factors II (prothrombin), VII, VIII, IX, X are the members belonging to coagulation cascade. All of them possess γ-carboxyglutamic acid residue which after binding with Calcium ions and association with the membrane phospholipids initiates the enzymatic cascading clotting actions eventually helping the wound healing. Protein C, S, and protein Z (PZ) are the anticoagulants that regulate clotting events since uncontrolled clotting also jeopardizes the lives exerting thrombosis. Vitamin K is a necessary cofactor to all for providing highly needed carboxylation to glutamic acid at its γ- amino position. Warfarin is a common anticoagulant which interacts with Vitamin K. In that situation consumption of broccoli along with Vitamin K should be avoided.
Cardiovascular effect – Studies have established a crucial role in the excessive generation of reactive oxygen and nitrogen species regarding the pathogenesis of ischemic myocardial damage leading to cardiac dysfunction. Sulfur linked various isothiocyanates are seen widely distributed within cruciferous vegetables including Broccoli. Among the members of isothiocyanate molecules, sulforaphane is counted being the most important one. Data revealed by the epidemiological studies indicates its superior beneficial effects on cardiovascular diseases acting as powerful antioxidant and antiinflammatory components. Sulforaphane activates NF-E2-related factor (Nrf2), basic leucine zipper transcription factor protein which acts as defense mechanism against oxidative stress and electrophilic toxicants by inducing numerous cytoprotective proteins including antioxidants and phase II detoxifying enzymes.
It is known that arrhythmogenesis is a genetic disorder intimately related to the generation of reactive oxygen species (ROS). The sympathomimetic agent like β-adrenergic receptor antagonist, Isoproterenol leads to oxidative stress locally in heart which eventually creates arrhythmia. In a way, adrenergic stimulation can bring fatality. But there are some molecules existing in vegetables like Broccoli that could provide beneficial role from these adversarial effects preventing cardiac arrhythmia reducing the fatality. Many antioxidants are known to impose preventive effects. Among them sulforaphane shows great promise. The extract from Broccoli becomes useful in this regard particularly for arrhythmogenesis since sulforaphane can regulate upstream molecular targets that includes the activation of Nrf-2, the major regulator of antioxidant enzymes gene expression. The production of sulforaphane enriched Broccoli and its subsequent tests as a dietary supplement to protect the heart from acute cardiac stress is on the way that could bring promising results for the people.