Glucosinolates (Mustard oil glycosides) are sulphur containing glycosides responsible for the pungent taste and characteristic flavor of drumstick, mustard, horse-raddish etc. They are the long lasting antioxidants actve in the body as many as 3 to 4 days after the food containing them has been consumed (Please see below). They are present in almost all the members of Brassicaceae, Capparaceae and related taxa. In the plant an enzyme myrosinase occurs spatially separated from these compounds. But on crushing the enzyme acts on the glucosinolates and liberate volatile isothiocyanates and glucose. The isothiocyanates have a general formula R N = C= S and various members of this group differ in R-group. More than 80 different isothiocyanates are reported and, due to their pungency and offensive odour, they protect the plants containing them from microbes, pests and herbivores.
Alkyl-, alkenyl-, methyl thio alkyl- and benzyl isothiocyanates are lipids in nature and thus can penetrate biomembranes and interact with epidermal and mucosal tissues. They are also antibiotic. Sinigrin present in mustard yielding allyl isothiocyanate and glucotropaeolin from Tropaeolum majus yielding benzyl isothiocyanate are two common glucosinolates present in plant kingdom.
Glucosinolates are one of the best antioxidants which act "indirectly" to activate the body's detoxification systems. These compounds affect the body's own antioxidant systems. This cascade of antioxidant activity may cycle over and over, continuing to circulate in the body as many as 3 to 4 days after the glucosinolate-containing food has been consumed. Among all of the cruciferous vegetables, broccoli sprouts have the highestlevel of the Glucosinolates.. Just two or three tablespoons of broccoli sprouts a day provide a powerful dose of glucosinolates. After broccoli sprouts, cauliflower sprouts are second highest in terms of containing the relevant glucosinolates. Cooking changes the properties of glucosinolates, so people eat both raw vegetables to gain the maximum benefits. Glucosinolates are also available in supplement form for those who do not eat enough plant and vegetable sources.
Glucosinolates are boroken down during chewing to their active form, sulforaphane (isothiocyanates), which is then what triggers the enzymatic process. Some of the beneficial effects of these compounds are the following:
1. Heal and prevent all types of cancers, such as stomach, colon, esophageal, lung and breast cancers. They work by eliminating cancer-causing toxins and helping destroy cancerous cells. Glucosinolate-breakdown products, particularly isothiocyanates and nitriles, have been shown to modulate carcinogen metabolising enzyme systems, induce cell cycle arrest or apoptosis. The anticancer potential of the different glucosinolate metabolites is diverse and their effect on the above mentioned cellular mechanisms is also affected by the model system employed. Results of in vivo studies with isolated glucosinolates or isothiocyanates compared to those with cruciferous vegetables demonstrate that the chemopreventive effect of cruciferous vegetables is due to combined effect of the different glucosinolate metabolites and the optimal combination of these compounds found in Cruciferae provide the beneficial health effects. In addition, the mineral selenium derived from crucifers also act as anti-tumour agent.
2. Help lower blood pressure. Glucoraphanin, also known as sulforaphane glucosinolate (SGS(TM)), a naturally-occurring compound found in broccoli sprouts and broccoli, may reduce risk of high blood pressure, cardiovascular disease and stroke by raising the antioxidant levels and thereby the anti-inflammatory capacities of cells and profoundly affect the cardiovascular system and can correct major dysfunctions such as hypertension and stroke (Wu et al., 2004). Rats fed on a glucoraphanin-rich diet exhibited increased tissue antioxidant defense mechanisms, lowered inflammatory response and improved cardiovascular health as demonstrated by decreased blood pressure and decreased inflammation in the heart, arteries and kidneys. This study is said to open up a whole new area of research that may lead to a simple, preventive measure that may help millions of people reduce their risk of cardiovascular disease.
3. Long lasting antioxidant activity. It is now proved that antioxidant defense mechanisms may be boosted by specific chemicals known as Phase 2 protein inducers such as Glucoraphanin or SGS. They play a role in boosting the body's natural Phase 2 enzyme antioxidant defense systems and functions as a powerful indirect antioxidant detoxifying carcinogens before they can damage cells. The long lasting nature of SGS is that its action is indirect working as a catalyst. It does not neutralize free radicals directly, but rather boosts the body's own antioxidant systems (including Phase 2 detoxification enzymes) that exert ongoing and prolonged antioxidant activity. The typical direct antioxidant molecules, such as Vitamins C and E, scavenge one free radical or other oxidant molecule at a time. (Once a direct antioxidant molecule binds to a free radical molecule, rendering it harmless, the antioxidant is consumed and is no longer active, and thus are active only for a short duration). But glucosinolates show a broad spectrum of activity, cycling over and over, removing many free radicals. It is like an army of antioxidants, ready to neutralize free radicals over a period of time, and continues to be effective in the body for at least a day, even after SGS is gone. More than 125 Studies attest to protective benefits of Sulforaphane and Broccoli Sprouts and an equal number of papers have been published on sulforaphane, SGS and broccoli sprouts.
4. Detoxifying the liver. The glucosinolates of Spanish black raddish (Raphanus sativus L. var. niger) were found to induce three detoxification enzymessuch as glutathione S-transferase, quinone reductase and thioredoxin reductase in liver cells such as Hepa-1c1c7 cells and Hep G2cells. Such processes increase the detoxification processes carried in the liver.
Source:
Nutraceuticals in “Useful Herbs of Planet Earth” (M.Daniel, 2012) Scientific Publishers, Jodhpur/ New Delhi,
Mammen Daniel
