Watercress / Helencha (হেলেঞ্চা)

General features: The botanical name is Nasturtium officinale. It is an aquatic flowering plant that belongs to the Brassicaceae family, commonly known as the cabbage family, within the Nasturtium genus. It is a fast-growing perennial vegetable plant that grows in Eurasia, North Africa, and parts of tropical regions in Southeast Asian countries like India, China, Bangladesh, Thailand, Cambodia, and their neighboring nations. It was introduced in China via Hong Kong and Macao by Europeans around 1800 AD. Since then, it has been cultivated in many tropical Asian countries [1]. The plant prefers to grow in flowing streams. The United Kingdom is considered its natural habitat. In Bengali, the plant is known as Helencha (হেলেঞ্চা). It grows approximately 24 inches long, with hollow stems that allow it to float in water. The leaf arrangement is pinnate, dark green, and round with a crispy texture. The small white flowers are inflorescences that grow in clusters. Like mustard, radish, horseradish, and wasabi, it has a pungent, spicy, or piquant flavor. Its crispy, peppery, and pungent taste adds flavor to salads and stir-fried vegetables. In many countries, it is a weed; however, in others, it is eaten daily as a vegetable or herb. The Centers for Disease Control and Prevention (CDC) in the US has ranked it among the healthiest vegetables, listing it as a “powerhouse fruit and vegetable.” According to the CDC, it has a nutrient density score of 100 out of 100. In fact, watercress is the only item that earns a perfect score [2,3]. It is classified as a cruciferous vegetable with high nutritional value, rich in antioxidants, vitamins C, K, and E, and a significant iron content, all of which contribute greatly to health.

Nutritional and medicinal benefits: The plant offers significant nutritional and medicinal potential for health. It is rich in antioxidants, vitamins such as A, C, and K, and minerals that can strengthen the immune system, support cardiovascular health, improve eyesight, and increase bone density. It promotes digestion, relieves constipation, and encourages healthy skin. The presence of glucosinolates, carotenoids, and flavonoids collectively produces anti-inflammatory, antibacterial, and notable anti-cancer effects. Additionally, it can boost athletic performance by increasing oxygenated blood flow in the body [4]. The nitrates in it may be responsible for improving blood flow and oxygen delivery [5].

History of uses: Watercress, the aquatic vegetable, has a millennia-old history dating back to almost 3000 years, encompassing Europe and Asia. It was once avidly used by the Persians, Greeks, and Romans for gaining strength or medicinal reasons. Around 400 BC, Hippocrates, the father of medicine, cultivated it on the island of Kos in the natural springs to treat a few illnesses, particularly blood and mental disorders. The Roman emperors used to eat it before making any ‘bold decisions. The Persian King Xerxes ordered his soldiers to eat to maintain good health, also to prevent or cure scurvy. It is also interesting that the Romans even consumed it along with vinegar to cure insanity. They thought it was an aphrodisiac and might cure baldness. Hildegard of Bingen (1098 – 1179 AD), the German Benedictine abbess and polymath, recommended steamed watercress to treat jaundice and fevers. In the 17^th century, watercress soup gained popularity in England, with claims that it cleanses the blood. British explorer Captain James Cook (1728 – 1779 AD) routinely consumed this vegetable during his global voyages to prevent scurvy. The plant arrived in America in the 18^th century and was picked up by the Native Americans to treat kidney problems and constipation. Lewis and Clark discovered watercress while trekking across the Louisiana Purchase. Around 1800 AD, farmers in England started cultivating to use in salads. Its sales boomed in the 19^th century in London and the markets of the British Islands. In the 20^th century, it gained popularity in the US and found uses in supplements and health drinks [6].

Phytochemicals: This vegetable plant is rich in versatile phytochemicals that benefit health. Both leaves and roots synthesize nearly similar compounds [7]. The most identified ones are glucosinolate derivatives like phenylethyl isothiocyanate, methylsulfinylalkyl isothiocyanate, 1-methoxy-3-indolylmethyl isothiocyanate, and 3-indolylmethyl isothiocyanate. Major flavonoids include apigenin, luteolin, kaempferol, myricetin, and quercetin. Phenolics include hydroxycinnamic acid and rutin. Carotenoids comprise β-carotene, lutein, and zeaxanthin [8].

Glucosinolates are sulfur compounds that, when crushed, release the enzyme myrosinase from the intracellular compartment of plant cells. This enzyme hydrolyzes them into isothiocyanate derivatives, which further break down into monoamine and carbon disulfide. The released isothiocyanates are potent inhibitors of bacteria. They alter membrane potential, trigger K+ release, disrupt cell integrity, and inhibit bacterial growth. They are also effective against methicillin-resistant Staphylococcus aureus [9].

Watercress is one of the richest sources of glucosinolates, producing majorly allyl isothiocyanate by the breakdown of gluconasturtiin. After conjugation of glutathione, they convert to mercapturic acid and later to N-acetylcysteine conjugate, which is excreted via urine. Isothiocyanates are broken down to ~ 60% during cooking. Besides glucosinolates, the plant also synthesizes a large section of flavonoids, phenolic acids, and carotenoids, including β-carotenoid, lutein, and zeaxanthin. The isothiocyanates are powerful antioxidants and have anti-inflammatory and cancer-curing properties. The presence of flavonoids and carotenoids makes this vegetable far more active in that regard. The other components are coumaric acid, sinapic acid, and caftaric acid. The oil from flowers contains caryophyllene oxide, limonene, p-cymene-8-ol, α-terpinolene, and myristicin. In addition to those, there are a few glucosides [4].

Pharmacological effects: Reports indicate that the primary metabolites are isothiocyanates, glucosinolates, polyphenolics, flavonoids, phenolic acids, terpenes, carotenoids, and vitamins B1, B2, B3, E, and C. Pharmacological studies also confirm several of its medicinal roles.

Anti-inflammatory effect – The anti-inflammatory activities of the plant have been verified by using the hydroalcoholic extract on carrageenan or formaldehyde-induced paw edema in rats, and also phorbol ester-induced ear edema in mice [10]. The results have shown that 4 – 6 mg/Kg/ body weight of the dried extract has a significant anti-inflammatory effect. The in vitro studies on Raw 264.7 cell lines indicate that NO and PGE2 production are drastically lowered, possibly due to the lowering of proinflammatory mediators. The isothiocyanates reduce the expression of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) enzymes by deactivating nuclear factor-κβ (NF-κβ) with subsequent stabilization of IκBα [11]. It has been further noted that the extract reduces the level of TNF-α and NO significantly in gentamicin-induced nephrotoxicity [12]. The extract also inhibits croton oil-induced edema and infiltration of inflammatory cells in the case of chronic and acute models, showing the lowering of the proinflammatory cytokines, particularly in acute inflammatory conditions [13].

Anticancer Effect – The anticancer properties of this plant are attributed to its ability to interfere with oxidative stress, apoptosis, and cell cycle progression. It is known that diets rich in cruciferous vegetables reduce the risk of lung, colon, and prostate cancers [14,15]. In the intestine, consumed glucosinolates are converted into various isothiocyanates, which play a chemopreventive role in controlling tumors or cancers [16,17]. In vitro studies have shown that the plant extract can protect against DNA damage caused by carcinogens [18,19]. The extract inhibits cell cycle progression in human colon carcinoma (HT-29) cell lines. Experiments with matrigel penetration of HT-115 colon cancer cells have demonstrated that it can also prevent invasion through matrigel [20]. Treatment with methylsulphinylheptyl isothiocyanate, an isolated component of watercress, reduces metalloprotease-9 (MMP-9) enzyme activity, which is necessary for cancer cell invasion, as tested in breast cancer cells (MDA-MB-231) [20]. Several other studies have confirmed that this aquatic vegetable can prevent or cure various cancers [21]. Additionally, the plant produces large quantities of β-carotene, lutein, and other carotenoids, along with several flavonoids. All these compounds possess strong antioxidant properties, which are also linked to antitumor activity [22].

Effect on glucose and lipid levels – Watercress has potent hypolipidemic and hypoglycemic roles without showing any adverse side effects [23]. It has been noticed that the daily consumption of this plant can significantly lower the glucose and cholesterol levels in circulation. Experiments on hyperlipidemic and hyperglycemic rats by intragastric administration of 500 mg/ Kg/Body weight for 10 – 30 days reduce the total cholesterol by 34.2 – 37%, triglyceride by 30.1 – 44.0%, LDL-C by 52.9 – 48% and enhance HDL-C by 27 % with considerable lowering of (76.6%) of blood glucose levels often better than insulin [24,25]. The mechanism indicates that the extract inhibits carbohydrate digestive enzymes, particularly α-glucosidase. It is further noticed that the presence of roseoside, pinoresinol, malic acid, and glycosides, along with other phenolics, is the underlying factor [26].

Roseoside and pinoresinol inhibit α-glucosidase, whereas malic acid impedes the action of α-amylase, α-glucosidase, and pancreatic lipase [26,27]. The experiments have further confirmed that the extract of watercress prevents the action of digestive enzymes, interrupting carbohydrate and lipid hydrolysis, effectively reducing the absorption of intestinal glucose and fatty acids [26].

Antioxidant effect – The in vivo experiments using hypercholesterolemic rats have shown that administration of the plant extract significantly enhances the activities of superoxide dismutase (SOD) and catalase while substantially reducing glutathione peroxidase (GPx), glutathione reductase, and malondialdehyde (MDA) levels [28]. Further, the consumption of this aquatic plant (~ 85g) for eight weeks, along with normal diets, shows a significant increment of antioxidant levels, particularly lutein and β-carotene [29]. It has also been demonstrated that the ethanolic extract (50 – 500 mg) inhibits lipid peroxidation in several tissues, like the liver (88.8 – 97.4%), brain (64.7 – 92.7%), and kidney (71.8 – 97.1%) [30]. Taking the plant two hours before exercising significantly reduces the build-up of lipid peroxidation, hydrogen peroxide, and lipid hydroperoxides. Antioxidants such as α- and γ-tocopherol and xanthophyll levels increase after eating this vegetable [31].  Watercress also boosts antioxidant enzyme levels, helping the body resist lead and arsenic damage [32].

Effect on nephrotoxicity –  The hydroalcoholic extract shows a protective action against mitochondrial dysfunction induced by gentamicin in mitochondria isolated from rat kidney. The drug significantly lowers the mitochondrial function and glutathione content. The administration of extract reduces glutathione oxidation, MDA, and swelling of mitochondria dose-dependently [33]. The extract also reduces ROS generation and blood urea nitrogen and creatinine modulated pathological changes in the kidney. It also prevents the elevation of inflammatory cytokines TNF-α and NO in gentamicin-induced nephrotoxicity [34]. It is also noticed that administration of the extract produces no substantial effect regarding chemical parameters like oxalate crystal formation. But it is noticed that at low doses, the extract can suppress calcium oxalate crystal formation in the kidney induced by ethylene glycol in rats [35].

Effect on hepatotoxicity – In normal laboratory rats, the watercress extract produces no changes in the levels of aminotransferase enzymes, AST and ALT (SGPT). However, animals given acetaminophen displayed significant liver damage, with elevated AST, ALT, and LDH levels; however, when they were treated with the extract, they showed a significant reduction. Further, the histopathological changes induced by acetaminophen are reversed significantly [36]. A large number of experiments have established the fact that watercress can protect the liver well from toxicity. Thus, it can be recommended as a therapeutic agent also for the cholestatic liver damage [37].

Effect on DNA damage – The event of DNA damage creates several chronic ailments, particularly concerning cancers and aging. Consumption of watercress as food enriched with polyphenols reduces oxidative stress as well as prevents DNA damage [38]. Further, this food does not induce any cytotoxicity, chromosomal instability, or clastogenicity, thus has no role in genetic damage and is not genotoxic in vivo [38,39,40]. The high concentration of lipid-soluble antioxidants and along with others, could be liable to stabilize the cellular DNA. Possibly, the antimutagenic effect depends mainly on its antioxidant capacity since phyto-ingredients of the plant extract upregulate GPx (glutathione peroxidase), SOD (superoxide dismutase) expression, reducing the possibility of DNA damage following the consumption of watercress [41,42,43].

Conclusion: Additionally, as a “superfood,” watercress, besides displaying its beneficial roles against numerous chronic diseases,  has demonstrated antimicrobial properties against a variety of pathogens, further supporting its traditional use in promoting overall health. The synergistic effects of its diverse phytochemicals contribute not only to its therapeutic potential but also to its value as a functional food in the diet. Regular consumption may provide cumulative benefits across multiple organ systems, emphasizing the importance of including watercress in balanced nutrition.

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