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Extracted from The sacred lotus (Nelumbo nucifera)– phytochemical and therapeutic profile - Dr Pulok K. Mukherjee1,2,*, Debajyoti Mukherjee1, Amal K. Maji1, S. Rai1 and Michael Heinrich2  Article first published online: 8 JAN 2010  DOI: 10.1211/jpp.61.04.0001  2009 Royal Pharmaceutical Society of Great Britain

The rhizomes are 60–140 cm long, 0.5–2.5 cm in diameter, yellowish white to yellowish brown, smooth, with longitudinal striations and brown patches, and with nodes and internodes. Transverse section of the rhizome shows an outer layer of epidermis, surrounded by cuticle followed by a dense sub-epidermal layer, a spongy layer and an inner dense layer, continuous with the parenchyma cells. When freshly cut, the rhizome exudes mucilaginous juice and shows a few large cavities surrounded by several larger ones. Fracture is tough and fibrous, and the odour is indistinct.

Traditional uses

The rhizome extract is used as a tonic.  The rhizome nodes are used in the treatment of nasal bleeding, haemoptysis, haematuria and functional bleeding of the uterus. It is included in Chinese herbal prescriptions for the treatment of tissue inflammation, cancer and chronic liver cirrhosis. The rhizome is also used for arresting bleeding, dissipating blood stasis, improving appetite, haematemesis and haemoptysis. Powdered rhizome is prescribed as a demulcent for haemarrhoids and is beneficial in dysentery and chronic dyspepsia.  External application in the form of a paste is useful in scabies and ring worm. The rhizome yields a nutritious arrowroot that is used for diarrhoea, dysentery and dyspepsia in children.

Phytochemistry

The rhizomes of lotus are consumed as a vegetable in Asian countries. They are used as health foods because of their mineral content. Abundant starch grains are present throughout the tissue. Fresh rhizome contains 31.2% starch, which shows no characteristic taste or odour…. Fresh rhizome contains 83.80% water, 0.11% fat, 1.56% reducing sugar, 0.41% sucrose, 2.70% crude protein, 9.25% starch, 0.80% fibre, l.10% ash and 0.06% calcium. The vitamins thiamine (0.22 mg/100 g), riboflavin (0.6 mg/100 g), niacin (2.10 mg/100 g) and ascorbic acid (1.5 mg/100 g) and an asparagine-like amino acid (2%) are also present in the rhizomes. The oxalate content of rhizome was found to be 84.3 mg/100 g.88,94 The following elements were also found: calcium −1.15%, copper −0.0015%, iron −0.053%, magnesium −0.398%, zinc −0.0032%, barium −0.00064%, potassium −0.756% and sodium −0.10%.95

Pharmacology and toxicology

Antidiarrhoeal activity

The antidiarrhoeal potential of N. nucifera rhizome extract has been reported. The extract produced significant inhibitory effects against castor-oil-induced diarrhoea and PGE2-induced enteropooling; the propulsive movements of a charcoal meal were also reduced significantly.  The observed antidiarrhoeal effect was reconfirmed by Talukder and Nessa in the rat.

Antimicrobial activity

Different extracts of rhizome showed significant antibacterial effects against Staphylococcus aureus, Escherichia coli, Bacillus subtilis, B. pumilis and Pseudomonus aeruginosa. The chloroform extract was found to be the most effective when compared with the standard drug chloramphenicol.   Antifungal and anti-yeast activities of the rhizome extract were evaluated against five different strains of fungi and yeast, including Candida albicaus, Aspergillus niger, A. fumigatus and Trichophytum mentagopyhtes; the extract showed potential activity in all the strains tested and the effect was comparable to that of griseofulvin, used as standard drug for comparison.

Hypoglycaemic activity

The oral hypoglycaemic effect of N. nucifera was demonstrated using an ethanol extract of the rhizome, which markedly reduced the blood sugar level of normal, glucose-fed hyperglycaemic and streptozotocin-induced diabetic rats, when compared with control animals. The extract improved glucose tolerance and potentiated the action of exogenously injected insulin in normal rats. The extract exhibited activity corresponding to 73% and 67% of that of tolbutamide in normal and diabetic rats, respectively. An anti-diabetic constituent (tryptophan) has been isolated from the nodes of lotus rhizome.  In glucose-fed hypoglycaemic mice, the methanolic extract of nodes at a dose of 400 mg/kg and 100 mg/kg of isolated tryptophan showed potential anti-diabetic activities.

Psychopharmacological activity

The methanol extract of the rhizome of N. nucifera produced significant psychopharmacological actions in rats and mice: reduction in spontaneous activity, and a decrease in exploratory behaviour in the head dip and Y-maze tests. Thus, the extract possesses most of the pharmacological characteristics of a minor tranquilizer.

Diuretic activity

The diuretic activity of N. nucifera rhizome was reported by Mukherjee and coworkers. The methanol extract of the rhizome induced significant diuresis in rats at doses of 300, 400 and 500 mg/kg. There was a dose-dependent increase in the volume of urine, with Na+ and Cl− excretion, accompanied by a significant excretion of K+. The increase in volume of urine was less than with the standard diuretic Furosemide (20 mg/kg).

Anti-inflammatory activity

We have reported the anti-inflammatory activity of N. nucifera rhizome and isolated betulinic acid against carrageenin- and serotonin-induced rat paw oedema. The rhizome extract at doses of 200 and 400 mg/kg, and betulinic acid at doses of 50 and 100 mg/kg (administered orally) showed significant anti-inflammatory activity; the effect was comparable to that of the standard drugs phenylbutazone and dexamethasone.

Antioxidant activity

Yang and coworkers have performed in-vitro studies of the antioxidant activity of methanol and acetone extracts of the N. nucifera rhizome using the DPPH assay and β-carotene bleaching assay. The methanol and acetone extract showed highest DPPH scavenging activity, at 66.7 and 133.3 mg/l, respectively; the methanol extract exhibited a higher antioxidant activity coefficient than ascorbic acid. The rhizome knot also exhibited radical scavenging activity, measured spectrophotometrically and by electron spin resonance.

Antipyretic activity

The methanolic extract of N. nucifera rhizome showed antipyretic activity in rats with yeast-induced pyrexia. Oral doses of the extract of 200, 300 and 400 mg/kg produced significant dose-dependent lowering of normal body temperature and yeast-provoked elevation of body temperature in rats. The result was comparable to that of the standard antipyretic drug paracetamol (150 mg/kg intraperitoneally).