Nelumbo nucifera, now placed in the mono-generic family Nymphaeaceae, has numerous common names (e.g. Indian lotus, Chinese water lily and sacred lotus) and synonyms (Nelumbium nelumbo, N. speciosa, N. speciosum and Nymphaea nelumbo). Nelumbo nucifera has been used as a medicinal herb in China and India. It has been recorded in the most famous medicinal book in China for more than 400 years. Different part of plant (leaves, seeds, flower, and rhizome) can be used in traditional system of medicine.
2. Definition & uses
Plants have been used as source of medicine by mankind since ancient times. The indigenous knowledge of many tradition communities has been formulated, been documented and eventually become organized systems of medicine such as ayurveda, siddha, unani, and other systems out of India. In Ayurveda this plant is used as a diuretic and anthelmintic and in the treatment of strangury, vomiting, leprosy, skin diseases and nervous exhaustion. In popular medicine it is used in the treatment of tissue inflammation, cancer, skin diseases, leprosy and as a poison antidote. Rhizomes are prescribed as demulcents for haemorrhoids and are beneficial in dysentery, chronic dyspepsia, and have nutritive, diuretic and cholagogue activities. The stem is used in indigenous Ayurvedic medicine as a diuretic, anthelmintic, to treat strangury, vomiting, leprosy, skin disease and nervous exhaustion. The leaves are used for the treatment of haematemesis, epistaxis, haemoptysis, haematuria, metrorrhagia and hyperlipidaemia. The flowers are useful in the treatment of diarrhoea, cholera, fever and gastric ulcers. The seeds and fruits are used as a health food in Asia and to treat many ailments, including poor digestion, enteritis, chronic diarrhoea, insomnia, palpitations, spermatorrhoea, leucorrhoea, dermatopathy, halitosis, menorrhagia, leprosy, tissue inflammation, cancer, fever and heart complaints, and as an antiemetic, poisoning antidote, diuretic and refrigerant. Lotus seedpods are sometimes used as a traditional medicine for haemostatic function. The seed powder mixed with honey is useful in treating cough. Embryos of lotus seed are used in traditional Chinese medicine to overcome nervous disorders, insomnia, high fevers (with restlessness) and cardiovascular diseases (e.g. hypertension, arrhythmia).
3. Chemical constituents
i) Fruits and seeds
The seeds of N. nucifera are rich in asparagin, fat, protein, starch and tannin. Normally, lotus seeds are rich in protein, amino acids, unsaturated fatty acids and minerals. Nelumbo seeds have also been found to contain a variety of minerals such as chromium (0.0042%), sodium (1.00%), potassium (28.5%), calcium (22.10%), magnesium (9.20%), copper (0.0463%), zinc (0.0840%), manganese (0.356%) and iron (0.1990%). Other relevant nutritional elements include total ash (4.50%), moisture (10.50%), crude carbohydrate (1.93%), crude fibre (10.60%), fat (72.17%), and protein (2.70%); its energy value is 348.45 cal per 100 g. The major secondary metabolites present in the seeds (Figure 1) are alkaloids such as dauricine (1), lotusine (2), nuci-ferine (3), pronuciferine (4), liensinine (5), isoliensinine (6), roemerine (7), neferine (8) and armepavine (9).[25,26,27,28,29,20,30,31] Procyanidin (10) was isolated from the seedpod of N. nucifera. Seeds also contain gallic acid (11), D(–)-3 0- bromo-O-methylarmepavine(12) D–1,2,3,4-tetrahydro-6-methoxy-1-(p-methox benzly) -2-methyl-7-isoquino- linol (13), saponins and carbohydrates. The seed polysaccharides have also been isolated and characterized. Acid hydrolysis and methylation showed that seed polysaccharides are mainly composed of four types of monosaccharide: D-galactose, L arabinose, D-mannose and D-glucose.
Combined gas/liquid chromatography–mass spectroscopy has shown that the leaves are rich in a number of alkaloids. In the analysis of non-phenolic fractions of the leaf extract, the major components had retention data and mass spectra identical to those of nuciferine, roemerine, anonaine (14), pronuciferine and N-nornuciferine (15). Two benzylisoquinoline alkaloids, (+)-1(R)-coclaurine (16) and (–)-1(S)-norcoclaurine (17), were also found in leaf extract of N. nucifera. Six non-phenolic bases were identified: roemerine, nuciferine, anonaine,pronuciferine, N-nornuciferine and liriodenine(18) and two phenolic bases, armepavine and N-methyl-coclaurine (19), were also found in N. nucifera leaf extract. Dehydro- emerine (20), dehydronuciferine (21), dehydroanonaine (22), Nmethylisococlaurine (23), anonaine, pronuciferine, Nnornuciferine, O-nornuciferine (24), nuciferine, remerine (25), roemerine, armepavine, liensinine, isoliensinine, negferine, asimilobine (26) and lirinidine (27) were isolated from leaves and petioles. The leaves also contain a glycoside, nelumboside (28), and flavonoids such as quercetin (29) and leuco-anthocyanidin which were identified as leucocyanidin (30) and leucodelphinidin (31). The presence of some other flavonoids in the leaves such as quercetin 3-O-aarabinopyranosyl-(1!2)-β-galactopyranoside, quercetin-3-O-β-Dglucuronide (32), rutin (33),(+)-catechin (34),hyperoside (35), isoquer-citri (36) and astragalin (37) has also been reported.
Several flavonoids have been identified in the stamens of N.nucifera. These include kaempferol (38) and seven of its glycosides: kaempferol 3-O- β -D-galactopyranoside (39), kaempferol 3-O-β-D-glucopyranoside (40), kaempferol 7-O-β -Dglucopyranoside (41), kaempferol 3-O-a-L-rhamnopyranosyl-( 1- 6)-β -D-glucopyranoside (42), kaempferol 3-O-a-Lrhamnopyranosyl-(1-2)- β -D-glucopyranoside (43), kaempferol 3-Oa-L-rhamnopyranosyl -(1-2)- β- D-glucurono-pyranoside (44), kaempferol-3- O- β- D-glucurono-pyranoside (45), kaempferol 3- O-β-D-glucuronopyranosyl methylester (46), myricetin 3 0 ,5 0 – dimethylether 3-O- β -D-glucopyranoside (47), quercetin 3-O- β – D-glucopyranoside (48), nelumboroside A (49) and nelumboroside B (50). It also contains two isorhamnetin glycosides: isorhamnetin 3-O-β-D-glucopyranoside (51) and isorhamnetin 3-O-a-L-rhamnopyranosyl- (1→6) -β -D-glucopyranoside (52). Some non-flavonoid compounds, including adenine, myo-inositol, arbutin (53) and β-sitosterol glucopyranoside (54), have also been identified in stamen extract.
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. The binding and disintegration properties of isolated Nelumbo starch have been compared with maize and potato starch; Nelumbo starch was found to be superior as an adjuvant in the preparation of tablets. The methanol extract of the rhizome has been found to possess a steroidal triterpenoid – betulinic acid. 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.
4. Pharmacological activities
N.nucifera has been screened scientifically for various pharmacological activities like anti-ischaemic activity, antioxidant activity, hepatoprotective activity, anti-inflammatory activity, anti-fertility activity, anti-arrhythmic activity, anti-fibrosis activity, antiviral activity, antiproliferative activity, antidiarrheal activity, psychopharmacological activity, diuretic activity, antipyretic activity, immunomodulatory activity, hypoglycaemic activity, aldose reductase inhibitory activity, antibacterial, aphrodisiac activity, antiplatelet activity, cardiovascular activity, anti-obesity activity, lipolytic activity, hypocholesterolaemic activity and anticancer activity.