Keywords

1 Introduction

Botanical Names

  • Nelumbo nucifera Gaertn

  • Nymphaea nelumbo Linn

Common Names

  • English: Lotus, Oriental Lotus, Bean of India, Hindu Lotus, Sacred Lotus, East Indian Lotus, Egyptian Bean, Sacred Water Lily, Sacred Water Lotus, Baladi Bean, Lotus Bean, Water Lotus, Indian Lotus, Egyptian Lotus, Chinese Water Lily

  • Hindi: Padam, Kamala, Kamal, Lalkamal, Kanwal, Ambuj, Kamal-Kakri

Nelumbo nucifera Gaertn (Sacred Lotus; 2n = 16) is a significant economic and medicinal aquatic plant, which has irreplaceable cultural and religious importance for Buddhists and Hindus and belongs to a small plant family of Nelumbonaceae that is currently kept in the mono-generic Nymphaeaceae family (Duke et al. 2002; Wang and Zhang 2005), with a solitary genus Nelumbo, which further contains two species namely, Asian Lotus/Indian lotus or Nelumbo nucifera Gaertn (found throughout Asia in China, India, Australia, and Russia) and American Lotus/Water chinquapin or Nelumbo lutea Pers. (Eastern and Southern North America) (Mukherjee et al. 1996a, b; Williamson and Schneider 1993; Sayre 2004).

The fossil records disclose that 15 million years ago there were eight Nelumbo nucifera Gaertn species at global level (Wang and Zhang 2005; You 1998). In Asia, the lotus is under cultivation for more than 7000 years for its edible seeds, leaves, rhizomes, and beautiful flowers (Yang et al. 2012; Kubo et al. 2009; Shen-Miller 2002; Ming et al. 2013). The lotus seeds with extraordinary longevity remain viable for 1300 years and lotus rhizomes stay vigorous for above 50 years and shows remarkable property of water repellency, well known as the Lotus Effect because of nanoscopic narrowly packaged distensions of its self-cleaning surface of leaf (Shen-Miller et al. 2002; Shen-Miller 2002). The parts of lotus plant like flowers, androecium, pollens, rhizomes, stems, and leaves are both used as food/vegetables and a part of indigenous system of medicine in China as well as India (La Cour et al. 1995; Anonymous 1992; Mukherjee et al. 2009; Sridhar and Bhat 2007). The different parts of Lotus like buds, leaves, roots, stalks, rhizomes, flowers, and fruits have been employed as plant-based drugs for cure against diseases of hypertension, cancers, diarrheal problems, cardiovascular issues, depression, and insomnia (Shen-Miller et al. 2002; Duke et al. 2002). Antioxidant potential of lotus plant parts, for example, leaves (Wu et al. 2003), roots (Jung et al. 2011; Ham et al. 2017), stamens (Jung et al. 2003), and lotus rhizomes (Cho et al. 2003; Hu and Skibsted 2002) is well recognized. Leaves of lotus plant have diverse antioxidant chemicals like ascorbic acid, phenolic compounds, carotenoid compounds, flavonoid compounds, and tocopherol compounds (Choe et al. 2011).

Nelumbo nucifera Gaertn has various vernacular and botanical names. Indian Nelumbo nucifera Gaertn is recognized as the Padma and/or Kamala which has two plant varieties, commonly called the Pundarika or Sveta Kamala (white lotus variety); and the Rakta Kamala (pink or reddish pink lotus variety) (Chopra 1958). All the parts of lotus plant have a distinctive name and almost all the parts have medicinal value, providing one or more drugs (Raghunath and Mitra 2005). The whole lotus plant along with the flower is well known as Padmini, the rhizomes of lotus as Kamalkand (Nadru in Kashmiri), the leaves of lotus as Sambartikai, the peduncle of lotus as Mrinal or Visa, the stamens of lotus as Kirijalika, the receptacle of lotus as Padma Makaranda or Padma-Madhu, Padmakosa, seeds of lotus as Karnika or Padmaksya (Pambuch in Kashmiri), and honey of lotus flowers is known as Makaranda or Padmamadhu (Anonymous 1982). Ming et al. (2013) sequenced the lotus genome of the Chinese traditional variety with estimated 929 Mbp genome size. A lotus root which is a popular vegetable known as Nadru in Kashmiri has antianxiety, antifungal and anti-inflammatory activities (Du et al. 2010).

1.1 Origin and History

Lotus was in existence since 135 million years in the aquatic environment of Northern Hemisphere. This plant was bestowed with honor in history by countries like India, China, and Egypt (Karki et al. 2012, 2013; Harer 1985), wherein flower of lotus can be appreciated in their traditional art, culture, and religion. Lotus is admired in Australia Pacific, China, India, Korea, and Japan (Harer 1985; Anonymous 1992). Nymphaea caerulea, commonly known as the Sacred Blue Lotus, showed distribution sideways the banks of River Nile (Harer 1985; Anonymous 1966) along with lotus. Egyptians, Hindus, and Buddhists worship lotus. Egyptians worshipped the flowers, fruits, and sepals of lotus plant. After Egypt, lotus was transferred to region of Assyria and extensively planted throughout Indian, Persian, and Chinese regions. Lotus is common in Australian, Chinese, Indian, Iranian, and Japanese regions. From China, lotus was introduced to Japanese region and subjected to cultivation for over 1000 years. In China, lotus is grown as a crop with industrial value on above 40,000 hectares of land. In India, lotus is pervasive, and established in Himalayan lakes as well (Sridhar and Bhat 2007). Lotus is the “National Flower of India.” It is sacred and symbol of purity and sanctity. The garlands made from the white or mainly pink flowers are used for the decoration and worship of Goddess Lakshmi as a “symbol of wealth” in temples (Mehra et al. 1975). Lotus was under cultivation in the Far East since 5000–7000 years (Wong 1987); by way of proof of cultivation of lotus plant from >3000 years for utilization as food, drugs, and in events of cultural and religious significance (Shen-Miller 2002). Sir Joseph Banks (1787) initiated horticulture of lotus plant in Western Europe as stove-house water lily. Today, lotus plant is prevalent virtually ubiquitously in plant herbal and botanical garden collections.

1.2 Distribution and Production (India, World)

Nelumbo nucifera Gaertn – the lotus is native to China, Japan, and India. The natural distribution of Lotus extends from Japan to northeast Australia and across the Caspian Sea. Lotus is extensively dispersed throughout the Caspian Sea to the Asian zone. Lotus is widespread in a range of countries like North Australia, China, Iran, Korea, and Malaysia (Lim 2016). Guo (2009) put on records that Nelumbo is extensively cultivated throughout Indian continent because of the belief of being a sacred plant by the Hindu religion. It is distributed throughout India and extends up to northwest Himalaya, Kashmir, West Bengal, central and southern Bihar, Orissa, Maharashtra, south India, and northeast India (Assam, Manipur, and Mizoram, etc.). In India, it grows in ponds, lakes, and tanks. Nelumbo nucifera Gaertn is grown in China, Japan, and India in terraced fields and in Indian country due to its fragrant flowers, seeds, fruits, and rhizomes (Anonymous 1966). The propagation of lotus is done by seeds and rhizomes in March to April mainly in ponds, and rhizomes are ready to harvest in October. Flowering takes place during hot and rainy seasons and seeds ripen toward the end of rains.

1.3 Botanical Description

Taxonomic Classification

(Mukherjee et al. 1996a, b)

Kingdom: :

Plantae

Sub Kingdom: :

Tracheobionta

Super Division: :

Spermatophyta

Division: :

Magnoliophyta

Class: :

Magnoliopsida

Subclass: :

Magnoliidae

Super order: :

Protaenae

Order: :

Proteales

Family: :

Nelumbonaceae/Nymphaeaceae

Genus: :

Nelumbo

Species: :

Nelumbo nucifera Gaertn.

1.4 Nutritional Value

The leaves, rhizomes, and stems of Nelumbo nucifera Gaertn are appetizing and can be prepared as vegetables (Anonymous 1992) or pickled and served with syrup (Phillips and Rix 1995). The lotus corolla find use in soups and garnishes, whereas the lotus stamens as added as tea additive (Ibrahim and Eraqy 1996). Lotus seeds can be used as popcorn, powdered, or eaten dry while the roasted seeds act as coffee substitute (Ling et al. 2005). Lotus known as Nadru in Kashmir is profoundly correlated with its culture and economy. Nadru-based cuisines like lotus stem and yoghurt curry (Nadru yakhni) stem rogan josh, stem-palakh, stem kabab, stem pickles, stem fish, etc. are an integral part of every Kashmiri religious, social, and/or cultural occasion. The nutritive value analyses of raw lotus plant parts done in the United States report the proximate composition per 100 g value as given in Table 2.1.

Table 2.1 Nutritive value of lotus root and lotus seeds, raw per 100 g
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2 Antioxidant Properties and Phytochemistry of Nelumbo nucifera Gaertn

Biological action of phytochemicals is related with their antioxidant prospective (Dey et al. 2016). The scientific investigations on the antioxidant activities of various lotus parts are highest, equaling to 18 in in vitro and 8 in in vivo conditions. Yet, no single index is believed to be adequate for determination of the entire antioxidant capability (Feng et al. 2016; Venkatesh and Dorai 2011; Karadag et al. 2009), owing to variety in reaction of chemical constituents (Lopez-Alarcon and Denicola 2013). According to Feng et al. (2016), inconsistencies are present in the outcomes acquired from embryos of different cultivars of lotus through the use of 2, 2-diphenyl-1-picrylhydrazyl (DPPH) and Ferric Reducing Antioxidant Power (FRAP) assays. Hitherto 12 phenolics and 89–90 flavonoids (out of which 47 were flavonols, 25–26 were flavones, 8 were flavan-3-ols, 4 were flavanons, and 5 were anthocyanins) were reported from leaf pulp of lotus, veins of lotus leaves, stalk of lotus leaves, receptacle of lotus, epicarp of lotus, coat of lotus, kernel of lotus, embryo of lotus, androecium, flower petals, gynoecium, and stalk of lotus plant. The seeds (Rai et al. 2006), leaves (Huang et al. 2010), rhizomes (Yang et al. 2007), and stamens (Hyun et al. 2003) of lotus plant exhibit antioxidant actions. Jung et al. (2003) anticipated that the OH at the carbon-3 locations structurally adds to the antioxidant property of flavonoids present in the stamens of lotus plant. When a glycoside hides the OH at the carbon-3 loci, half maximal inhibitory concentration (IC50) values reduce severely. Kaempferols have excellent antioxidant activities in 2, 2-Diphenyl-1-Picrylhydrazyl, peroxynitrite scavenging activity (PSA), and overall reactive oxygen species; while kae 3-GlnPyr-methylester and kae 3-GlnPyr illustrated slighter scavenging properties in DPPH and PSA. Kae 3-GluPyr and Kae 3-GalPyr show activity merely in the assay of peroxynitrite scavenging activity (Jung et al. 2003). Hyun et al. (2006) observed analogous outcome for IC50 antioxidant rates of isorhamnetin glycosides in male reproductive part of lotus. The glycosylation affects antioxidant ability, solubility of aglycones, and the stability of aglycones (Zhu et al. 2017). The flavonoids of lotus with C-glycosides present in the embryo of lotus demonstrate high in vitro antioxidant capability compared to O-glycosides (Zhu et al. 2017). Polyphenols possess antioxidant activity responsible for many health advantages (Lee et al. 2012; Devkota et al. 2015). The antioxidant activities of phenolic acids are directed by their chemical structures. The antioxidant activity of phenols enhances with the increase in number of hydroxyl groups (Moure et al. 2001). The seed gallic acid which has 3-hyroxyl (OH) groups showed higher antioxidant potential than caffeic and chlorogenic acid which have 2-hyroxyl groups and p-hydroxybenzoic acid having 1-hyroxyl group (Yen et al. 2005). The polysaccharides also show scavenging action and reduction property of leaf extracts of this plant, besides phenolic acids and flavonoids (Zhang et al. 2015). The seeds of lotus plant encompass alkaloids, saponins, phenolic acids, and carbohydrates which possess a great degree of antioxidant activity (Mukherjee et al. 2010a, b).

2.1 Antioxidant Properties and Phytochemicals Present in Fruit/Receptacle of Nelumbo nucifera

Various scientific investigations are available on the separation and identification of the chemical compounds present in the receptacle of lotus plant. Ling et al. (2005) improved, characterized, and scrutinized the antioxidant potential of procyanidins of Nelumbo nucifera Gaertn receptacle. With mass spectroscopy, Ling et al. (2005) inferred presence of huge concentrations of dimers than monomers and tetramers of catechin and epicatechin procyanidins in sample extracts. The natural polyphenols in seedpod of lotus signifies its source as antioxidants. Wu et al. (2013) isolated and verified five diverse flavonol glycosides in receptacle of lotus plant out of which hyperoside and isoquercitrin were antioxidants. Hu (2005) analyzed the nutritive value and antioxidant capability of lotus receptacle wherein they obtained and identified quercetin-3-O-β-D-glucopyranoside – a dietary flavonoid in lotus.

The receptacle of lotus plant contains judicious but noteworthy magnitude of key secondary metabolites which are phenolics. Phenolics exhibit a variety of bio-pharmacological effects in conjunction with antioxidation (Ling et al. 2005), such as improvement in learning ability and memory proficiencies (Gong et al. 2008), protection from experimental myocardial wounds and ischemic disorders (Zhang et al. 2004), radio protecting action (Duan et al. 2010), and antitumor effects (Duan et al. 2004). The quantity of total phenolic acids ranged from 255.65 to 477.61 mg/g, flavonoid compounds ranged from 353.31 to 540.84 mg/g, and pro-anthocyanidins ranged from 112.41 to 358.42 mg/g which are responsible for antioxidant capability of receptacle of lotus extract in 11 diverse cultivars of China. The methods used for their estimation were DPPH, 2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) diammonium salt, superoxide anion radical scavenging, reducing power, activities of antioxidation, metal chelation, and β-carotene bleaching. In DPPH free radical scavenging activity (IC50), the entire phenolic acid content (r = 0.9529) showed positive correlation (Zheng et al. 2012).

2.2 Antioxidant Properties and Phytochemicals Present in Seed of Nelumbo nucifera Gaertn

The linoleic acid, an unsaturated fatty acid, was mainly copious at 0.285 g/100 g of seeds of lotus plant (Lim 2016). The annexin proteins and a myriad of natural compounds which function as antioxidants were reported in seeds of lotus (Chu et al. 2012). Three alkaloids, known as neferine, liensine, and isoliensinine, were efficaciously separated and identified from seeds of Nelumbo nucifera Gaertn through liquid chromatography (Chen et al. 2007). Liu et al. (2009) furthermore reported analogous results from crude extracts of embryos of lotus seeds. Besides, other major secondary metabolites, Mehta et al. (2013) reported dauricine alkaloid, roemerine alkaloid and pronuciferine alkaloid from the seeds of lotus plant. Diverse flavonoids, for example, rutin, Syringetin-3-O-glucoside, and astragalin have been isolated in seed coats of Nelumbo nucifera Gaertn plant (Lim 2016). Youn et al. (2010) isolated and analyzed structures of four diverse alkyl 4-hydroxybenzoates from seeds of lotus plant by NMR spectroscopy.

The mass of seed of Nelumbo nucifera Gaertn has 3.74% integuments, 3.03% plumule, and 93.23% dicotyledons. Nelumbo nucifera Gaertn contains glutathione content of 13 g in its plumule and 164 g in its cotyledon. Nelumbo nucifera Gaertn seeds show abundance of asparagin, fats, starch, proteins, and tannins (Toyoda 1966) and a variety of minerals and nutritional elements for example; K-potassium (28.5%), chromium (0.0042%), magnesium (9.20%), Na-sodium (1.00%), Ca-calcium (22.10%), Mg-manganese (0.356%), Co-copper (0.0463%), zinc (0.0840%), and iron (0.1990%), overall ash (4.50%), crude content of carbohydrates (1.93%) and dietary fibre (10.60%), moisture (10.50%), fats (72.17%), and proteins (2.70%) (Indrayan et al. 2005). The major secondary metabolite alkaloids of seeds of Nelumbo nucifera Gaertn are pronuciferine, lotusine, nuci-ferine, liensinine, neferine, dauricine, isoliensinine, roemerine, and armepavine (Qian 2002; Wu et al. 2004; Liu et al. 2006; Wang et al. 1991; Furukawa et al. 1965; Tomita et al. 1965; Furukawa 1966), Procyanidin (Ling et al. 2005). The gallic acid, D(–)-3 0-bromo-O-methylarmepavine D–1,2,3,4-tetrahydro-6-methoxy-1-(p-methoxy benzyl)-2-methyl-7-isoquino-linol, carbohydrates, and saponins (Rai et al. 2006) are also present in seeds. The seed polysaccharides isolated and characterized by acid hydrolysis and methylation are four categories of monosaccharide, which are D-mannose, D-galactose, D-glucose, and L-arabinose (Das et al. 1992).

The seed extract prepared in ethanol demonstrates antioxidant action by the use of 2, 2-diphenyl-1picrylhydrazyl (DPPH) assay, wherein free radical scavenging results showed 6.49 mg/ml median inhibition concentration (IC50) (Sohn et al. 2003). Nelumbo nucifera Gaertn seeds and receptacle possess activities of antioxidation and free-radical scavenging. The hydro-alcoholic seed extract possess antioxidant potential as revealed by in vitro and in vivo models, DPPH assay, and nitric oxide methods (Rai et al. 2006), wherein the complete phenolics amount was reported as 7.61% with strong free radical scavenging capability showing low median inhibition concentration (IC50) values (16.12 μg/ml) compared to a standard free radical scavenger, that is, rutin (IC50, 18.95 μg/ml) 50 and 84.86 ± 3.56 mg/ml which is reduced than rutin (IC50: 152.17 μg/ml) by the DPPH and nitric oxide assays respectively (Rai et al. 2006).

In vivo study of the hydroalcoholic extract of lotus seeds in Wistar rats at a dosage of 100 mg/kg and 200 mg/kg for 4 days followed by the carbon tetrachloride action lead to considerable dose-dependent enhancement in levels of SOD, catalase, and causes reduction in TBA reactive substances comparative to 100 mg/kg dosage to that of vitamin E at 50 mg/kg (Jiqu et al. 2010). The Swiss Albino mice show no signs and symptoms of acute toxicity up to dosage of 1000 mg/kg body weight (Gutteridge and Halliwell 2000). The macrophage RAW264.7 cell lines showed major free radical scavenging against ROS, and defensive effects against sodium nitroprusside, peroxynitrite induced cytotoxicity, and DNA damage when treated with seed extracts of lotus plant. In comparison to 0.1% butylated hydroxytoluene (BHT), the seed procyanidin and tannin exhibit lipid lipoxygenase inhibition, auto-oxidation, and free radical scavenging ability. Procyanidin at concentration of 62.5 mg/ml showed IC50 value of 21.6 mg/ml and inhibited lipoxygenase action by over 90% (Rai et al. 2006; Ling et al. 2005). Procyanidin and tannin of seed pods have numerous pharmacological properties along with auto-oxidation of lipids, inhibition of lipoxygenase, and free radical scavenging activity paralleled to 0.1% BHT, which inhibits autoxidation of lard (Yen et al. 2006) and remodels age-linked antioxidant deficits in older rats (Ling et al. 2005). Ushimaru et al. (2000) investigated the enzymes with antioxidative potential and their alterations in seedlings of lotus plant, which reacts to deficiency in oxygen levels by the process of germination under aquatic conditions. The enzymatic properties of superoxide dismutase (SOD), dehydro-ascorbate reductase, and glutathione reductase were lesser in lotus seedlings subjected to germination in submerged conditions along with darkness (SD) compared to seedlings subjected to germination in air along with darkness (AD) (Ushimaru et al. 2000).

2.3 Antioxidant Properties and Phytochemicals Present in Rhizomes of Nelumbo nucifera Gaertn

The fresh rhizomes of lotus plant have starch (31.2%) devoid of distinctive flavor or odor (Mukherjee et al. 1995b). The methanolic lotus rhizome extract possesses a betulinic acid which is a steroidal triterpenoid (Mukherjee et al. 1997c). The fresh rhizome has 83.80% water content, 0.11% fat content, 1.56% reducing sugar content, 0.41% sucrose content, 2.70% crude protein content, 9.25% starch content, 0.80% rhizome fibre content, l.10% ash content, 0.06% Ca-calcium content, thiamine content of 0.22 mg/100 g, riboflavin content of 0.6 mg/100 g, niacin content of 2.10 mg/100 g, ascorbic acid content of 1.5 mg/100 g, asparagine-like amino acid content of 2.00%, and oxalate content of 84.3 mg/100 g (Mukherjee et al. 1996a, b, c).

The antioxidant potential of the methanol rhizome extract and acetone rhizome extract by DPPH assay wherein the maximum DPPH scavenging action was found at 66.73 mg/l in methanol and 133.3 mg/l in acetone (Yang et al. 2007). The methanol rhizome extract revealed an elevated coefficient of antioxidant action contrast to that of ascorbic acid. The lotus rhizome knot showed radical scavenging property which was quantified by spectrophotometer and electron spins resonance (Hu and Skibsted 2002).

2.4 Antioxidant Properties and Phytochemicals Present in Flowers of Nelumbo nucifera Gaertn

Lotus flowers vary in color which became the basis for investigating the phytochemical constitution of the lotus plant. Jung et al. (2003) had obtained seven previously reported flavonoids in androecia of lotus plant together with a few alternatives of the kaempferol. Anthocyanins were also found in flower petals of the lotus plant (Yang et al. 2009). Deng et al. (2013), through HPLC analysis, identified and quantified the flavonoid compounds of 108 cultivars from petals of flowers of lotus plant and found 19 different flavonoid compounds from the class of anthocyanins, flavonols, and flavones. Chen et al. (2013) reported 5 variants of anthocyanins and 20 supplementary flavonoids from petal extracts of 12 varied genotypes wherein the cyanidin 3-O-glucoside is one of the reported anthocyanins. The flower stamens and petals comprise approximately indistinguishable array of astragalin flavonoid, rutin flavonoid, and myricetin 3-O-galactoside flavonoids (Lim 2016). Further, beta-carotene carotenoids were reported from flowers of 4 Nelumbo nucifera Gaertn varieties growing in two different provinces of Thailand (Phonkot et al. 2010).

The flavonoids with potent antioxidant activities recognized in androecia of Nelumbo nucifera Gaertn are kaempferol and its seven glycosides: kaempferol 3-O-β-D-glucopyranoside, kaempferol 3-O-β-D-galactopyranoside, kaempferol-3- O-β-D-glucuronopyranoside, kaempferol 3-O-a-L-rhamnopyranosyl-(1–2)-β-D-glucuronopyranoside, kaempferol 7-O-β-D glucopyranoside, kaempferol 3-O-a-L-rhamnopyranosyl-(1-6)-β-D-glucopyranoside, quercetin 3-O-β-D-glucopyranoside, kaempferol 3-O-a-Lrhamnopyranosyl-(1-2)-β-D-glucopyranoside, myricetin 3 0, 5 0-dimethylether 3-O-β-D-glucopyranoside, kaempferol 3-O-β-D-glucuronopyranosyl methyl ester, nelumboroside A and nelumboroside B and two isorhamnetin glycosides known as isorhamnetin 3-O-β-D-glucopyranoside, and isorhamnetin 3-O-a-L-rhamnopyranosyl-(1_6)-β-D-glucopyranoside (Hyun et al. 2006; Jung et al. 2003; Lim et al. 2006). Lim et al. (2006) reported non-flavonoids from stamen extract which includes adenine, arbutin, and β-sitosterol glucopyranoside and myo-inositol. The methanolic stamen and ethyl acetate stamen extracts were used for studying the antioxidant activity of stamen of lotus flower in scavenging genuine peroxynitrites (ONOO-), DPPH, and ROS (Jung et al. 2003).

The kidney homogenates by use of 2v, 7′-dichloro-dihydrofluoresce in diacetate scavenges DPPH free radicals and peroxynitrites (ONOO¯) and inhibits ROS generation by DCHF-DA in lotus (Jung et al. 2003). The IC50 value (DPPH) of stamen of lotus solutions in methanol of Pathum, Boontharik, Sattabongkot, and Sattabuut were 68.30_6.30, 62.22_ 4.00, 31.60_ 3.40, and 40.90_1.50 _g.mL-1, respectively, whereas of mixed-solvent solutions of Pathum, Boontharik, Sattabongkot, and Sattabuut were 2.21_0.06, 2.23_0.05, 1.29_ 0.02, and 1.83_0.07 mg.mL-1, respectively. The IC50 value (DPPH) of Sattabongkot solutions in both solvents was drastically lesser than that of others (p < 0.05, at the confidence level of 95%), while the methanol solutions were higher comparative to mixed solvents by 40 folds. The methanol solution retains flavonoids owing to their analogous polarity (Phonkot and Aromdee 2006; Harborne 1998). The mixed-solvent solution retained carotenoids (Phonkot and Aromdee 2006; Horwitz 2000).

2.5 Antioxidant Properties and Phytochemicals Present in Leaves of Nelumbo nucifera Gaertn

Nelumbo nucifera Gaertn leaves have potential as a resource of antioxidants. A range of alkaloids N-nornuciferine, (−)-caaverine, (−)-nuciferine, and roemerine were found in the plant leaves (Lim 2016). A total of 15 phytochemical compounds were isolated and identified from leaves of lotus plant, out of which lysicamine, (−)-nuciferine, and (−)-asimilobine were reported as potential natural antioxidants (Liu et al. 2014). The anonaine, liriodenine, and astragalin phytochemicals were also reported in lotus leaves (Mehta et al. 2013). Flavonoids, for example, astragalin, rutin, and quercetin, have been efficaciously isolated from ethanolic leaf extracts of lotus plant (Ohkoshi et al. 2007). Goo et al. (2009) isolated six diverse flavonoid quercetin forms from the methanolic extract of leaves of lotus plant. Chen et al. (2012) mined 13 diverse flavonoids from leaves of Nelumbo nucifera Gaertn. Out of which five flavonoids were novel in leaves of lotus plant identified by the use of an improved extraction technique and HPLC investigative method. The above-mentioned reports accentuate the varied amount of bioactive compounds of Nelumbo nucifera Gaertn leaves. The overall phenolic acids content of leaf extract of Nelumbo nucifera Gaertn plant was decided by Folin–Ciocalteau assay (Zoecklin et al. 1995). The phenolic content of Nelumbo nucifera Gaertn leaves comprises rutin, quercetin, and gallic acid (Lim 2016).

The combined gas/LC/MS has revealed that lotus leaves contain numerous alkaloids. The (+)-1(R)-coclaurine and (−)-1(S)-norcoclaurine benzylisoquinoline alkaloids showed presence in extracts of leaves. The non-phenolic fractions of leaves of Nelumbo nucifera Gaertn revealed majority compounds with retention data and mass spectra indistinguishable from anonaine, roemerine, pronuciferine, nuciferine, N-nornuciferine, liriodenine (Mukherjee et al. 1996a, b; 2009), and armepavine and N-methyl-coclaurine phenolic bases as well are present (Kunitomo et al. 1973) Dehydroemetine, remerine, armepavine, roemerine, O-nornuciferine, dehydronuciferine, nuciferine, dehydroanonaine, isoliensinine, N-methylisococlaurine, anonaine, negferine, pronuciferine, liensinine, asimilobine and lirinidine glycoside, nelumboside, flavonoids such as quercetin, quercetin 3-O-aarabinopyranosyl-(1! 2)-_-galactopyranoside, quercetin-3-O-_-D-glucuronide, rutin, (+)-catechin, hyperoside, isoquercitri, and astragalin and leuco-anthocyanidin (leucocyanidin and leucodelphinidin) showed presence in leaves of lotus and petioles (Tomita et al. 1961; Kupchan et al. 1963; Shoji et al. 1987; Nagarajan et al. 1966; Kashiwada et al. 2005; Ohkoshi et al. 2007).

Wu et al. (2003) reported hydrogen peroxide-mediated cytotoxicity in Caco-2 cells to explore the prospective antioxidant capability of the methanol extract from Nelumbo nucifera Gaertn leaves. A dose-dependent protective influence against ROS-induced cytotoxicity was detected on treatment of Caco-2 cells with 10 mM hydrogen peroxide and methanol extract of leaves (0.1 mg/ml to 0.3 mg/ml). Lotus extracts revealed concentration-dependent antioxidant potential against hemoglobin-induced linoleic acid peroxidation and Fenton reaction-mediated plasmid DNA oxidation (Wu et al. 2003; Huang et al. 2010a, b). The ethanolic extract of lotus leaves showed in-vivo antioxidant action at 100 mg/kg counter to carbon tetrachloride (CCl4) induced liver toxicity in Sprague–Dawley rats and KM mice comparative to the standard which was a hepatoprotective drug (silymarin) of 100 mg/kg (Wang 2010). The structures of major chemical constituents present in Nelumbo nucifera Gaertn are given in Fig. 2.1.

Fig. 2.1
figure 1figure 1figure 1

Chemical structure (2-dimensional and 3-dimensional) of major phytochemicals present in Nelumbo nucifera Gaertn

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2.6 Antioxidant Properties of Products Prepared from Nelumbo nucifera Gaertn

Scientific investigators have endeavored to incorporate the extracts of different parts of Nelumbo nucifera Gaertn like leaves, roots, flowers, and epicarp of seed into different products, together with animal meat, syrup, broth, and liquor and scrutinized their consequence on antioxidant activities.

According to Huang et al. (2011), the root knot and extracts of Nelumbo nucifera Gaertn leaves at 3% (w/w) act as antioxidant agent against porcine and bovine minced meat. The lotus root knot was extra effectual against oxidation of lipids during meat storage conditions Extracts of epicarp of lotus seeds equal to 100 μg/mL concentration retard early oxidation of the lipids in homogenates of pork during storage conditions (Qi and Zhou 2013). On incorporation of leaf powder of lotus plant during storage, the thiobarbituric acid reactive substances of the refrigerated chicken pastry improved (Choi et al. 2011). Shukla et al. (2016) reported a substantial enhancement in both TPC (521 mg/mL) and TFC (63 mg/mL) was reported throughout fermentation in syrup developed with incorporation of root of lotus plant. This syrup moreover exhibited elevation in antioxidation action, with IC50 value of 87.25% in DPPH assay, 99.52% in NO assay, and 44.4% in SOD assay. Additionally, syrup showed anti-tyrosinase action elevation up to 49.8%. Hwang et al. (2015) reported that broth of Nelumbo nucifera Gaertn leaves under fermentation for above 180 days displayed antioxidant action analogous to ascorbic acid. Lee et al. (2005) reported that leaves and flowers of Nelumbo nucifera Gaertn were practiced to produce customary Korean liquor with antioxidation ability plateau of 80% inhibition at concentration of >25 μg Korean liquor.

3 Potential Health Benefits

Plants have been exploited as a resource of drugs by human since antiquity. The aboriginal comprehension of several traditional communities has been devised, documented, and ultimately developed as structured medicinal systems, for example, Ayurveda, Siddha, Unani, and other medicinal systems outside India. Nelumbo nucifera Gaertn is fundamentally exploited in Ayurvedic and Unani systems of medicine as cooling, narcotic, astringent, diuretic, and antidiabetic. All the parts of Nelumbo nucifera Gaertn are employed therapeutically in contradiction of different human diseases in oriental medicine (Zhou et al. 2009). Ayurveda advocates use of this plant as diuretic and antihelmintic, and for alleviation of strangury, nausea, leprosy, disorders of skin, nervous fatigue (Khare 2004; Sridhar and Bhat 2007), cancer, inflammation of tissue, and as an antidote against toxic substances (Chopra et al. 1956; Liu et al. 2004). Lotus effectively acts as a prospective antioxidant (Rai et al. 2006), antipyretic (Deepa et al. 2009), showed antiplatelet (Brindha and Arthi 2010b) and hypoglycemic activity (Mani et al. 2010). Conventionally all parts of Nelumbo nucifera Gaertn have therapeutic properties.

Lotus rhizomes have nutritive value; they cure dysentery and unremitting dyspepsia; act as diuretic, cholagogue, and demulcent for hemorrhoids; and aid to cure fever (Mukherjee et al. 1997a, c; Kirtikar and Basu 1975; Chatterjee and Pakrashi 1991). The fresh and fleshy rhizome is sweet and aromatic; possess tonic effect; and are consumed for their nutritious value and as a curry known as Nadru Yakhni in Kashmir province of Jammu and Kashmir, India. The rhizome when heated in gingelly oil and rubbed on head of a person provides cooling effect to the rubbed area and eyes. It is excellent in cases of dysentery, diarrhea, and dyspepsia. The rhizome paste is applied in ringworm and cutaneous infections (Anon 1966; Nadkarni 1954). The saline lotus rhizome extract possesses bacteriostatic potential (Anonymous 1966). Lotus leaves alleviate hyperlipidemia, epistaxis, hematemesis, hematuria, hemoptysis, and metrorrhagia (Onishi et al. 1984). The paste of fresh Nelumbo nucifera Gaertn leaves along with sandalwood is useful in the vicinity of burning heat of the skin. The leaf stakes provide cooling effect to forehead in cephalalgia; the milky juice is given in diarrhea (Kirtikar and Basu 1933; Nandkarni 1954) and the tender leaves act as refrigerant in fever. The flowers of Nelumbo nucifera Gaertn treat fever, diarrheal disorder, cholera, and gastric ulcers (Chopra et al. 1956). Nelumbo nucifera Gaertn seeds are utilized in folk medications to cure inflammation of tissue, various types of cancers, diuretics, and the skin syndromes (Mukherjee et al. 2010a). Lotus Nelumbo nucifera Gaertn receptacles are occasionally utilized as a traditional medication for hemostatic purposes (Ling et al. 2005). The Lotus Nelumbo nucifera Gaertn seeds and fruits are exploited as a fitness foodstuff in Asia, and in treating deprived digestion, chronic diarrheal disorder, spermatorrhea, insomnia, enteritis, halitosis, heart palpitations, dermatopathy, menorrhagia, leucorrhoea, leprosy, tissue inflammation, cancer, fever, cardiac problems, antiemetic, antidote, diuretic, and refrigerant (Chopra et al. 1956; Mukherjee et al. 1996a, b; Varshney and Rzóska 1976). The powder of seeds of Nelumbo nucifera Gaertn blended with honey is beneficial in treatment of cough (Khare 2004). The seed embryos are employed in traditional Chinese medicine (TCM) for conquering disorders of nervous system, insomnia, towering fevers, and cardiovascular syndromes (Chen et al. 2007).

The numerous pharmacological activities of Nelumbo nucifera Gaertn reported include antioxidant (Hu and Skibsted 2002; Hyun et al. 2006), hepatoprotective (Rao et al. 2005), anti-analgesic (Chakravarthi and Gopakumar 2009), immunomodulatory (Mukherjee et al. 2010a), antifertility (Chauhan and Agarwal 2009), psychopharmacological (Mukherjee et al. 1996d), antipyretic (Sinha et al. 2000; Mukherjee et al. 1996e), anticancer (Chopra 1958; Liu et al. 2004; Liu et al. 2006), antiviral (Kuo et al. 2005; Kashiwada et al. 2005), hypoglycemic, antidiarrheal, antifungal, antibacterial, anti-inflammatory, and diuretic activities (Mukherjee et al. 1995a; Mukherjee et al. 1996c; 1997a, b). The other reported pharmacological properties of Nelumbo nucifera Gaertn are given in Table 2.2.

Table 2.2 Pharmacological properties of different parts of Nelumbo nucifera Gaertn
Full size table

4 Conclusions and Future Pathways

Nelumbo nucifera Gaertn possess great momentous advantages in contradiction of the free radicals and ROS species damage. Nelumbo nucifera Gaertn is testified to contain an assortment of chemical ingredients which would function as frontrunners in the exploration for novel therapeutic agents. With the accessibility of principal studies, additional scientific investigations on Nelumbo nucifera Gaertn should be designed to probe the molecular mechanisms of action by means of specific biological screening models (in vitro) and clinical trials (in vivo) and biosynthetic pathways of isolated phytoprinciples to discover novel leads and the genes responsible from them for modern day drug designing. Furthermore, scientific investigations need to be extended to develop and standardize the procedures for proficient mining and confirmation of active principles of this traditional and medicinal herb Nelumbo nucifera Gaertn for the purpose of their utilization in precise herbal formulations for curing various human disorders devoid of side effects and should be advanced for human clinical trials. Finally, there is urgent need for conservation of lotus plant as its habitat is getting disturbed, threatened, and polluted because of various anthropogenic activities.