Keshav Raj Paudel 1,*, Nisha Panth 1
Abstract
Nelumbo nucifera Gaertn. (Nymphaeaceae) is a potential aquatic crop grown and consumed throughout Asia. All parts of N. nucifera have been used for various medicinal purposes in various systems of medicine including folk medicines, Ayurveda, Chinese traditional medicine, and oriental medicine. Many chemical constituents have been isolated till the date. However, the bioactive constituents of lotus are mainly alkaloids and flavonoids. Traditionally, the whole plant of lotus was used as astringent, emollient, and diuretic. It was used in the treatment of diarrhea, tissue inflammation, and homeostasis. The rhizome extract was used as antidiabetic and anti-inflammatory properties due to the presence of asteroidal triterpenoid. Leaves were used as an effective drug for hematemesis, epistaxis, hemoptysis, hematuria, and metrorrhagia. Flowers were used to treat diarrhea, cholera, fever, and hyperdipsia. In traditional medicine practice, seeds are used in the treatment of tissue inflammation, cancer and skin diseases, leprosy, and poison antidote. Embryo of lotus seeds is used in traditional Chinese medicine as Lian Zi Xin, which primarily helps to overcome nervous disorders, insomnia, and cardiovascular diseases (hypertension and arrhythmia). Nutritional value of lotus is as important as pharmaceutical value. These days' different parts of lotus have been consumed as functional foods. Thus, lotus can be regarded as a potential nutraceutical source.
1. Introduction
Traditional medicine or indigenous medicine denotes medical practice developed by local ethnic people via use of natural herbs and mineral. Different place of world has its own history of traditional medicine, for example, ayurvedic medicine originated from Southeast Asia, unani medicine originated in Arab countries/middle east, and acupuncture and traditional Chinese medicine (TCM) originated in China [1–3]. Herbal plants contain secondary metabolite like alkaloids, glycosides, terpene, steroids, flavonoids, tannins, and so forth. Some chemical substances are phenols or their oxygen-substituted derivatives such as tannins while some may contain nitrogen or sulphur that are biologically active and useful for the prevention of disease and treatment of ailment and preserve well-being in humans and animals. Polyphenols exhibit antioxidant activity which lead to many health benefits [4, 5]. Apart from biological activity in human, these chemicals function as plant defense mechanisms against their predator. For human, many of these herbal products and spices serve as useful medicinal source since antiquity [6].
2. History
Nelumbo nucifera comes under the family Nelumbonaceae, which has various local tribal names (Indian lotus, bean of India, Chinese water lily, and sacred lotus) and several botanical names (Nelumbium nelumbo, N. speciosa, N. speciosum, and Nymphaea nelumbo). As far as the history is concerned, this beautiful flowering aquatic plant has been honored in the history by three countries: China, India, and Egypt [7–9]. Pictorial representation of the flower can be seen in the art of all of these countries' cultures, symbolizing perfection, purity, and beauty. On the dietary aspect, almost all parts of the plant are used in preparing diverse cuisines depending upon cultures of that place. History reveals that sacred blue lotus (Nymphaea caerulea) was distributed and widespread along the Nile river banks [9, 10]. In ancient period, Egyptians worshipped different parts of lotus, widely depicted in their architectural design. Initiation of lotus horticulture in western Europe was introduced by Sir Joseph Banks during 1787 in the form of stove-house water lily whereas these days it is widespread almost everywhere in modern herbal garden. Mostly, lotus plants are popular in Australia pacific, China, India, Korea, and Japan [9, 11].
3. Physical Characteristics and Description
Nelumbo nucifera is a large aquatic rhizomatous herb consisting of slender, elongated, creeping stem with nodal roots. Lotus is perennial plant with both aerial and floating orbicular leaves. Aerial leaves are cup shaped and floating leaves have flat shape. Its petioles are considerably long and rough with distinct prickles. Flowers vary in color from white to rosy and are pleasantly sweet-scented, solitary, and hermaphrodite. Flower average diameter is 10–25 cm, and it is ovoid and glabrous. Fruit which contain seeds, are black in color, and are hard and ovoid are arranged in whorls; seeds ripened and were released as a result of bending down of pod to the water. Tuberous roots are 8 inches long and 2 inches in diameter. Smooth outer skin of the lotus root is green in color; however, the inner part possesses numerous big air pockets running throughout the length of the tuber assisting for floating in the aquatic system [12, 13].
4. Phytochemicals and Constituents
The reported chemical constituents in the different parts of Nelumbo nucifera are as shown in the following.
(1) Embryo. The phytochemicals reported in embryo of Nelumbo nucifera are shown in Figure 1 [14, 15].
Figure 1.
Major chemical constituents present in Nelumbo nucifera embryo.
(2) Stamen. The phytochemicals reported in stamen of Nelumbo nucifera are shown in Figure 2 [12, 16–18].
Figure 2.
Major chemical constituents present in Nelumbo nucifera stamen.
(3) Flower. The phytochemicals reported in flower of Nelumbo nucifera are shown in Figure 3 [16, 19].
Figure 3.
Major chemical constituents present in Nelumbo nucifera flower.
(4) Leaf. The phytochemicals reported in leaf of Nelumbo nucifera are shown in Figure 4 [12, 16, 19, 20].
Figure 4.
Major chemical constituents present in Nelumbo nucifera leaf.
(5) Seed. The phytochemicals reported in seed of Nelumbo nucifera are shown in Figure 5 [12, 16].
Figure 5.
Major chemical constituents present in Nelumbo nucifera seeds.
5. Reported Pharmacological Activity of Nelumbo nucifera
5.1. Antioxidants
Hydroalcoholic extract of Nelumbo nucifera (HANN) seeds was investigated for antioxidant potency using in vitro and in vivo models. In vitro results showed that HANN exhibited significant DPPH (1,1-diphenyl-2-picrylhydrazyl) free radical scavenging activity with IC50 values of 6.12 ± 0.41 μg/mL and nitric oxide (NO) scavenging activity with IC50 value of 84.86 ± 3.56 μg/mL. These results were even better than rutin used as standard. In in vivo model, HANN administration to Wistar strain rats at a dose of 100 and 200 mg/kg body weight for a time period of 4 days prior to carbon tetrachloride (CCl4) administration resulted in a significant dose-dependent raise of superoxide dismutase (SOD) and catalase enzyme level and significant fall in the level of thiobarbituric acid reactive substances (TBARS), as compared to CCl4 treated alone (control group) in both liver and kidney. The changes observed at 100 mg/kg body weight treatment were comparable to those observed for tocopherol (50 mg/kg) treatment. Nelumbo nucifera seeds contain variety of phytochemical-like saponins, alkaloids, polyphenolics, and carbohydrates supporting significant antioxidant activity of HANN [21]. Lee et al., 2005, studied the antioxidant effect of Korean Traditional Lotus Liquor (Yunyupju) which was made from lotus blossom and leaves. The antioxidant effects were dose-dependent and reached a peak (about 80% inhibition) at a concentration of more than 25 μg of lotus liquor. The liquor exhibited significant DPPH scavenging activities (IC50 = 17.9 μg) [22]. Yen et al., 2006, reported the reactive nitrogen species scavenging activity of lotus seed extracts. The potency of lotus seed extracts, namely, water extract (LSWE), ethyl acetate (LSEAE), and hexane (LSHE), to inhibit reactive nitrogen species in macrophage RAW 264.7 cells was investigated. In results, all the extracts of lotus suppress NO production in lipopolysaccharide stimulated RAW 264.7 cells. There was a dose-dependent inhibition of the accumulation of NO upon decomposition of sodium nitroprusside (SNP). In comparison, the potency order was LSEAE > LSWE > LSHE. Further supportive role of lotus extracts to protect DNA breakage in macrophage RAW 264.7 cells promoted by SNP was shown in comet assay. LSWE, LSEAE, and LSHE, at a dose of 0.2 mg/mL, showed 63%, 59%, and 38% inhibition of DNA damage induced by peroxynitrite, respectively. All extracts were found to be peroxynitrite scavengers and thus capable of preventing tyrosine nitration [23]. Ling et al., 2005, extracted the procyanidins from lotus seedpod with Me2CO/H2O. Among the monomers, dimers, and tetramers of procyanidins, the extract contained high amounts of dimers whereas catechin and epicatechin were the base units. These procyanidins were also investigated for lipid peroxidation, lipoxygenase enzyme activity, and reactive free radical scavenging activity. The superoxide radical scavenging potency of lotus pod procyanidin shows the IC50 value of 17.6 mg/L (4-fold less potent as compared to IC50 4.1 mg/L of ascorbic acid). The study also revealed that 0.1% of procyanidins have a significant antioxidant activity in a system of soybean oil, even better than butylated hydroxytoluene (BHT) at a similar concentration [24]. Kim et al., 2014, showed that 80% methanol extract of Nelumbo nucifera seed's embryo decreases in ROS production in mouse hippocampal HT22 cells and scavenges DPPH free radical (IC50 value as 240.51 μg/mL) and H2O2 (IC50 value as 1769.01 μg/mL) [25].
5.2. Antisteroids
The antisteroidogenic activity of N. nucifera seed extract in the ovary and testis of the rat was studied by Gupta et al., 1996. In this study, petroleum ether extract fraction was orally given to sexually immature female rats and mature male rats up to 15 days at alternative day. There was a marked delay in sexual maturation in prepubertal female rats as revealed from age of vaginal opening and first estrus (cornified smear) whereas there was reduction in sperm motility and sperm count in male rats. Furthermore, the application of extract resulted in accumulation of ascorbic acid and cholesterol and reduction in δ-5-3-β-hydroxysteroid dehydrogenase and glucose-6-phosphate dehydrogenase activity in the ovary and testis. Thus, this research explores that the petroleum ether extract can suppress the genesis of steroids in reproductive organs of rats [26]. Similarly, Wethangkaboworn and Munglue, 2014, purpose the 3 hypotheses for inhibitory effect of N. nucifera seed extract on male rat sexual behavior to support its antifertility activity: (1) suppression of hypothalamic gonadotropin releasing hormone production, (2) pituitary gonadotropic hormone production, including follicle stimulating hormone (FSH) and luteinizing hormone (LH), or (3) testosterone production [27]. Mutreju et al., 2008, showed that administration of N. nucifera to female rats caused estrogen inhibition due to its antiestrogenic nature [28].