Chapter 1. Introduction

Transcription

1 Chapter 1 Introduction

2 1.1. Introduction Increased demand for food to tackle hunger and malnutrition problems is pertinent in India over the last few decades. In India, vast majority of the population suffers from malnutrition; this is mainly due to deficiency of nutrients in foods. Moringa oleifera Lam., (syn. Moringa pterygosperma Gaertn., 2n = 28), belongs to family Moringaceae, commonly known as horseradish or drumstick tree, is an affordable and readily available source of major nutrients and nutraceutical compounds, and it can be used to eradicate the malnutrition. Different vegetative and reproductive parts of Moringa oleifera tree are shown in figure 1. Moringa species are often considered as important famine foods because of their high tolerance to drought and arid conditions owing to their tuberous roots (Sena et al. 1998). Almost each and every part of Moringa trees are useful for medicinal, functional food preparations and nutraceuticals; including roots, leaves, flowers, green pods and seeds (Anwar et al. 2007). Immature pods, flowers and leaves of this tree are used for culinary purposes in different parts of the word (Siddhuraju and Becker 2003). Moringa seeds oil (yield 30-40% by weight, known as Ben oil ) is used for the production of cooking oil, biodiesel (da Silva et al. 2010), high value lubricant (Sharma et al. 2009), to manufacture perfumes and hair care products (Tsaknis et al. 1999), and edible preparations of medical importance in relevance to liver protection (Al-Said et al. 2012). Fresh leaves of M. oleifera have been established as rich source of carotenoids (Bhaskarachary et al. 1995), iron (Anjorin et al. 2010), folate (Devi et al. 2008), fatty acids (Amaglo et al. 2010), tocopherols (Ching and Mohamed 2001), ascorbic acid (Bineesh et al. 2005), phenolics and glucosinolates (Bennett et al. 2003), but no efforts have been made to evaluate these phytoconstituents in Indian cultivars. Similarly information of these phytoconstituents in fruits and flowers are not 1

3 available. Knowledge on nutrient composition in different edible parts and cultivars of Moringa will be useful to nutritional experts for selecting nutrient-rich fresh material for food formulation and proper diet recommendation. Variations in level of different nutrients can be obtained by challenging genetic and environmental factors (Strålsjö et al. 2003; Kuti and Konuru 2005). The variability due to genetic factors can be assessed by studying genetic diversity (Muluvi et al. 1999). Therefore, same such studies were conducted to quantify the carotenoids, folate, iron, ascorbic acid, tocopherol and fatty acids in in different cultivars of M. oleifera, followed by assessment of genetic diversity in studied cultivars. The content of some unique compounds and nutritionally important phytoconstituents in leaves of M. oleifera are given in table 1.1 and

4 (a) (b) (c) (d) (e) M. oleifera M. oleifera (f) Figure 1.1. Different vegetative and reproductive parts of Moringa oleifera tree. (a) Field grown M. oleifera tree, (b) potted plant, (c) fruit, (d) bundle of foliage, (e) flowers and (f) M. oleifera cultivars established in field as germplasm. 3

5 Table 1.1. Content and structure of some important unique compounds reported in leaves of M. oleifera ame of Phytochemical Content (mg/100g FW) 4-Hydroxybenzyl (sinalbin) 59.0 Structure 4-O-(a-L-rhamnopyranosyloxy)- benzylglucosinolates (R1=R2=R3=H ) 4-O-(α-L-Acetyl-rhamnopyranosyloxy)- benzylglucosinolates (R2=R3 =H; R2=Ac) 3-Caffeoylquinic acids (Neochlorogenic acid) Caffeoylquinic acids (Chlorogenic acid) Kaempferol-3-O-rutinoside (R3= GlcRha; R3 =H; R4 =OH) Kaempferol-3-O-glucoside (R3= Glc; R3 =H; R4 OH) Quercetin-3-O-rutinoside (R3= GlcRha; R3 = R4 =OH) Quercetin-3-O-glucoside (R3= Glc; R3 = R4 =OH) Quercetin-3-O-6 malonylglucoside (R3= GlcMal; R3 = R4 =OH) Source- Sánchez-Machado et al. (2010)

6 Table 1.2. Content of nutritionally important phytoconstituents in leaves of M. oleifera Major Class Phytoconstituents Per 100g Reference Total carotenoids 42.1 (Bhaskarachary et al. 1995) (Lakshminarayana et al. 2005) 19.7 (Bhaskarachary et al. 1995) 5.2 (Begum and Pereira 1977) β-carotene 3.2* (Monica 2005) Carotenoids (mg) 5.7 (Tee and Lim 1991) 4.6* Neoxanthin 1.9* Violaxanthin 3.7* (Lakshminarayana et al. 2005) Lutein 10.0 Zeaxanthin 0.82* 5.6* (Monica 2005) 5.7* (Barminas et al. 1998) Fe 7.4* (Sena et al. 1998) 4.5* (Freiberger et al. 1998) 4.1 (Anjorin et al. 2010) Minerals (mg) 346 Ca 324* Mg 72 (Anjorin et al. 2010) 342* Na 90* K 460 Tocopherol (mg) α-tocopherol 9 (Ching and Mohamed 2001) Vitamin C (mg) Ascorbic acid 249 (Yang et al. 2006) Folate/Vitamin B9 (μg) Total folate 101 (Devi et al. 2008) Oxalate (mg) Oxalic acid 224* (Nambiar and Seshadri 2001) Aspartate 316* Glutamate 342* Serine 188* Histidine 140* Glycine 206* Amino Acids (mg) Threonine 158* (Sánchez-Machado et al. 2010) Alanine 250* Proline 248* Tyrosine 96* Arginine 244* Valine 226* 5

7 Methionine 28* Isoleucine 178* Leucine 350* Phenylalanine 178* Lysine 306* Total 3454* C8: C12: C14: C14:1w5 0.5 C16: C16:1w C18: Fatty acids (% of total fatty acid) C18:1w C18:1w C18:2w *Converted to fresh weight basis from reported dry weight (fresh weight = dry weight x 5; by considering the 80% moisture content). Significant losses of carotenoids and folates occur during processing of the leaves (Chen et al. 1995; Strålsjö et al. 2003), which is a bottleneck in the maintenance of effective levels of these phytoconstituents in processed products. This problem could be addressed by increasing the content of phytoconstituents in preharvest conditions. A novel elicitor mediated approach thus seems to be possible for increasing the carotenoid synthesis in Moringa leaves. Similarly, mineral content in plants is significantly influenced by soil fertility and therefore external application of mineral formulation is also found beneficial to enhance the minerals content in plants (Fernández et al. 2004). C18:3w C20: C20:4w C22: Saturated FAs Monounsaturated FAs 7.23 Polyunsaturated FAs Unsaturated FAs

8 A few reports on the tissue culture methods for clonal propagation of Moringa oleifera has been described through the use of nodal explants obtained from nonaseptic sources, either from young seedlings or mature plants (Stephenson and Fahey 2004; Islam et al. 2005; Marfori 2011). The conservation of Moringa species is thus of great use from biodiversity, ethnobotanical, dietary and pharmacological perspectives. Several factors such as, host-related factors, food matrix and absorption modifiers may influence the iron and folate absorption (Strube et al. 2002). Moringa leaves also contain high amounts of ascorbic acid and carotenoids, which are known enhancers of iron absorption (Strube et al. 2002). Ascorbic acid reduces the ferric form of iron (Fe +3 ) into ferrous (Fe +2 ) in duodenum, as divalent metal ion transporter 1 (DMT1) transports only ferrous iron (McKie et al. 2001). So the investigations were also conducted to estimate the bioavailability of iron and folate from dehydrated leaves of M. oleifera, in iron and folate depleted rats, respectively. As M. oleifera is becoming popular as an important food commodity in view of its current status as the natural nutrition of the tropics (Anwar et al. 2007), there is ample scope for nutritional characterization, enhancement, biological activity in animals and further improvement for health benefits and sustainable development. With this background, the objectives of the Ph.D. study were set as follows: 1. Screening of leaves of Moringa oleifera germplasm for folic acid, iron and carotenoids 2. Enhancing folic acid, iron and carotenoid content in Moringa oleifera leaves through elicitors 3. In vitro propagation of selected variety of Moringa and hardening of tissue cultured plants in field condition 4. Studies on bioavailability of folic acid and iron in animal models 7