2.2 Geographic DistributionMoringa oleifera(Family: Moringaceae) is a perennial angiosperm plant, which includes several other species. It is a native of the Himalayan region that is widely cultivated throughout tropical and sub-tropical countries of the world including Saudi Arabia. The plant has numerous medicinal applications and is used as a traditional medicine for the treatment of various illnesses such as skin diseases, respiratory distress, ear and dental infections, hypertension, diabetes, anemia, and cancer ( Al-Asmari et al.,2015).
The “Moringa” tree is grown mainly in semi-arid, tropical, and subtropical areas. It is native to the sub-Himalayan tracts of India, Pakistan, Bangladesh and Afghanistan (Fahey., 2005). It grows best in dry sandy soil; it tolerates poor soil including coastal areas. It is a fast-growing, drought resistant tree. Today it is widely cultivated in Africa, Central and South America, Sri Lanka, India, Mexico, Malaysia, Indonesia and the Philippines. Moringa is a short, slender, deciduous, perennial tree about 10 m tall with drooping branches, brittle stems and branches, corky bark, feathery pale green 30–60 cm long compound leaves, with many small leaflets which are 1.3–2 cm long, 0.6–0.3 cm wide, fragrant white or creamy-white flowers having 2.5 cm in diameter and borne in sprays, pendulous brown triangular pods, splitting lengthwise into 3 parts when dry, containing about 20 dark brown seeds embedded in the pith, pod tapering at both ends. Main root is thick (Alhwarat and Al-Mahameed., 2013).
2.3 Plant Morphology
It is considered one of the world’s most useful tree, as almost every part of the Moringa tree can be used for food or has some other beneficial property. In the tropics, it is used as forage for livestock, and in many countries Moringa micronutrient liquid, a natural anthelmintic (kills parasites) and adjuvant (to aid or enhance another drug) is used as a metabolic conditioner to aid against endemic diseases in developing countries (Foidle et al., 2001). Moringa oleifera is the most nutrient-rich plant yet discovered. Moringa provides a rich and rare combination of nutrients, amino acids, antioxidants, antiaging and anti-inflammatory properties used for nutrition and healing. M. oleifera is a miracle tree with a great indigenous source of highly digestible proteins, Ca, Fe and vitamin C (Fahey, 2005). Some articles and research studies have reported that the dry leaves of M. oleifera contain 7 times more vitamin C than orange, 10 times vitamin A than carrot, 17 times calcium than milk, 15 times potassium than bananas, 25 times iron than spinach and 9 times proteins than yogurt (Fuglie, 1999). In addition, it contains vitamin B complex, chromium, copper, magnesium, manganese, phosphorus and zinc (Fuglie, 2000). Thurber and Fahey (2009) stated M. oleifera leaves as rich protein source, which can be used by doctors, nutritionists and community health conscious persons to solve worldwide malnutrition or under nutrition problems. According to researchers Moringa has the potential to combat vitamin A and other micronutrient deficiencies (Nambiar, 2006). Moringa has been in use since centuries for nutritional as well medicinal purposes. Another important point is that Moringa leaves contain all of the essential amino acids, which are the building blocks of proteins. It is very rare for a vegetable to contain all of these amino acids. Moringa contains these amino acids in a good proportion, so that they are very useful to our bodies.
2.4 Phytochemical composition of Moringa oleifera
Phytochemicals are, in the strictest sense of the word, chemicals produced by plants. Commonly, the word refers to only those chemicals which may have an impact on health, or on flavor, texture, smell, or color of the plants, but are not required by humans as essential nutrients. An examination of the phytochemicals of Moringa species affords the opportunity to examine a range of fairly unique compounds. In particular, this plant family is rich in compounds containing the simple sugar, rhamnose, and it is rich in a fairly unique group of compounds called glucosinolates and isothiocyanates . For example, specific components of Moringa preparations that have been reported to have hypotensive, anticancer, and antibacterial activity include 4-(4′-O-acetyl-?-L-rhamnopyranosyloxy)benzylisothiocyanate,4-(?-L-rhamnopyranosyloxy)benzyl isothiocyanate, niazimicin , pterygospermin , benzyl isothiocyanate , and 4-(?-L- rhamnopyranosyloxy) benzyl glucosinolate. Along with these compounds, it is also rich in a number of vitamins and minerals as well as other more commonly recognized phytochemicals such as the carotenoids (including ?-carotene or pro-vitamin A).
According to Rahaman (2017), Moringa oleifera is a rich source of benzyl glucosinolate and isothiocyanates (ITCs). Several major phytochemicals of Moringa oleifera are glucosinolates, phenolics, flavonoids, crude fats, fatty acid, and major nutrient, mineral, and total protein.