Antioxidant Activities, Phytochemical, And Micro-Nutrients Analysis Of African Moringa (Moringa Ovalifolia)

ABSTRACT

Moringa ovalifolia (African Moringa) is endemic to southern Africa, and it is distributed from southern to central Namibia to south western Angola. At the moment, little is documented on the phytochemical content, miro-nutrients and antioxidant activities of M. ovalifolia. Hence, this study was aimed at evaluating the phytochemical, micro- nutritients and antioxidant activities of M. ovalifolia. Fresh Moringa leaves, bark, flowers and seeds (ponds) were collected from five different sites. Soxhlet extraction method was used for extraction, and thereafter different analyses were performed using UV-Vis spectrophotometer. Antioxidant properties were investigated using three indicators: reducing activity (700 nm), DPPH (2, 2-diphenyl-1-picrylhydrazyl) radical scavenging activities (515 nm) and total phenolic content (740 nm). High perfomance liquid chromatography (HPLC) with UV detector (254 nm) was used in the identification and quantification of flavonols. Elemental composition of the leaves was determined using the Inductively coupled plasma optical emission spectroscopy (ICP-OES). The total phenolic content of M. ovalifolia remained almost the same in samples from different sites, but varies in different plant parts. M. ovalifolia leaves, flowers reduced DPPH by nearly 20%, while the seed and bark reduced the DPPH by 12%. The following flavonols were present: Kaempferol, Quercetin and Myrietin. High amounts of quercetin were recorded, with the highest amount of about 16 844.47 ± 194.336 mg/Kg in leaves from site 4. Micro-nutrients analysis revealed the presence of: Ba (2.1±0.13 mg/Kg), Cd (6.2±0.29 mg/Kg), Co (3.4±0.17 mg/Kg), Li (10.9±0.05 mg/Kg), Mn (17.7±0.17 mg/Kg), Si (12.6±0.14 mg/Kg), Al (28.4±2.63 mg/Kg), Zn (59.1±0.88 mg/Kg), Cu

iii

(29.8±0.42 mg/Kg), Ni (27.4±0.99 mg/Kg), Fe (84.7±2.21 mg/Kg), Na (190.5±7.15 mg/Kg), Ca (2427.90±187.62 mg/Kg), K (6399.92±387.04 mg/Kg) and Mg (3974.94±262.69 mg/Kg) from site 1. The leaves have a high conentration of these elements: Ca, K and Mg compared to other elements present. The concentration of different elements varies from site to site, and sample to sample. These variations could have been influenced by geographical location, soil conditions, climatic conditions and other factors. Hence results of this study indicates that M. ovalifolia can play a role in improving the health and nutrition, particularly in malnourished populations.

Keywords: Moringa ovalifolia, Macronutrients, Micronutrients, Metal content, Elemental analysis, Flavonoids, Total phenolics, ICP-OES, HPLC, Soxhlet extraction, DPPH radical scavenging activies, Reducing power, UV-Vis spectrophotometer