Nutrient profiling and medicinal properties of Moringa oleifera Lam.

Abstract

Moringa oleifera Lam. is a nutritious and medicinally important tree species belonging to the family Moringaceae, and is a fast-growing, deciduous, drought-tolerant and tropical perennial tree. The medicinal properties of moringa is being attributed to the numerous primary metabolites and bioactive components, present in significant amounts in various parts of the plant. The study was conducted in the KAU moringa variety, Anupama and the nutrient content in leaves, young shoots, flowers and pods were evaluated. The study also assessed the seasonal variability in primary and secondary metabolites, medicinal properties of moringa leaves and the effect of processing on nutrient and medicinal properties of moringa leaves. Moringa flowers, leaves, young shoots and pods are good sources of all nutrients. Among the various parts, moringa leaves had the highest moisture content of 85.40 per cent. The highest protein content was observed in moringa young shoots (6.09 g per 100g) and the highest fat content was observed in moringa flowers (0.18 g per 100g). Moringa leaves are rich sources of beta carotene and vitamin C with 16265 µg per 100 g and 115 mg per 100 g, respectively. Moringa leaves had a fibre content of 6.59 g per 100 g. Moringa leaves had the highest calcium, iron and phosphorus content (238 mg per 100g, 5.12 mg per 100 g and 95.10 mg per 100 g, respectively), while the highest zinc content was observed in moringa flowers (0.34 mg per 100 g). The highest total phenol content and flavonoid content were observed in leaves with 123.60 mg and 2.12 mg per 100 g, respectively. The phytates content of moringa leaves was found to be 18.7 mg per 100 g. The highest amount of oxalates and tannins was noticed in moringa pods (15.7 and 0.31 mg per 100 g, respectively). In vitro availability of minerals like calcium, zinc, iron and phosphorous were analysed. The moringa leaves were found to have high in vitro availability for calcium (94.52 per cent) and zinc (91.30 per cent). The highest in vitro availability of iron was observed in moringa pods (79.02 per cent), whereas the highest in vitro availability of phosphorus was found in young shoots at 89.11 per cent. Physical and nutritional constituents of moringa leaves were analysed at an interval of two months for one year. Variations in primary and secondary metabolites were observed in monthly intervals. The highest amount of moisture, protein, fat, beta carotene and fibre was observed in the months of July-August. The leaves had the highest total phenol, total flavonoid, oxalates and tannins contents in the month of July-August. The presence of various volatile and nonvolatile compounds were analysed and variations were observed in certain months. Volatile compounds identified were docosane, tetracontane, αtocopherol-β-D-mannoside, vitamin E, octadecanoic acid, 1,3- dipalmitin trimethyl ether, docosahexaenoic acid, 1,2,3- propanethyl ester, triacontane and isophytol. Non-volatile compounds like indoleacrylic acid, anthranilic acid, 3- hydroxycoumarin, 19-noretiocholanolone, haplophytine, pheophorbide a, apigenin-7-glucoside, kaempferol, quercetin, maritimetin, irinotecan, sertindole and myricetin 7-rhamnoside were present in all months. In Kerala, moringa leaves are not consumed during the month of Karkidakam, due to their bitter taste. Hence, a comparative evaluation was done to know the changes taking place in Karkidakam, which falls from July-August. Non-volatile compounds identified exclusively in the month of JulyAugust (Karkidakam) were adenosine, phenyl alanine, ketotifen, umbeliferone, benzofuran, oxopalmitate, gingerglycolipid A, hematoporphyrin, euphormin and oligomycin C. Volatile compounds exclusively present in the month of JulyAugust were α-tocopherol-β-D-mannoside, triacetyl trithiophosphite, αtocopherol–β–D mannoside, dihydromorphine, morphinan. Among these compounds, adenosine, oligomycin C, euphormin, umbelliferone, morphinan and dihydromorphine are known to be toxic compounds. Compounds in cyanogenic pathway was increased during heavy rainfall in moringa leaves. The compounds hematoporphyrin, euphormin and umbeliferone are intermediates in cyanide pathway. Organoleptic evaluation of cooked moringa leaves and moringa leaf soup were done at bimonthly intervals and the lowest overall acceptability scores of 6.95, 6.90 were obtained during July-August respectively and the highest overall acceptability scores (7.92 and 7.89) were observed in January-February respectively. Moringa leaves possess potent antioxidant, antimicrobial and antiproliferatory activities. A positive correlation was observed with concentration and per cent inhibition of free radicals. The projected IC50 values for DPPH, hydroxyl and superoxide radical scavenging activity are 51.57, 49.86 and 89.32, respectively. The effective concentration (EC50) for total antioxidant activity is 3.60 µg/ml. Moringa leaves showed antimicrobial activity against human pathogens like Staphylococcus aureus, Pseudomonas aeruginosa, Shigella sonnei, Salmonella typhi, Escherichia coli, Aspergillus niger and Candida albicans. The anti-proliferatory activity was studied in hepatic cancer cell lines using moringa leaf extract. The proliferation of cancer cell lines was inhibited by moringa leaf extract and the per cent inhibition increased with the concentration of the leaf extract. The projected IC50 value, for the anti-proliferatory activity of the hepatic cancer cell line was 41.32 µg/ml. The study also evaluated the effect of processing on nutrient content and medicinal properties of shade dried leaves (room temperature), oven dried leaves (50ºC for 8 hrs) and steamed leaves (3 minutes). Shade drying of moringa leaves was found to be the best drying method. On drying, the protein, fibre and mineral content in leaves became concentrated, whereas a statistically significant decrease in beta carotene and vitamin C content was observed. Antioxidant, antimicrobial and anti-proliferative activity was higher in shade dried leaves compared to oven dried and steamed dried leaves. It is proved that there is immense scope for developing nutraceuticals, molecular docking and value-added products from different parts of the moringa tree.