Profiling of polyphenolics, nutrients and antioxidant potential of germplasm’s leaves from seven cultivars of Moringa oleifera Lam.
Graphical abstract
Introduction
Moringa oleifera L. is a member of the Moringaceae family, native to India and Pakistan, which grows naturally at moderate altitude. Currently, moringa plants are widely cultivated in the Middle East, Africa and Southern Asia as a multipurpose crop (Sánchez et al., 2006, Nouman et al., 2014a), using a production system characterized by high biomass yield and fast re-growth after pruning (Foidl et al., 2001). Moringa crops can produce approximately 580 t/ha of moringa fresh shoot biomass annually. However, this yield is strongly dependent on the season, the weather conditions, the cultivar considered, and on the application of fertilizers (Palada et al., 2007). Besides yield, the analysis of the nutritional composition of moringa biomass has allowed to describe an interesting and balanced content of crude protein (16.8%), carbohydrates (9.9%), starch (7.9%) and lipids (4.9%) (Foidl et al., 2001).
To date, moringa leaves are used by agro-food and biochemical industries as a food, fodder, biopesticide, green manure, natural coagulant for turbid water, and plant growth enhancer (Bennett et al., 2003, Anwar et al., 2007, Gidamis et al., 2003, Nouman et al., 2012, Nouman et al., 2014b). Since moringa leaves have been investigated as a valuable source of dietary proteins and essential amino acids, hence, over the last several years their use as an ingredient in livestock and humans nutrition has been encouraged (Amaglo et al., 2010). Besides their use as an ingredient for foods and feeds; an impressive range of intrinsic bioactive phytochemicals including glucosinolates, isothiocyanates, carotenoids, and phenolic compounds of moringa leaves, has allowed to envisage their potential applications as a functional food and nutraceutical health promoter (Bennett et al., 2003, Fahey, 2005, Anwar et al., 2007, Amaglo et al., 2010, Leone et al., 2015). However, to date the biological activity and medicinal functions of moringa extracts has been mainly supported by in vitro assays based upon their antioxidant capacity and bioactives profile (Anwar et al., 2007, Sultana et al., 2009).
Data available on phytochemical composition of moringa plants suggest that the polyphenolic content of moringa is closely dependent on the germplasm considered, maturity stage, and agro-climatic conditions (Anwar et al., 2006, Nouman et al., 2014a). In this connection, to the best of our knowledge, so far these data are limited to specific germplasm (mostly Ghanaian or Malaysian cultivars), which have been mainly evaluated for polyphenolic content and innovative applications by food/pharmaceutical industries (Freiberger et al., 1998, Bennett et al., 2003). Whilst no such evaluation has been performed regarding moringa leaves of Pakistan (Black and White) as well as Chinese and African cultivars including ‘Tumu’, ‘Sunyaw’, ‘Kumasi’, and ‘Techiman’.
To date the antioxidant capacity of moringa leaves was supported by non-enzymatic assays namely DPPH and linoleic acid peroxidation (LAP) assays. DPPH is a non-biological radical extensively used to test the antioxidant capacity of plant extracts (Gironés-Vilaplana et al., 2014), whilst LAP assay is based on the capacity to inhibit of the linoleic acid peroxidation of vegetal samples (Osawa and Namiki, 1981). Thus, the implementation of these two methods with assays devoted to evaluate the enzymatic antioxidant activity could provide a more complete information regarding the antioxidant properties of moringa leaves.
The aim of this work was to evaluate the selected nutrients (protein and minerals content) and polyphenolic composition as well as the enzymatic (superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activities) and non-enzymatic antioxidant capacity of hydro-methanolic extracts of moringa leaves from seven cultivars representing the cultivars most extensively grown in the region (‘Tumu’, ‘Sunyaw’, ‘Kumasi’, ‘Techiman’, ‘China’, ‘Pakistan Black’, and ‘Pakistan White’). This information is intended to be integrated with the nutritional evaluation of moringa leaves in order to identify the most valuable cultivars and guarantee the sustainability of moringa crop in Pakistan.
Section snippets
Reagents
All LC–MS grade solvents were obtained from J.T. Baker (Phillipsburg, NJ). Formic acid was purchased from Panreac (Barcelona, Spain). The standards quercetin-3-O-glucoside and 5-O-caffeoylquinic acid were from Sigma–Aldrich (Steinheim, Germany). Ultrapure water was produced using a Millipore water purification system.
Plant material and sample preparation
M. oleifera seeds of the cultivars ‘Tumu’, ‘Sunyaw’, ‘Kumasi’, ‘Techiman’, ‘China’, ‘Pakistan Black’ (black seeded moringa), and ‘Pakistan White’ (white seeded moringa) were
Phenolic compounds
The HPLC-PDA-ESI-MSn analysis of hydro-methanolic extracts of moringa leaves revealed a wide range of phenolic compounds, being flavonols the major class (Table 1). Moreover, hydroxycinnamic acids were also detected in the analysed samples. Some of these compounds were recently identified in moringa leaves (Bennett et al., 2003, Amaglo et al., 2010, Khartivasan et al., 2013). Thus, according to retention time, molecular masses, and fragmentation patterns twelve flavonols and five cinnamic acids
Conclusions
To date, only a limited number of studies dealing with the nutritional and phytochemical composition of M. oleifera and the biological activity of its leaves’ extracts are available. In this connection, the overall results obtained in the present work revealed crucial differences regarding the phenolic profile of Moringa leaves as well as on the content of total and individual phenolics (phenolic acids and flavonols) along with enzymatic and non-enzymatic antioxidant activities among seven M.
Acknowledgement
This work was supported by national funds from FCT—Portuguese Foundation for Science and Technology, under the project PEst-OE/AGR/UI4033.
References (40)
- et al.
Profiling selected phytochemicals and nutrients in different tissues of the multipurpose tree Moringa oleifera L. grown in Ghana
Food Chem.
(2010) A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding
Anal. Biochem.
(1976)- et al.
Assay of catalase and peroxidases
Methods Enzymol.
(1955) - et al.
The mechanism of catalase action: 1. Steady-state analysis
Arch. Biochem. Biophys.
(1952) - et al.
Polyphenolic content and antioxidant properties of Moringa oleifera leaf extracts and enzymatic activity of liver from goats supplemented with Moringa oleifera leaves/sunflower seed cake
Meat Sci.
(2012) - et al.
Isolation, identification and stability of acylated derivatives of apigenin 7-O-glucoside from chamomile (Chamomilla recutita [L.] Rauschert)
Phytochemistry
(2004) - et al.
Plant seeds as mineral nutrient resource for seedlings—a comparison of plants from calcareous and silicate soils
Ann. Bot.
(1998) - et al.
Maximizing total phenolics, total flavonoids contents and antioxidant activity of Moringa oleifera leaf extract by the appropriate extraction method
Ind. Crops Prod.
(2013) - et al.
Role of superoxide dismutases (SODs) in controlling oxidative stress in plants
J. Exp. Bot.
(2002) - et al.
Effect of salinity on yield and quality of Moringa oleifera seed oil
Grasas y Aceites
(2006)