This study focused on two woody leafy vegetables Leptadenia hastata Decne and Senna obtusifolia Link, commonly consumed in Senegal. Leaves were col-lected from three regions. Then, proximate analyses and micronutrients were carried out to evaluate their nutritional values. Results revealed that protein level of S. obtusifolia (SO) is richer (21.75%) than Leptadenia hastata (LH) (18.16%). The cellulose and carbohydrate contents of the two vegetable’s leaves are in the same order except those of LH from Widou which are less rich in cellulose (8.31%) and richest in carbohydrate (6.35%). These leaves are also good sources of various mineral elements and especially iron. Leaves of LH appear to be richer in iron and magnesium, while SO appears to be richer in calcium. Vitamin C intakes of SO leaves are better than those of LH and respectively range from 142 to 196.5 and 22.5 to 159.5 mg/100 g. According to the use of this leafy vegetable by the populations, a domestication opportunity is thus justified to ensure availability and accessibility of these significant sources of micronutrients.
Human populations of the western Sahel depend upon a number of wild plant foods to satisfy a substantial part of their nutritional requirements and this dependency increases during drought times [
In Senegal, the most commonly exploited parts of species are respectively leaf (40%), roots (20%), and bark (13.3%) ( [
Three batches of Leptadenia hastata and two of Sesbania obtusifolia leaves were
consecutively harvested and sampled in three regions of Senegal (
Analyses for protein, cellulose, total carbohydrate and ashes (total mineral) were carried out according to the procedure described in the AFNOR standards [
10 g. of leaves powder was dissolved in metaphosphoric acid solution dilued in 4% distilled water (Metaphosphoric acid ~65% HPO3 basis from Sigma (St. Louis, MO, USA) to extract the ascorbic acid. The mixture was centrifuged at 1000 g for 15 min. A second extraction was conducted after removing supernatant. All supernatants were added before the determination of total ascorbic. Analysis was completed using Thermo Scientific HPLC 1000 SCM (with Licrospher 100 RP-18 column from Thermo Fisher Scientific Inc., Illkirch, France).
Separations were achieved using a mobile phase of 0.01% isocratic sulfuric acid (from Sigma (St. Louis, MO, USA). The volume injection was 10 µL. The comparison was carried out using external calibration between 10 and 200 mg/L L-Ascorbic acid (L-Ascorbic acid A5960 BioXtra, ≥ 99.0% from Sigma, St. Louis, MO, USA) as described by Dhuique-Mayer et al., (2007) [
The content of select lipid-soluble vitamins including vitamin A (as carotenoids) was determined using HPLC 1100 Agilent. The solvent extraction was a mixture of ethanol/hexane (4:3 v/v) with CaCO3 and 0.1% of butylhydroxytoluen (added as an antioxidant). 0.5 g of dried leaves powder was mixed with 20 mL of extract solution and centrifuged at 15,000 g for 15 min at 4˚C. A second extraction was conducted with 20 mL of extract solution. All supernatants were recovered and evaporated to dryness under nitrogen. After evaporation to dryness, samples were solubilized in a mixture of dichloromethane/Tert-Butyl methyl ether/methanol. Separations were carried out by gradient elution with water (solution A)/methanol (solution B)/Tert-Butyl methyl ether (solution C) as follows: initial conditions 40%A/60% B; 0 - 5 min, 20% A/80% B; 5 - 10 min, 4%A/81% B/15% C; 10 - 60 min, 4% A/11% B/85% C; 60 - 71 min, 100% B 71 - 72 min, and back to the initial conditions for re-equilibration. To record chromatograms with Agilent 1100, a detector at 350, 400, 450 and 470 nm was used. Comparisons were carried out using authentic standards as reported by Dhuique-Mayer et al. (2007) [
A 500 mg portion of leaves powder was incinerated at 500˚C, weighed and desilicated with 4 mL of 40% hydrofluoric acid from Sigma (St. Louis, MO, USA). The obtained solution was then evaporated at 90˚C to dryness. The residue was mixed with 50 mL distilled water followed by filtration. Detection of sodium, potassium, calcium, magnesium, phosphorus, copper, zinc and iron were realized using inductive coupled plasma atomic emission spectrometry (ICP-AES, Varian Vista) with coupled charge device detector (Agilent France, Massy). Quantification of element concentrations was carried out using specific calibration of 5 points for each element in the range 0 to 1000 µg/L (Mineral standard from Fisons Scientific Equipment, Loughborough, England). The limits of quantification (LOQ) related to samples were 0.05 mg/100 g for Ca, K, Na, Mg P and 0.005 mg/100 g for Fe, Zn, Mn, Cu.
All analyses were carried out in triplicate and the data were analyzed using excel software.
Maronutrients composition of this two species show a good level of protein (
The ash content that reflects the total mineral content reveals a greater richness of L. hastata than S. obtusifolia. However in detail, the conclusions are not accurate. The two-way analysis of variance (ANOVA) reveals a strong similarity of the different mineral elements contained in the leaves of both species, despite their provenance (Bakel, Kédougou and Widou) (
Comparatively to others legumes, protein levels of SO (21.75% ± 9.88%) are relatively close to beans [
Species | Leptadenia hastata | Senna obtusifolia | |||
---|---|---|---|---|---|
Parameters | Bakel | Kédougou | Widou* | Bakel | Widou* |
Protein | 14.37 ± 0.56a | 18.16 ± 2.54a | 15.96 ± 1.13a | 21.75 ± 9.88a | 19.55 ± 1.70a |
Cellulose | 11.47 ± 1. 31a | 11.29 ± 0.79a | 8.31 ± 0.86b | 14.63 ± 1.73a | 16.33 ± 9.44a |
Ash | 15.01 ± 3.33a | 14.25 ±5.97a | 12.34 ± 1.92a | 6.43 ± 0.21a | 5.24 ± 0.73a |
Sugar | 3.71 ± 0.19a | 3.47 ± 0.22a | 6.35 ± 0.39b | 4.38 ± 0.15a | 5.51± 0.41a |
Saccharose | 3.35 ± 0.19 | 3.06 ± 0.22 | 5.58 ± 0.39 | 3.8 ± 0.15 | 4.31 ± 0.25 |
Species (mg/100 g DM) (mg/100 g DM) | Leptadenia hastata (N = 3) | Senna obtusifolia (N = 3) | |||
---|---|---|---|---|---|
Elements | Bakel | Kédougou | Widou | Bakel | Widou |
P | 322 ± 2.13a | 213 ± 0.15a | 302 ± 1.17a | 425 ± 0.08a | 292 ± 0.70a |
K | 2042 ± 11.49a | 2417 ± 87.7a | 1956 ± 13.6a | 1749 ± 91.8a | 1968 ± 2.4a |
Ca | 3248 ± 14.67a | 3876 ± 17.49a | 2385 ± 62.7a | 4594 ± 15.02b | 2482 ± 56.5a |
Mg | 800 ± 29.6a | 578 ± 13.7a | 688 ± 18a | 383 ± 68b | 342 ± 62b |
Na | 21.4 ± 0.2a | 12.31 ± 0.2a | 20.33 ± 0.2a | 17.76 ± 0.01a | 17.70 ± 0.06a |
Cu | 0.91 ± 0.35a | 1.05 ±0.41a | 1.35 ± 0.39a | 1.11 ± 0.27a | 0.8 ± 0.06a |
Fe | 119.95 ± 5.16a | 97.79± 65.62 b | 68.4 ± 25.04b | 55.41 ± 6.64b | 84 ± 15.2b |
Mn | 8.48 ± 4.06a | 7.51 ± 0.76a | 6.77± 2.24a | 6.31 ± 0.32a | 4.96 ± 0.65a |
Zn | 2.92 ± 0.93a | 4.87 ± 0.89a | 3.3± 0.19a | 3.9 ± 0.65a | 2.81 ± 0.29a |
β-carotène | 17.95 ± 0.75a | 22.7 ± 1.1a | 16.8 ± 0.3a | 26.85 ± 2.6a | 13.5 ± 0.25a |
Vitamine C | 56 ± 11.31a | 22.5 ± 12.02a | 159.5 ± 84.15a | 142 ± 56.57a | 196.5 ± 31.82a |
Values are means of three (3) individual measurements ± standard deviation. Means in each column followed by different superscript letters are significantly different (Tukey’s HSD, p < 0.05).
Elements | Actual average (Senegal) | Freiberger et al., 1998 (Niger) | [ | [ |
---|---|---|---|---|
(mg/100 g) | (mg/kg) | |||
P | 213 - 322 | 2.3 | 2.2 | |
K | 1956 - 2417 | 19.8 | 30421 | - |
Ca | 2385 - 3876 | 21.4 | 17106 | 7.1 |
Mg | 578 - 800 | 5.66 | 4696 | 1.0 |
Na | 12.31 - 21.4 | 1.1 | 934 | Traces |
Cu | 0.91 - 1.35 | 9.5 | 13.2 | - |
Fe | 68.4 - 119.95 | 211 | 437 | 15.4 |
Mn | 6.77 - 8.48 | 81.9 | 78.5 | - |
Zn | 4.87 - 2.92 | - | 52.7 | - |
higher (24.06%). However, the protein content of leaves from Niger found by several authors is mixed and varies between 14% and 22.8% (
Comparing mineral content, Senegal’s LH samples are significantly richer than those from Niger and Uganda (
The levels of micronutrients such as manganese, copper and zinc are important to report because they are of the order of mg/100 g whereas they are generally expressed in mg/kg (
These results encourage the more frequent use of these two leafy vegetables by populations where dietary habits permit since the consumption of leafy vegetables is linked to the traditions and dietary patterns of each ethnic and socio-economic group [
The nutritional intake of Leptadenia hastata and Senna obtusifolia in the diet is significant from the point of view of mineral elements. To overcome the difficulties of availability of these two leaf vegetables during the lean season, domestication would be an appropriate response to contribute for food security of the populations.
This work was conducted with technical support of CESAM-RESCIF and financial support from:
1) USAID Program (USAID-YAAJEENDE, p. 255: Project of Agricultural and Nutritional Development for Food Security in Senegal).
2) LabEx DRIIHM through CNRS financial.
Ayessou, N.C., Cissé, M., Gueye, M., Ndiaye, C. and Diop, C.M. (2018) Nutritional Potential of Two Leafy Vegetables Leptadenia hastata Decne and Senna obtusifolia Link Consumed in Senegal. Food and Nutrition Sciences, 9, 77-85. https://doi.org/10.4236/fns.2018.92006