Nutritional and Toxicological Potentials of Mucuna pruriens Seed

Enechi Osmond C., Emmanuel N. Tufon and Ogugua Victor N.

Department of Biochemistry, University of Nigeria, Nsukka, Nigeria

ABSTRACT:

Since animals and animal products are very expensive sources of nutrients especially in developing countries, it is very important to exploit other sources of acquiring nutrients that will be less expensive. This work was therefore aimed at evaluating the nutritional and toxicological potentials of Mucuna pruriens seed in view of proposing a less expensive source of nutrient in developing countries. The phytochemical analysis was carried out using the method of Harbourne et al. (1973). The proximate analysis, elementary analysis and determination of toxicants were determined using standard biochemical methods. Results of the phytochemical analysis showed the presence of alkaloids, proteins, carbohydrates, saponins, tannins in high concentration; flavonoids in moderate concentration while cyanogenic glycosides and steroidal aglycones were absent. Proximate analysis revealed high percentage of crude protein (30.1±0.25%) while ash (8.2±0.2%), moisture (7.67±0.34%) and fiber (3.2±0.01%) were in moderate percentages. The mineral composition indicated the presence of iron (33.75±0.18µg/100g), potassium (700.02±48.7µg/100g) and phosphate (622±7.29µg/100g). The results also showed the presence of some toxicants, oxalate (11887.5±517.1µg/g) in high concentration while phytate (61.3±0.45µg/g), hemagglutinin (14.67±0.69µg/g) and cyanogenic glycosides (0.013±0.59µg/g) were present in low concentrations. We therefore conclude from our results that well processed Mucuna pruriens seed would not only be a less expensive source of nutrient in developing countries but may also provide medical benefits.

KEYWORDS: Toxicology, Mucuna pruriens, Nutrients, Toxicology, Phytochemistry.

INTRODUCTION:

Food nutrients are those major nutritional constituents found in food to replenish the body and maintain body balance (Enechi, 2001). The need to meet nutritional requirement through adequate food supplies has been a basic determinant of stability and progress. Inadequate food production is posing a major nutritional problem (Chiba et al., 1979). Cereals and its products are the staple diet and a major source protein and energy for both adults and children (Oke, 1979). The dependence of cereals as the staple diet has led to the neglect of legumes and this in turn has led to decrease in their cultivation and availability (Aylward and Jal, 1975). Mucuna pruriens is one of the lesser known legume trees found in the Nigerian ecosystem (Obizoba, 1983). Although, Mucuna pruriens has a lot of potentials as a rich source of food nutrients in developing countries, there is scarcity of information on the nutritive value. This work therefore is aimed at investigating the nutritional and toxicological potentials of Mucuna pruriens with a view of determining its nutritional value as well as recommending a less expensive source of food nutrient in developing countries.

MATERIALS AND METHODS:

Collection and preparation of plant materials:

The seed of mucuna pruriens were collected from locally dense vegetative area of Affa in Udi Local Government Area, Enugu State Nigeria. They were botanically identified by Mr. Njokuocha of the Department of Botany, University of Nigeria, Nsukka. The seeds were carefully DE hulled using a knife and dried for 24 hours in an oven at 60^oC. They were then milled with a locally fabricated attrition mill to a mesh size of 1.0dmm. The ground samples were further milled into fine powder using a clean milling machine.

Phytochemical analysis:

The phytochemical constituents were investigated by the method of Harboune et al. (1973). Phytochemical tests were carried out to detect the presence of alkaloids, flavonoids, cyanogenic glycosides, proteins, carbohydrates, saponins, tannins and steroidal aglycones.

Chemical analysis:

Crude protein and crude fiber contents were determined using methods described by Pearson (1976). Crude protein determination was done using Kjedhal’s method while crude fibre was done using Wendee’s method. Total ash content was determined by furnace incineration using the method of James (James). The moisture content was determined using the method described by Amadi et al. (2004).

Toxicological studies:

Tannin was determined by the Folin-Denis’s spectrophotometric method as described by Pearson, 1976. Phytate content was determined by the spectrophotometric method as described using the method described by Hang and Lantzsch, 1983. The oxalate was determined using the method described by Amadi et al. (2004). The haemagglutin was determined using the method of Arntifield et al. (1985).

Statistical Analysis:

Data entry and analysis were done using SPSS version 12.0 and values were represented as mean ± SD. The difference between groups were compared for statistical significance using sample t-test with the level of significance set at p<0.05.

RESULTS:

The results of the phytochemical analysis (table 1) indicate the presence of alkaloids, flavonoids, proteins, carbohydrates, saponins and tannins. Saponins are known to have hypocholesterolemic properties (Price et al., 1987). This could confer some chemo- protection against heart diseases to users. Also the presence alkaloids and tannins could well account for the use of the seeds as stimulants and aphrodisiacs.

Table 1: Phytochemical composition of seeds of mucuna pruriens

Phytochemicals	Composition
Alkaloids	+++
Flavonoids	+++
Cyanogenic glycosides	–
Proteins	+++
Carbohydrates	+++
Saponins	+++
Tannins	+++
Steroidal aglycones	–

Key; +++ = High; ++ = Moderate; + = Trace elements; - = Absent

The results of the proximate analysis (Table 2) indicate high concentration of protein (30.1±0.25g %) in Mucuna pruriens seeds which falls within the range reported by Boulter (1997) for other legumes. The fiber content (3.2±0.01g %), moisture (7.76±0.34%) and ash content (8.2±0.2g %) were present in moderate concentrations.

Table 2: Proximate analysis of Mucuna pruriens seed

Components	% Composition
Crude protein	30.1±0.25
Moisture content	7.67±0.34
Fiber content	3.2±0.19
Ash content	8.2±0.2

The elemental analysis (Table 3) of Mucuna pruriens revealed that the seed is a rich source of potassium (700.02±48.70µg/100g), iron (33.75±0.18 µg/100g) and phosphate (622±7.29 µg/100g). The results on Table 4 indicate the presence of some toxicants. Oxalate (11887.5±517.1µg/g) and were within the limits acceptable as safe by World Health Organization (Munro and Bassir, 1969). The Phytate (61.3±0.45µg/g), hemagglutinin (14.67±0.69µg/g) and cyanogenic glycosides (0.013±0.59µg/g) were low.

Table 3: Elemental analysis of seeds of Mucuna pruriens

Mineral elements	Content (µg/100g)
Potassium	700.02±48.70µg/100g
Phosphate	622±7.24µg/100g
Iron	33.75±0.18µg/100g

Table 4: Toxicants in seeds of Mucuna pruriens

Toxicants	Content (µg/g)
Oxalate	1188.7±517.1
Phylate	61.3±0.45
Hemagglutinin	14.67±0.69
Cyanogenic glycosides	0.013±0.59

DISCUSSION:

From the results of our study we therefore strongly recommend that the increased use of well processed Mucuna pruriens seeds would not only be an excellent source of nutrients in developing countries but may also provide medicinal benefits to its users. However, their bioavailability should be ascertained since a number of phytochemicals are capable of complexing with nutrients thus reducing the bioavailability of the nutrients (Enechi et al., 1996). Oxalates are known to reduce the bioavailability of some nutrients, thus the need for further processing of the seed of Mucuna pruriens before making them available in the diet.

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Received on 12.06.2011

Accepted on 11.09.2011

Research Journal of Pharmacognosy and Phytochemistry. 3(5): Sept.- Oct.2011, 241-243