Determination of Chemical Composition of Senna-siamea (Cassia Leaves)

Introduction

Plants have been found to be the source of energy for the animal kingdom. In addition, plant can synthesize a large variety of chemical substances that are of physiological importance (Kretovich, 2005). Medicinal plants therefore, are groups of plant which in one or more if its parts contain substances that can be used for the synthesis of useful drugs (Sofowora, 2000).

Today, lots of plant materials are used in the production of enormous array of medicines. Stuffness and Douros (1982) reported that 50% of all modern chemical drugs are of natural product origin. It was reported that 60-80% of the population in every developing countries of the world relies on medicinal plants in the treatment of some diseases. This is mainly because of shortage of hospitals and health centre as well as medical staff and financial constraints. Although the actual number of the medicinal plant is not known but there is no doubt that most of the plants around us are medicinal (Hill, 1992). Some of the common uses of medicinal plants sold in the markets include pain relief, antimalaria, treating of skin infections and fumigation (Hailu et al., 2005).

In the last two centuries, there has been serious investigations into the chemical and biological activities of plants and these have yielded compounds for the development of synthetic organic chemistry and the emergence of medicinal chemistry as a route for the discovery of more effective therapeutic agents (Roja and Rao, 2000).

Senna siamea is an evergreen tree commonly cultivated in our area especially in fuel plantation. It is a medium size tree up to 15-20cm tall, with a straight trunk up to 30 cm in diameter, bole short, crown usually dense and rounded at first, later becoming irregular and spreading with dropping branches, Bank grey or light brown, smooth but becoming slightly fissured with age (Bernard, 2005). Senna siamea is effective in managing constipation association with a number of causes including surgery, childbirth and the use of narcotic pain relievers (Hill, 1992). It is used locally as antimalaria drugs especially when decocted (the leaves, bark) (Lose et al., 2000). In traditional medicine, the fruit is used to charm away intestinal worms and to prevent convulsion in children. The young fruits and leaves are also eaten as vegetables in Thailand. The flowers and young fruits are used as curries (Kiepe, 2001).

This study is designed to determine the chemical composition of the leaves of Senna siamea for public and dietary awareness of its nutritional status.

Materials and Methods

Plant material preparation: The leaves of Senna siamea were collected from Ado-Ekiti and identified in the science herbarium of the department of Plant Science and Forestry, University of Ado-Ekiti, Ekiti State, Nigeria. The leaves were sun dried for about five days and then grounded into fine powder using a food blender. (without metal contamination). The grounded samples were stored in an air-tight labeled plastic container from which samples were removed for chemical analysis.

Table 1:	Proximate composition of Senna siamea

Preparation of plant extract: 100g of the powdered leaves sample was weighed into a container containing 100ml of hexane. This was lest for 5 days until the solvent evaporated completely and the leave was recovered. This was done to extract the active ingredients.

Analysis of extract: The mineral constituents of the leaves namely iron, manganese, magnesium, potassium, calcium, sodium, copper, cadmium, lead, phosphorus and vanadium were determined using the methods of analysis described by A.O.A.C. (1990). The proximate analysis namely Crude protein, crude fibre, moisture content, ash content fat content and carbohydrate were also determined by the methods described by A.O.A.C.(1990).

The phytochemical constituent of the leaves namely Alkaloids, saponin, Anthraquinones, Tannins and phlobatanins were determined using the method of Trease and Evans (1978). Oxalate was determined using the method of Day and Ununderword (1986). Phytate was determined using the method of Wheeler and Ferrell (1971).

Results

The results of the determination of the proximate, elemental phytochemicals and antinutrients compositions of Senna siamea leaves are represented in Table 1, 2, 3 and 4 respectively.

Discussion

Proximate analysis of a food is the nutritional composition of that food. It is the estimation of the nutritive value of human food in its chemical form. The proximate analysis as shown In Table 1 reveals that Senna siamea contains protein (4.01%), crude fibre (12.36%), moisture content (46.01%), ash content (12.93%) crude fat (12.02%)and carbohydrate content (7.67%).

The values shows that the protein content is relatively low but it can contribute to the formation of hormones which controls a variety of body functions such as growth, repair and maintenance of body protein (Mau et al., 1999). The moisture, Ash, crude fibre and crude fat content are relatively high. According to Michael and David (2002). The high content of ash is useful in assessing the quality of grading the plant and also gives an idea of the amount of minerals present in the sample.

Table 2:	Elemental composition of Senna siamea

ND -Indicates not detected

Table 3:	Phytochemical screening of Senna siamea

+ indicates present

Table 4:	Antinutrient screening of Senna siamea

+ indicates present

The fat content can be used for storage and transport forms of metabolic fuel. The relatively high carbohydrate content can be used as energy source and also it is necessary in the digestion and assimilation of other foods. The proximate composition of Senna siamea show a fairly good nutrient constitution when compared to other common vegetables such as Amaranthus hybridus (Nwaogu et al., 2006).

Table 2 shows the mineral content of Senna siamea. The need for supplementary diet rich in mineral content is necessary for a singular ration, to avoid metal deficiency syndrome like rickets and clarification of bones, as a result of calcium deficiency. Distorted enzymatic activity and poor electrolyte balance of the blood fluid are related to inadequate Na, k, mg and Zn, as they are the most required elements of living cells. The leaves of Senna siamea have fairly adequate concentrations of sodium, potassium, calcium, magnesium and iron in comparison with those reported for A. hybridus leaf extract (Nwaogu et al., 2006)

The result of phytochemical screening and antinutrient composition of Senna siamea are given in Table 3 and 4 respectively. Saponin, alkaloids, antraquinones and phylobatannins were the major phytochemical identified in the leave extract. These phytochemical exhibit diverse pharmacological and biochemical actions when ingested by animals (Amadi et al., 2006).

Saponin reduces the uptake at certain nutrients including glucose and cholesterol at the gut through intra-luminal physicochemical interactions. Hence, it has been reported to have hypocholesterolemic effect (Price et al., 1987) and thus may aid in lessening the metabolic burden that would have been placed in the liver. Alkaloids are often toxic to man and may have dramatic physiological activities hence their wide use in medicine (Shelton, 2000).

The antinutritional contents include phytate, tannin and Oxalate. Oxalate can complex with most essential trace metals therefore making them unavailable for enzymatic activities and other metabolic activities. Tannins are capable of lowering available protein by antagonistic competition and can therefore elicit protein deficiency syndrome, ‘kwashiorkor’ Phytic acid has complicated effect in human system including indigestion of food and flatulence (Maynard, 1997).

These antinutritional factors can easily be reduced to tolerable limits by proper simple processing techniques such as soaking cooking, frying (Ekpo et al., 2004; Ekpo and Eddy, 2005b).

This present study reveals that Senna siamea contains essential nutrients for good human and animal health.