Pakistan Journal of Nutrition 9 (7): 709-715, 2010 ISSN 1680-5194 © Asian Network for Scientific Information, 2010 Corresponding Author: Ekeanyanwu Raphael Chukwuma, Department of Chemical Sciences, Novena University, Ogume, Delta State, Nigeria 709 The Phytochemical Composition and Some Biochemical Effects of Nigerian Tigernut (Cyperus esculentus L.) Tuber Ekeanyanwu Raphael Chukwuma , Njoku Obioma and Ononogbu Ikpendu Christopher 1 2 2 Department of Chemical Sciences, Novena University, Ogume, Delta State, Nigeria 1 Department of Biochemistry, University of Nigeria, Nsukka, Enugu State, Nigeria 2 Abstract: The phytochemical composition of the tigernut tuber and the effect of the aqueous extract on some biochemical parameters such as blood glucose, serum protein, albumin and cholesterol, white blood cells, red blood cells, haemoglobin, erythrocyte sedimentation rate and packed cell volume were determined in rats administered different concentrations of the extract. From the result of the phytochemical analysis, the presence of alkaloids, cyanogenic glycosides, resins, tannins, sterols and saponins were observed in the raw tuber, however only alkaloids, sterols and resins were observed in the roasted tuber. Analysis of the antinutrient composition yielded oxalates (0.25±0.65 g/100 g), phytate (1.97±0.81 mg/100 g), saponins (0.88±0.02/100 g), tannins (9.50±0.46 mg/100 g) and cyanogenic glycosides (1.80±0.69 mg/100 g). Roasting numerically decreased the levels of the anti-nutritive factors analyzed. At the end of the treatment period, the mean weights of the animals increased. The blood glucose level decreased significantly in concentration dependent manner (p<0.05) and serum albumin level increased significantly in a concentration dependent manner (p<0.05) in the groups administered the different concentrations of the extract. There was no significant effect (p>0.05) on serum cholesterol and protein and on total and differential white blood cell, red blood cell, haemoglobin, packed cell volume and erythrocyte sedimentation rate. The results therefore indicate the absence of undesirable effect in the use of the tigernut tuber even in the raw form at least at the administered concentration and for the duration of feeding. The findings are of nutritional, health and industrial relevance since the tuber is currently being used as food in many homes in Nigeria. Key words: Cyperus esculentus, tigernut, phytochemicals, biochemical effects INTRODUCTION The worsening food crisis and the consequent wide spread prevalence of malnutrition in developing and underdeveloped countries have resulted in high mortality and morbidity rates, especially among infants and children in low income groups (Enujuigba and Akanbi, 2005). The reliance on starchy roots and tubers and protein deficient cereals as main staples results in consumption of non-nutritious foods. The insufficient availability of nutrient rich diets and high cost of available ones have prompted an intense research into harnessing the potentials of the lesser known and underutilized crops, which are potentially valuable for human and animal foods to maintain a balance between population and agricultural productivity, particularly the tropical and subtropical areas of the world. Cyperus esculentus (Tigernut) is an underutilized plant of the family Cyperaceae, which produces rhizomes from the base and tubers that are some what spherical (Cortes et al., 2005). The plant is not really a nut but a tuber first discovered some 4000 years ago (Lowe and Whitewell, 2000). It has other names like yellow nutsedge, chufa, flatsedge, rush nut, water grass, earth almond, northern nut grass and nut grass (Shilenko et al., 1979). Cyperus esculentus is known in Nigeria as aya in Hausa, ofio in Yoruba and akihausa in Ibo. Cyperus esculentus grows mainly in the middle belt and northern regions of Nigeria (Okafor et al., 2003), where three varieties (black, brown and yellow) are cultivated (Umerie et al., 1997). Among these, only two varieties, yellow and brown are readily available in the market. The yellow variety is preferred to all other varieties because of its inherent properties like its bigger size, attractive colour and fleshier body (Belewu and Abodurin, 2006). Cyperus esculentus can be eaten raw, roasted, dried, baked or be made into a refreshing beverage called kuunu (Oladele and Aina, 2007). Cyperus esculentus was reported as healthy and helps in preventing heart, thrombosis and activates blood circulation. It helps in preventing cancer, due to high content of soluble glucose. It was also found to assist in reducing the risk of colon cancer (Adejuyitan et al., 2009). The nut is rich in energy content (starch, fat, sugars and protein), mineral (phosphorus, potassium)