Abstract

Michael O. Ekeh

The phytochemical, proximate composition, amino acid profile and the effects of the extracts of two varieties of Cyperus esculentus (tiger nuts) on sickle cell blood were investigated. One hundred grams (100g) powdered samples of each fraction of the two varieties of the plant were used for batch extraction procedures to generate the crude aqueous extracts (CAEs) and the methanol water soluble fractions (MWS) used for hemoglobin polymerization and the Fe2+/Fe3+ determinations. The following nutrients and antinutrients were identified and quantified with their values expressed in (%) for the proximate composition and mg/100g for the anti-nutrients compositions. Four varieties of the nut were used for the work based on size and texture and these were designated as follows :- (large (L) and small (S) varieties; wet (W) and dry (D). The results of the proximate composition for the four (4) samples were as follows: ash 1.80±0.1(W), 2.68±0,2 (D); moisture- 42.80±0.2(W), 32.16±0.2(D); crude fiber-18.0±0.1(W), 21.36±0.1(D);crude lipid-14.10±0.0(W), 19.67±0.2(D); crude protein- 4.82±0.1 (W),7.94±0.2(D) and carbohydrates- 18.44 ±0.0(W), 16.19±0.1(D). For the small seeded variety: ash-1.75±0.1(W), 1.79±0.2 (D);moisture- 24.22±0.1(W), 9.7±0.0(D); crude fiber- 15.22±0.1(W), 15.60±0.1(D); crude lipid- 11.50±0.0(W), 27.54±0.0(D); crude protein-3.63±0.1(W),3.94±0.1(D)and carbohydrates-16.39±0.1(W), 15.60±0.0(D). The phytochemicals showed the trend: saponins-0.76±0.02 (L) and 0.65±0.01 (S); cyanogenic glycosides1.07±0.2(L) and 0.85±0.2(S); phytate- 2.35±0.2 (L) and 2.12±0.1 (S); oxalates- 0.50±0.2(L) and 0.42±0.1(S). The total free amino acid concentration of the four samples was equally determined and the result expressed in mg/100g of sample. For the large variety (L)- 169.6±0.0(W) and 161.20±0.0 (D); the small variety (S)- 165.60±0.1(W) and 160.40±0.1( D). There is no significant difference between the free amino acid concentrations of the two varieties and samples at p≤ 0.05. Hemoglobin polymerization inhibition assay showed the following result for the relative percent inhibition by the CAE and MWS fractions respectively of the large and small varieties. For the (L) variety, CAE (85.20%) and MWS (86.20); for the (S) variety- CAE (84.06%) and MWS (85.51%). When compared with the values of the standard antisickling agents- Phe (85.47) and ascorbic acid (84.89); there is no significant difference in the relative percent inhibition by these samples at p ≤ 0.05. The amino acid profiles of the two varieties were the same and only varied in the relative concentrations of the wet and dry samples. Results showed the presence of the following major antisickling and essential amino acids at various concentrations expressed in mg/ 100 g. The antisickling amino acids included: Phe, Lys, Arg, Histidine, Serine, and Aspartate – 2.37(W) and 2.37 (D); 4.16 (W) and 4.78 (D); 18.29(W) and 20.17 (D); 1.94 (W) and 2.32 (D); 2.27 (W) and 2.37 (D); 5.73 (W) and 6.86 (D). Some essential amino acids identified included: valine (3.14 (W) and 2.50 (D); methionine-0.73 (W) and 0.89 (D); leucine -3.71 (W) and 4.01( D) and Isoleucine- 2.07 (W) and 1.79 (D). The CAEs and MWSs of the large and small varieties improved the oxidant status of sickle cell erythrocytes by increasing the Fe2+/Fe3+ ratio remarkably. The fractions of the two varieties increased the ratio to varying degrees. For the L variety, the CAE and MWS values were: 72.19% and 41.96%.while for the small variety; 57.73% and 36.74%. It can be deduced that the two varieties of Cyperus esculentus studied are very nutritious and exhibited high antisickling effectiveness by inhibiting sickle cell hemoglobin gelation and improving the oxidant status of the erythrocytes. These extracts can be of immense nutritionally and therapeutic relevance in the management of nutritionally related syndromes like anemia, kwashiorkor and moreover sickle cell disease.