FATTY ACID COMPOSITION, TOTAL PHENOLICS CONTENT, TOTAL FLAVONOIDS AND ANTIOXIDANT ACTIVITY OF NIGER SEED (Guizotia abyssinica) COLLECTED FROM SOME AREAS OF ETHIOPIA

Abstract The seed of G. abyssinica is the most important oil crop in Ethiopia, providing 50–60% of the country’s indigenous edible oil. The fatty acid types and composition; and the composition and concentration of other phytochemicals including plant secondary metabolites vary with respect to species type, geographical origin, cultivation season and varietal type. However, there are only few data on the fatty acid composition of some varieties of G. abyssinica collected from some selected areas of Ethiopia. The objective of this study was profiling fatty acid composition and to determine total phenolic content, total flavonoids, and evaluate antioxidant activities. Seed samples were obtained from the farmers of selected areas of five zone major producers of G. Abyssinica. The dried seed samples ground to fine powder, sieved with 50mm and subjected to horizontal shaker extraction with chloroform/methanol (2:1, v/v). Then extracted lipid was ix derivatized with HOCH3/H2SO4 in n-hexane. Then Identification of individual FAs was carried out by comparison of their mass spectra with those of the reference mass spectra library NIST 11. The extract was analyzed using GC-MS. The result indicated that a total of 12 FAs have been identified in each G. abyssinica sample in which the fatty acid profile showed a high content of linoleic acid (up to 74.67%) together with palmitic acid (10.66 %), oleic acid (11.02 %), and stearic acid (8.761 %) were major FAs. The FAs concentration of Guizotia abyssinica samples was determined using undecanoic acid internal standard. The total FAs concentration; 240.41, 280.45, 292.24, 312.65 and 347.57mg/g of FAME were determined of sample variety in site of Horo Gudru Wolega, East Wolega, West wolega, East Gojjam and North Gondar respectively. The total FA concentration of Guizotia abyssinica were varied within Guizotia abyssinica location varieties. Ultra sonic extractor was used for extraction of bioactive compounds in two solvent systems (80% methanol extract and 100% methanol) to evaluate antioxidant activities, total phenolic content and total flavonoids contents of G. abyssinica. The result for samples had total phenolic content ranged from (10.89 ± 0.39 - 11.78 ± 0.028 mg GAE/g), total flavonoids contents (5.42 ± 0.03 - 6.67 ± 0.06 mg CE/g) of 80% methanol extract respectively. West wolega scored lower values of TPC and TFC in both solvent systems. 80% methanol extract had better antioxidant activities.