Studies on the Effects of Extracts of Fresh Khat/Catha edulis Leaves on the Oxidation of Niger Seed Oil

The methanolic extract of the fresh leaves of khat/Catha edulis was investigated using established procedures for its phytochemical constituents and effect on lipid oxidation. The phytochemical analysis revealed the presence of alkaloids, tannins, phenols, and flavonoids. The effects of the extract on oxidation of locally produced edible NSO (niger seed oil) was assessed through the measurement of peroxide value, iodine value and conjugated diene concentration for a period of sixteen days. Control setup involving NSO without the extract was also kept for the same period of time under similar conditions. It was observed that the peroxide value and conjugated diene value of the oil containing varying concentrations of the extracts of khat leaves increased significantly, relative to the control, showing that the extract of the khat leaves promoted deterioration of the oil. In a similar manner, the iodine value of NSO with and without added khat leaves extract was assessed. It was observed that the iodine value of the oil containing the khat leaves extract decreased more rapidly than the control, suggesting that the double bonds in the fat constituting the oil were diminished by the extract of the khat leaves. It is thus inferred from the present study that methanolic extract of fresh khat leaves leads to deterioration of NSO. It can also be suggested from the results of the present investigation that the health problems khat chewers face may be related to the oxidative damaging effects of these leaves exert on biomolecules found in the body.