Determination of Antioxidant and Antibacterial Activities of Yirgacheffe Arbica Coffee Leaves

Abstract

The use of coffee plants is more focused on the coffee beans as a brewing drink or as a food additive. Parts of the coffee plant, such as leaves, are considered as waste and have not been properly utilized. The current study investigates the antioxidant activities and antibacterial activities of Arabica coffee leaves from Yirgacheffe, Gidio Zone, Ethiopia. As a reference, the crude extracts of green/raw and medium roasted beans of coffee were screened for their in vitro antioxidant properties and antibacterial activities. Antioxidant activities were measured by DPPH assay and the reducing power. The findings of this research show that the coffee leaves possessed the highest antioxidant activities in both DPPH and reducing power assays. A linear correlation between concentrations of coffee extract of the leaves and reducing power was observed with a coefficient of y = 0.00312x + 0.0802, (R2 = 0.99472). These results indicated the extract of leaves of coffee has a strongest antioxidant activities compared with green and medium roasted coffee extracts. Moreover, coffee extract has found to be more effective against gram positive bacteria; S.aureus than negative bacteria strains; E. coil. Antioxidant activities for leaf of coffee samples were slightly higher than for the corresponding green and roasted samples while antibacterial activities was significantly lower in leaf of coffee compared to that of green and roasted samples (p < 0.05). Thus, coffee leaf is a very promising resource in the areas of food and pharmaceutical industry, especially, in the beverage industry.