INVESTIGATION OF TOTAL PHENOLIC, FLAVONOID, NUTRITIONAL CONTENTS, AND ANTIOXIDANT ACTIVITY OF LEAF, FRUIT AND BARK OF GESHO (Rhamnus Prinoides )

<strong>Abstract</strong>: Rhamnus prinoides locally known as Gesho is one of the most important plants used as a bittering agent for local alcoholic beverages in Ethiopia. Although it has many uses, yet its practical application is limited to the preparation of local alcoholic drinks. There is a paucity of scientific data regarding the chemical contents of its aerial parts. The present study investigated total phenolic contents (TPC), total flavonoid content (TFC), antioxidant activities, proximate and mineral compositions of leaf, fruit and bark of Gesho. The samples were collected from deferent plants near the local farm land of Adola district at Guji Zone Adola district and dry at room temperature. The TPC and TFC were determined using Folin-Ciocalteu reagent and Aluminum chlorine methods, respectively. Antioxidant activities were determined using 2, 2 diphenyl-1–picrylhydrazyl (DPPH) and ferric reducing power assays. The mineral (Mg, Ca, Fe, and Zn) analysis was done using atomic absorption spectrophotometer (AAS) while Na and K contents of samples were assessed using flame photometer. The leaf has the highest total phenolic content (48.44 1.58 milligram gallic acid equivalent/gram of dried extract) and total flavonoid content (18.78  2.08 milligram catechin equivalent/gram of dried extract). The bark showed the strongest DPPH scavenging activity (EC50 = 48.01 ± 1.20 μg/mL) and the strongest ferric reducing power (49.43 5.62 milligram equivalent of ascorbic acid/gram of dried extract). The leaf part has contained the highest values of Ash (10.45 ± 0.04 %) and carbohydrate (60.60 ± 0.62 %); the fruit part has the highest moisture (5.94 ± 0.01 %) and fat (11.67 ± 0.01 %) contents. The bark has contained the highest fiber (59.52 ± 0.12%). The leaf part contained large amounts of K (3745.25 ± 47.02 ppm), Ca (337.25 ± 3.61 ppm), Na (159.32 ± 2.51 ppm), Fe (11.23 ± 0.17 ppm), and Zn (3.32 ± 0.08 ppm) compared to other parts. The bark contained the highest Mg (596.35 ± 15.20 ppm) content. The result indicates that Gesho aerial parts not only used as bittering agent but also source of functional ingredients in Ethiopian traditional beverages. These abundant phytochemicals could also reduce oxidation of alcoholic drinks in to organic acids. Phytochemicals are known for their health benefits so there is a possibility of enhancing Ethiopian local alcoholic drinks to the grade of functional foods. It is possible to prepare other healthy drinks using gesho as one ingredient.