Browsing by Author "Kebede Teshome"
Item The Bitter Constituent of Gesho ( Rhamnus Prinoides ) Leaves(Addis Ababa Universty, 1994-06) Kebede Teshome; Abegaz Berhanu (PhD)Gesho, Rhamnus prinoides L’Herit (Rhamnaceae) is a shrub or tree which can be up to 6 m tall. It is cultivated in Ethiopia for use as an ingredient in the making of the home brewed drinks-Telia and Tej. Phytochemical investigations of the leaves of this plant resulted in the isolation and characterization of the bitter prinicple- a naphthaenic lactone glucoside named geshoidin, in addition to three anthraquinones, a pre-anthraquinone and a flavonol. These compounds are chrysophanol (1), physcion (2), musizin (19), emodin (3), rhamnocitrin (40) and /3- sorigenin-8-0-/3-D-glucoside (68). Acetylated and methylated derivatives as well as hydrolysis products of the glucoside and the permethylated compound are also characterized. These include|6-sorigenin-8-0-/3-D-glucoside-peracetate(69), /3-sorigenin-8- 0-/3-D-glucoside-permethylate (70) , /3-sorigenin (22) and /3-sorigenin-l -methylether (71), respectively. Compounds 2 and 3 have been isolated previously from the fruits of R. prinoides. 19 and 40 have not been reported from this plant while 68 is a novel natural product , Based on spectroscopic data, two possible explanations are offered for the upfield chemical shift of the peri hydroxyl proton in 68. A sensory panel concluded that compound 68 is a bitter principle in the leaves of Gesho. At least 1% of the dry leaves of Gesho contain this bitter component