Isolation,Charactorisation and electrochemistry of geshoidin from rhamnus prinoides

Abstract

The leaves and the stems of Rhamnus Prinoides (Amharic name, Gesho and Sesotho name, Mofifi) are used as traditional medicine to treat pneumonia, gonorrhea, rheumatism, stomach-ache, as a gargle and so many more. In some countries such as Ethiopia, the leave and stems are used in traditional fermented beverages such as Tella and Tej. Chemical investigation on the leaves resulted in the isolation of a characteristic bitter principle known as naphthalenic compound β-sorigenin-8-O-β-D-glucoside. Then, the name Geshoidin was proposed for this novel glucoside. The structure of Geshoidin was established from the spectroscopic analysis of natural products. The electrochemical behaviour of Geshoidin was investigated at a glassy carbon electrode in mixtures of citric acid and di-sodium hydrogen orthophosphate aqueous buffer system over a wide pH range (pH 2-11) using cyclic voltammetry. Chemically irreversible single oxidation and reduction peaks were obtained in the potential and pH region investigated. Variations in the peak potential and peak current of the oxidation peak have been observed as function of pH. The wave characteristics, the reversibility of the reactions, the diffusion coefficient and the number of electrons transferred have been studied. Linear sweep voltammetry was applied for the voltammetric determination of Geshoidin and a linear calibration curve over the range 1.00 x 10-6 - 1.00 x 10-4 mol dm-3 Geshoidin was achieved. The detection limit was found to be 5.00 x 10-7 mol dm-3 Geshoidin. For eight successive determinations of 1 x 10-5 mol dm-3 Geshoidin, a relative standard deviation (RSD) of 3.2% was obtained. Thabang Fernando