الفهرس 
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Abstract
The present thesis is concerned with the analysis of certain drugs used for treatment of obesity, namely: green tea extract (GTE) and two representative examples of its pure catechins namely; (-) epicatechin (EC) and (-) epigallocatechin gallate and chromium picolinate (Cr-Pic). Different analytical techniques were developed for the analysis of the studied compounds. The thesis includes four main parts: Part IThis part involves a general introduction about different drugs used for treatment of obesity. Also, it includes the chemical and physical properties of the studied drugs, their pharmacological action followed by a literature review about the previous methodologies used for the estimation of the investigated drugs.Part II: It deals with the assay of GTE total catechins in GTE raw material and tablet formulation via oxidative coupling reaction with MBTH using spectrophotometry. The procedures are based on the formation of orange-colored products detectable at 473 or 455 nm, respectively, when catechins react with (MBTH) in the presence of FeCl; or (K2S2O5). The absorbance-concentration plots were rectilinear over the ranges (4.0-20.0) or (4.0-40.0) µg cm³ with limits of detection (LOD) 0.393 or 0.493 µg cm³ for methods I & II, respectively. Part III: This part is concerned with the development of a sensitive spectrofluorimetric method for the estimation of total catechins in GTE in both raw material and tablet formulations. This method relies on determining the GTE ethanolic solution’s native fluorescence at 312 nm following excitation at 227 nm. The calibration graph displayed a linear regression for values between 0.05 and 1.0 µg mL¹. The detection and quantification limits of the proposed technique were 0.008 and 0.026 µg mL¹, respectively. Part IV: This part includes a cyclic voltammetric study for the estimation of Cr-Pic in raw material and its capsule formulations. This study aims to investigate the electrochemical behavior of chromium picolonate (Cr-Pic) in KBr medium using cyclic voltammetry (CV) with an Au electrode. The study analysis of Cr-Pic in commercial capsules. explores the applicability of the developed method for the الصيدOxidation and reduction waves of Cr-Pic were lincarly dependent on iliits concentration, and calibration curves were linearthe range (0.662-3.23) µM with limits of datection (0:2) (0.053) )M and limits of quantitation (0.654) or (0.163) µM forintthe gold electrode reduction and oxidation waves, respectivelyExperimental parameters were properly discussed and validated for all adopted methodologies. All the results were compared statistically with those given by the official, manufacturer or reported methods.