ANALYTICAL STUDY ON CERTAIN NATURAL ANTIDIABETICS

Abstract

The thesis consists of seven parts: Part I: Introduction This part includes a general introduction to diabetes, its types, symptoms and complications. It also includes introduction to herbal drugs, their importance, factors leading to their world’s growth, factors affecting their composition, importance of their quality control and classes of herbal drugs with antidiabetic effect. Part II: Literature Review This part includes two sections: Section A: Literature Review of Trigonelline This section includes a review of the structure, physical properties, natural sources, pharmacological effects, mechanism of action, thermal stability and different reported methods for the analysis of trigonelline. Section B: Literature Review of Gallic Acid This section includes a review of the structure, physical properties, natural sources, pharmacological effects, mechanism of action, thermal stability and different reported methods for the analysis of gallic acid. Part III: Analytical Study on Trigonelline This part includes four sections: Summary XXV Section A: HPTLC Determination of Trigonelline This section includes simple, sensitive, selective, accurate, precise and robust HPTLC method for determination of trigonelline in pure form and in Trigonella foenum-graecum seeds extract using acetonitrile: methanol: water (3: 2: 1, v/v/v) as mobile phase with UV detection at 265 nm. The proposed method showed advantages over the reported HPTLC methods for determination of trigonelline in Trigonella foenum-graecum seeds extract as decreasing run time and increasing linearity range using polynomial regression. The proposed method showed a good linearity over rang of 100-2000 (ng/spot) with 2.43 and 7.36 (ng/spot) as LOD and LOQ, respectively. The proposed method was successfully applied for determination of pure trigonelline with mean percentage recovery 100.44 ± 0.862. The average percentage recovery obtained using standard addition technique in Trigonella foenum-graecum seeds extract was 99.806 ± 0.758. This indicates accuracy of the proposed method for determination of trigonelline in pure form and in Trigonella foenum-graecum seeds extract. Statistical comparison showed no significant difference between the results obtained from the proposed method and the published one. Section B: Optimization of Microwave Assisted Extraction of Trigonelline from Trigonella foenum-graecum Seeds and Comparison with Other Conventional Techniques This section includes a general introduction to microwave assisted extraction (MAE) including its theory, advantages and applications. Summary XXVI It also includes developing a new extraction technique of trigonelline from Trigonella foenum-graecum seeds using microwaves which was not reported in literature before. Optimization of the parameters affecting MAE efficiency of trigonelline from Trigonella foenum-graecum seeds was studied. The proposed HPTLC method was applied for quantification of trigonelline during this study. The optimum MAE conditions were 50% methanol as extraction solvent, solid/liquid ratio 1:20 (g/ml), two extraction cycles 3 min each under 40% microwave irradiation power. The extraction efficiency of MAE was compared with conventional extraction techniques as heat reflux extraction (HRE) and maceration extraction (ME). MAE showed the best results as 7.89 (mg/g) trigonelline yield were obtained in 6 min compared to 6.16 and 3.59 (mg/g) trigonelline yield in 3 h and 15 h using HRE and ME, respectively. MAE also showed the best precision over the other extraction techniques. If the extraction yield obtained from MAE is to be considered as 100% performance level then, 3h of HRE and 15h of ME can attain 78.07% and 45.50% performance efficiency (in terms of extraction yield of trigonelline). Section C: HPLC Determination of Trigonelline This section includes simple, sensitive, selective, accurate, precise and robust HPLC method for determination of trigonelline in pure form and in Trigonella foenum-graecum seeds extract on C18 column using gradient elution with 0.025% acetic acid in water (solution A) and acetonitrile (solution B) at flow rate 0.7 ml/min and diode array detection