I= EFFECTS OF DIETARY FIBER ON THE BIOAVAILABILITY OF TRACE ELEMENTS IN THE BODY
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Title of Thesis
EFFECTS OF DIETARY FIBER ON THE BIOAVAILABILITY OF TRACE ELEMENTS IN THE BODY

Author(s)
Samina Yunus Khan
Institute/University/Department Details
Department of Chemistry/ University of Karachi
Session
1999
Subject
Chemistry
Number of Pages
292
Keywords (Extracted from title, table of contents and abstract of thesis)
trace elements, dietary fiber, ihp, calcium bioavailability, copper bioavailability, iron bioavailability

Abstract
Studies of Fe(111) with IHP were carried out oat pH 3.0,5.0 and 8.0. The predominant stocihiometry of the complexes were found out to be ML, M2L and ML2 dependent pH and the related concentration of metal and ligand. The stability constants of complexes were calculated through spectrophotometric and potentiometric methods and found to be comparable. The work yielded the stability constants in the range of 1012 for ML complexes, 1022 for ML2 complexes M2L complexes. For the potentiometric study computer program “BEST” was used to get more reliable results.

The proposed structure of the various species of the complexes were proposed and the structural confirmation was made by and I.R study of the complex.

Thermodynamic stability of ht complexes was assessed by working out various thermodynamic parameters. Preliminary data was gathered by pH titration at temperatures ranging from 25oC to 65 oC. The data was ten processed and analyze by computer program BEST for the refinement of the logβ values. Graphs were plotted with InK versus 1/T which gave ∆H/R as slope and ∆S/R as intercept.

Change in enthalpy values were found to be -5.12x103 KJmol-1 for ML complexes, -6.32x102 KJmol-1 for M2L complexes and 8.07x102 KJmol-1 for ML2 complexes. Change in entropy values were found to be 4.192J-1 for ML complexes, 5.182 J-1 for M2L complexes and 2.828 J-1 for ML2 complexes.

The reduction of the complex was performed by ascorbic acid dithionite and hydroquinone at pH 4.5 and at 30oC. The redox potential(εº ox)values with different reductants were found to be -1.58x10-1V with ascorbate, 1.338V with dithionite, and -6.89x10-1V with hydroquinone.

The rate of the of the reduction was deduced by using computer program “Rate 2” and “spectrokinetics” using diode array spectrometer. The rate of reduction was found to be 2.74x10-1 sec-1 with ascorbate dithionite and 1.79x10-1 sec-1 with hydroquinone.

Interaction of Fe(111)-IHP complex with other chelathors of the biological environment like gallic acid, tannic acid and salicylhydroxamic acid was observed. The general trend was found to be:

Saliclhydroxamic Acid > Gallic Acid > Tannic Acid

The rates of replacement show that the fastest replacement is accompanied by salicylhydroxamic acid rate of 2.71x10-1 sec-1followed by Gallic Acid rate being 0.47x10-1 sec-1, and then by tannic acid its rate being 0.44 x10-1 sec-1.

Interaction of the Fe(111)-IHP complex with copper, zinc and calcium was also observed to see for the replacement of Fe(111). It was noted that zinc and calcium have the tendency to form binuclear complex when in limiting concentration and remove iron from the complex when present in excess concentration. The structures of the related complexes were also proposed.

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S. No. Chapter Title of the Chapters Page Size (KB)
1 0 Contents
127.75 KB
2 1 Introduction 1
393.47 KB
  1.1 The dietary fiber 2
  1.2 Dietary fiber hypothesis 4
  1.3 Phytates and minerals 5
  1.4 Food processing and IHP 14
  1.5 Anti Carcinogenicity of IHP 17
  1.6 Cellular signaling contribution of IHP 22
  1.7 Inhibitory effects of IHP 23
  1.8 Effects on iron bioavailability 23
  1.9 Effects on Zinc bioavailability 31
  1.10 Effects copper bioavailability 33
  1.11 Effects on calcium bioavailability 34
  1.12 Siderophores 37
3 2 Materials and Methods 54
229.12 KB
  2.1 Materials 54
  2.2 Chemical and solutions 55
  2.3 Instrumentation 59
  2.4 Potentiomeric methods 61
  2.5 U.V/VIS spectrophotometric 70
  2.6 Reduction of the complex 77
  2.7 Interaction of iron-IHP complex 80
  2.8 With other Chelators 81
  2.9 Interaction of iron-IHP complex 82
  2.10 With other metals 82
  2.11 Thermodynamic stability of the Fe(111)-IHP complex 83
  2.12 I.R Spectroscopy 84
4 3 Results and discussion 86
1093.62 KB
  3.1 Stoichiometry of Iron(III)-IHP complexes 86
  3.2 I.R Study of iron(111)-IHP complex 115
  3.3 Potentiometric study of iron(111)-IHP complexes 152
  3.4 Determination of the stability constants of iron(111)-IHP complexes by spectrophotometric method 139
  3.5 Reduction of the iron(111)IHP complex with ascorbic acid, dithionite and hydroquinone and cyclic voltammetry of the complex 169
  3.6 Interaction of iron(111)-IHP complex by gallic acid, salicylhydroxamic acid and tannic acid 203
  3.7 Interaction of iron(111)-IHP complex with zinc, copper and calcium 233
5 4 Conclusion 264
257.97 KB
  4.1 Future directions 270
  4.2 Reference 273