Chelators - BUGEMA UNIVERSITY

Chelators otherwise called chelants, chelating agents or sequestering agents, are substances or compounds that bind to metal ions to form stable and water-soluble complexes that can easily be excreted from the body system.

If you may recall metabolism of drugs in Pharmacology or Toxicology, you will realize that the whole purpose of metabolism of drugs is to change them from the hydrophobic (water-hating) state which can easy be absorbed by body cells into the more hydrophilic (water-loving) ones that can easily be excreted by the body. This is based on the fact that cells are surrounded by very hydrophobic structures. These structures only allow hydrophobic molecules or at least very tiny hydrophilic molecules to penetrate.

As such chelators are used for heavy metal poisoning such as Iron, Lead, Mercury, Cadmium, Arsenic, et cetera. They are also known to work for common medical problems such as cardiovascular diseases.

This presentation will define chelators, give their classifications, examples and what they are used for.

1. ENVIRONMENTAL BIOCHEMISTRY AND TOXICOLOGY BIOC 261 1 Lecturer: Madam Leah

2. PRESENTATION BY MUUNDA MUDENDA 15/BSB/BU/R/0004 2 Presented on: 24 th October, 2017.

3. Question: “Discuss Chelating agents and Antidotes.” 3

4. OBJECTIVES To explain what chelating agents are; Definition Classification Examples Mechanism of Action, and Their practical Applications. 4

5. 2. To explain what antidotes are; Definition Classification Examples Mechanism of Action, and Their practical Applications. 5

6. 3. Establish the relation that exists between chelators and antidotes. 6

7. WHAT ARE CHELATING AGENTS? These are also called; chelants , chelators , or sequestering agents . 7

8. Definition of chelating agents Chelators/ Chelating agents are chemical compounds that react with metal ions to form a stable, water-soluble complex. A chelating agent is a substance whose molecules can form several bonds to a single metal ion . A compound/ substance having ability to form complexes with heavy metal and prevent or reverse the binding of metallic cation to ligands of the body 8

9. So what is chelation? Chelation is a process of reaction between a metal ion and a complexing agent that produce a stable , non-ionized , nontoxic & water soluble complexe which can be eliminated easily. 9

10. Confusing chelates with chelating agents 10

11. What is chelation therapy? Chelation therapy is treatment used in conventional medicine for removing heavy metals (including mercury) from the blood. 11

12. Chelation therapy is the preferred medical treatment for reducing the toxic effects of metals. 12

13. Chelating agents are capable of binding to toxic metal ions to form complex structures which are easily excreted from the body removing them from intracellular or extracellular spaces. 13

14. What do chelators act on? Chelators are commonly used on heavy metals. When heavy metals that can cause toxicity, such as; Lead Mercury Arsenic Cadmium a ccumulate in the body, chelators are used to reduce their concentration. 14

15. Ideal Chelating Agents More affinity for metals (xenobiotics) than endogenous ligand High solubility in water Resistance to biotransformation Form non toxic complexes with toxic metal Accelerate mobilization and/or removal of the metals Cheap and easy to administer Easy excretion of chelating complex 15

16. CLASSIFICATION OF CHELATING AGENTS 1.Dimercaprol ( BAL ), Succimer (DMSA ),DMPS 2.D-Penicillamine & N- acetylpenicillamine 3.EDTA derivatives 4.Desferrioxamine,Deferiprone,Defrasirox 5.Trientene 16

17. Dimercaprol (BAL) (2-3 DIMERCAPTOPROPANOL) Synthesized by Stocken and Thompson during world war II Developed as antidote to lewisite( arsenical war gas ) BAL-British anti lewisite Oily, Pungent smelling, Viscous liquid 17

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29. SUMMARY 29

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