2016-11-30 1 Chemistry of Heterocyclic Compounds Porphyrins Purines and pyrimidines Nucleosides and nucleotides Introduction to Introduction to Introduction to Introduction to Heterocyclic Compounds Heterocyclic Compounds Heterocyclic Compounds Heterocyclic Compounds Cyclic compounds with one or more other elements along with carbon atoms are heterocyclic compounds. Non carbon atoms are the hetero atoms. Common hetero atoms are the N, S, O etc. Number of drugs in pharmaceutical science are heterocyclic compounds. 3 5-MEMBERED HETEROCYCLIC COMPOUNDS HAVING ONE HETERO ATOM FURAN PYRROLE THIOPHENE
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Chemistry ofHeterocyclic Compounds€¦ · Number of drugs in pharmaceutical science are heterocyclic compounds. 3333 5-MEMBERED HETEROCYCLIC COMPOUNDS HAVING ONE HETERO ATOM FURAN
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Chemistry of Heterocyclic Compounds
Porphyrins
Purines and pyrimidines
Nucleosides and nucleotides
Introduction to Introduction to Introduction to Introduction to
Among few naturally occurring productsthat contain the thiazole nucleus arevitamin B1 and the pencillins.
Vitamin B1
(Thiamine)General pattern of the penicillins
�5-MEMBERED HETEROCYCLIC COMPOUNDS HAVING MORE
THAN ONE HETERO ATOMS
�5-MEMBERED HETEROCYCLIC COMPOUNDS HAVING MORE
THAN ONE HETERO ATOMS
IMIDAZOLE
Among the few naturally occurring productsknown to contain the imidazole nucleus areamino acids (histidine), purines, uric acid.
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�6-MEMBERED HETEROCYCLIC COMPOUNDS HAVING
ONE HETERO ATOM
PYRIDINE PIPERIDINE
PYRIMIDINE PYIRIDAZINE PYRAZINE
�6-MEMBERED HETEROCYCLIC COMPOUNDS HAVING MORE
THAN ONE HETERO ATOMS
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�6-MEMBERED HETEROCYCLIC COMPOUNDS HAVING
ONE HETERO ATOM
PYRIDINE
Nicotinamide and isoniazide – derivatives of piridine.
Nicotinamide, also known as niacin, is a vitamin.
Isoniazid is biologically active and proved to be highly effective in the treatment of tuberculosis.
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�6-MEMBERED HETEROCYCLIC COMPOUNDS HAVING
ONE HETERO ATOM
PYRIDINE
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PYRIMIDINE
�6-MEMBERED HETEROCYCLIC COMPOUNDS HAVING MORE
THAN ONE HETERO ATOMS
Pyrimidines
The pyrimidines are heterocyclic compounds whose basic structure is a six-membered ring containing carbon and nitrogen atoms as illustrated by the parent compound, pyrimidine.
Pyrimidines
Thymine, cytosine, and uracil are substituted pyrimidines found in nucleic acid. Their structural formulas are as follows:
21212121
�CONDENSED HETEROCYCLIC COMPOUNDS.
INDOLEPURINE
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22222222
�CONDENSED HETEROCYCLIC COMPOUNDS
INDOLE
Tryptophan- Indole group
Purines
PurinesThe parent substance, purine,
consists of pyrimidine ring attached toimidazole ring. The structural formulaof the purine is as follows:
Nucleosides and nucleotidesNucleosides and nucleotidesNucleosides and nucleotidesNucleosides and nucleotidesFunctionsFunctionsFunctionsFunctions
• Nucleotides are precursors of the nucleic acids, deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).
• The nucleic acids are concerned with the storage and transfer of genetic information.
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• The universal currency of energy, namely ATP,is a nucleotide derivative.
• Nucleotides are also components of importantco-enzymes like:
- NAD+ and FAD, and
- metabolic regulators such as cAMP and cGMP.
Nucleosides and nucleotidesNucleosides and nucleotidesNucleosides and nucleotidesNucleosides and nucleotidesFunctionsFunctionsFunctionsFunctions
Composition of NucleotidesComposition of NucleotidesComposition of NucleotidesComposition of Nucleotides
A nucleotide is made up of 3 components:
- a. Nitrogenous base (a purine or a pyrimidine)
- b. Pentose sugar, either ribose or deoxyribose
- c. Phosphate groups esterified to the sugar.
Composition of NucleotidesComposition of NucleotidesComposition of NucleotidesComposition of Nucleotides
• When a base combines with a pentose sugar, a nucleoside is formed.
• When the nucleoside is esterified to a phosphate group, it is called a nucleotide or nucleoside monophosphate.
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Composition of NucleotidesComposition of NucleotidesComposition of NucleotidesComposition of Nucleotides
• When a second phosphate gets esterified to theexisting phosphate group, a nucleoside diphosphateis generated.
• The attachment of a 3rd phosphate group results inthe formation of a nucleoside triphosphate.
• The nucleic acids (DNA and RNA) are polymers ofnucleoside monophosphates
Bases Present in the Nucleic AcidsBases Present in the Nucleic AcidsBases Present in the Nucleic AcidsBases Present in the Nucleic Acids
• Two types of nitrogenous bases;
- the purines and pyrimidines are present in
nucleic acids.
Purine BasesPurine BasesPurine BasesPurine Bases
• The purine bases present in RNA and DNA are the
same;
- adenine and guanine.
�Adenine is 6-amino purine
�Guanine is 2-amino, 6-oxy purine
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Purine BasesPurine BasesPurine BasesPurine Bases
�Purine has a numbering scheme that does not match rules, and represents a historical numbering pattern.
�The numbering of the purine ring with the structure of adenine and guanine are shown in Figure.
THIAMINE is vitamin B1, named as the "thio-vitamine"("sulfur-containing vitamin") is a vitamin of theB complex
These two words are often confused
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NucleosidesNucleosidesNucleosidesNucleosides
• Nucleosides are formed when bases are attached to the pentose sugar, D-ribose or 2-deoxy-D-ribose.
Sugar groups in nucleic acids
O OH
OHOH
CH2
OH
O OH
OH
CH2
OH
Ribose Deoxyribose
The only difference in the two compounds is thatdeoxyribose is lacking an oxygen atom (second carbon atom).
NucleosidesNucleosidesNucleosidesNucleosides
• All the bases are attached to the corresponding pentose sugar by a beta-N-glycosidic bond between the 1st carbon of the pentose sugar and N9 of a purine or N1 of a pyrimidine.
• The deoxy nucleosides are denoted by adding the prefix d- before the nucleoside.
NucleosidesNucleosidesNucleosidesNucleosides
The carbon atoms of the pentose sugar are denoted by using a prime number to avoid confusion with the carbon atoms of the purine or pyrimidine ring.
Numbering in base andsugar groups.
Atoms in sugar isdenoted with primednumbers.
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NucleosidesNucleosidesNucleosidesNucleosides
• Nucleosides with purine bases have the suffix -sine,
while pyrimidine nucleosides end with -dine.
• Uracil combines with ribose only; and thymine with
deoxy ribose only.
NucleosidesNucleosidesNucleosidesNucleosides
The names ofthe differentnucleosides aregiven in Table.
NucleotidesNucleotidesNucleotidesNucleotides
• These are phosphate esters of nucleosides.
Base plus pentose sugar plus phosphoric acid
is a nucleotide
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NucleotidesNucleotidesNucleotidesNucleotides
• The esterification occurs at the 5th or 3rd hydroxyl group of the pentose sugar.
• Most of the nucleoside phosphates involved in biological function are 5'-phosphates.
NucleoNucleoNucleoNucleotidestidestidestides
NucleotidesNucleotidesNucleotidesNucleotides
• Since 5'-nucleotides are more often seen, they are simply written without any prefix.
• For example, 5'-AMP is abbreviated as AMP; but 3' variety is always written as 3'-AMP.
• Moreover, a base can combine with either ribose or deoxy ribose, which in turn can be phosphorylated at 3' or 5' positions.
• Nicotinamide adenine dinucleotide (NAD) is a coenzyme found in all living cells.
• The compound is a dinucleotide, because it consists of two nucleotides joined through their phosphate groups.
• One nucleotide contains an adenine base and the other nicotinamide.
• Nicotinamide adenine dinucleotide exists in two forms, an oxidized and reduced form abbreviated as NAD+ and NADH respectively (In metabolism is involved in redox reactions)