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1 19.4 Amines React as Bases 19.5 Heterocyclic Amines and Alkaloids Chapter 19 Amines and Amides.

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Presentation on theme: "1 19.4 Amines React as Bases 19.5 Heterocyclic Amines and Alkaloids Chapter 19 Amines and Amides."— Presentation transcript:

1 Amines React as Bases 19.5 Heterocyclic Amines and Alkaloids Chapter 19 Amines and Amides

2 2 Like ammonia, amines are weak bases in water. NH 3 + H 2 O NH OH – ammonium hydroxide CH 3 —NH 2 + H 2 O CH 3 —NH OH – methylammonium hydroxide Amines React as Bases

3 3 An amine salt: Forms when an amine is neutralized by acid. Is named by replacing the amine part of the name with ammonium followed by the name of the negative ion. CH 3 —NH 2 + HCl CH 3 —NH 3 + Cl – Methylamine methylammonium chloride Neutralization forms Amine Salts

4 4 Properties of Amine Salts Amine salts are: Solids at room temperature. Soluble in water and body fluids. The form used for drugs.

5 5 Cocaine Cocaine is sold illegally as an amine salt. Cocaine is reacted with NaOH to produce the free amine form known as “crack.”

6 6 Heterocyclic Amines In a heterocyclic amine, a five- or six-atom ring contains one or more nitrogen atoms.

7 7 Alkaloids are: Physiologically active nitrogen-containing compounds. Produced by plants. Used as stimulants, anesthetics, and antidepressants. Often habit forming. Alkaloids

8 8 Caffeine: Is a stimulant of the central nervous system. Is found in coffee beans, tea, chocolate, and soft drinks. Contains an imidazole ring. Caffeine

9 9 Nicotine Nicotine: Increases the adrenaline level in the blood. Causes addiction to tobacco. Contains a pyrrolidine ring.

10 10 Alkaloids Related to Morphine Alkaloids such as morphine and codeine are produced by the poppy. For centuries, morphine and codeine have been used as painkillers. Heroin is a modification of morphine.

11 11 Pharmacology An area of research in pharmacology is to design drugs with some of the characteristics of alkaloids. The structures of cocaine and morphine are modified to produce anesthesia, but without the addictive side effects.

12 12 Pharmacology Parts of the morphine structure that produce anesthesia are found in procaine, lidocaine, and demerol.

13 13 Nervous System Amines Derived from amino acids Neurotransmitters A nerve can be thought of as transmitting a stimulus from one part of the body to another by means of a moving wave of ions. When the wave reaches the end of a neuron, it causes the release of a transmitter that migrates to a receptor cell, where it triggers the propagation of another wave. Neuron → Chemical transmitter → Receptor cell, muscle fiber, or another neuron

14 14 Acetylcholine Muscles are sensitive to acetylcholine Acetylcholine is synthesized from amino acids serine and methionine L-Serine → ethanolamine, amino alcohol HO-CH 2 -CH 2 -NH methyl groups from methionine → choline, another amino alcohol HO-CH 2 -CH 2 -N + (CH 3 ) 3 → O || acetylcholine, CH 3 -C-O-CH 2 -CH 2 -N + (CH 3 ) 3 Once the desired response has been provoked, the acetylcholine must be removed

15 15 Catecholamines Derivatives of dopamine (3,4-dihydroxyphenethylamine) Precursor is amino acid tyrosine Include norepinephrinene, epinephrine (adrenaline), L-dopa Produced in the brain and adrenal gland These hormones permit the body to react to stress by increasing blood flow to muscles, lungs, and brain. They also stimulate cellular metabolism.

16 16 Stimulant Drugs: Amphetamines Synthetic amines related to β-phenylethylamine Act as stimulants by mimicking natural brain amines. Amphetamine has been used for weight reduction (no longer recommended; weight loss was only temporary). Amphetamine induces excitability, restlessness, tremors, insomnia, dilated pupils, increased pulse rate and blood pressure, hallucinations, and psychoses.

17 17 Serotonine (5-hydroxytryptamine, or 5-HT) Found in cells of the central nervous system, where it functions as a transmitter in relation to sleep. Also produced in the intestinal mucosa. The drug lysergic acid diethylamide (LSD) probably competes with serotonin, since LSD toxicity can be treated by serotonin administration. Precursor is amino acid L- Tryptophan.

18 18 Serotonin (5-hydroxytryptamine, or 5-HT) is a monoamine neurotransmittermonoamineneurotransmitter Serotonin - Wikipedia, the free encyclopedia ( Serotonin is involved in sleep, sensory perception, regulation of body temperature, etc. Diets high in carbohydrate lead to high levels of serotonin. Lots of protein lowers the serotonin concentration. That may seem strange, because protein has lots of tryptophan and carbohydrates have little. Protein is only 1% tryptophan. In the presense of all those other amino acids, little tryptophan reaches the brain. With a carbohydrate meal, the hormone insulin lowers the level of the other amino acids in the blood, allowing relatively high levels of tryptophan to reach the brain.

19 19 γ-Aminobutyrate (GABA) Precursor is amino acid L-Glutamate Present in high concentrations in the brain Inhibit synaptic transmission

20 20 Histamine Precursor is amino acid L- Histidine Released as a result of allergies Causes the expansion of capillaries and edema (probably by constricting the smaller veins that lead to them) The resulting drop in blood pressure may induce shock Antihistamines are structurally similar to histamine Antihistamines can prevent the physiological changes produced by histamine release during allergic reactions

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