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Natural Polymer

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Title: Green Chemistry Author: Patrick Last modified by: User Created Date: 8/15/2009 8:18:36 AM Document presentation format: (4:3) – PowerPoint PPT presentation

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Title: Natural Polymer


1
Natural Polymer
2
Protein
  • A protein is a complex, high-molecular-weight,
    organic compound that consists of amino acids
    joined by peptide bonds.
  • Proteins are essential to the structure and
    function of all living cells and viruses.

3
Examples of Amino acids
  • L-alanine L-Asparagine

4
Peptide bond
  • 1. amino acid
  • 2. amino acid ionic form
  • 3. formation of peptide linkage

5
Polysaccharides
  • Polysaccharides are relatively complex
    carbohydrates.
  • They are polymers made up of many monosaccharides
    joined together by glycosidic linkages
  • They are very large, often branched, molecules.
    They tend to be insoluble in water, and have no
    sweet taste.

6
Example of polysaccharides
  • starch
  • glycogen
  • cellulose
  • Polysaccharides have a general formula of
    Cn(H2O)n-1 where n is usually a large number
    between 200 and 500.

7
e.g. Starch
  • Starches are insoluble in water.
  • They can be digested by hydrolysis catalyzed by
    enzymes called amylases, which can break the
    alpha-linkages. Humans and other animals have
    amylases, so they can digest starches.
  • Potato, rice, wheat, and maize are major sources
    of starch in the human diet.

8
Structure of Starch
9
e.g. Cellulose
  • The structural components of plants are formed
    primarily from cellulose. Wood is largely
    cellulose and lignin, while paper and cotton are
    nearly pure cellulose.
  • Cellulose is a polymer made with repeated glucose
    units bonded together by beta-linkages.

10
Structure of Cellulose
11
Glycogen
  • Glycogen is a polysaccharide that is the
    principal storage form of glucose in animal
    cells.
  • Most of glucose units are linked by a a-1,4
    glycosidic linkage, a few of them also makes a
    a-1,6 glycosidic bond with a second glucose which
    results in creating of a branch. Glycogen has a
    large number of non-reducing ends with a free
    hydroxy group at carbon 4.

12
Glycogen (with glycosidic linkage)
13
  • Glycogen

14
  • Reducing sugar must have this structure

15
(No Transcript)
16
DNA
  • Deoxyribonucleic acid (DNA) is a nucleic acid
    usually in the form of a double helix that
    contains the genetic instructions specifying the
    biological development of all cellular forms of
    life, and most viruses.
  • DNA is a long polymer of nucleotides and encodes
    the sequence of the amino acid residues in
    proteins using the genetic code.

Nucleotide
17
  • Each spiral strand, composed of a sugar phosphate
    backbone and attached bases, is connected to a
    complementary strand by hydrogen bonding (non-
    covalent) between paired bases, adenine (A) with
    thymine (T) and guanine (G) with cytosine (C).

18
  • Adenine and thymine are connected by two hydrogen
    bonds (non-covalent) while guanine and cytosine
    are connected by three.

19
Development of Aspirin
20
Stage 1
  • Lead compound?
  • Salicylic acid

21
Stage 2
  • One of the hydroxy functional groups in salicylic
    acid was modified with an acetyl group(forming an
    ester), which greatly reduced the negative side
    effects of salicylic acid.

22
Stage 3
  • Aspirin was at first available as a powder in
    sachets, but due to its low solubility. Bayer
    then decided to pellet the powder and solid as
    tablets.

23
Stage 4
  • No, it was not properly performed, as we can see
    that there was no short-term and long term
    testings conducted on animals. Besides, the Phase
    1 and Phase 2 of clinical research also had not
    been conducted as Bayer distributes aspirin
    powder to physicians to give to the patients
    directly.

24
Stage 5
  • FDA modifies the aspirins labeling information

25
Development of cis-platin
26
Compound Discovery
  • Square planar Pt(II) complex
  • Discovered by Barnett Rosenberg (Michigan) in mid
    1960s
  • discovered that electrolysis products from a
    platinum electrode inhibited mitosis in
    Escherichia coli (E. coli) bacteria. The bacteria
    grow to 300 times their normal length but cell
    division fails.

27
  • In the 1970s, a series of experiments were
    conducted at Michigan State University to test
    the effects the cis-diamminedichloroplatinum(II),
    along with other platinum coordination complexes,
    on tumors artificially implanted in rats. This
    study found that cis-diamminedichloroplatinum(II)
    was the most effective out of this group, which
    started the medicinal career of cis-platin.
  • Approved for clinical use by the American Food
    and Drug Administration (FDA) in 1978, it
    revolutionized the treatment of certain cancers.
    Detailed studies on its molecular mechanism of
    action, using a variety of spectrocopic methods
    including X-ray, NMR and other physico-chemical
    methods, revealed its ability to form
    irreversible crosslinks with bases in DNA.

28
  • Uses of Cis-platin
  • widely used anticancer drug for testicular
    cancer, ovarian cancer and nasopharyngeal cancer

29
Mode of Action
  • Cis-platin is given to patients by injection.
  • It retains its neutral form in the serum due to
    high Cl-.
  • It passes through the cell membrane.
  • Hydration of cis-platin in cytoplasm due to low
    Cl- .
  • Cationic Pt(II) complexes reacts with DNA to form
    Pt-DNA adduct.

30
Mode of action
  • inside the cell
  • Pt (NH3)2Cl2 H2O ? Pt (NH3)2Cl(H2O) Cl-
  • Pt(NH3)2Cl(H2O) H2O ? Pt(NH3)2(H2O)22

31
DNA Deoxyribonucleic acid
  • Polymers of nucleotides
  • A Nucleotide a ribose phosphate nitrogen
    base

Double helical structure
Nitrogen Bases are linked by hydrogen bonding
32
Pt - DNA Adduct
  • Cis-platin reacts preferably at the GG sequence
    via coordinating to the N7 of guanine
  • A Pt(NH3)2(dGdG) complex was prepared and
    characterized by X-ray crystallography

33
Pt-DNA Adduct
  • Platination of DNA caused deformation of the
    helix because the destacking of guanine bases,
    which would normally be parallel to one another.
  • ?no more cell division and stop cancer.

34
Side Effect of taking cis-platin
  • Problem of toxic side effects kidney damage,
    nerve damage, nausea and vomiting, hearing loss,
    hair loss, etc.
  • Hydrolytic products of cis-platin,
    Pt(NH3)2(H2O)22, Pt (NH3)2Cl(H2O) are
    highly electrophilic and reactive to other
    intracellular components.

35
Development -carboplatin
  • Same curing effect but with lower required doses
    and reduced side effects
  • less toxic to the peripheral nervous system and
    the kidneys
  • due to the presence of the bidentate
    dicarboxylate ligand in carboplatin slows down
    the degradation of carboplatin into potentially
    damaging derivatives.

2nd generation carboplatin
36
Development
  • 3rd generation

37
Part 1Over-the Counter Drugs
  • 1) Aspirin
  • 2) Acetaminophen
  • 3) Vitamin C

38
Aspirin
  • used as an analgesic (against minor pains and
    aches)
  • antipyretic (against fever)
  • anti-inflammatory
  • an anticoagulant ("blood-thinning") effect and is
    used in long-term low-doses to prevent heart
    attacks.

39
Paracetamol or acetaminophen
  • a common analgesic and antipyretic drug that is
    used for the relief of fever, headaches, and
    other minor aches and pains.
  • a major ingredient in numerous cold and flu
    medications and many prescription analgesics.
  • safe in standard doses, but, accidental overdoses
    are fairly common.

40
Vitamin C
  • prevents scurvy.
  • It is a strong antioxidant.

41
Part 2Perscription Drugs
  • 4) Albuterol
  • 5) Amlodipine
  • 6) Loratadine
  • 7) Amoxicillin
  • 8) Omeprazole

42
Albuterol
  • Relieve the symptoms of asthma
  • protection against exercise-induced asthma

43
Loratadine
  • a drug used to treat allergies
  • relieve nasal congestion.

44
Amoxicillin
  • an antibiotic used to treat bacterial infections
    caused by susceptible microorganisms.
  • acts by inhibiting the synthesis of bacterial
    cell walls.

45
Omeprazole
  • used in the treatment of dyspepsia-a constant
    pain in the stomach.
  • Constant pains include indigestion, heartburn and
    nausea.
  • Most oral omeprazole preparations are
    enteric-coated, due to the rapid degradation of
    the drug in the acidic conditions of the stomach

46
Green Chemistry
47
12 principles
  • Atom Economy
  • (Molecular Weight of desired product) /
    (Molecular Weight of all reactants) 100
    Yield (Actual yield) / (Theoretical yield)
    100

48
Atom Economy
  • FM 74.0 102.9 98.1
    136.9
  • CH3(CH2)2CH2OH NaBr H2SO4 ? CH3(CH2)2CH2Br
    NaHSO4 H2O
  • mol 0.0219 0.0258 0.0460
    0.0175
  • yield ???? 80
  • atom economy 136.9/(74.0102.998.1) 50
  • it produces too much side products during the
    reaction, therefore it is much better to reduce
    the amount of waste generated in the first place.

49
Supercritical CO2
  • Advantages for extraction
  • High penetration power (like a gas) but high
    extraction power as a liquid
  • Can dissolve most organic cpds of small molecular
    masses
  • Leaves no residual trace of liquid o material
  • Friendly to the environment
  • Low toxicity
  • Stable, no rxn with most organic cpds
  • Relative low critical temp.

50
Extraction of caffeine
  • Green beans are soaked in water
  • Supercritical CO2 is forced through the green
    coffee beans many times.
  • Caffeine, being a small molecule, can easily
    dissolve in supercritical CO2.
  • After extraction, the supercritical CO2 fluid is
    then vaporized for reuse and the caffeine can
    then be isolated for resale to e.g. cola
    manufacturers.
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