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Biol 444 Chem 444 Bratton, Heather Bui, Steven Chan, Hiu Fai

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Presentation on theme: "Biol 444 Chem 444 Bratton, Heather Bui, Steven Chan, Hiu Fai"— Presentation transcript:

1 Biol 444 Chem 444 Bratton, Heather Bui, Steven Chan, Hiu Fai
Doan, Chad Ho, Joyce Karimbabai Massihi, Anna Krasner, Danielle Loi, William Malette, Jacqueline Nguyen, Trang Robles, Marisa Tallorin, Lorillee Truong, Daniel C Udeh, Francis Villalvazo, Adrianne Yeh, Enrenn Bautista, Candie Chen, John Chida, Odette Cueva, Carla Golanbar, Gelareh Kashiwabara, Claudine Kopilec, Jaimisyn Lau, Jensen Le, Giang-Tuong Lee, Margaret Mata, Francisca Nguyen, Thuy Nhi Phillips, Irving Romero, Marcelo Wang, Tony Wittig, Michelle Chem 444 Biol 444

2 Primary (1°) Metabolism
- Construct common biological macromolecules from simple building blocks found within every cell - Typically a process of polymerization, stringing monomers together into a macromolecule that performs a cellular function sugars polysaccharides amino acids proteins fats phospholipid bilayers - Block production: cell dies (primary metabolites are essential)

3 Secondary (2°) Metabolism
- Synthesize compounds that are unique to a particular species or genus (unlike common proteins, lipids, etc.) - Molecules may have extremely complex structures - These molecules typically have no effect on the producing organism, but are often highly biologically active against other organisms (competitors, pathogens, predators) - Often present at extraordinary concentrations, >10% of the dry weight of the organism inference is, they must do something

4 Natural Products: Folk to Modern Medicines
- Humans have long used chemicals in plant and animal extracts for many purposes: medicines, poisons, recreational stimulants - Since the 1800’s, chemists have characterized and synthesized such natural products, uncovering the basis for folk remedies Identifying the mechanism of action of natural products was the genesis of modern drug discovery - - The active ingredients in many ancient curatives are still used medicinally today

5 Natural Products 1: Toxins
Rotenone - Natural fish + insect poison Curare (Tubocurarine chloride) - Derived from 2 South American plant genera - Used as arrow-tip poison by native peoples - Blocks transmission of acetylcholine signal to muscles, causing instant paralysis - 1st drug used as muscle relaxant in surgery

6 Natural Products 1: Toxins
Hyoscine (= scopolamine) - Derived from plants: deadly nightshade (belladonna), mandrake - In ancient Greece, mandrake was used as an anaesthetic (or poison, in higher doses) - “Witches” smeared extracts on their armpits: avoided toxic oral route, got maximum hallucinogenic effect = felt like they were flying - Blocks certain acetylcholine receptors - Modern use: prevention of motion sickness (patches behind the ear)

7 Natural Products 2: Medicines
COCH3 Salicin Acetyl-salicilic acid: aspirin - From Willow tree bark, which was used in folk remedies for treating fevers - Led to synthetic analogue, modern aspirin

8 Natural Products 2: Medicines
Ventolin Ephedrine - From Ephedra plants, basis of ancient Chinese herbal remedy “Ma Huang” (100 AD) for treating respiratory illness - Used clinically since 1926 as bronchodilator to treat asthma - Similar to adrenaline, but also stimulates heart (not good in a drug) - Stimulated research resulting in the non-stimulant drug Ventolin

9 Natural Products 2: Medicines
Quinine - Found exclusively in the bark of the Chinona tree - Used as a malaria treatment since 1600’s - Now synthetic derivatives used, due to widespread resistance

10 Natural Products 3: Stimulants
Nicotine Caffeine Caffeine-containing plant leaves + seeds have long been brewed to produce stimulant drinks - Such stimulants naturally act as feeding deterrents to repel insect herbivores that consume plants leaves - Tobacco plant can up its production of nicotine 4-fold when under attack by insects; nicotine by-products are used as insecticides

11 Natural Products 3: Stimulants
Cocaine Coca leaves have been used as a source of cocaine for > 2,000 yrs - Used by Incas in religious ceremonies - Introduced to Europe by conquistadores - Leaves chewed daily by >8 million native peoples in the Andes, to alleviate feelings of hunger and fatigue - Inhibits re-uptake of excitatory neurotransmitter dopamine

12 Natural Products 4: Halucinogens
Morphine (= opium) Heroin (synthetic derivative) - Found in only 2 species of poppy flower (Papaver) - Milky exudate of seed capsules is 25% opiate - Used as a baby calming treatment in ancient Egypt - Binds to brain receptors for short peptides called enkephalins, derived from endorphins

13 Natural Products 4: Halucinogens
Similar spatial relationships of (*)-marked atoms responsible for similar pharmacological effects Enkephalin Morphine * * * *

14 Natural Products 4: Halucinogens
Tetrahydrocannabinol Lysergic acid Lysergic acid Diethylamine (LSD, synthetic) - Lysergic acid is the parent compound from which ergot alkaloids are derived, such as LSD - Produced by fungus; often affected stored grain in Middle Ages - Such compounds found in Aztec “magical” preparation ololuiqui - Structural mimics of human neurotransmitter 5-hydroxytryptamine

15 Secondary Metabolites
- Produced from a small number of key intermediates, often generated as by-products of primary metabolism acetate (in the form of acetyl coA) mevalonate 4-carbon sugars - Perhaps arose as a means of dealing with excess metabolic intermediary compounds -2o metabolites then took on ecological roles as toxins, etc.

16 Secondary Metabolites
- Typically play ecological roles in nature, deterring would-be pests, predators or pathogens - Affect humans due to structural resemblance to innate neurotransmitters, or by binding to proteins in a way that disrupts normal cellular function - Natural products are the basis for a big % of pharmaceutical drugs currently on the market -

17 Simple building blocks serve as the basis for each major
pathway of secondary metabolism: (1) Shikimate Aromatics (ring - C3 chain) (2) Amino acids Alkaloids, Penicillins (N-containing) (3) Mevalonate Terpenes, Steroids (4) Acetate Polyketides (aromatics, macrocycles)

18 (1) (2) (3) (4) Shikimate pathway Alkaloids
(photosynthesis) Polysaccharides Glycosides Nucleic Acids phosphoenol pyruvate (1) Shikimate pathway Aromatic Compounds Lignans Shikimate (2) aromatic amino acids aliphatic amino acids Alkaloids Peptides Penicillins Cyclic Peptides pyruvate CITRIC ACID CYCLE acetyl CoA CH3COSCoA CH3COSCoA -O2CCH2COSCoA CH3COCH2COSCoA CH3COSCoA Isoprenoids (terpenes, steroids, carotenoids) CH3COSCoA (3) (4) mevalonate Polyketides, Fatty Acids Prostaglandins, Macrocyclic Antibiotics

19 (1) Shikimate pathway from the Japanese flower shikimi (シキミ, Illicium anisatum) (A) Biosynthesis of aromatic amino acids (tyrosine, phenylalanine, and tryptophan) lead to alkaloids (B) Build aromatic secondary metabolites Shikimate Podophyllotoxin

20 Shikimate biosynthesis
Chorismate Shikimate PEP Prephenate Other shikimate metabolites: ring-C3 ...ring-C2 ...ring-C1 + NH3 - NH3 Cinnamic acid Tyrosine, Phenylalanine

21 Biosynthesis of phenyl compounds
ring-C1 type vanillin vanillic acid salicin salicylic acid - In plants, many shikimate metabolites are allelopathic: they inhibit growth of competitors - Insoluble forms often linked to sugars in plant tissue - Soluble acidic forms leach out into surrounding soil in rain

22 Lignans & Lignins Polymerization: complex lignins Enzymatic coupling:
phenylalanine Cinnamic acid Polymerization: complex lignins Enzymatic coupling: dimeric lignans Cinnamyl alcohol Large % of woody plant biomass Podophyllotoxin

23 Podophyllotoxin - An important shikimate compound
- Used by native Americans to cure warts - Powerful inhibitor of mitosis; found to block enzyme tubulin polymerase -

24 Flavanoid Biosynthesis
Shikimate + 3 acetates = flavanones Cause bitter tastes in plants, especially polymerized tannins; deter feeding by herbivores Derived compounds are responsible for much of plant color

25 (2) Alkaloids (2) Amino acids Alkaloids, Peptides, Penicillins
Strychnine (alkaloid) Cyclosporin A (cyclic peptide)

26 Alkaloid characteristics
- Non-(normal)-peptide, non-nucleic acid compounds that contain nitrogen - Common in fungi, plants, insects + amphibians - Derived from amino acid precursors

27 Tyramine Tyrosine Dopamine Mescaline - potent hallucinogen from the peyote cactus - competitively binds to dopamine receptors

28 Penicillin Biosynthesis
a-adipate + cysteine valine - start with peptide made of 3 amino acids (including a non-standard a.a., a-adipate)

29 isopenicillin synthase
a-adipate + cysteine valine isopenicillin synthase epimerase penicillin N isopenicillin N cephalosporins penicillins

30 Penicillins: Mechanism of Action
This class of antibiotics interferes with synthesis of the cell wall of Gram-positive bacteria (Staphylococci, Streptococci) Cell wall is a repeating polymer of disaccharide, tetrapeptide repeats cross-linked into a 3D matrix (1) cleave here (transpeptidase) sugar - sugar - phospholipid L-ala — D-glu — L-lys — D-ala — D-ala (glycine)5 (2) cross-link here

31 Penicillins: Mechanism of Action
Penicillins inhibit the bacterial transpeptidase enzyme by mimicking its natural substrate, the terminal D-ala—D-ala Transpeptidase attacks the b-lactam ring of penicillin, forms a covalent bond; enzyme is now out of business

32 (1) NO CLASS next Monday (2) For NEXT WEDNESDAY – - bring to class a small amount of some spice, seeds, leaves, fruit, or medicinal herb - pick something with a strong taste/smell, or that you know is used in a folk remedy - at Wednesday’s lecture, you will put your material in a tube and label it; I will then add solvent and extract the natural products from it over the weekend - in the next lab, you will bioassay the extracts of your material for antibiotic activity and cytotoxicity

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