Medicinal Chemistry/ CHEM 458/658 Chapter 7- Biological Membranes

Transcription

1 Medicinal Chemistry/ CHEM 458/658 Chapter 7- Biological Membranes Bela Torok Department of Chemistry University of Massachusetts Boston Boston, MA 1

2 Introduction The cell membrane separates the cell the intracellular fluid from the surrounding medium (extracellular fluid). 2

3 Introduction Eukaryotic cell 3

4 Fluid Mosaic model The Plasma Membrane 4

5 The Plasma Membrane Lipid components - glycerophospholipids 5

6 The Plasma Membrane Lipid components - sphingolipids 6

7 The Plasma Membrane Lipid components - sphingolipids 7

8 The Plasma Membrane Lipid components - glycosphingolipids Tay-Sachs-, Gaucher-, Krabbe s-, Fabry s and Niemann-Pick diseases 8

9 The Plasma Membrane Lipid components - glycosphingolipids 9

10 The Plasma Membrane Lipid components - cholesterol 10

11 The Plasma Membrane Protein components - Integral proteins e.g ion- or water-channels Jens C. Skou 1997 Roderick MacKinnon

12 The Plasma Membrane Protein components - Integral proteins e.g porins, aquaporins Peter Agre

13 The Plasma Membrane The carbohydrate component 13

14 The Plasma Membrane Similarities and differences between plasma membranes in different cells 14

15 The Plasma Membrane Bacterial cell walls - peptidoglycans Safranin Crystal violet 15

16 The Plasma Membrane Bacterial cell walls - peptidoglycans 16

17 The Plasma Membrane Bacterial cell walls - peptidoglycans 17

18 The Plasma Membrane Bacterial cell exterior surfaces teichoic acids 18

19 The Plasma Membrane Bacterial cell exterior surfaces 19

20 The Plasma Membrane Animal cell exterior surfaces Virus Tissue Human Skin 20

21 The Transfer of Species through Membranes Energetics of membrane transport G=RTln(c 2 /c 1 )+ZF V G can predict whether a transport process must be active ( G>0) or passive ( G<0). Osmosis Filtration Passive diffusion 21

22 The Transfer of Species through Membranes Facilitated diffusion/transport 22

23 The Transfer of Species through Membranes Facilitated diffusion/transport - Ion Channels X-Ray structure of the KcsA K + channel 23

24 The Transfer of Species through Membranes Active Transport - Na + - K + - ATPase 24

25 The Transfer of Species through Membranes Active Transport - Ca 2+ - ATPase 25

26 The Transfer of Species through Membranes Active Transport - ABC Transporter Mechanism multidrug resistance 26

27 The Transfer of Species through Membranes Active Transport - Endocytosis vs. Exocytosis 27

28 The Transfer of Species through Membranes Active Transport - Endocytosis vs. Exocytosis 28

29 Drug Action on Cell Membranes and Walls Action on enzymes and receptors or blocking ion channels Disrupting the membrane/wall - inhibiting enzymes that produce compounds to maintain the membrane - inhibiting processes involved in formulation of the membrane/ cell wall - forming channels and making the cell wall porous 29 - making the cell wall more porous by breaking down sections of it

30 Drug Action on Cell Membranes and Walls Antifungal agents -fungal infections (mycoses) superficial external layer of skin/hair (cutaneous/subcutaneous) systemic internal tissues/organs (primary pathogens/opportunistic pathogens) action damage cell membrane loss of essential cellular components Counter action antifungal agents fungistatic fungicidal action Fungal microorganisms eukaryotic cells with chitin cell wall (targeting ergosterol biosynthesis) 30

31 Drug Action on Cell Membranes and Walls Antifungal agents Azoles (!) Lotrimin Spectazole Exelderm Terazole, Zazole Diflucan 31

32 Drug Action on Cell Membranes and Walls Antifungal agents Azoles Action: inhibition of cytochrome P-450 oxidases (P-450 DM ) (detoxification) 32

33 Drug Action on Cell Membranes and Walls Antifungal agents Allylamines and related compounds Action: inhibition of squalene oxidase squalene accumulation in membrane loss of membrane intergrity Naftin Lamisil 33

34 Drug Action on Cell Membranes and Walls Antifungal agents Phenols and related compounds Action: disrupt cell membrane Strepsils Gojo antimicrobial soap Loprox 34

35 Drug Action on Cell Membranes and Walls Antibacterial antifungal agents Action: disrupt cell membrane Abelcet Natacyn (plus cheese additive) Panolog Gris-PEG (vetmed too) 35

36 Drug Action on Cell Membranes and Walls Antibacterial agents Antibiotics Action: - Ionophoric antibiotic action 36

37 Drug Action on Cell Membranes and Walls Antibacterial agents Antibiotics Ionophoric antibiotic action usually for Gram-positive - Channel formation ion transport - Carriers 37

38 Drug Action on Cell Membranes and Walls Antibacterial agents Antibiotics Cell wall synthesis inhibition multiple types (3) 1. Drugs that inhibit the formation of starting materials 38

39 Drug Action on Cell Membranes and Walls Antibacterial agents Antibiotics Cell wall synthesis inhibition 1. Drugs that inhibit the formation of staring materials 39

40 Drug Action on Cell Membranes and Walls 40

41 Drug Action on Cell Membranes and Walls Antibacterial agents Antibiotics Cell wall synthesis inhibition 2. Drugs that inhibit the synthesis of the peptidoglycan chain 41

42 Drug Action on Cell Membranes and Walls Antibacterial agents Antibiotics Cell wall synthesis inhibition 2. Drugs that inhibit the synthesis of the peptidoglycan chain 42

43 Drug Action on Cell Membranes and Walls Antibacterial agents Antibiotics Cell wall synthesis inhibition 3. Drugs that inhibit the cross-linking of the peptidoglycan chain 43

44 Drug Action on Cell Membranes and Walls Antibacterial agents Antibiotics Cell wall synthesis inhibition 3. Drugs that inhibit the cross-linking of the peptidoglycan chain 44

45 Drug Action on Cell Membranes and Walls Antibacterial agents Antibiotics Cell wall synthesis inhibition 3. Drugs that inhibit the cross-linking of the peptidoglycan chain β-lactame antibiotics sensitive 45

46 Drug Action on Cell Membranes and Walls Antibacterial agents Antibiotics Cell wall synthesis inhibition 3. Drugs that inhibit the cross-linking of the peptidoglycan chain β-lactame antibiotics mode of action 46

47 Drug Action on Cell Membranes and Walls Antibacterial agents Antibiotics Cell wall synthesis inhibition 3. Drugs that inhibit the cross-linking of the peptidoglycan chain β-lactame antibiotics decomposition under acidic conditions 47

48 Drug Action on Cell Membranes and Walls Antibacterial agents Antibiotics Cell wall synthesis inhibition 3. Drugs that inhibit the cross-linking of the peptidoglycan chain β-lactame antibiotics increase stability 48

49 Drug Action on Cell Membranes and Walls Antibacterial agents Antibiotics Cell wall synthesis inhibition 3. Drugs that inhibit the cross-linking of the peptidoglycan chain other β-lactame antibiotics 49

50 Drug Action on Cell Membranes and Walls Antibacterial agents Antibiotics Cell wall synthesis inhibition 3. Drugs that inhibit the cross-linking of the peptidoglycan chain extra additives - β-lactamase inhibitors 50

51 Drug Action on Cell Membranes and Walls Antibacterial agents Antibiotics Cell wall synthesis inhibition 3. Drugs that inhibit the cross-linking of the peptidoglycan chain alternative approach - β-lactamase resistant drugs 51

52 Drug Action on Cell Membranes and Walls Antibacterial agents Antibiotics Cell wall synthesis inhibition Polypeptide antibiotics Surfactants 52

53 Drug Action on Cell Membranes and Walls Local anaesthetics 53

54 Drug Action on Cell Membranes and Walls Local anaesthetics mode of action: blocking the Na + channels - blocks external entry - enters channel and acts as a stopper in the middle region - binds to the (channel) proteins and distort them 54

55 Drug Action on Cell Membranes and Walls Local anaesthetics mode of action: SAR: 55