Anti Bio Tika

14022007 : 09.0010.40 Hari Purnomo, ANTIBIOTIKA, FARKIM II. 1

ANTIBIOTIKA

3H CC

HN

C(R ) H 2

C

HNH

HC

(R )

C O

C H 3 OH 3CO

(Z )

C H

N HR 1

H O

O H

C O 2 C

H

NHR

CO

CH

(R )

NH

R 3

Ar

Hari Purnomo


Penggolongan :A. Antibiotika ß laktam

1. Turunan Penisilin

2. Turunaan Sefalosporin

3. Turunan ß laktam Non Klasik

B. Turunan Amfenikol

C. Turunan Tetrasiklin

D. Turunan Aminoglikosida

E. Turunan Makrolida

F. Turunan Polipeptida

G. Turunan Linkosamida

H. Turunan Polien

I. Turunan Ansamisin

J. Turunan Antrasiklin

K. Fosfomisin

a. Sefalosporin kla sikb. Pra- Sefalosporin

c. Sefamis ind. Oksasefem

a. Turunan asam amidinopenisilanatb. Turunan asam penisilanatc. Karbapenemd. Oksapeneme. Turunan ß laktam Monosiklik

?


Penggolo ngan Berdasarkan Mekanis me Kerja



The Action of Antimicrobial Drugs

Figure 20.2


1. Inhibition of Cell Wall Synthesis :Penicillin, bacitracin, cephalosporin, Vancomisin

Penici l l ins and Cephalosporins

C

N C

CS CH3

CH3

COOHHC

CH H

O

NHC

O

R

C

NC

C

CS

H2

CH2 O C

CH3

O

C

CH

O

NHC

O

R

Penicillin nucleus

Cephalosporin nucleus

B-lactam ring

basitrasin


Cell wall structure

Pennicilinbinding protein (PBP)

Gram positive

Gram negative


Cell wall structure Gram negative


Gram positiveCell wall structure

Pennicilinbinding protein (PBP)


Spectrum of antimicrobial activity

• Narrow spectrum drugs affect only Grampositive cells or only Gramnegative cells.

• Broad spectrum drugs affect both Grampositive and Gramnegative cells.

• The normal flora is affected, too.


Fig. 131


Antibiotic Target 1: Cell WallCell wall is pep tido gl ycan , a repeating polymer of di-saccharide, tetra-peptide repeats cross-linked into a 3D matrix

β-lactam antibiotics interfere with cell wall biosynthesis of Gram-positive bacteria (Staphylococci, Streptococci)

- weakened PG cell wall = cells pop from osmotic shock


Antibiotic Target 1: Cell WallBacterial tr ans peptidase enzyme forms crosslinking amide bonds between #3 L-Lysi ne and #4 D-Alani ne residues

TPase cuts off #5 D-Ala residue, then links L-Lys side chain to the remaining D-Ala


βlactams: Mechanism of Actionβ-lactams inhibit transpeptidase by mimicking its substrate, the terminal D-Ala—D-Ala

Transpeptidase attacks the β-lactam ring of penicillin, forms a covalent bond that is slow to hy dr olyze ; enzyme is deactivated

Normally, the enzyme forms a temporary bond with D-Ala that is rapidly broken by the side chain of Lysine


Bakteri ………..Dinding sel bakteri …….. PeptidoglikanSintesis Peptidoglikan ada 3 tahap :Tahap I : Pembentukan UDPNAcMur pentapeptidaTahap II : Pembentukan akseptor dekapeptidamidTahap III : Pembentukan peptidoglikan ( salah satu bahan baku D –Alanil D Alanin ) ( Penisilin , sefalosporin bekerja pada tahap ini )


Penici l l ins and Cephalosporins

C

N C

CS CH3

CH3

COOHHC

CH H

O

NHC

O

R

C

NC

C

CS

H2

CH2 O C

CH3

O

C

CH

O

NHC

O

R

Penicillin nucleus

Cephalosporin nucleus

B-lactam ring


Penici l l ins

Common nucleus

B-lactam ring

C

N C

CS CH3

CH3

COOHHC

CH H

O

NHC

O

R


. History

• Alexander Fleming (1928)– In England, noticed that S. aureus did not grow

around a colony of mold on agar– The mold was Penicillium notatum.– He isolated the inhibitory substance. Called it

penicillin.– Penicillin was unstable.


• Florey and Chain (1940)– In England– Resumed study of penicillin– Isolated and purified penicillin– USA became involved– Penicillin used during WWII


• Penicillin is an antibiotic. • “Antibiotic” is from antibiosis, meaning against

life.• antibiotic A substance that is produced by one

microorganism (a bacterium or fungus) that kills or inhibits the growth of another microorganism.


• Major producers of antibiotics discovered throughout the years:– Molds

• Penicillium• Cephalosporium

– Bacteria• Streptomyces• Bacillus


(a) Penicillins Natural (Pen G, Pen V [oral])

best vs. G+ betalactamase resistant, but lower activity

nafcillin, oxacillin, methicillin expanded spectrum (G+ and G)

ampicillin, piperacillin, mezlocillin, ticarcillin

acid resistant (oral) amoxycillin, Pen V, oxacillin




Penici l l ins

Penicillin G

Penicill in V

CH2 C

N C

CS CH3

CH3

COOHHC

CH H

O

NHC

O

Common nucleusO CH2

CH

NH2

Common nucleusAmpicillin


O C H 2

C H 2

C H

N H 2

Benzil penisilin ( Penisilin G )

R =Fenoksimetilpenisilin ( Penisilin V )

A m pis ilin

R =

R =


O C H 3

O C H 3

C H

C l

H NO

C H

N H 2

H O

Metisilin

Kloksasilin

R =

R =

AmoksisilinR =



(S )

N

O

O HH

C

H 3C

H 3C

S

(S )

(R )O H

H

N '

OR

H

Penisilin

(S )

N "H

O

O HH

C

H

H

H

(R )

O

H

N '

OR

H

DAlanilDAlanin


Stabilitas cincin βLactam





Degradasi dengan βLactamase


N

S

CO O H

HN

O

H

H

X

E nzim

H N

S

CO O H

N

O

H

H

X

Enzim

Degradasi dengan βLactamase


Resistance: βlactamase Enzymes

Bacteria produce enzymes to hydr olyze the β-la ctam r ing before drugs can reach inner membrane where PG synthesis occcurs


A cell may produce 100,000 lactamase enzymes, each of which can destroy 1,000 penicillins per second 100 million molecules of drug destroyed per second

Resistance: βlactamase Enzymes


Overcoming βlactam Resistance

Aug menti n combines β-lactam antibiotic w/ cla vula nat e, a “suic id e” β-lactam that occupies the β-lactamase enzymes - Allows active drug (amoxacillin) to reach target enzymes, PG-synthesizing transpeptidases lining the inner membrane

(resistance) slow tohydrolyze

(cell wall enz.)


Resisten βLactamase

Less tolerance to the steric hindrance near the side chain of amida bond.

Attached directly to the side chain carbonyl and both ortho position are sustituted by methoxy resistant

Movement of one of the OCH3 to para position, putting methylen between the aromatic ring6APA sensitif

Resistant to enzyme degradation based on differential Steric hindrance


Stabilitas terhadap asam

Stabilitas terhadap asam


(S )

N

OH

H 2C

S

(S )

(R )O H

H

N '

OR

H

(S )

N "H

O

O HH

C

H

HH

(R )

O

H

N '

OR

H

COC H 3

DAlanilDAlanin

Cephalo spori ns


(b) Cephalosporins (less sensitive to betalactamases)1st gen: G+ action

cephalexin, cephalothin, cefazolin

2nd gen: G+ and G action, including Bacteroides, but not Pseudomonas

cefaclor, cefuroxime, cefoxitin

3rd gen: G mostly, including Pseudomonas can penetrate the CNS, so can be used for meningitis ceftazidime, cephotaxime, cephoperazone

4th gen: slightly expanded spectrum cefepime, cefirome


(c) monobactams monocyclic betalactam ring, so resistant to betalactamases

effective vs. G only, not G+ or anaerobes aztreonam

(d) carbapenems broad spectrum (G+ and G), but may be toxic imipenem, meropenem (reduced toxicity)

Side Effects (of beta lactams): allergy (pen > ceph > mono) toxicity (carba (seizures) > ceph (thrombophlebitis) >

pen > mono


Vancomycin: Mechanism of ActionVancomycin, the crucial “drug of last resort,” inhibits PG synth by binding dir ectl y to the D-Ala—D-Ala end of the peptide

- forms a cap over the end of the chain; blocks cross-linking

Capped peptides cannot be cross-linked

Weak cell walls cells die


Vancomycin: Mechanism of Action

Completely surrounds its target peptide, preventing enzymes from reacting with the end of the peptidoglycan chain

3D model of Vancomycin incomplex with D-Ala—D-Ala

note “cup-like” shape of Van


Vancomycin makes 5 H- bo nds with the D-Ala—D-Ala cap of the PG peptide

- Blocks access to tran speptidase enzyme - You l ive !

Vancom yci n

D-Ala D-Ala


Van Resistance: DAlaDLactateVancomycin-resistant bacteria have peptidoglycan chains that end in D-Ala— D-Lac tat e, instead of the usual D-Ala—D-Ala

(A) What genes are necessary to make this change?

(B) How does this confer resistance?

D-Ala— D-Ala

D-Ala— D-Lac tat e


Genetics of Van Resistance

VanAVanH

VanX

5 gene pr oducts are required to produce Lac-terminal PG

- 2 “sensor” genes detect Van, turn on other 3 genes

- 2 synthesize the critical D-Ala—D-Lactate piece

- 1 destroys the pool of D-Ala—D-Ala in the cell (equilibrium)

reduction

hydrolysis

1,000 fold lower affinity for Van


Vancomycin: Mechanism of Action

D-Ala—D-Ala cap makes 5 H- bon ds with Vancomycin

D-Ala—D-Lac makes 1 le ss H- bo nd Resistance Yo u die


Genetics of Van ResistanceWhy did penicillin resistance appear in 2 years, but Van resistance take 30 years to become a major health hazzard?

One answer: geneti c co mp lexity of resistance mechanism

Penicillin resistance requires the activity of one gene pr od uct (β-lactamase enzyme)

- usually 2-4 year lag when only 1 gene is involved

Van resistance takes 5 gen e pr oducts

- apparently delays development of infectious, highly resistant strains when multiple gene products are involved


Overcoming Van Resistance

Approach #1: Screening of semi-synthetic analogues of Van found that hy dr opho bic der ivati ves restore potentcy 100-fold

- Partitions drug to membrane surface, thus altering activity and availability to target enzymes

chlorinated bi-phenyl substituent


Overcoming Van ResistanceApproach #2: Screening combinatorial libraries for novel small molecules that cl eave the D-Ala—D-Lac depsipeptide

- Look for drugs that can effectively function like an enzyme

Combinatorial library of 300,000 tripeptide derivatives yielded 3 hits , all w/ an N-terminal serine & an intramolecular H-bond

Pharmacophore deduced from computer modelling studies

N

HO

NH2

OSProC5 “resens iti zed ” bacteria with Van-resistance, by cleaving their D-Ala—D-Lac depsipeptide

SPr oC 5 Chiosis & Boneca, Science 2001


(Vancomycin, teicoplanin [Eur]) (Glycopeptides )Mode of Action: block transglycosylationResistance: use alalactate rather than alaala to end

pentapeptide side chain: chromosomal (vanB) and plasmid (vanA)

genesUses: Staphylococci, Enterococci, not G



3H CC

HN

C(R ) H 2

C

HNH

HC

(R )

C O

C H 3 OH 3CO

(Z )

C H

N HR 1

H O

O H

C O 2 C

H

NHR

CO

CH

(R )

NH

R 3

Ar

V ancom ycin

acy l D a lany l D a lan in

Combine with Substrat


Mekanisme kerja yang sejenis dengan Vancomisin ( mengikat Dalanil D alanin ) :

Ristocetin A & B , Ristomysin A & B , Actinoidin A & B , Avoparcin A & B , Antibiotik A35512B


2. BacitracinMode of Action: blocks ~P and de~P of bactoprenolUses: topical only mainly vs. G+, so used in

conjunction w/ othersSide effects: poorly absorbed, renal toxicity


Bacitracin


Mekanisme kerja basitrasin :

Menghambat deposforilasi piroposfat membentuk carrier, sehingga memblok ketersediaan MurN Ac pentapeptida ( Sintesa tahap 2 peptidoglikan )

Dinding sel tidak terbentuk


Cycloserine and phosphonomycin

Mekanisme kerja :

Sikloserin mirip dengan alanin strukturnya . Adanya sikoserin menyebabkan / menghalangi pembentukan UDP N Ac –pentapeptida ( tahap 1 sintesa peptidoglikan )

Dinding sel tidak terbentuk

cycloserine: Dala analog, so inhibits alanine racemase : neurotoxic, so rarely used (sometimes for UTI)


N C

CO

O

HH

H H

H

H

H

D A lan in

N C

CO

N(E )

HH

H H

H

O

H

S ik loserin

C N

CO

O

H

HH H

H

H

H

L A lan in

N C

CO

O

HH

H H

H

H

H

D A lan in

N C

CO

N(E )

HH

H H

H

O

H

S ik loserin


U T P + N Acety lg lucosam ine1 P

U D PG lcN Ac

U D PG lcN Acpyruva te eno l ethe r

dst ... dst

pyrophospha t

PEPC O

H O 2C

H 2C P O 3H

phosphoeno lp iruva te

Sintesis Peptidoglikan ada 3 tahap :Tahap I : Pembentukan UDPNAcMur pentapeptida

Mekanisme kerja phosphonomycin :


C CO

HH

H 3C PO 3HC O

H O 2C

H 2C PO 3H

C CO

H H

H 3C PO 3HC O

H O 2C

H 2C PO 3H

phosphonom ycin phosphoeno lp iruva te


2. Disruption of cell membrane function

Polymyxins• Mode of Action: dissolve phosphatidylethanolamine, a

specialized PL in G membranes (ours, too)• Uses: toxic, so topical only (often in conjunction with

bacitracin and neosporin)



3. Inhibition of Protein Synthesis

Examples : tetracycline

erytromycin

streptomycin

chloramphenicol

Tetracycline (aromatic polyketide)

Erythromycin (macrolide polyketide)

Kanamycin(aminoglycoside)


• Ribosom– Due to differences in ribosomes– Eucaryotic cells have 80S (60S + 40S subunits)

ribosomes.– Procaryotic cells have 70S (50S + 30S subunits)

ribosomes.– Examples:

• Chloramphenicol and erythromycin bind to the 50S subunit.

• Tetracyclines bind to the 30S subunit.



Review of Initiation of Protein Synthesis

30S1 32 GTP

1 2 3 GTP

Initi atio n Facto rs

mRNA

3

1

2 GTP

30S Initiation Complex

f-met-tRNASpectinomyci

n

Aminoglycosides

12

GDP + P i 50S

70S Initiation Complex

AP



Review of Elongation of Protein Synthesis

GTP

AP

Tu GTP Tu GDP

Ts

TsTu

+

GDPTs

Pi

P ATetr acyc lin

e

AP

Ery th rom yc in

Fusidi c A cid

Chlo ra mph eni col

G GTPG GDP + Pi

G

GDP

AP

+GTP



The Action of Antimicrobial Drugs

Figure 20.4


1.Aminoglycosides (streptomycin, neomycin, gentamycin, tobramycin)Mode of Action: Bind to 30S rib, block initiation by preventing attachment of tRNAfMet

Resistance: altered P12 ribosomal protein, aminoglycosidases, altered permeability (e.g. Streptococci)Uses: G enterics, often in synergy with cephalosporins or penicillins (facilitate entry of the aminoglycosides)



2.Tetracycline (doxycycline)Mode of Action: inhibits binding of aatRNA to the Asite of the ribosome (30S)Uses: rickettsia, chlamydia, mycoplasmasSide effects: toxicity, dizziness, ringing in ears, fluorescent teeth in newborns replacement of native flora

Tetracycl ine

OH

H3C OH

O

N

OH

C

O OH

OH

CH3H3C

ONH2

Interfere with protein biosynthesis at the ribosomal level: bind to 30S ribosome

inhibit subsequent binding of aminoacyltransferRNA




Tetracycl ine

OH

H3C OH

O

N

OH

C

O OH

OH

CH3H3C

ONH2



Degradation reaction involve the C6hydroxyl cleavage of the C ring in alkaline solution (pH 8.5)

Α stereo orientation of the C4 dimethylamino moiety essential for the bioactivity Epimerization produce 4epitetracycline inactive


3. Chloramphenicol

Mode of Action: inhibits peptidyl transferase reaction (50S)Resistance: chloramphenicol acetyl transferase (CAT)Uses: no longer a drug of choice




50 S Subunit Ribosom

Several functional domains mapped on E.Coli 30 S and 50 S subunits by the technique of immune electron microscopy ( Courtesy of Dr. H. G. Wittmann )


30 S Subunit Ribosom

Several functional domains mapped on E.Coli 30 S and 50 S subunits by the technique of immune electron microscopy ( Courtesy of Dr. H. G. Wittmann )



4. Macrolides (erythromycin, clarithromycin)Mode of Action: binds to rRNA and inhibits translocation (50S)Resistance: methylation of rRNAUses: G+ and some G

5. Lincomycin / ClindamycinMode of Action: same as macrolidesUses: specific use against anaerobes Bacteroides) does not penetrate CNS


6. Others: Nitrofurantoin: inhibits 30S, used vs.

UTI, conc. in urine “Synercid” = quinupristin + dalfopristin:

inhibits 30S, used to treat VRE and VRSA in the US (Streptogramin in Europe)

Linezolid: inhibits 50S, used to treat VRE and MRSA

Methenamine: releases formaldehyde in acidified urine, used to treat UTI


4. Inhibition of nucleic acid synthesis

Examples : Rifamycin ( Transcription),

Quinolin ( DNA replication )

Nalidixic acid ( DNA replication )

Anti tbc

Inhibition of nucleic acid synthesis– Stop DNA replication

• Many antiviral drugs do this.• Example: AZT

– Or stop RNA synthesis• Example: rifampicin


4. DNA inhibitors

1.Quinolones (nalidixic acid)Mode of Action: inhibit DNA gyraseResistance: altered DNA gyrase, drug exclusionUses: not very soluble, so use fluorinated Qs instead (ciprofloxacin and derivatives) vs. UTI and other (mostly) G infections, but not Pseudomonas


2.Rifamycin (rifampin)Mode of Action: blocks RNA polymeraseResistance: altered RNA polymerase b subunitUses: with isoniazid to delay resistance in Mycobacteria : crosses CNS, so used for meningitis : blocks assembly of poxvirusesSide effects: excreted in sweat and urine (orange!)

3. MetronidazoleMode of Action: unknown reaction product breaks DNA strandsUses: antiprotozoal (Giardia) : vs. anaerobic bacteria (Bacteriodes, Clostridium)


5. Action as antimetabolites

Examples : Sulfanilamide

Trimetoprim

PABA

Sulfamethoxazole

Trimethoprim



Folic Acid

N

NH2N

OH

N

NCH2 N C

O

NH

C

COOH

C

C

COOH

H2

H2

H

PABA

H


Sulf anila mid e Para-aminobenzoic acid (PABA)

SO2NH2

NH2 NH2

COOH

Sulfacetamid H COOH3

Sulfa diazine H

Sulfanilamid H H

N

N

R1

R2

R1 R2

R2


– Sulfonamides (Sulfa drugs)• Inhibit folic acid synthesis• Broad spectrum

Antibacterial Antibiotics Competitive Inhibitors

Figure 5.7


Sulf anila mid e Para-aminobenzoic acid (PABA)

SO2NH2

NH2 NH2

COOH


H 2N

C O HO

PABA

S OO

N H 2

NHH ...........................

........................

6,9 A

C OH O

NHH

...........................

........................

6,7

2,4

2,3

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

14022007 : 09.0010.40 Hari Purnomo, ANTIBIOTIKA, FARKIM II. 100Figure 20.13


SMX = SulfametoksazoleTMP = TrimetoprimPABA = Para Amino Benzoic AcidDHPA = DiHydroPteroatDHFA = DiHydro Folic AcidTHFA = Tetra Hydro Folic Acid

TH F A

D H P A

D H F AT M P

L G lu tam at

S M X

PA B AP terid in

E nz im d ih id rop te roa t s in te tase

T im in M etion in , g lis in ,aden in , guan in

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Anti Bio Tika