Antiviral drugs 1. Adamantane derivatives 2. Neuraminidase inhibitors 3. Viral replication inhibitors 4. Viral proteases inhibitors 5. Imunotherapeutics ©assoc. prof. Oldřich Farsa, Ph.D., 2015 Replication cycle of the influenza virus type A 6. Assembly 1. Binding u Hemagglutinin t Neuraminidase M2 ion channel ■? Sialic acid-galactose 1. Adamantane derivatives 1 -aminotricyklo[3.3.1.1 Jdecane 1 -aminoadamantane amantadine •also antiparkinsonic 1 -(aminoethyl)tricyklo[3.3.1.1 Jdecane 1 -(1 -aminoethyl)adamantane rimantadine • against influenza of type A only; ineffective against swine influenza H1N1 •mechanism of action: inhibition of replication of influenza virus type A by blocking of transmembrane protein - proton channel M2 •mainly prophylactic •frequent resistance (M gene mutation) •adverse effects: frequent; sleeplessness, hallucinations, orthostatic hypotension, depressions, nausea, vomiting Ion channel M2 of the influenza virus H1N1 2009 (swine influenza) of 97 amino acid rests in every unit; every unit contains the C-terminal domain from 54 AA, the transmembrane domain from 19 AA and the extracelullar N-terminal domain from 24 AA •proton-selective channel is controlled by endosomal pH values; it leads endosomal protons into the virion •this channel is probably fundamental for the life cycle of the virus Interaction of amantadine with proton channel M2 of viruses H5N1 (A) and H1N1 (B) •adamantane antivirotics are bound to the outside Jipoid pocket" nearTrp41 (in addition H-bridge to Asp 44), the molecule acts as an „molecular wedge", which stabilizes close conformation of the channel gate and increases energy barrier for its opening •blue spots represent sizes or electron clouds of lipophilic fragments of M2 channel which interact with the drug by hydrophobic interactions Interaction of rimantadine with proton channel M2 of H5N1 (A) and H1N1 (B) viruses 2. Viral neuraminidase inhibitors Neuraminidase (sialidase, acyl-neuramidyl hydrolase): •glycoprotein •glucosidase which cleaves specifically glycoside bonds a-2^3 and a-2^6 to galactose • enzyme cleaving N-acetylneuraminic acid away from more complex oligosaccharides on the cell surface and thus facilitating releasing of virions from the infected cell and their spreading to other cells of host organism •also acts as a superficial antigen of the influenza virus with principal significance for the immunity response •in mammals and birds, 9 neuraminidase serotypes and 16 hemagglutinin serotypes have been found up to now (hemagglutinin is also a superficial antigen) o N-acetylneuraminic acid Aceneuramic acid [INN] N-acetylneuraminic acid and 1 experimental neuraminidase inhibitors o N-acetylneuraminic acid Aceneuramic acid [INN] o R = -CH 3 2-Deoxy-2,3-dehydro-N-acetylneuraminic acid DANA R = -CF^ 2-Deoxy-2,3-dehydro-N-trifluoroacetylneuraminic acid FANA Viral neuraminidase inhibitors •intranasal administration only -Lv. administration oseltamivir •dimeric and multimeric forms with expected Rapivab ® greater activity, longer elimination half-time approved in the Tamiflu®cps. and greater bioavailability are being U.S.A December developed 14th, 2014 •effective against H1N1 (swine), not against H5N1 (bird) •development of forms for i.v. or i.m. administration A model of binding of zanamivir to the active site of neuraminidase of reconstructed H1N1 virus from 1918 (similar to swine 2009) 3. Inhibitors of replication of RNA viruses hq. h n x=o ho' 1-P-D-ribofuranosyl-1,2,4-triazole-3-carboxamide ribavirin •broad spectrum including SARS-coronavirus (Severe Acute Respiratory Syndrome) •known since 1970th •approved for treatment of HCV (hepatitis C; ± pegylated interferon) and RSV (respiration syncytial virus) in children •mechanisms of action: 1. inhibition of inosine-5'-monophosphate dehydrogenase (changes IMP to xanthosine-5'-monophosphate in de novo synthesis of GMP) 2. direct interference with transcription and replication Rebetol®, Copegus® X = NH viramidin syn. taribavirin [USAN] •prodrug, expected lower toxicity (hemolysis), clinical trials of the 3rd phase for HCV completed Mechanism of action of ribavirin Glutamine PRPP PRA 5-phosphoribosyl amine Ribavirin Ribavirin-MP inosine monophosphate IMP XMP / succinyl AMP GMP I dGDP «— GDP I I dGTP GTP AMP I ADP —► dADP I j ATP dATP 3. Inhibitors of replication of RNA viruses favipiravir 5-fluoro-3-hydroxypyrazine-2-carboxamide T-705 •broad spectrum including influenza A, B, C •clinical trials of the 1st and 2nd phases (pharmacokinetics, dose finding for influenza) •mechanism of action: after entering the cell, phosphorylation to monophosphate by phosphoribosyl transferase and further to triphosphate by gell kinase; in this form the drug inhibits RNA-dependent RNA-polymerase •in vitro very active against H5N1 (bird) and seasonal influenzas •low toxicity, no cytotoxic effect 3. Inhibitors of replication of RNA viruses Reverse transcriptase inhibitors •reverse transcriptase = RNA-dependent DNA-polymerase discovered in 1970th by Temin, Mizutani and Baltimor in oncoviruses •catalyses reversal" transcript of viral RNA into DNA in retroviruses Thymidine analogues OH 3'-azido-2', 3'-dideoxythymidine zidovudine azidothymidin, AZT Retrovir® 2', 3'-didehydro-2', 3'-dideoxythymidine stavudine Zerit® •treatment of HIV infections Reverse transcriptase inhibitors Cytidine analogues nh2 nh2 oh 2',3'-dideoxycytidine zalcitabine ddC Hivid® R = -H 2',3'-dideoxy-3'-thiacytidine lamivudine 3TC Epivir® R = -F 2',3'-dideoxy-5-fluor-3'-thiacytidin emtricitabine Emtriva® •treatment of HIV infections Reverse transcriptase inhibitors Purine derivatives {(1R)-4-[2-amino-6-(cyclopropylamino)-9H 2',3'-didehydroinosine -purin-9-yl]cyclopent-2-en-1-yl}methanol abakavir ABC Ziagen® didanosine ddl Videx® Nucleotide reverse transcriptase inhibitors HoN 9-(fosfonylmethoxyethyl)adenine adefovir •originally developed against HIV, in doses which were needed it was nephrotoxic •now treatment of HBV (hepatitis B) adefovir dipivoxil •a prodrug with improved lipophilicity and bioavailability •prof. Antonín Holý, Inst, of Org. Chem. and Biochem., Prague •nominated for Nobel Prize Nucleotide reverse transcriptase inhibitors O (R)-9-[(2-fosfonylethoxy)propyl]adenine tenofovir •against HIV H3C «tenofovir disoproxil fumarate •clinical studies for HBV and HIV Viread ® tbl., Truvada ® cps. (+ emtricitabin) Inhibitors of DNA polymerase of herpetic viruses •DNA polymerase of Herpesviridae family consists of 2 units: the catalytic subunit UL 54 + additive protein UL44 O HN* o N H2N N O OR H2N N O OR OH R = -H aciclovir Aciclovirum PhEur R = ganciclovir valaciclovir valganciclovir •nucleoside analogues, guanine derivatives •herpetic infections including HCMV (human cytomegalovirus) •prodrugs - valine esters have improved biological availability Inhibitors of DNA polymerase of herpetic viruses O penciclovir Vectavir ® drm crm CH3 O famciclovir •competitive inhibitor Famciclovir Arrow ® por tbl flm Inhibitors of DNA polymerase of herpetic viruses o oh y—p—oh foscarnet Foscarnetum natricum hexahydricum PhEur •CMV retinitis, other herpesviruses, HIV •mechanism of action: inhibits viral DNA polymerase by binding to the diphosphate binding site and by blocking of cleaving of diphosphate away from the triphosphate of terminal nucleoside which is added to the growing DNA chain •blocks also reversal transcriptase Viral proteases inhibitors Inhibitors of HCV (hepatitis C virus) NS3 protease •hepatitis C: 2 - 15 % of the world population are estimated to be infected, WHO: 1.7.108 people (2006) • 10 - 20 % overcomes the virus, the rest becomes permanent virus hosts, in 10-20 %, cirrhosis or liver cancer is developed •transfer is parenteral, sexual or vertical (mother^child) NS3 protease •situated on the N-terminal domain of NS3 protein •probably an important site of intervention •responsible for the intramolecular cleavage on NS3/4A site and following processes •it simultaneously corrupts synthesis of interferon regulation factor 3 (IRF-3) of the host which leads to decrease of immunity response Inhibitors of HCV (hepatitis C virus) NS3 protease MK-7009 Immunotherapeutics: antibodies CDLPQTHSLG SRRTLMLLAQ MR^ISLFSCL KDRHDFGFPQ EEFGNOFOKA ET1PVLHEMI OQIFNLFSTK QGVGV7E7PL LDKFYTELYQ QLNDLEAtbvi KYFORmTYL KEKKYSpEwV EWRAEIMRS LRSKE DSSAAWDETL MKEDSILAVR FSLSTNLQES interferon a Interferoni alfa-2 solutio concentrata PhEur X1 = Lys a 7 2a X1 =Arga •antiviral activity during synthesis of viral RNA and proteins •antiprolifetive activity •production by a recombinant technology on bacteria •also pegylated: peginterferon alfa-2a (Pegasys ®) - at N-terminal, N2, N6-dikarboxy-Lys esterified with PEG-monomethylether is attached; possibility of oral administration