Elansolids, novel natural metabolites of Flexibacter and antibiotically active derivatives thereof.

Over the past 20 years, there has been a rapid decline in the number of antibiotics approved annually. At the same time the fast emergence of resistance to most antibacterial drugs diminishes their effectiveness considerably and necessitates a constant supply of new antibiotics for effective treatment of infections. The discovery of novel antimicrobial agents has become an increasing challenge. Still, microbial natural products remain the most promising source of novel antibiotics. They own an element of structural complexity which is required for the inhibition of many bacterial protein targets.

The invention relates to novel natural secondary metabolites, the production of the metabolites by fermentation as well as a biological and a chemical derivatization providing a family of antibiotically active compounds.

The present invention describes new kinds of compounds having anti-bacterial activity.

The present invention relates to compounds (Elansolids) of the general formula (I):

(I) wherein

R1 is a hydrogen atom, a halogen atom, a hydroxy, an amino, a mercapto, an alkyl, an alkenyl, an alkynyl, a heteroalkyl, a cycloalkyl, a heterocycloalkyl, an alkylcyclo-

alkyl, a heteroalkylcycloalkyl, an aryl, a heteroaryl, an aralkyl or a heteroaralkyl group,

R2 is a hydrogen atom, a halogen atom, a hydroxy, an amino, a mercapto, an alkyl, an alkenyl, an alkynyl, a heteroalkyl, a cycloalkyl, a heterocycloalkyl, an alkylcyclo- alkyl, a heteroalkylcycloalkyl, an aryl, a heteroaryl, an aralkyl or a heteroaralkyl group,

R3 is a hydrogen atom, a halogen atom, a hydroxy, an amino, a mercapto, an alkyl, an alkenyl, an alkynyl, a heteroalkyl, a cycloalkyl, a heterocycloalkyl, an alkylcyclo- alkyl, a heteroalkylcycloalkyl, an aryl, a heteroaryl, an aralkyl or a heteroaralkyl group,

R4 is a hydrogen atom, a halogen atom, a hydroxy, an amino, a mercapto, an alkyl, an alkenyl, an alkynyl, a heteroalkyl, a cycloalkyl, a heterocycloalkyl, an alkylcyclo- alkyl, a heteroalkylcycloalkyl, an aryl, a heteroaryl, an aralkyl or a heteroaralkyl group,

R5 is a hydrogen atom, a halogen atom, a hydroxy, an amino, a mercapto, an alkyl, an alkenyl, an alkynyl, a heteroalkyl, a cycloalkyl, a heterocycloalkyl, an alkylcyclo- alkyl, a heteroalkylcycloalkyl, an aryl, a heteroaryl, an aralkyl or a heteroaralkyl group, and

R6 is a hydrogen atom, a halogen atom, a hydroxy, an amino, a mercapto, an alkyl, an alkenyl, an alkynyl, a heteroalkyl, a cycloalkyl, a heterocycloalkyl, an alkylcyclo- alkyl, a heteroalkylcycloalkyl, an aryl, a heteroaryl, an aralkyl or a heteroaralkyl group, or

wherein R1 and R6 together are an oxygen atom, a sulfur atom or a NH group,

or a pharmacologically acceptable salt, solvate, hydrate or a pharmacologically acceptable formulation thereof.

The expression alkyl refers to a saturated, straight-chain or branched hydrocarbon group that contains from 1 to 20 carbon atoms, preferably from 1 to 12 carbon atoms, especially from 1 to 6 carbon atoms, for example a methyl, ethyl, propyl, iso-propyl, n-butyl, iso-butyl, tert-butyl, n-pentyl, n-hexyl, 2,2-dimethylbutyl or n-octyl group.

The expressions alkenyl and alkynyl refer to at least partially unsaturated, straight- chain or branched hydrocarbon groups that contain from 2 to 20 carbon atoms, preferably from 2 to 12 carbon atoms, especially from 2 to 6 carbon atoms, for example an ethenyl, allyl, acetylenyl, propargyl, isoprenyl or hex-2-enyl group. Preferably, alkenyl groups have one or two (especially one) double bond(s) and alkynyl groups have one or two (especially one) triple bond(s).

Furthermore, the terms alkyl, alkenyl and alkynyl refer to groups in which one or more hydrogen atoms have been replaced by a halogen atom (preferably F or Cl) such as, for example, a 2,2,2-trichloroethyl or a trifluoromethyl group.

The expression heteroalkyl refers to an alkyl, alkenyl (e.g. heteroalkenyl) or alkynyl group in which one or more (preferably 1 , 2 or 3) carbon atoms have been replaced by an oxygen, nitrogen, phosphorus, boron, selenium, silicon or sulphur atom (preferably oxygen, sulphur or nitrogen). Examples for heteroalkyl groups are alkyloxy, alkyloxyalkyl, alkenyloxyalkyl, alkenyloxy, alkyloxyalkenyl, alkylamino, alkylaminoalkyl, dialkylamino, dialkylaminoalkyl, alkylthio or alkylthioalkyl groups. The expression heteroalkyl furthermore refers to a carboxylic acid or to a group derived from a carboxylic acid such as, for example, acyl, acyloxy, acyloxyalkyl, acylalkyl, alkoxycarbonyl, alkyloxycarbonylalkyl, carboxyalkylamide, alkylcarbonylamino, alkylcarbonylaminoalkyl, alkylaminocarbonyl, alkylaminocarbonylalkyl, or alkoxycarbonyloxy.

Examples of heteroalkyl groups are groups of formulae R ^a -O-Y ^a -, R ^a -S-Y ^a -, R ^a -N(R ^b )-Y ^a -, R ^a -CO-Y ^a -, R ^a -O-CO-Y ^a -, R ^a -CO-O-Y ^a -, R ^a -CO-N(R ^b )-Y ^a -, R ^a -N(R ^b )-CO-Y\ R ^a -O-CO-N(R ^b )-Y\ R ^a -N(R ^b )-CO-O-Y ^a -, R ^a -N(R ^b )-CO-N(R ^c )-Y\

R ^a -O-CO-O-Y ^a -, R ^a -N(R ^b )-C(=NR ^d )-N(R ^c )-Y ^a -, R ^a -CS-Y ^a -, R ^a -O-CS-Y ^a -, R ^a -CS-O-Y ^a -, R ^a -CS-N(R ^b )-Y ^a -, R ^a -N(R ^b )-CS-Y ^a -, R ^a -O-CS-N(R ^b )-Y\ R ^a -N(R ^b )-CS-O-Y ^a -, R ^a -N(R ^b )-CS-N(R ^c )-Y ^a -, R ^a -O-CS-O-Y ^a -, R ^a -S-CO-Y ^a -, R ^a -CO-S-Y ^a -, R ^a -S-CO-N(R ^b )-Y ^a -, R ^a -N(R ^b )-CO-S-Y ^a -, R ^a -S-CO-O-Y ^a -, R ^a -O-CO-S-Y ^a -, R ^a -S-CO-S-Y ^a -, R ^a -S-CS-Y ^a -, R ^a -CS-S-Y ^a -, R ^a -S-CS-N(R ^b )-Y ^a -, R ^a -N(R ^b )-CS-S-Y ^a -, R ^a -S-CS-O-Y ^a -, R ^a -O-CS-S-Y ^a -

(preferred are R ^a -O-Y ^a -, R ^a -S-Y ^a -, R ^a -N(R ^b )-Y ^a -, R ^a -CO-Y ^a -, R ^a -O-CO-Y ^a -, R ^a -CO-O-Y ^a -, R ^a -CO-N(R ^b )-Y ^a - and R ^a -N(R ^b )-CO-Y ^a -,),

R ^a being a hydrogen atom, a CrC ₆ alkyl, a or a C ₂ -C ₆ alkynyl group; R ^b being a hydrogen atom, a CrC ₆ alkyl, a C ₂ -C ₆ alkenyl or a C ₂ -C ₆ alkynyl group; R ^c being a hydrogen atom, a CrC ₆ alkyl, a C ₂ -C ₆ alkenyl or a C ₂ -C ₆ alkynyl group; R ^d being a hydrogen atom, a C _r C ₆ alkyl, a C ₂ -C ₆ alkenyl or a C ₂ -C ₆ alkynyl group and Y ^a being a bond, a Ci-C ₆ alkylene, a C ₂ -C ₆ alkenylene or a C ₂ -C ₆ alkynylene group (preferrably, R ^a , R ^b , R ^c and R ^d are independently H or CrC ₆ alkyl and Y ^a is a bond or C ₂ -C ₆ alkylene), each heteroalkyl group containing at least one carbon atom and it being possible for one or more hydrogen atoms to have been replaced by fluorine or chlorine atoms. Specific examples of heteroalkyl groups are methoxy, trifluoromethoxy, ethoxy, n- propyloxy, isopropyloxy, te/f-butyloxy, methoxymethyl, ethoxymethyl, methoxyethyl, methylamino, ethylamino, dimethylamino, diethylamino, isopropylethylamino, methylaminomethyl, ethylaminomethyl, diisopropylaminoethyl, enol ether, dimethyl- aminomethyl, dimethylaminoethyl, acetyl, propionyl, butyryloxy, acetyloxy, methoxycarbonyl, ethoxycarbonyl, N-ethyl-N-methylcarbamoyl and N- methylcarbamoyl. Further examples of heteroalkyl groups are nitrile, isonitrile, cyanate, thiocyanate, isocyanate, isothiocyanate and alkylnitrile groups.

The expression cycloalkyl refers to a saturated or partially unsaturated (for example cycloalkenyl), cyclic group that contains one or more rings (preferably 1 or 2), containing from 3 to 50 carbon atoms, preferably 3 to 14, further preferably from 3 to 10 (especially 3, 4, 5, 6 or 7) carbon atoms. The expression cycloalkyl refers furthermore to groups in which one or more hydrogen atoms have been replaced by fluorine, chlorine, bromine or iodine atoms or by OH, =O, SH, =S, NH ₂ , =NH or NO ₂

groups, thus, for example, cyclic ketones such as, for example, cyclohexanone, 2- cyclohexenone or cyclopentanone. Further specific examples of cycloalkyl groups are a cyclopropyl, cyclobutyl, cyclopentyl, spiro[4,5]decanyl, norbomyl, cyclohexyl, cyclopentenyl, cyclohexadienyl, decalinyl, bicyclo[4.3.0]nonyl, tetralin, cyclopentylcyclohexyl, fluorocyclohexyl or cyclohex-2-enyl group.

The expression heterocycloalkyl refers to a cycloalkyl group as defined above in which one or more (preferably 1 , 2 or 3) ring carbon atoms have been replaced by an oxygen, nitrogen, silicon, selenium, phosphorus or sulphur atom (preferably oxygen, sulphur or nitrogen). A heterocycloalkyl group has preferably 1 or 2 ring(s) containing from 3 to 10 (especially 3, 4, 5, 6 or 7) ring atoms. The expression heterocycloalkyl refers furthermore to groups in which one or more hydrogen atoms have been replaced by fluorine, chlorine, bromine or iodine atoms or by OH, =O, SH, =S, NH ₂ , =NH or NO ₂ groups. Examples are a piperidyl, piperazinyl, morpholinyl, urotropinyl, pyrrolidinyl, tetrahydrothiophenyl, tetrahydropyranyl, tetrahydrofuryl or 2-pyrazolinyl group and also lactams, lactones, cyclic imides and cyclic anhydrides.

The expression alkylcycloalkyl refers to groups containing both cycloalkyl and also alkyl, alkenyl or alkynyl groups in accordance with the above definitions, for example alkylcycloalkyl, cycloalkylalkyl, alkylcycloalkenyl, alkenylcycloalkyl and alkynylcyclo- alkyl groups. An alkylcycloalkyl group preferably contains a cycloalkyl group that contains one or two rings containing from 3 to 10 (especially 3, 4, 5, 6 or 7) carbon atoms, and one or two alkyl, alkenyl or alkynyl groups having 1 or 2 to 6 carbon atoms.

The expression heteroalkylcycloalkyl refers to alkylcycloalkyl groups as defined above in which one or more (preferably 1 , 2 or 3) carbon atoms have been replaced by an oxygen, nitrogen, silicon, selenium, phosphorus or sulphur atom (preferably oxygen, sulphur or nitrogen). A heteroalkylcycloalkyl group preferably contains 1 or 2 ring systems having from 3 to 10 (especially 3, 4, 5, 6 or 7) ring atoms, and one or two alkyl, alkenyl, alkynyl or heteroalkyl groups having from 1 or 2 to 6 carbon atoms. Examples of such groups are alkylheterocycloalkyl, alkylheterocycloalkenyl, alkenyl-

heterocycloalkyl, alkynylheterocycloalkyl, heteroalkylcycloalkyl, heteroalkyl- heterocycloalkyl and heteroalkylheterocycloalkenyl, the cyclic groups being saturated or mono-, di- or tri-unsatu rated.

The expression aryl or Ar refers to an aromatic group that has one or more rings containing from 6 to 50 carbon atoms, preferably 6 to 14, further preferably from 6 to 10 (especially 6) carbon atoms. The expression aryl (or Ar) refers furthermore to groups in which one or more hydrogen atoms have been replaced by fluorine, chlorine, bromine or iodine atoms or by OH, SH, NH ₂ or NO ₂ groups. Examples are a phenyl, naphthyl, biphenyl, 2-fluorophenyl, anilinyl, 3-nitrophenyl or 4-hydroxyphenyl group.

The expression heteroaryl refers to an aromatic group that has one or more rings containing from 5 to 50 ring atoms, preferably 5 to 14, further preferably from 5 to 10 (especially 5 or 6) ring atoms, and contains one or more (preferably 1 , 2, 3 or 4) oxygen, nitrogen, phosphorus or sulphur ring atoms (preferably O, S or N). The expression heteroaryl refers furthermore to groups in which one or more hydrogen atoms have been replaced by fluorine, chlorine, bromine or iodine atoms or by OH, SH, NH ₂ or NO ₂ groups. Examples are 4-pyridyl, 2-imidazolyl, 3-phenylpyrrolyl, thiazolyl, oxazolyl, triazolyl, tetrazolyl, isoxazolyl, indazolyl, indolyl, benzimidazolyl, pyridazinyl, quinolinyl, purinyl, carbazolyl, acridinyl, pyrimidyl, 2,3 ^' -bifuryl, 3-pyrazolyl and isoquinolinyl groups.

The expression aralkyl refers to groups containing both aryl and also alkyl, alkenyl, alkynyl and/or cycloalkyl groups in accordance with the above definitions, such as, for example, arylalkyl, arylalkenyl, arylalkynyl, arylcycloalkyl, arylcycloalkenyl, alkylarylcycloalkyl and alkylarylcycloalkenyl groups. Specific examples of aralkyls are toluene, xylene, mesitylene, styrene, benzyl chloride, o-fluorotoluene, 1 H-indene, tetralin, dihydronaphthalene, indanone, phenylcyclopentyl, cumene, cyclohexyl- phenyl, fluorene and indan. An aralkyl group preferably contains one or two aromatic ring systems (1 or 2 rings) containing from 6 to 10 carbon atoms and one or two

alkyl, alkenyl and/or alkynyl groups containing from 1 or 2 to 6 carbon atoms and/or a cycloalkyl group containing 5 or 6 ring carbon atoms.

The expression heteroaralkyl refers to an aralkyl group as defined above in which one or more (preferably 1 , 2, 3 or 4) carbon atoms have been replaced by an oxygen, nitrogen, silicon, selenium, phosphorus, boron or sulphur atom (preferably oxygen, sulphur or nitrogen), that is to say to groups containing both aryl or heteroaryl and also alkyl, alkenyl, alkynyl and/or heteroalkyl and/or cycloalkyl and/or heterocyclo- alkyl groups in accordance with the above definitions. A heteroaralkyl group preferably contains one or two aromatic ring systems (1 or 2 rings) containing from 5 or 6 to 10 carbon atoms and one or two alkyl, alkenyl and/or alkynyl groups containing 1 or 2 to 6 carbon atoms and/or a cycloalkyl group containing 5 or 6 ring carbon atoms, 1 , 2, 3 or 4 of those carbon atoms having been replaced by oxygen, sulphur or nitrogen atoms.

Examples are arylheteroalkyl, arylheterocycloalkyl, arylheterocycloalkenyl, arylalkylheterocycloalkyl, arylalkenylheterocycloalkyl, arylalkynylheterocycloalkyl, arylalkylheterocycloalkenyl, heteroarylalkyl, heteroarylalkenyl, heteroarylalkynyl, heteroarylheteroalkyl, heteroarylcycloalkyl, heteroarylcycloalkenyl, heteroarylhetero- cycloalkyl, heteroarylheterocycloalkenyl, heteroarylalkylcycloalkyl, heteroarylalkyl- heterocycloalkenyl, heteroarylheteroalkylcycloalkyl, heteroarylheteroalkylcycloalkenyl and heteroarylheteroalkylheterocycloalkyl groups, the cyclic groups being saturated or mono-, di- or tri-unsaturated. Specific examples are a tetrahydroisoquinolinyl, benzoyl, 2- or 3-ethylindolyl, 4-methylpyridino, 2-, 3- or 4-methoxyphenyl, 4-ethoxy- phenyl, 2-, 3- or 4-carboxyphenylalkyl group.

As already stated above, the expressions cycloalkyl, heterocycloalkyl, alkylcycloalkyl, heteroalkylcycloalkyl, aryl, heteroaryl, aralkyl and heteroaralkyl refer to groups in which one or more hydrogen atoms of such groups have been replaced by fluorine, chlorine, bromine or iodine atoms or by OH, =O, SH, =S, NH ₂ , =NH or NO ₂ groups.

Furthermore, all cycloalkyl, heterocycloalkyl, alkylcycloalkyl, heteroalkylcycloalkyl, aryl, heteroaryl, aralkyl and heteroaralkyl groups as defined herein may be optionally substituted.

The expression "optionally substituted" refers to groups in which one or more hydrogen atoms have been replaced by fluorine, chlorine, bromine or iodine atoms or by OH, =O, SH, =S, NH ₂ , =NH or NO ₂ groups. This expression refers furthermore to groups that are substituted by one or more (e.g. 1 , 2 or 3) unsubstituted C-i-Cβalkyl, C ₂ -C ₆ alkenyl, C ₂ -C ₆ alkynyl, C _r C ₆ heteroalkyl, C ₃ -Ci ₀ cycloalkyl, C ₂ - Cgheterocycloalkyl, C ₆ -Ci ₀ aryl, d-Cgheteroaryl, C ₇ -C-ι ₂ aralkyl or C ₂ -Cn heteroaralkyl groups.

Owing to their substitution, compounds of formula (I) may contain one or more centres of chirality. The present invention therefore includes both all pure enantiomers and all pure diastereoisomers and also mixtures thereof in any mixing ratio. The present invention moreover also includes all cis/trans-isomers of the compounds of the general formula (I) and also mixtures thereof. The present invention moreover includes all tautomeric forms of the compounds of formula (I).

Preferred are compounds of formula (I) wherein R1 , R2, R3, R4, R5 and R6 are independently of each other a hydroxy, an amino, a mercapto, an alkyl, an alkenyl, an alkynyl, a heteroalkyl, a cycloalkyl, a heterocycloalkyl, an alkylcycloalkyl, a heteroalkylcycloalkyl, an aryl, a heteroaryl, an aralkyl or a heteroaralkyl group.

Further preferred are compounds of formula (I) wherein R1 is a hydroxyl group or a group of formula NH ₂ , OR7 or NHR8, wherein R7 and R8 are independently an alkyl, an alkenyl, an alkynyl, a heteroalkyl, a cycloalkyl, a heterocycloalkyl, an alkylcycloalkyl, a heteroalkylcycloalkyl, an aryl, a heteroaryl, an aralkyl or a heteroaralkyl group.

Especially preferred are compounds of formula (I) wherein R1 is a hydroxyl group.

Further preferred are compounds of formula (I) wherein R2 is a hydroxyl group.

Further preferred are compounds of formula (I) wherein R3 is a hydroxyl group.

Further preferred are compounds of formula (I) wherein R4 is a hydroxyl group.

Further preferred are compounds of formula (I) wherein R5 is a hydroxyl group.

Further preferred are compounds of formula (I) wherein R6 is a group of formula NHR9 wherein R9 is an alkyl, aryl, heteroaryl, aralkyl or heteroaralkyl (preferably, aryl or heteroaryl, especially a phenyl, naphthyl, biphenyl or a pyridyl) group, all of which groups may optionally be substituted by one or more (e.g. 1 , 2 or 3) substituents.

Further preferred are compounds of formula (I) wherein R6 is a group of formula OR10 wherein R10 is an alkyl, aryl, heteroaryl, aralkyl or heteroaralkyl (preferably, aryl or heteroaryl, especially a phenyl, naphthyl, biphenyl or a pyridyl) group, all of which groups may optionally be substituted by one or more (e.g. 1 , 2 or 3) substituents.

Further preferred are compounds of formula (I) wherein R6 is a group of formula SR11 wherein R11 is an alkyl, aryl, heteroaryl, aralkyl or heteroaralkyl (preferably, aryl or heteroaryl, especially a phenyl, naphthyl, biphenyl or a pyridyl) group, all of which groups may optionally be substituted by one or more (e.g. 1 , 2 or 3) substituents.

Especially preferred are compounds of formula (I) wherein R9 is a phenyl, naphthyl, biphenyl or a heteroaryl group having from 5 to 10 ring atoms (1 or 2 rings) and from one to 4 heteroatoms selected from O, S and N; all of which groups may optionally be substituted by 1 , 2, 3 or 4 substituents, preferably selected from F, Cl, OH, NH ₂ , OMe, SMe, COOH, COOMe, an optionally substituted phenyl group and an optionally substituted heteroaryl group having 5 or 6 ring atoms and 1 , 2 or 3 heteroatoms selected from S, O and N.

Especially preferred are compounds of formula (I) wherein R10 is a phenyl, naphthyl, biphenyl or a heteroaryl group having from 5 to 10 ring atoms (1 or 2 rings) and from one to 4 heteroatoms selected from O, S and N; all of which groups may optionally be substituted by 1 , 2, 3 or 4 substituents, preferably selected from F, Cl, OH, NH ₂ , OMe, SMe, COOH, COOMe, an optionally substituted phenyl group and an optionally substituted heteroaryl group having 5 or 6 ring atoms and 1 , 2 or 3 heteroatoms selected from S, O and N.

Especially preferred are compounds of formula (I) wherein R11 is a phenyl, naphthyl, biphenyl or a heteroaryl group having from 5 to 10 ring atoms (1 or 2 rings) and from one to 4 heteroatoms selected from O, S and N; all of which groups may optionally be substituted by 1 , 2, 3 or 4 substituents, preferably selected from F, Cl, OH, NH ₂ , OMe ₁ SMe, COOH, COOMe, an optionally substituted phenyl group and an optionally substituted heteroaryl group having 5 or 6 ring atoms and 1 , 2 or 3 heteroatoms selected from S, O and N.

Moreover preferred are groups of formula (I) wherein R2 is a group of formula OC(=O)R2' or NHC(=O)R2" wherein R2' is an alkyl, an alkenyl, an alkynyl, a heteroalkyl, a cycloalkyl, a heterocycloalkyl, an alkylcycloalkyl, a hetero- alkylcycloalkyl, an aryl, a heteroaryl, an aralkyl or a heteroaralkyl group and R2" is an alkyl, an alkenyl, an alkynyl, a heteroalkyl, a cycloalkyl, a heterocycloalkyl, an alkylcycloalkyl, a heteroalkylcycloalkyl, an aryl, a heteroaryl, an aralkyl or a heteroaralkyl group.

Moreover preferred are groups of formula (I) wherein R3 is a group of formula OC(=O)R3' or NHC(=O)R3" wherein R3' is an alkyl, an alkenyl, an alkynyl, a heteroalkyl, a cycloalkyl, a heterocycloalkyl, an alkylcycloalkyl, a heteroalkylcycloalkyl, an aryl, a heteroaryl, an aralkyl or a heteroaralkyl group and R3" is an alkyl, an alkenyl, an alkynyl, a heteroalkyl, a cycloalkyl, a heterocycloalkyl, an alkylcycloalkyl, a heteroalkylcycloalkyl, an aryl, a heteroaryl, an aralkyl or a heteroaralkyl group.

Moreover preferred are groups of formula (I) wherein R4 is a group of formula OC(=O)R4' or NHC(=O)R4" wherein R4' is an alkyl, an alkenyl, an alkynyl, a heteroalkyl, a cycloalkyl, a heterocycloalkyl, an alkylcycloalkyl, a hetero- alkylcycloalkyl, an aryl, a heteroaryl, an aralkyl or a heteroaralkyl group and R4" is an alkyl, an alkenyl, an alkynyl, a heteroalkyl, a cycloalkyl, a heterocycloalkyl, an alkylcycloalkyl, a heteroalkylcycloalkyl, an aryl, a heteroaryl, an aralkyl or a heteroaralkyl group.

Moreover preferred are groups of formula (I) wherein R5 is a group of formula OC(=O)R5' or NHC(=O)R5" wherein R5' is an alkyl, an alkenyl, an alkynyl, a heteroalkyl, a cycloalkyl, a heterocycloalkyl, an alkylcycloalkyl, a heteroalkylcycloalkyl, an aryl, a heteroaryl, an aralkyl or a heteroaralkyl group and R5" is an alkyl, an alkenyl, an alkynyl, a heteroalkyl, a cycloalkyl, a heterocycloalkyl, an alkylcycloalkyl, a heteroalkylcycloalkyl, an aryl, a heteroaryl, an aralkyl or a heteroaralkyl group.

Moreover preferred are groups of formula (I) wherein R6 is a group of formula OC(=O)R6' or NHC(=O)R6" wherein R6' is an alkyl, an alkenyl, an alkynyl, a heteroalkyl, a cycloalkyl, a heterocycloalkyl, an alkylcycloalkyl, a heteroalkylcycloalkyl, an aryl, a heteroaryl, an aralkyl or a heteroaralkyl group and R6" is an alkyl, an alkenyl, an alkynyl, a heteroalkyl, a cycloalkyl, a heterocycloalkyl, an alkylcycloalkyl, a heteroalkylcycloalkyl, an aryl, a heteroaryl, an aralkyl or a heteroaralkyl group.

Further preferred are compounds of formula (I) wherein R1 and R6 together are an oxygen atom.

It is to be noted that the present invention also encompasses all possible combinations of all preferred embodiments.

Especially preferred, the compound of formula (I) has the following structure (Elansolid Ai and/or A ₂ ):

It has been observed, that Elansolid A ₂ is transformed into Elansolid Ai in solution (especially in DMSO).

Further, especially preferred, the compound of formula (I) has the following structure (Elansolid B ₁ ):

Further, especially preferred, the compound of formula (I) has the following structure (Elansolid B ₂ ):

Further, especially preferred, the compound of formula (I) has the following structure (Elansolid Ci):

Further, especially preferred, the compound of formula (I) has one of the following structures:

The therapeutic use of compounds of formula (I), their pharmacologically acceptable salts or solvates and hydrates and also formulations and pharmaceutical compositions also lie within the scope of the present invention, especially, the use of

compounds of formula (I) ₁ their pharmacologically acceptable salts or solvates and hydrates and also formulations and pharmaceutical compositions for the treatment of bacterial infections as well as their use for the preparation of medicaments for the treatment of bacterial infections.

The pharmaceutically compositions according to the present invention comprise at least one compound of formula (I) as active ingredient and, optionally, carrier substances and/or adjuvants. Further, these pharmaceutically compositions may comprise other antimicrobial ingredients.

Examples of pharmacologically acceptable salts of the compounds of formula (I) are salts of physiologically acceptable mineral acids, such as hydrochloric acid, sulphuric acid and phosphoric acid, or salts of organic acids, such as methanesulphonic acid, p-toluenesulphonic acid, lactic acid, acetic acid, trifluoroacetic acid, citric acid, succinic acid, fumaric acid, maleic acid and salicylic acid. Further examples of pharmacologically acceptable salts of the compounds of formula (I) are alkali metal and alkaline earth metal salts such as, for example, sodium, potassium, lithium, calcium or magnesium salts, ammonium salts or salts of organic bases such as, for example, methylamine, dimethylamine, triethylamine, piperidine, ethylenediamine, lysine, choline hydroxide, meglumine, morpholine or arginine salts. Compounds of formula (I) may be solvated, especially hydrated. The hydration may take place, for example, during the preparation process or as a consequence of the hygroscopic nature of the initially anhydrous compounds of formula (I). When the compounds of formula (I) comprise asymmetric C-atoms, they may be present either in the form of achiral compounds, diastereoisomeric mixtures, mixtures of enantiomers or in the form of optically pure compounds.

The pro-drugs to which the present invention also relates consist of a compound of formula (I) and at least one pharmacologically acceptable protecting group which will be removed under physiological conditions, such as, for example, an alkoxy-, aralkyloxy-, acyl- or acyloxy group, such as, for example, an ethoxy, benzyloxy, acetyl or acetyloxy group.

The present invention relates also to the use of those active ingredients in the preparation of medicaments. In general, compounds of formula (I) are administered either individually, or in combination with any other desired therapeutic agent, using the known and acceptable methods. Such therapeutically useful agents may be administered, for example, by one of the following routes: orally, for example in the form of dragees, coated tablets, pills, semi-solid substances, soft or hard capsules, solutions, emulsions or suspensions; parenterally, for example in the form of an injectable solution; rectally in the form of suppositories; by inhalation, for example in the form of a powder formulation or a spray; transdermal^ or intranasally. For the preparation of such tablets, pills, semi-solid substances, coated tablets, dragees and hard gelatine capsules, the therapeutically usable product may be mixed with pharmacologically inert, inorganic or organic pharmaceutical carrier substances, for example with lactose, sucrose, glucose, gelatine, malt, silica gel, starch or derivatives thereof, talcum, stearic acid or salts thereof, skimmed milk powder, and the like. For the preparation of soft capsules, pharmaceutical carrier substances such as, for example, vegetable oils, petroleum, animal or synthetic oils, wax, fat and polyols may be used. For the preparation of liquid solutions and syrups, pharmaceutical carrier substances such as, for example, water, alcohols, aqueous saline solution, aqueous dextrose, polyols, glycerol, vegetable oils, petroleum and animal or synthetic oils may be used. For suppositories, pharmaceutical carrier substances such as, for example, vegetable oils, petroleum, animal or synthetic oils, wax, fat and polyols may be used. For aerosol formulations, compressed gases that are suitable for this purpose, such as, for example, oxygen, nitrogen and carbon dioxide may be used. The pharmaceutically acceptable agents may also comprise additives for preserving and stabilising, emulsifiers, sweeteners, flavourings, salts for altering the osmotic pressure, buffers, encapsulation additives and antioxidants.

Combinations with other therapeutic agents may comprise other antimicrobial ingredients.

For the prevention and/or treatment of bacterial infections, the dose of the biologically active compound according to the invention may vary within wide limits and may be adjusted to individual requirements. Generally, a dose of from 10 mg to 4000 mg per day is suitable, a preferred dose being from 50 to 3000 mg per day. In suitable cases, the dose may also be below or above the stated values. The daily dose may be administered as a single dose or in a plurality of doses. A typical individual dose contains approximately 50 mg, 100 mg, 250 mg, 500 mg, 1 g or 2 g of the active ingredient.

Also the following methods for producing compounds (Elansolids) of formula (I) lie within the scope of the present invention.

Compounds of formula (I) (Elansolids) can be produced by culturing a selected gliding bacterium of the genus Chitinophagha spec. [Flexibacter spec] It is understood that the production of Elansolid like substances is not limited to the use of the particular organism described herein, which is given for illustrative purpose only. The invention also includes the use of any mutants which are capable of producing Elansolid type substances including natural mutants as well as artificial mutants which can be produced from the described organism by conventional means such as irradiation or treatment with mutagens. Also genetically manipulated mutants and the expression of the gene cluster responsible for biosynthesis in the producer strain or by heterologous expression in host strains are part of the invention.

Compounds of formula (I) can be attained by feeding nucleophilic precursors to growing cultures of FxGBFI 3 (mutasynthesis) or by chemical reactions (e.g. derivatization of Elansolid Ai and /or A ₂ and/or other Elansolids).

The microorganisms, which can be used for the production of Elansolids Ai and A ₂ and the Elansolid B derivatives, belong to genus Chitinophaga [Flexibacter]. The isolate Fx GBF13 used for production is closely related to Chitinophage sancti [Flexibacter sancti] according to 16S rDNA sequencing. The strain has been

deposited at the German Collection of Microorganisms and Cell Cultures (DSMZ) Braunschweig, Germany under the accession number DSM 21134.

Elansolids are produced in liquid culture, by growing in media containing one or several different carbon sources, and one or different nitrogen sources. Also salts are essential for growth and production. Suitable carbon sources are different mono-, di-, and polysaccharides like glucose, sucrose, lactose or carbon from amino acids like peptones. Nitrogen sources are ammonium, nitrate, urea, chitin or nitrogen from amino acids. The following inorganic ions support the growth or are essential in synthetic media:Ca-ions, Mg-ions, Fe-ions, Mn-ions, Zn-ions, K-ions, sulfate-ions, Cl- ions, phosphate-ions.

Temperatures for growth and production are between 10 ⁰ C to 40 ⁰ C, preferred temperatures are between 15 ⁰ C and 37 ⁰ C, especially between 20 ⁰ C to 25 ⁰ C.

The test cultures were grown on CAS agar plates of the following composition: Casitone Difco, 10 g/l; MgSO ₄ x 7 H ₂ O, 1 g/l; CaCI ₂ x 2 H ₂ O, 1 g/l; HEPES buffer 50 mM; agar 15 g/l; pH adjusted to 7.0. The cultures were incubated at 20 °C.

Production of Elansolids by fermentation in bioreactors

Example: Fermentation in complex medium.

Precultures in Erlenmeyer flasks:

Medium composition: Casitone Difco, 10 g/l; MgSO ₄ x 7 H ₂ O, 1 g/l; CaCI ₂ x 2 H ₂ O,

1 g/l; Hepes buffer 50 mM; pH adjusted to 7.0.

2 x 500 ml of the above medium in 1 I Erlenmeyer flasks are autoclaved and inoculated with 10% of a FxGBFI 3 preculture. Incubation for 4 days at 20 ⁰ C in a rotary incubator at 300 rpm.

Fermentation in a 10 I bioreactor:

The medium used was identical with the medium in shake flasks. 10 I of fermentation broth were inoculated with 1 I of preculture. The fermentation was run at 20 ⁰ C with a stirrer speed of 100 r.p.m. and an aeration of 0,1 wm for 4 days.

Production in 100 I bioreactor:

The medium was identical with that in the 10 I bioreactor but without HEPES buffer.

For continuous adsorption of the Elansolids 2 % (v/v) of XAD 16 adsorber resin

(Rohm and Haas, Frankfurt/M) was added before autoclaving.

Fermentation parameters: The total fermentation volume was 70 I. The aeration rate was 0,1 vvm. The initial stirrer velocity was 100 r.p.m. and a pθ2 of 20% was maintained by regulation of the stirrer velocity. A pH of 7.0 was maintained by regulation with 10% sulphuric acid solution and 10% solution of KOH. Foam formation was inhibited by addition of silicone antifoam (Tegosipon, Goldschmidt AG,

Essen). After 7 days of fermentation the XAD resin was harvested. (Fig. 1 )

Isolation of Elansolid A ₁

The XAD 16 resin of the above fermentation was harvested by sieving, washed with water, and eluted in a chromatography column with 9 L of acetone/methanol (1 :1 ). The organic solvent was removed from the eluate by evaporation, and the remaining water was extracted three times with ethyl acetate. The combined ethyl acetate portions were dried with sodium sulphate and evaporated to dryness. The oily

residue was partitioned between methanol and n-heptane. Evaporation of the methanol yielded 14.0 g raw extract, which was separated in portions of 800 mg by RP-MPLC [column 48*3 cm (Kronlab) ODS AQ 120 16 C18; eluent A: CH ₃ CN/H ₂ O 4:6, 50 mM NH ₄ OAc, pH 5.5; eluent B: CH ₃ CN/H ₂ O 50:50, 50 mM NH ₄ OAc, pH 5.5, gradient 100% A to 100% B in 360 min, flow: 12 ml/min; UV detection at 254 nm]. The Elansolid Ai containing fraction was evaporated to yield 32 mg/run. The product was further purified by RP-HPLC [column 250*21 mm, Nucleodur 100-7-C18 (Macherey-Nagel); eluent A: CH ₃ CN/H ₂ O 1 :1 , 50 mM NH ₄ OAc, pH 5.5, eluent B: CH ₃ CN/H ₂ O 7:3, 50 mM NH ₄ OAc, pH 5.5, gradient 100% A to 100% B in 30 min, flow 15 ml/min; UV detection at 254 nm] to yield 18 mg Elansolid Ai. The total yield from the 70 L fermenter was 315 mg.

Elansolid A ₁ : C ₃₇ H ₄₈ O ₆ MW = 588.8; HRMS: [El] ⁺ calcd. 588.3451 , found 588.3399 UV(MeOH): λ _max (Ig ε) = 225 (4,23), 257 sh (4,56), 270 (4,71), 280 (470) nm. IR (KBr): v = 3419, 2961 , 2929, 1693, 1616, 1515, 1249 crτϊ ¹ . TLC (silica gel, UV detection at 254 nm, dichlormethane/methanol 85:15) Rf = 0.47. Analytical RP-HPLC: column 125*2 mm Nucleodur 120 5 μm C18 (Macherey-Nagel), solvent A: water/acetonitrile 95/5, 5 mM NH ₄ OAc, pH 5.5, solvent B = water/acetonitrile 5/95, 5 mM NH ₄ OAc, pH 5.5; gradient from 10% B to 100% B in 30 min, 10 min 100% B, flow 0.3 ml/min. R ₄ = 20,4 min.

Table 1. NMR Data of Elansolid A ₁ in DMSO-d ₆

[ ¹ H 600 MHz, ¹³ C 150 MHz; internal standard solvent signal δ _H /δ _c = 2.50/39.51]

9 4.75 m br 9 66.6 d 4.82 ddd 8.8, 4.8, 4.0 br

10 5.53 dd 10.8,9.8 10 134.4 d 5.55 dd 10.6,8.8

11 5.99 dd 11.2, 10.6 11 128.2 d 5.99 t 10.6, 11.5

12 6.57 dd 14.4, 11.0 12 127.5 d 6.59 dd 14.3, 11.5

13 6.14 dd 14.3, 11.4 13 130.2 d 6.15 dd 14.3, 11.3

14 6.22 dd 11.4, 10.6 14 125.4 d 6.23 t 11.3, 10.6

15 5.74 dd 10.6, 10.6 15 134.4 d 5.74 t 10.6

16 2.85 dd 10.6,2.5 16 40.2 d 2.89 dd 10.6, 3.8 br

- - - - 17 134.3 S - - -

18 5.45 s br. 18 122.8 d 5.47 S br. (dq2, 1.1)

19 2.58 dd 12.0,2.5 19 54.9 d 2.60 d 12.0 br

- - - - 20 74.3 S - - -

21b 1.69 d 13.6 21 59.7 t 1.72 d 14.0

21a 1,55 d 13.6 1.58 d 14.0

- _ _ - 22 37.2 S - - -

23 1.75 dd 12, 11.2 23 44.1 d 1.77 t 12.0

24 2.17 dd 11.2,4.0,2.6 24 47.1 d 2.17 ddd 11.3,3.8,2.7

25 5.93 d 2.6 25 74.4 d 5.96 d 2.7

- - - - 26 130.1 S - - -

27 6.86 d 8.5 27 126.3 d 6.88 d 8.7

28 6.62 d 8.5 28 114.7 d 6.64 d 8.7

- _ - 29 156.2 S - - -

30 1.67 S 30 11.9 q 1.72 S

31 0.89 d 6.8 31 10.2 q 0.89 d 6.8

32 1.41 S br 32 20.9 q 1.44 dd 2.3, 1.1

33 1.00 S 33 26.4 q 1.03 S

34 1.21 S 34 23.8 q 1.23 S

35 0.92 S 35 29.9 q 0.89 S

7 OH 4.86 d 4.5 4.78 d 5.3

9 OH 4.70 d 3.8 4.56 d 4.9

20 OH 4.48 S 4.30 S

29 OH 9.33 S 9.33 S

Signals for 27 and 28 have double intensity;

Isolation of Elansolid A ₂ :

Adsorber resin Amberlite XAD16 was harvested from 100 L of fermentation broth by sieving. Elution of the products was done with 5 L of acetone to yield raw Elansolid A ₂ . After evaporation of the acetone, the residual water was extracted three times with ethyl acetate. The organic layer was dried with anhydrous sodium sulfate, filtrated, and concentrated in vacuo to give a crude extract of 13.2 g.

200 mg of this extract was further purified in 4 preparative HPLC runs on a Gemini RP18 column (250x21 mm, 100 5 μm C18, Phenomenex) with a solvent gradient from 20/80 acetonitrile/water in 40 min to 100% acetonitrile, flow rate: 20 ml/min. After evaporation and freeze drying 30 mg of Elansolid A ₂ was obtained.

Elansolid A ₂ : C ₃₇ H ₄₈ O ₆ MW = 588.8; HRMS: ESI+ calcd.: 589.3529, found 589.3530; UV(Ethanol) λ _max (Ig ε): 229 (4.18), 268 (4.73), 279 sh, 296 sh 319 sh nm; IR (KBr) v = 3424, 2962, 2928, 1689, 1627, 1615, 1515, 1235 cm ^'1 ; Analytical RP-HPLC: column 125x2 mm Nucleodur 120 5 μm C18 (Macherey-Nagel), solvent A: water/acetonitrile 95/5, 5 mM NH ₄ OAc, pH 5,5 - solvent B: water/acetonithle 5/95, 5 mM NH ₄ OAc, pH 5,5; solvent gradient from 10%B to 100%B in 10 min; flow: 0.3 ml/min. R _t = 9.4 min.

Table 2. NMR Data of Elansolid A ₂ in DMSO-cfe (room temperature; 70 ⁰ C)

22 - - - 22 37.26 S - - -

23 1.78 t 11.92 23 44.19 d 1.80 t 12.7, 11.2

24 2.12 m _ 24 47.56 d 2.15 ddt 11.2, 2.2

25 6.12 S - 20/25 74.38 2d 6.14 d 2.2

26 _ - 26 131.23 S - - -

27 6.91 d 7.70 27 126.80 d 6.93 d 8.4

28 6.62 d 8.44 28 114.72 2d 6.63 d 8.4

29 _ _ - 29 156.53 S - -

OH 9.43 S br. OH - - 9.27 br. s. -

30 1.71 S _ 30 11.60 q 1.73 S -

31 0.85 d 6.97 31 10.44 q 0.88 d 6.60

32 1.45 S - 32 20.92 q 1.47 S -

33 1.01 S - 33 26.31 q 1.02 S -

34 1.19 S br. 34 23.87 q 1.21 S -

35 1.03 S - 35 30.08 q 1.05 S -

[1] broad 13 ^1J C shift detected in HMBC

Example: Production of Elansolids by fermentation in synthetic medium and fermentation process optimized for the production of Elansolid A ₂ .

Precultures in Erlenmeyer flasks:

Medium composition: Casitone Difco, 10 g/l; MgSO ₄ x 7 H ₂ O, 1 g/l; CaCI ₂ x 2 H ₂ O,

1 g/l; Hepes buffer 50 mM; pH adjusted to 7.0.

2 x 500 mL of the above medium in 1 L Erlenmeyer flasks are autoclaved and inoculated with 10% of a FxGBFI 3 preculture. Incubation for 4 days at 20 ⁰ C in a rotary incubator at 300 rpm.

Production in a 150 L bioreactor with synthetic medium:

Medium composition:

Glutamine, 2g/L; MgSO ₄ X 7 H ₂ O, 0,2 g/l; Fe-EDTA, 1 mg/l; MnSO ₄ , 5 mg/l; ZnCI ₂ ,

5 mg/l. For continuous adsorption of the Elansolids 2 % (v/v) of XAD 16 adsorber resin (Rohm and Haas, Frankfurt/M) was added before autoclaving.

After autoclavation the following separately autoclaved components were added:

5 L of a 20% solution of sucrose and 1 L of a 7 % solution of KH ₂ PO ₄ .

Fermentation parameters:

The total fermentation volume was 100 L. The aeration rate was 0.07 wm. The initial stirrer velocity was 100 r.p.m. and a pθ ₂ of 20% was maintained by regulation of the stirrer velocity. A pH of 6.0 was maintained by regulation with 10% KOH solution. The fermentation temperature was kept at 20 ⁰ C. Foam formation was inhibited by addition of silicone antifoam (Tegosipon, Goldschmidt AG, Essen). The fermenter was inoculated with 2 I of a preculture grown in complex medium as described above. After 7 days of fermentation the XAD resin was harvested. A typical analytical RP HPLC is shown in Figure 3.

Derivatives of Elansolids A ₁ or A ₂ at carbon C-25 (R6)

The enhanced reactivity of lactones toward nucleophiles makes hydrolysis their preferred reaction which is effected under variety of reaction conditions including reagents, catalysts, solvents and temperature. The chemoselectivity allows reactions of multifunctional compounds, very often of rather complicated structure. The ring cleavage occurs e.g. under basic (alkali metal hydroxides or alkoxides, ammonia, tertiary amines) or acidic (Bronsted or Lewis acids) conditions. The effective cleavage of the lactone ring occurs also in reactions with nitrogen nucleophiles which include ammonia, primary and secondary amines and hydrazine derivatives, as commonly used reagents. Sulphur and selenium derivatives are prepared in reactions of lactones with S- and Se-nucleophiles.

The effective nucleophilic reducing agents include metal hydrides, of which lithium aluminium hydride is the most frequent used reagent. Metalloorganic reagents effectively cleave lactones, while new carbon-carbon bonds are formed. Other reducing agents like sodium borohydride and other complex boron hydrides can also be used.

Under opening of the lactone ring system derivatives of Elansolids A at position C25 (R6) can be obtained by reaction with nucleophilic (preferably low molecular weight) chemicals.

Under neutral aqueous conditions the residue can be a hydroxy group (R6 = OH, Elansolid Bi) from reaction with water or a methoxy group formed in presence of methanol (R6 = OCH ₃ , Elansolid B ₂ ). Under alkaline conditions in presence of ammonium ions, the residue is an ammonium group (R6 = NH ₂ , Elansolid B ₃ ).

Of special interest is the group of Elansolid C derivatives, which result from a nucleophilic attack of more complex chemical structures. Such derivatives show especially high inhibitory activity against pathogens. Examples are derivatives which result from nucleophilic attack by substituted aromatic amines (like Elansolid C-i). The new ring system at R6 can e.g. be aromatic or heteroaromatic and may also be optionally substituted. The ring system can be substituted at different positions and with different substituents such as e.g. COOH, COOMe, SO ₃ H, SO ₂ NH ₂ , CH=CHCOOH, halogen atoms, OH, bi- and polycylic aryl or heteroaryl groups.

Derivatives at C-25 (R6) can be obtained by mutasynthesis, i.e. by feeding the growing cultures of FxGBFI 3 with the respective chemicals like e.g. methyl-2- aminobenzoic acid, 2-aminopyridine-3-carboxylic acid, anthranilic acid, p- aminobenzoic acid, 4-aminobenzamide, sulfanilic acid, sulfanilamide or by chemical derivatization of purified Elansolids Ai and A ₂ with e.g. mercapto benzoic acid, salicilic acid, 4-hydroxybenzoic acid, 4-hydroxybencoic acid methyl ester, hydroxycinnamic aicd.

Isolation of Elansolid Bi

Wet cell mass and adsorber resin Amberlite XAD-16 (0.2 L) from a fermentation (10 L) of strain FXGBF13 was harvested by centrifugation and extracted with 3 portions of acetone (1.7 L each). The aqueous mixture which remained after evaporation of the acetone was extracted with ethyl acetate (1 L in all). The organic solution was dried with sodium sulphate and evaporated to yield about 6.8 g of raw product. 3 g of the residue was separated by silica gel flash chromatography (column 8.5 ^χ 4 cm, silica gel ICN 60 63-200 μm), solvents CH ₂ CI ₂ (0.5 L), CH ₂ CI ₂ /CH ₃ OH 95:5 (0.75 L), CH ₂ CI ₂ /CH ₃ OH 85:15 (0.75 L). According to TLC analyses the fractions containing Elansolid Bi were combined, and evaporated to dryness (yield 1.56 g). 110 mg of the enriched product was separated further by RP-HPLC [column 250*21 mm, Nucleodur 100 10 μm C18, Macherey-Nagel, solvent 70% acetonitrile in water with 50 mM NH ₄ OAc, detection UV absorption at 235 nm] to yield 15 mg of Elansolid

Elansolid B-i:

MF C ₃₇ H ₅₀ O ₇ , MW = 606.8, ESI-MS: m/z 605.3 [M-H]-.

UV: λ ma _x (Ig ε) = 262 (sh 4.61), 272 (4.65), 282 (4.69), 296 (4.51) nm.

TLC (silica gel 254, dichloromethane/methanol 85:15): R _f = 0.28.

HPLC: column 125 ^χ 2 mm Nucleodur 120 5 μm C18 (Macherey-Nagel), solvent A: water/acetonitrile 95/5 plus 5 mM NH ₄ OAc ₁ pH 5.5, solvent B: water/acetonitrile 5/95 plus 5 mM NH ₄ OAc ₁ pH 5.5) gradient: 10% B to 100% B in 30 min, 10 min 100% B, flow 0.3 mL/min. R ₁ = 10.1 min.

Table 3. NMR data of Elansolid B ₁ (R = OH) in DMSO-Gf ₆ ,

[ ¹ H 600 MHz, ¹³ C 150 MHz, internal ref. ¹ H/ ¹³ C δ = 2.50/39.51 ppm]

Signals for 27 and 28 have double intensity;

Isolation of Elansolid B ₂

Amberlite XAD16 resin (1.2 L) was harvested by sieving from 70 L of fermentation broth of Flexibacter FXGBF13 and was washed with water. After eluting the resin with 9 L of methanol, the organic solvent was evaporated. The remaining water was extracted three times with ethyl acetate. The organic layer was concentrated to yield

15 g of raw extract.

The residue was resolved in methanol and partitioned with n-hexane. The methanol layer was concentrated to yield 14.1 g of crude extract.

650 mg of the extract was further separated by MPLC [column 48*3 cm, Kronlab ODS AQ 120, 16 μm, C18, eluent: acetonitrile/50 mM NH ₄ OAc buffer 48:52, flow

16 mL/min, UV detection at 254 nm). The Elansolid B ₂ containing fraction was evaporated to yield 74.9 mg.

Elansolid B ₂ :

MF C ₃₈ H ₅₂ O ₇ , MW = 620.8

ESI-MS: m/z 619.2 [M-H]-.

UV: λ _max (Ig ε) = 229 (4.30), 259 (sh 4.60), 270 (4.66), 281 (4.68), 294 (4.53) nm.

IR (KBr): v = 3390, 3023, 2964, 2926, 2890, 1688, 1615, 1512, 1201 crτϊ ¹ .

TLC (silica gel; UV 254 nm, dichlormethane/methanol 85:15): R _f = 0.40.

HPLC (column 125*2 mm Nucleodur 120 5 μm C18 (Macherey-Nagel), solvent A: water/acetonitrile 95/5, 5 mM NH ₄ OAc, pH 5.5, solvent B: water/acetonitrile 5/95,

5 mM NH ₄ OAc, pH 5.5, gradient from 100% A to 100% B in 30 min, 10 min 100% B, flow 0.3 mL/min): R ₄ = 15.8 min.

Table 4. NMR Data of Elansolid B ₂ in DMSO-d ₆

[ ¹ H 600 MHz, ¹³ C 150 MHz, internal ref. ¹ H/ ¹³ C δ = 2.50/39.51 ppm]

Signals for 27 and 28 have double intensity; signal C-16 under solvent signal;

Elansolid Ci (a C25 anthranilic acid derivative)

Production by Mutasynthesis:

The fermentation is performed in a 15 L bioreactor with 10 L of complex culture medium as describe for Elansolids A production. After sterilization anthranilic acid - dissolved in a small volume of methanol - is added to give a final concentration of 50 mg/L. The fermentation process is run as described above. After 5 days of fermentation at 20 ⁰ C a suspension of Amberlite XAD 16 (150 ml) is added. After one hour of stirring the resin is harvested. Elansolid Ci is observed as main component. (Fig. 2).

Anthranilic acid may be replaced by other nucleophiles to give futher Elansolid derivatives by mutasynthesis.

Isolation of Elansolid C ₁

From 10 L of fermentation broth adsorber resin XAD 16 (150 ml_) was harvested by sieving (200 μm pore size). The resin was washed with water and eluted with 1 L of

acetone in 3 steps. After evaporation of the acetone, the residual water layer was extracted three times with ethyl acetate. The organic layer was dried with sodium sulphate, filtrated, and concentrated in vacuo to give a crude extract of 489 mg. The extract was separated by RP-HPLC in 10 runs [column 250*21 mm, Nucleodur 100-7-C18, (Macherey-Nagel), eluent acetonitrile/50 mM NH ₄ OAc buffer, gradient from 20% to 70% acetonitrile in 40 min, flow 15 mL/min, UV detection at 254 nm]. After evaporation of the Elansolid Ci containing fraction the water layer was extracted with ethyl acetate to yield Elansolid Ci (71 mg).

Elansolid Ci: MF C ₄₄ H ₅₅ NO ₈ , MW = 725.9.

(+)-HR-ESI-MS: found 748.3830, calcd. 748.3825 [M+Na] ⁺ .

UV: λ _max (Ig ε) = 220 (4.35), 259 (4.45), 273 (sh), 282 (sh), 346 (3.48) nm.

IR (KBr): v = 3377, 2963, 1686, 1614, 1511 , 1237 crτϊ ¹ .

TLC (silica gel, UV detection at 254 nm, CH ₂ CI ₂ /MeOH 85:15): Rf = 0.48.

HPLC: column 125*2 mm Nucleodur 120 5 μm C18 (Macherey-Nagel), solvent A: water/acetonitrile 95/5, 5 mM NH ₄ OAc, pH 5.5, solvent B: water/acetonitrile 5/95, 5 mM NH ₄ OAc, pH 5.5, gradient: 10% B to 100% B in10 min, 10 min 100% B, flow 0.3 mL/min. R ₄ = 6.6 min.

Table 5. NMR data of Elansolid C ₁ in d ₆ -DMSO

[ ¹ H 600 MHz, ¹³ C 150 MHz; internal standard: solvent signal δ _H /c = 2.50/39.51 ppm]

^[a] the signals of H9 and H25 overlapp partially; Signals for 27 and 28 have double intensity; signal C-16 under solvent signal;

Elansolids of formula (I) by chemical synthesis:

1 ) Reaction of Elansolids Ai or A ₂ with 2-aminobenzoic acid in ammonia/methanol 1 :1 , pH 8, at RT for 16 h yields Elansolid Ci.

2) Reaction of Elansolids A-i or A ₂ with 2-mercaptobenzoic acid under the same conditions yields the corresponding mercaptobenzoic acid derivative (e.g. compound 095-33).

The reactions can be monitored by RP-HPLC-MS.

The derivatisation of Elansolids Ai or A ₂ (or other derivatives like e.g. Elansolid Bi, B ₂ or Ci) at groups R2-R5 can be carried out using usual chemical reactions and synthesis methods known to a person skilled in the art.

General procedure for the derivatisation of Elansolids A ₁ or A ₂ :

Reactant (e.g. anthranilic acid) (10 mg) and 20 μl_ TEA were added to a solution of 20 mg of the raw fermentation extract in 5 ml_ of ethanol. The reaction mixture was stirred overnight at room temperature. The solvent was removed with nitrogen gas, ethyl acetate (4 ml_) was added, and the solution was washed with phosphate-buffer at pH 7. The aqueous layer was extracted twice with ethyl acetate, additionally. The combined organic layer was extracted with water and the organic solvent was evaporated under reduced pressure. The oily residue was separated by RP HPLC [column: Nucleodur 250x21 mm 100 5 μm C18 (Macherey-Nagel), solvent A: water/acetonitrile 8/2 with 0,1 % acetic acid, solvent B: water/acetonitrile 6/4 with 0,1% acetic acid, gradient from 100% A to 100% B in 60 min, 60 min.100% B; flow rate: 20 mL/min; UV detection at 254 nm]. After evaporation of the Elansolid fraction the remaining water was freeze-dried.

Table 6: Chemical structures of Elansolid derivatives:

Table 7: Yields and retention times of Elansolid derivatives in analytical RP HPLC

Analytical HPLC: column 125x2 mm, Nucleodur 100 5 μm C18 (Macherey-Nagel); flow rate 0.3 ml/min; UV detection; solvent gradient 10% B in 10 min to 100% B, solvent A: 5/95 acetonitrile/water + 5 mM NH ₄ OAc pH 5.5, solvent B: 95/5 acetonitrile/water + 5 mM NH ₄ OAc pH 5.5.

Table 8: Chemical data of Elansolid derivatives:

The ¹ H and ¹³ C NMR spectra are shown in Figures 4 to 45.

Characterization of the antibiotic activity of Elansolids:

The determination of minimum inhibitory concentrations was performed as described in J. Antimicrob. Chemother. 2001 ;48 Suppl 1 :5-16.

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Antibiotic activity of Elansolid A ₂ :

Elansolid d: Antibiotic spectrum against gram positive bacteria

Elansolid Ci exhibits a bactericidal activity against selected gram-positive bacteria. The minimal inhibition concentration (MIC) is 0.4 μg/ml against Micrococcus luteus and 1.7 μg/ml against a clinical isolate of a multiresistant S. aureus (MRS3).