Journal of Antimicrobial Chemotherapy (1992) 30, Suppl. A, 1-8
Antimicrobial activity against Staphylococcus aureus of semisyntbetic injectable streptogramins: RP 59500 and related compounds
'Rhdne-Poulenc Rorer, Centre de Recherche de Vitry-Alfortville, 13 Quai Jules Guesde-BP 14, 94403 Vitry sur Seine. France and *Rhdne-Poulenc Rorer, Dagenham Research Centre, Rainham Road South, Dagenham, Essex RM10 7XS, UK Pristinamycin displays unique antibacterial properties due to the synergy between its two components, pristinamycin I and pristinamycin II. Because this antibiotic is not water-soluble, its administration is restricted to the oral route, and its therapeutic potential is thereby limited. Novel water-soluble derivatives of the naturally-occurring antibiotic pristinamycin were obtained by modifications of its two major components. The modifications included regioselective and stercoselective substitution a to the carbonyl group in the 4-oxo-pipecolic acid residue of pristinamycin IA (PIA) and stereoselective conjugate addition to the double bond of the dehydroproline ring in pristinamycin IIA (PIIA). We report here the in-vitro and in-vivo activities of some representative water-soluble derivatives of pristinamycin IA and pristinamycin IIA against Staphylococcus aureus reference strains, sensitive or resistant to mcthknUin and/or macrolides.
Introduction
Pristinamycin is a naturally-occurring streptogramin antibiotic isolated from Streptomyces pristinaespiralis (Mancy, Ninet & Preud'homme, 1961; Preud'homme, Tarridec & Belloc, 1968). The two major components of this drug are pristinamycin IA (24-38%), a peptidic macrolactone belonging to the group B streptogramins, and pristinamycin IIA (54-68%), a polyunsaturated macrolactone belonging to the group A streptogramins (Figure l(a)). The drug is active against most major Gram-positive and some Gram-negative bacteria. It has been used in Europe for over 25 years in general practice for the treatment of staphylococcal infections, without any increase in the incidence of resistant strains (Mutton & Andrew 1983). Individually, pristinamycin I and pristinamycin II are bacteristatic, whereas in association they are bactericidal (Videau, 1982). The synergic relationship between the two components also extends considerably the spectrum of biological activity; the mixture is active against more than 96% of Staphylococcus aureus strains tested so far, including those strains resistant to commonly used antibiotics, such as methicillin or erythromycin. This synergy is also reflected in an increased potency, both in vitro, where the activity of the mixture is tenfold higher than that of the sum of the individual components, and in vivo, for the treatment of staphylococcal infections in animal models. Optimum synergy is achieved when the ratios of PIA and PIIA are between 1:9 and 9:1. 1
0305-7453/92/30AOOI +08 J03.00/0
© 1992 Tlw British Society for Antimicrobial Chemotherapy
Downloaded from http://jac.oxfordjournals.org/ at University of California, San Francisco on December 11, 2014
J. C. Barriere*, D. H. Bouanchaod*, J. M. Paris', O. RoUn', N. V. Harris6 and C. Smith*
J. C Barrfee et al
pristinamycin lit (o)
5Spotition
(c)
(b)
26 poiition
(a )
RP54476
Fignre. Structural formulae of RP 59500 and related compounds: (a) Pristinamycin IA and pristinainycin II A ; (b) 5*-amino and 5*-thiomethykne pristinamycin IA;(c) S^-thiomethyl pristinamycin IA; (d) 26-thio, 26-iulphinyI and 26-sulphonyl pristinamycin 11^ (e) the components of RP 59500.
Downloaded from http://jac.oxfordjournals.org/ at University of California, San Francisco on December 11, 2014
priitinamycin \k
Scxnbyntbetic streptogramim
3
Materials and methods Synergy The fractional inhibitory concentration (FTC) index was determined by chequerboard dilution in microtitre plates, and was calculated as described by Krogstad & Moellering (1986). Microorganisms The strains used were: S. aureus IP 8203 or S. aureus Smith, sensitive to both erythromycin and spiramycin; S. aureus Fau, resistant to erythromycin and sensitive to spiramycin and S. aureus Due, resistant to both erythromycin and spiramycin. MIC determinations The in-vitro activities were determined as described by Ericsson & Sherris (1971). MICs were determined by the following agar dilution method: two-fold dilutions of antibiotic in sterile distilled water were prepared from stock solutions and incorporated into agar media. Spots of about 104 cfu of each strain were applied to plates with a Denley Multipoint Inoculator. Inoculated plates were incubated at 35-37°C for 18 h. MICs were denned as the lowest concentration of antibiotic which completely inhibited growth. Determination of Effective Dose (ED) were calculated 7 days after infection as described by Miraglia (1976). Animals Mice (strain OF,; IFFA Credo, Les Oncins, France) weighing 20 ±2 g were used (six male and six female per group). Origin of water-soluble derivatives The water-soluble derivatives of pristinamycin IA and pristinamycin IIA examined so far have been described previously in patents (Corbet et al., 1983a, 19836, 1983c, 1984; Barriere, Cotrel & Paris, 1986; Barriere, Bastard & Paris, 1987a; Barriire et al., 19876;
Downloaded from http://jac.oxfordjournals.org/ at University of California, San Francisco on December 11, 2014
The incidence of antibiotic-resistant strains of S. aureus in hospitals, in particular strains exhibiting multiple resistance to the commonly used antibiotics, has risen during the last IS years, and continues to be a problem. Despite the excellent properties of pristinamycin, its therapeutic use has been limited. Technical difficulties are encountered when it is assayed in blood. More important, the very poor water solubility of the components has restricted its use to cases where oral administration is possible. The treatment of most hospitalized patients is thus excluded, since for intravenous administration, drugs must be in a water-soluble form. Therefore, we initiated a programme to synthesise novel water-soluble derivatives of pristinamycin I and pristinamycin II that retained all the biological properties of the natural components (Paris et al., 1990). A suitable synergic mixture could then be selected for clinical trials to assess its potential for the treatment of 5. aureus infections in hospitals.
4
J. C Barrier* et aL
Chatterjee et al., 1988). Pristinamycin IA derivatives have been partially described in the current literature (Paris et al., 1985). The strategy and general methodology for the preparation of these and other derivatives will be discussed in a forthcoming publication. Results Pristinamycin IA water-soluble derivatives
Pristinamycin II water-soluble derivatives Semi-synthetic derivatives of pristinamycin IIA, substituted with an amino-containing function at the 26-position, were soluble in water in the form of their corresponding Table
L
Comparative activity against S. aureus of some representative 5£-aminomethylene and thiomethylene pristinamycin I derivatives
Compound (R) xio T> J CD -NR.RjandSR
Alone ^
In-vitro activity (MIC mg/L) Assocation with PIIA £ry, Efy. £ry, gyncrgy
8
30
1
0-5
+
15
60
1
2
+
4
15
1
2
+
-S-tCHjJj-NlCH,),
4
8
025
0-5
+
-S-tCH^-N
1
2
0-12
0-25
+
4
15
0-25
0-5
+
2-4
8
0-12
025
+
—NH—(CHj)2—N(CH,)i -NH-(CHt)t-N -HH—/
-S—/
PI
N-CH,
N—CHj
N-CH,
N —CH,
Ery*, Erythroniyciii-«en*itive; Ery*, erythromycin-rcsistaiic
Downloaded from http://jac.oxfordjournals.org/ at University of California, San Francisco on December 11, 2014
The introduction of an amino-containing function at the 55-position, yielded products that were in the form of the corresponding acid salts soluble in water. More than 60 56-aaaao or 5 these compounds were more potent than natural pristinamycin in association with pristinamycin IA in vivo. MICs for the 26-sulphinyl and 26-sulphonyl derivatives were similar to those of pristinamycin IIA. When administered orally to mice, these compounds were more potent than pristinamycin IIA. The synergy resulting from their association with pristinamycin I was markedly greater than that observed with natural pristinamycin. Discussion Pristinamycin IA derivatives
The in-vitro antibacterial activity of the 5£-aminomethylene derivatives against both erythromycin-resistant and erythromycin-sensitive S. aureus was lower than that of pristinamycin IA. In contrast, the in-vitro activity of the 55-thiomethylene derivatives was of the same order of magnitude as that of pristinamycin IA. Both series of compounds showed synergy with pristinamycin IIA. The 55-thiomethyl pristinamycin IA derivatives were, in general, more active than either the 5£-aminomethylene or the 5
Antimicrobial activity against Staphylococcus aureus of semisyntbetic injectable streptogramins: RP 59500 and related compounds
'Rhdne-Poulenc Rorer, Centre de Recherche de Vitry-Alfortville, 13 Quai Jules Guesde-BP 14, 94403 Vitry sur Seine. France and *Rhdne-Poulenc Rorer, Dagenham Research Centre, Rainham Road South, Dagenham, Essex RM10 7XS, UK Pristinamycin displays unique antibacterial properties due to the synergy between its two components, pristinamycin I and pristinamycin II. Because this antibiotic is not water-soluble, its administration is restricted to the oral route, and its therapeutic potential is thereby limited. Novel water-soluble derivatives of the naturally-occurring antibiotic pristinamycin were obtained by modifications of its two major components. The modifications included regioselective and stercoselective substitution a to the carbonyl group in the 4-oxo-pipecolic acid residue of pristinamycin IA (PIA) and stereoselective conjugate addition to the double bond of the dehydroproline ring in pristinamycin IIA (PIIA). We report here the in-vitro and in-vivo activities of some representative water-soluble derivatives of pristinamycin IA and pristinamycin IIA against Staphylococcus aureus reference strains, sensitive or resistant to mcthknUin and/or macrolides.
Introduction
Pristinamycin is a naturally-occurring streptogramin antibiotic isolated from Streptomyces pristinaespiralis (Mancy, Ninet & Preud'homme, 1961; Preud'homme, Tarridec & Belloc, 1968). The two major components of this drug are pristinamycin IA (24-38%), a peptidic macrolactone belonging to the group B streptogramins, and pristinamycin IIA (54-68%), a polyunsaturated macrolactone belonging to the group A streptogramins (Figure l(a)). The drug is active against most major Gram-positive and some Gram-negative bacteria. It has been used in Europe for over 25 years in general practice for the treatment of staphylococcal infections, without any increase in the incidence of resistant strains (Mutton & Andrew 1983). Individually, pristinamycin I and pristinamycin II are bacteristatic, whereas in association they are bactericidal (Videau, 1982). The synergic relationship between the two components also extends considerably the spectrum of biological activity; the mixture is active against more than 96% of Staphylococcus aureus strains tested so far, including those strains resistant to commonly used antibiotics, such as methicillin or erythromycin. This synergy is also reflected in an increased potency, both in vitro, where the activity of the mixture is tenfold higher than that of the sum of the individual components, and in vivo, for the treatment of staphylococcal infections in animal models. Optimum synergy is achieved when the ratios of PIA and PIIA are between 1:9 and 9:1. 1
0305-7453/92/30AOOI +08 J03.00/0
© 1992 Tlw British Society for Antimicrobial Chemotherapy
Downloaded from http://jac.oxfordjournals.org/ at University of California, San Francisco on December 11, 2014
J. C. Barriere*, D. H. Bouanchaod*, J. M. Paris', O. RoUn', N. V. Harris6 and C. Smith*
J. C Barrfee et al
pristinamycin lit (o)
5Spotition
(c)
(b)
26 poiition
(a )
RP54476
Fignre. Structural formulae of RP 59500 and related compounds: (a) Pristinamycin IA and pristinainycin II A ; (b) 5*-amino and 5*-thiomethykne pristinamycin IA;(c) S^-thiomethyl pristinamycin IA; (d) 26-thio, 26-iulphinyI and 26-sulphonyl pristinamycin 11^ (e) the components of RP 59500.
Downloaded from http://jac.oxfordjournals.org/ at University of California, San Francisco on December 11, 2014
priitinamycin \k
Scxnbyntbetic streptogramim
3
Materials and methods Synergy The fractional inhibitory concentration (FTC) index was determined by chequerboard dilution in microtitre plates, and was calculated as described by Krogstad & Moellering (1986). Microorganisms The strains used were: S. aureus IP 8203 or S. aureus Smith, sensitive to both erythromycin and spiramycin; S. aureus Fau, resistant to erythromycin and sensitive to spiramycin and S. aureus Due, resistant to both erythromycin and spiramycin. MIC determinations The in-vitro activities were determined as described by Ericsson & Sherris (1971). MICs were determined by the following agar dilution method: two-fold dilutions of antibiotic in sterile distilled water were prepared from stock solutions and incorporated into agar media. Spots of about 104 cfu of each strain were applied to plates with a Denley Multipoint Inoculator. Inoculated plates were incubated at 35-37°C for 18 h. MICs were denned as the lowest concentration of antibiotic which completely inhibited growth. Determination of Effective Dose (ED) were calculated 7 days after infection as described by Miraglia (1976). Animals Mice (strain OF,; IFFA Credo, Les Oncins, France) weighing 20 ±2 g were used (six male and six female per group). Origin of water-soluble derivatives The water-soluble derivatives of pristinamycin IA and pristinamycin IIA examined so far have been described previously in patents (Corbet et al., 1983a, 19836, 1983c, 1984; Barriere, Cotrel & Paris, 1986; Barriere, Bastard & Paris, 1987a; Barriire et al., 19876;
Downloaded from http://jac.oxfordjournals.org/ at University of California, San Francisco on December 11, 2014
The incidence of antibiotic-resistant strains of S. aureus in hospitals, in particular strains exhibiting multiple resistance to the commonly used antibiotics, has risen during the last IS years, and continues to be a problem. Despite the excellent properties of pristinamycin, its therapeutic use has been limited. Technical difficulties are encountered when it is assayed in blood. More important, the very poor water solubility of the components has restricted its use to cases where oral administration is possible. The treatment of most hospitalized patients is thus excluded, since for intravenous administration, drugs must be in a water-soluble form. Therefore, we initiated a programme to synthesise novel water-soluble derivatives of pristinamycin I and pristinamycin II that retained all the biological properties of the natural components (Paris et al., 1990). A suitable synergic mixture could then be selected for clinical trials to assess its potential for the treatment of 5. aureus infections in hospitals.
4
J. C Barrier* et aL
Chatterjee et al., 1988). Pristinamycin IA derivatives have been partially described in the current literature (Paris et al., 1985). The strategy and general methodology for the preparation of these and other derivatives will be discussed in a forthcoming publication. Results Pristinamycin IA water-soluble derivatives
Pristinamycin II water-soluble derivatives Semi-synthetic derivatives of pristinamycin IIA, substituted with an amino-containing function at the 26-position, were soluble in water in the form of their corresponding Table
L
Comparative activity against S. aureus of some representative 5£-aminomethylene and thiomethylene pristinamycin I derivatives
Compound (R) xio T> J CD -NR.RjandSR
Alone ^
In-vitro activity (MIC mg/L) Assocation with PIIA £ry, Efy. £ry, gyncrgy
8
30
1
0-5
+
15
60
1
2
+
4
15
1
2
+
-S-tCHjJj-NlCH,),
4
8
025
0-5
+
-S-tCH^-N
1
2
0-12
0-25
+
4
15
0-25
0-5
+
2-4
8
0-12
025
+
—NH—(CHj)2—N(CH,)i -NH-(CHt)t-N -HH—/
-S—/
PI
N-CH,
N—CHj
N-CH,
N —CH,
Ery*, Erythroniyciii-«en*itive; Ery*, erythromycin-rcsistaiic
Downloaded from http://jac.oxfordjournals.org/ at University of California, San Francisco on December 11, 2014
The introduction of an amino-containing function at the 55-position, yielded products that were in the form of the corresponding acid salts soluble in water. More than 60 56-aaaao or 5 these compounds were more potent than natural pristinamycin in association with pristinamycin IA in vivo. MICs for the 26-sulphinyl and 26-sulphonyl derivatives were similar to those of pristinamycin IIA. When administered orally to mice, these compounds were more potent than pristinamycin IIA. The synergy resulting from their association with pristinamycin I was markedly greater than that observed with natural pristinamycin. Discussion Pristinamycin IA derivatives
The in-vitro antibacterial activity of the 5£-aminomethylene derivatives against both erythromycin-resistant and erythromycin-sensitive S. aureus was lower than that of pristinamycin IA. In contrast, the in-vitro activity of the 55-thiomethylene derivatives was of the same order of magnitude as that of pristinamycin IA. Both series of compounds showed synergy with pristinamycin IIA. The 55-thiomethyl pristinamycin IA derivatives were, in general, more active than either the 5£-aminomethylene or the 5
