Maridomycin, a new macrolide antibiotic: in vivo antibacterial activity of 9-propionylmaridomycin

The in vivo protecting activity of 9-propionylmaridomycin, a derivative of the new macrolide antibiotic, maridomycin, was compared with that of other macrolide antibiotics in mice infected with Staphylococcus aureus, Streptococcus pyogenes, and Diplococcus pneumoniae. The protective effect was almost similar to that afforded by several known macrolide antibiotics in mice infected intraperitoneally with certain strains of the gram-positive species described above. The skin lesion caused by intradermal challenge of S. aureus in mice also responded very effectively to treatment with 9-propionylmaridomycin.

Chemical modification of maridomycin, a new macrolide antibiotic

Maridomycin, a new macrolide antibiotic, and tetrahydromaridomycin were acylated into their mono, di, and tri acyl derivatives. These derivatives were compared with the parent antibiotic, maridomycin, for their (i) in vitro antimicrobial activities, (ii) protective effect in mice infected with Staphylococcus aureus (oral administration), (iii) blood levels attained in rats, and (iv) acute toxicity in mice (intraperitoneal administration). All the derivatives showed either the same or less activity in vitro, but 9-acyl, 9, 2'-diacylmaridomycin and 9, 13, 2'-triacetyltetrahydromaridomycin demonstrated improved therapeutic effects together with higher blood levels and low toxicity. 9-Propionylmaridomycin showed the most favorable biological properties.

Maridomycin, a new macrolide antibiotic. In vitro antibacterial activity of 9-propionylmaridomycin

9-Propionylmaridomycin shows in vitro antibacterial activity against gram-positive bacteria and has some action on Neisseria gonorrhoeae and Vibrio cholerae, but is generally inactive against many gram-negative rods. This antibiotic exhibits strong activity against clinical isolates of Staphylococcus aureus which are highly resistant to erythromycin or oleandomycin, or both, but which are sensitive to josamycin and kitasamycin. Strains resistant to josamycin and kitasamycin were also found to be resistant to this antibiotic. A significant feature of 9-propionylmaridomycin is a lack in its ability to induce resistance induction in resistance-inducible strains of staphylococci to erythromycin. Several antibacterial features of 9-propionylmaridomycin such as the influence of medium pH, inoculum size, effect of addition of horse serum, development of resistance, cross resistance, and bacteriostatic activity were shown to be almost identical to those of josamycin and kitasamycin. The antibacterial activity of 9-propionylmaridomycin was stable in solutions at pH levels of 4, 7, and 9.

Fluid phase destruction of C2 hu by C1 hu. 3. Changes in activity for synthetic substrates upon cell binding, heat inactivation and interaction with C1INH

The enzymatic efficiency of C[unk]1^* for its natural substrates C4 and C2 or the synthetic substrates N-α-acetylglycyl-L-lysine methylester acetate (AGLMe), N-acetyl-L-arginine methylester (AAMe), p-tosyl-L-arginine methylester (TAMe) and N-acetyl-L-tyrosine methylester (ATMe) was found to be reduced by cell binding, most likely due to both steric and conformational effects. TAMe and AAMe competitively inhibited the effect of fluid phase or cell bound C[unk]1 on C4 or C2 examined separately, but the protection of C2 by synthetic substrates was largely reversed in the presence of C4. ATMe had no inhibitory effect on the enzymatic activity of fluid phase or cell bound C[unk]1 but did prevent the interaction between cell bound [unk]4[unk]2 and C3, and between [unk]4[unk]2[unk]3 and C5, C6 and C7.

The haemolytic inactivation of C[unk]1 by heat or C[unk]1INH was accompanied by loss of activity against C2, TAMe and ATMe without appreciably affecting its capacity to inactivate C4 or hydrolyse AAMe. It is suggested that the allosteric alteration of C[unk]1 induced by C4 so as to uncover its specificity for C2 and broaden its specificity for synthetic substrate esters, involves a heat labile C4 receptor which is possibly blocked by the C[unk]1INH.