Antimicrobial activity against gram-positive bacteria

A related antibiotic, chromoxymycin [186], isolated from S. rubropurpureus No. 6362, is active against P388 leukaemia and B16 melanoma and exhibits antimicrobial activity against Gram-positive bacteria. The structure of chromoxymycin is very close to that of hedamycin, except that the C-l2 quinone-carbonyl is reduced and attached to a 5-[(2-carboxyethyl)aminocarbonyl]-Ar-hydroxypyrrol-2-yl moiety, and that the iV V-dimethylvancosamine attached to C-10 is no longer in the boat conformation (as in hedamycin), but rather in the chair conformation. All the other substituents remain the same. 

Newly synthesized compounds 22, 23, 25c-e, 26d and 29e were screened in vitro for their antimicrobial activities against Gram positive bacteria Staphylococcus aureus (NCTC-7447), Bacillus cereus (ATCC-14579) and Gram negative bacteria Serratia marcesens (IMRU-70) and Proteus merabitis (NTCC-289) using the paper disk diffusion method for the antibiotic sensitivity technique [60]. The tested compounds were dissolved in N,N-dimclhylformamidc (DMF) to obtain a 1 mg/mL solution. The inhibition zones of microbial growth produced by different compounds were measured in millimeters at the end of an incubation period of 48 h at 28 °C. DMF alone showed no inhibition zone. 

Synthesis of l-aza-5-silabicyclo[5.2.0]nonan-9-one, a silylated bicyclic lactam 329 (Figure 20) which shows antimicrobial activity against Gram positive bacteria was also achieved <1995JOC8403>. 

Roseoflavin. Roseflavin [51093-55-1], C gH23N50g, (28), mol wt 405.41,mp 274-297 C, [ot]p = -320 (O.lMNaOH), was isolated from a culture medium of Streptomjces davamnsis as dark, reddish-brown fine needles (from ethanol) the 8-methyl group of riboflavin is substituted by a dimethylamino group. This stmcture was confirmed by the synthesis. Roseflavin shows antimicrobial activity against gram-positive bacteria (108). 

At the beginning, permethylated peptide libraries were derived by a post-modification of peptide libraries attached to the solid-phase support. The amide bond functionalities were alkylated using a solution of sodium hydride in dimethylsulfoxide, followed by addition of neat methyl iodide, therefore generating libraries from libraries . A peptide library that underwent this simple chemical transformation was used to identify compounds with potent antimicrobial activity against Gram-positive bacteria [21]. 

From the sponge I, variabilis was isolated variabilin (7a), a furanosesterterpene containing a tetronic acid moiety, which showed antimicrobial activity against Gram-positive bacteria Staphylococcus aureus [28] and Sarcina lutea [29]. 

Theoneberine (81) exhibited antimicrobial activity against Gram positive bacteria and cytotoxicity against murine L1210 and human Kb cells (IC50 2.9 and 10 [tg/ml, respectively). A class of novel bisabolene... 

Peptaibolin, Ac-Leu-Aib-Leu-Aib-Pheol, an unusual short-sequence representative of the peptaibols. It exhibits moderate antimicrobial activity against Gram-positive bacteria and yeasts. The total synthesis, 3-D structure, and membrane-modifying properties of peptaibolin and selected analogues were described in 2001 [H. Hulsmannetal.,... 

Vinylamycin, a 14-membered cyclodepsi-peptide ( depsipeptides) isolated from the culture broth of Streptomyces sp. (MI982-63F1). Vinylamycin consists of D-valine, alanine, 4-amino-2,4-pentadienoic acid, and 2-hydroxy-3-(2-hydroxyethyl)-4-methyldecanoic acid. It exhibits broad and moderate antimicrobial activities against Gram-positive bacteria [M. Igarashi et al., J. Antibiot. 1999, 52, 873]. 

There is a group of antibiotics that possess the pyrrolo[l,4]benzodiazepine skeleton and show antimicrobial activity against Gram-positive bacteria, along with antiviral, antiphage, and antitumor activities. Anthramycin and tomaymycin are typical alkaloids in this group. 

Rifamycin B is an ansamycin antibiotic produced by Streptomyces medi-terranei (subsequendy reclassified as Nocardia mediterranet) [1—4].This antibiotic shows antimicrobial activities against Gram-positive bacteria and acid-fast bacteria, and the toxicity for mammalian systems is low. Rifamycin... 

Compound exhibited moderate antimicrobial activity against gram-positive bacteria. 

Synthetic monoglycerides (102) with epimino fatty acids showed antimicrobial activity against Gram-positive bacteria and yeasts [121]. Laboratory preparations of 2-ethyl-i-oleoyl-aziridine (103) showed a wide spectrum of antifungal and antimicrobial activity [122]. 

More recently, Lee et al. have also employed this strategy for the construction of the B/Z-1,3-butadiene motif required for the synthesis of (—)-cochleamycin A using a biomimetic type transannular Diels-Alder reaction, (Figure 8.10) [38]. The enantiomer exhibits antimicrobial activity against Gram-positive bacteria and has modest cytotoxic activity. The unsymmetrical bis-alkoxyalkynylsilane 85 was prepared as a mixture of diastereoisomers at silicon by the addition of the secondary alcohol 84 to the bis-alkynylsiloxane 83 (Scheme 8.16). Although the... 

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