[Isolation and identification of antibiotics produced by Actinoplanes brasiliensis INA 3802]. / Vydelenie i identifikatsiia antibiotikov, produtsiruemykh shtammom Actinoplanes brasiliensis INA 3802.

In the screening programme for new antibiotics produced by Actinoplanes brasiliensis an antibiotic complex A-3802 was isolated and studied in detail. It had a marked therapeutic effect in the treatment of staphylococcal sepsis in albino mice and was low toxic. Two components of the complex i.e. A-3802-IV-3 and A-3802-IV-4 were identified with the lantibiotics actagardin and its diamide disulfoxide. Antibiotics A-3802-V-4 and A-3802-VI-7 were shown to be new antibiotics of the same group.

[Effect of carbohydrate components of ristomycin A on platelet aggregation in human plasma]. / Vliianie uglevodnogo sostava ristomitsina A na agregatsiiu trombotsitov plazmy krovi cheloveka.

In the process of the investigation, conditions for specific removal of arabinose in tetrasaccharide of ristomycin A, a glycopeptide antibiotic as well as conditions for simultaneous removal of arabinose and mannose-2 bound to actinoidinic acid were determined. The role of arabinose in manifestation of the ristomycin A ability to induce platelet aggregation was shown to be important. Mannose-2 also had the same ability while its level was somewhat lower.

[Chemical modification of ristomycin A with bifunctional reagents]. / Khimicheskaia modifikatsiia ristomitsina A bifunktsional'nymi reagentami.

Various bifunctional reagents by the free NH2 group of ristomycinic acid of ristomycin A were used for selective chemical modification of the antibiotic. The bifunctional reagents were the following: di-N-hydroxysuccinimide ether of suberic acid and 4,4'-difluoro-3,3'-dinitrodiphenylsulfone. Bis-N,N'-derivatives of ristomycin A were prepared using these reagents. The derivatives inhibited the growth of Bac. subtilis but the concentrations required for the inhibition were 2-4 times higher than those of ristomycin A. It was noted that the MIC of the bis-N,N'-derivatives depended on the length and flexibility of the "binding foot". The MIC of the bis-N,N'-derivative prepared with using suberic acid was 2 times higher than that of the derivative prepared with the use of 4,4'-difluoro-3,3'-dinitrodiphenylsulfone.

[Biospecific analytical chromatography of glycopeptide antibiotics of the vancomycin group]. / Analiticheskaia biospetsificheskaia khromatografiia antibiotikov-glikopeptidov vankomitsinovoi gruppy.

An affinity sorbent was synthesized on the basis of aminoethyl cellulose and dipeptide of the D-Ala-D-Ala-OH fragment of growing peptidoglycan of the bacterial cell wall. It was shown that the sorbent had highly selective affinity to antibiotics of the vancomycin group and their biologically active derivatives and provided their biospecific chromatography.

[Selective modification of the free amino groups of the antibiotic ristomycin A]. / Izbiratel'naia modifikatsiia svobodnykh aminogrupp antibiotika ristomitsina A.

Selective chemical modification of ristomycin A (I) by the free NH2 groups was performed. 6 different N-acyl and N-aminoacyl derivatives of I were obtained. 5 of them showed antibacterial activity within 0.4-10.0 micrograms/ml against 4 test microbes. The biological activity of the derivatives depended on the substituent type and the molecule total charge: mono-N-L-isoleucyl-I with the charge of +2 had the highest activity and N,N'-disuccinyl-I had the lowest activity.

[Retroaldol cleavage of the glyopeptide antibiotic ristomycin A during alkaline inactivation]. / O retroal'dol'nom rasshcheplenii antibiotika-glikopeptida ristomitsina A v khode shchelochnoi inaktivatsii.

The chemical and physicochemical characteristics of one of the two inactive components, i.e. the reduced product of alkaline inactivation (PAH-II) of ristomycin. A were studied. The components formed on the antibiotic incubation in mild alkaline media: 0.05 M NaOH, 37 degrees C, 1.5-2 hours. It was shown that the retroaldol cleavage of the C alpha-C beta bond of the phenol serine fragment of the trinuclear dideschlorvancomycinic acid G at the aglycone N-end was one of the causes of ristomycin A rapid inactivation under such conditions.

[Isolation and study of the antibiotics produced by a culture of Str. iverini (Gause et al., 1957) Pridham et al., 1958]. / Vydelenie i izuchenie antibiotikov, produtsiruemykh kul'turoi Str. iverini (Gause et al., 1957) Pridham et al., 1958.

An antibiotic complex consisting of echinomycin and triostin A was isolated from Str. iverini (Gauze et al., 1957) Pridham et al., 1958. Hydrolysis of the antibiotics resulted in formation of an aglycone identified with quinoxaline carboxylic acid. The UV spectrum of the aglycone and the antibiotics of the echinomycin-triostin group was studied.

[New amino acid from the antibiotic, ristomycin A]. / Novaia aminokislota iz antibiotika ristomitsina A.

A new amino acid E was isolated from a mixture of the products of the reductive hydrolysis of ristomycin A 57% HJ in the presence of red phosphorus. Its characterization was performed. The new amino acid was formed as a result of reductive dehydration of the respective beta-oxyamino acid present in the native antibiotic and being completely destroyed during general acid or alkaline hydrolysis.

[Quantitative amino acid makeup and the characteristics of the amino groups of ristomycin and the products of its partial acid hydrolysis]. / Kolichestvennyi aminokislotnyi sostav i kharakteristika aminogrupp ristomitsina i produktov ego chastichnogo kislotnogo gidroliza.

The quantitative amino acid composition of ristomycin A, a glycopeptide antibiotic, peptides I-IV (from partial acid hydrolysis of the antibiotic) and their dinitrophenylic derivatives was determined. It was shown that both ristomycin and free peptides I-IV contained one residue of ristomycinic acid and one residue of actinoidinic acid, diamino-dicarbonic amino acids of the glycylphenolic type. Peptides I-IV had close molecular weights, i.e. 1100-1200 and differed from each other in the gradually increasing numbers of NH2- and COON- groups, from one in peptide I to four in peptide IV. The quantitative amino acid analysis of the dinitrophenylic derivatives of ristomycin and peptides I-IV showed that the free NH2-group in peptide I belonged to ristomycinic acid, the same as in the antibiotic, while in peptides III-IV at least one of the free NH2-groups belonged to ristomycinic acid and the other belonged to actinoidinic acid.