Avilamycin is an antibiotic complex produced by cultures of the organism Streptomyces viridochromogenes, strain NRRL 2860. These compounds belong to the orthosomycin family of antibiotics. Structural composition of the major avilamycins and several minor avilamycins are known. Nine additional minor avilamycins, designated F through N, have been isolated via semi-preparative silica gel or reverse-phase high performance liquid chromatography with final purification using a reverse-phase column loading solvent switching technique. 1H NMR and mass spectroscopy, negative ion fast atom bombardment (neg FAB) and electron impact, were used to structurally identify the avilamycins. All of the compounds were microbiologically active and similar in structure to other known avilamycins. Using classical degradation studies1, 2) avilamycin was shown to be a member of the orthosomycin family of antibiotics, (flambamycin3) and the everninomicins4)). Structural characterization of avilamycins A, B and C was first reported by WRIGHT5), in an addendum, and later published by KELLER-SCHIERLEIN6.7). The structures of four additional avilamycins D" D2, E and A' have recently been reported (personal communication, A. P. RAUN, Eli Lilly and Company with Ciba-Geigy, March, 1981). All of the above avilamycins are derivatives of A with changes at the C-45 linkage and/or the C-56 ketone adduct. The purpose of this study was to determine the structure of several additional minor components present in analytical standards of avilamycin and extracts of the fermentation product. Several unique modifications of avilamycin were found.

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Fourteen collaborating laboratories assayed maleic hydrazide (MH), 6-hydroxypyridazin-3(2H)-one, in technical and formulated products by reversed-phase liquid chromatography (LC) with sulfanilic acid as an internal standard. The active MH in the samples (6 lots) ranged from 16% (expressed as the potassium salt) to 98% (MH in the technical). A small amount of 1 M KOH was added to the technical MH and analytical standards to create the potassium salt of the analyte which is soluble in water. Test samples and standards were extracted with water containing the internal standard before analysis by LC on a C8 column with an ion-pairing eluting solution and UV detection at 254 nm. The concentration of MH was calculated by comparing the peak area response ratios of the analyte and the internal standard with those in the analytical standard solution. Eleven laboratories weighed each test sample twice with single analysis. Three laboratories weighed each sample once and made duplicate injections on the LC system. The data were analyzed using the 11 laboratories' results. A second data analysis was done including all laboratory results using a Youden pair approach, selecting one of 2 duplicate assay values randomly for each laboratory and sample. In the first data analysis, the repeatability standard deviation ranged from 0.07 to 1.39%; reproducibility standard deviation ranged from 0.22 to 1.39%. In the second data analysis (using all laboratory data), repeatability standard deviation ranged from 0.09 to 0.86%; reproducibility standard deviation ranged from 0.22 to 1.31%.

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