Novel anthelmintic metabolites from an Aspergillus species; the aspergillimides.

Two members of a novel class of anthelmintics, the aspergillimides, have been isolated from the Aspergillus strain IMI 337664. This novel fungus also produced two known and one structurally novel paraherquamide. This paper describes the fermentation, isolation, structure elucidation and anthelmintic activity of aspergillimide (VM55598, 1), 16-keto aspergillimide (SB202327, 2), and the paraherquamides VM54159 (3), SB203105 (4) and SB200437 (5). The aspergillimides are equivalent to paraherquamides which have lost both the dioxygenated 7-membered ring and the phenyl ring to which this is fused; gaining in their place a C8-keto group. SB203105 is the first example of a 4-substituted paraherquamide.

Further novel metabolites of the paraherquamide family.

Four novel metabolites of a Penicillium strain, IMI 332995, which has previously been reported to produce paraherquamide and a number of related metabolites, are herein described. VM55596 is the first N-oxide to be found in this family of compounds. Unusual oxidative substitution is also seen in VM55597. VM55599 appears to be the first documented example of the hexacyclic indole species that have long been postulated as biosynthetic precursors of metabolites of the brevianamide, paraherquamide and marcfortine families.

A novel series of milbemycin antibiotics from Streptomyces strain E225. I. Discovery, fermentation and anthelmintic activity.

A novel series of milbemycin antibiotics were produced by soil isolate, strain E225 which was shown to be a Streptomyces species. The antibiotics displayed anthelmintic activity against Trichostrongylus colubriformis in the gerbil. Two of the compounds, VM 44857 and VM 44866 were shown to be potent anthelmintics against mixed nematode infections in sheep.

Antimycoplasmal activities of the pseudomonic acids and structure-activity relationships of monic acid A derivatives.

The antimycoplasmal activities of the pseudomonic acids isolated from Pseudomonas fluorescens NCIB 10586 are reported. Structure-activity relationships of a variety of ester, amide and thiol ester derivatives of the nucleus, monic acid A, are described. Enhanced antimycoplasmal activity is reported for a number of monic acid A esters and the most potent derivative, m-nitrobenzyl monate A, is a 100-fold more active against Mycoplasma hyopneumoniae than pseudomonic acid A.

Reproducible pneumonia in gnotobiotic piglets induced with broth cultures of Mycoplasma hyopneumoniae and the effect of animal passage on virulence.

The virulence of a laboratory adapted culture of Mycoplasma hyopneumoniae strain NB12 was determined in three- to five-day-old gnotobiotic piglets. Intranasal inoculation or exposure to an aerosol of the culture caused low incidences of pneumonia in the piglets. Passage of M hyopneumoniae strain NB12 in gnotobiotic piglets resulted in a rapid increase in virulence. After only three in vivo passages, severe pneumonia involving most lobes of the lung developed in all inoculated piglets within three and a half weeks. All 49 piglets inoculated with the piglet-passaged NB12 strain in nine subsequent experiments developed pneumonia but the extent of the pneumonic lesions varied considerably from piglet to piglet. The histopathology of the lung lesions was similar to that reported as being induced by other strains of M hyopneumoniae in gnotobiotic piglets and resembled that seen previously in conventionally reared neonatal piglets inoculated with homogenised lung from pigs with enzootic pneumonia. Aspiration pneumonia caused by milk inhalation occurred in some piglets. The pneumonia induced with the piglet-passaged NB12 strain was judged to be suitable for the study of porcine enzootic pneumonia or for the evaluation of chemotherapeutic agents.

Therapeutic significance of nocardicin A stimulation of phagocyte function in experimental Pseudomonas aeruginosa infection.

Nocardicin A, a monocyclic beta-lactam antibiotic with modest anti-pseudomonal activity in vitro, controlled an otherwise fatal Pseudomonas infection in mice when given in doses which produced blood levels well below the minimum bactericidal concentration. In even smaller doses, it converted the partial protection afforded by modest doses of carbenicillin into full protection. Human polymorphonuclear leucocytes exposed to low concentrations of the drug in vitro and peritoneal macrophages recovered from mice treated with nocardicin A exhibited an unusually specific form of enhanced activity. Chemotaxis and phagocytosis were not affected, but intracellular killing of Ps. aeruginosa was significantly increased. This was shown to be due to an effect on the phagocyte and not to facilitated killing of organisms damaged by extracellular exposure to the antibiotic. It is argued that the effect on phagocyte function is sufficient to contribute materially to the therapeutic effect of nocardicin A.