L-Tenuazonic Acid, a New Inhibitor of Paenibacillus Larvae

Abstract

A search for bioactive compounds, inhibitors of Paenibacillus larvae, the causal agent of American foulbrood, a honeybees' disease, was carried on. Extracts of two fungal strains, Alternaria brassicicola and Alternaria raphani, isolated from pollen collected from beehives, exhibited a specific inhibitory activity against this bacterium. From these extracts and by means of chromatographic steps and bioassay-guided fractionation, three tetramic acids were isolated. The compounds were identified by spectroscopic methods and the absolute stereochemistry was chemically determined. L-Tenuazonic acid was shown to be responsible for the antibiotic activity. This compound showed a MIC of 32 lg/ml, comparable with that of oxytetracycline, an antibiotic currently used for the prevention of American foulbrood.q Dedicated to the memory of Dra Alicia M. Seldes.

An Antifungal Tetrapeptide from the Culture of Penicillium canescens

“…Previously unexplored environments have their own ecosphere, interactions, and evolution that might contain new producer organisms. Environments such as the open sea and marine sediment, and even extreme environments such as hot springs, demonstrate that the diversity of microorganisms is far greater than anticipated, and a growing number of new natural products are being isolated from them [1].In this context, fungal strains in pollen from beehives were investigated for antimicrobial metabolites [2] [3]. In this study, we describe the isolation and identification of bioactive metabolites, including a previously undescribed tetrapeptide together with other compounds, from a strain of Penicillium canescens whose organic extract showed antimicrobial activity.…”

1H,1′H-[3,3′]biindolyl from the terrestrial fungus Gliocladium catenulatum

“…The P. larvae strain C, used in this study, was isolated from beehives at the province of Buenos Aires, Argentina, and classified and maintained at the Laboratorio de bacteriología, Departamento de Producciió n Animal, INTA, EEA Balcarce, Argentina. 10 An inoculum density of 10 8 bacteria per ml was used. The incubations were carried out at 37 1C in 10% CO 2 .…”

Synthesis, characterization, and biological activities of novel (Z)‐3‐((E)‐1‐(alkyloxyimino)ethyl)‐5‐arylidene‐4‐hydroxypyrroline‐2‐one derivatives

“…An important representative of the tetramic acids is tenuazonic acid, which is a metabolite produced by some phytopathogenic fungi [7]. Since its isolation in 1957 from the culture filtrates of Alternaria tenuis [8], it has been found possessing antitumor, antiviral, antibacterial, and herbicidal activities [9][10][11][12]. Reutericyclin [13] is a typical 1,3-bisacyltetramic acid that is extracted from cells and culture filtrates of Lactobacillus reuteri and found to inhibit the growth of Salmonella and Helicobacter, the latter being the causative agent of stomach ulcers.…”