Ascopyrone P, a novel antibacterial derived from fungi

Abstract

Aims: To assess the antimicrobial efficacy of ascopyrone P (APP), a secondary metabolite formed by the fungi Anthracobia melaloma, Plicaria anthracina, Plic. leiocarpa and Peziza petersi belonging to the order Pezizales. Methods and Results:In vitro testing using a well diffusion procedure showed that APP at a high concentration (approximately 5%) inhibited the growth of Gram‐positive and Gram‐negative bacteria. Using an automated microbiology reader, growth curve analysis showed that 2000–4000 mg l−1 APP caused total or significant bacterial inhibition after incubation for 24 h at 30°C. Against certain yeast strains, 1000– 2000 mg l−1 APP enhanced growth, although at higher concentrations inhibition of some yeasts was observed. Clostridium and fungal strains were not sensitive to 2000 mg l−1 APP. No significant cidal effect was observed after 2 h against Listeria monocytogenes or Escherichia coli. Results were identical whether the APP samples tested had been produced enzymatically or chemically. Conclusions: At a level of 2000 mg l−1, APP demonstrated growth inhibitory activity against a broad range of bacteria, but not yeasts or moulds. Significance and Impact of the Study: A possible application for this novel natural antimicrobial is in food preservation, to control the growth of Gram‐negative and Gram‐positive bacteria in raw and cooked foods. Effective dosage levels would be 500–4000 mg kg−1, depending on food type. The efficacy, organoleptic and safety aspects of this compound in food still need to be assessed.

Inhibition spectrum studies of microthecin and other anhydrofructose derivatives using selected strains of Gram-positive and -negative bacteria, yeasts and moulds, and investigation of the cytotoxicity of microthecin to malignant blood cell lines

“…2005). The AF derivative ascopyrone P has been shown to have both antimicrobial activities and antioxidantal activities (Thomas et al. 2002; Thomas et al.…”

“…Inhibition spectrum testing of microthecin and AF derivatives on microbial growth was performed using a Bioscreen growth analyser as described before (Thomas et al. 2002; Thomas et al.…”

“…2008). After managing to produce sufficient quantities of these compounds, ascopyrone P was investigated for its antioxidant and antimicrobial activities in our laboratory (Thomas et al. 2002; Thomas et al.…”

A new chemical synthesis of Ascopyrone P from 1,5-anhydro-d-fructose

“…Likewise, an enzymatic preparation of APP from starch has recently been patented. 10 In view of the interesting properties of APP and the lack of efficient synthetic procedures for its preparation, we undertook the investigation of synthesis of APP from 1,5-anhydro-D D-fructose (3). This rare sugar is formed by degradation of starch by a-1,4-glucan lyase (EC 4.2.1.13) 11, 12 and can now be produced enzymatically from starch 13 but has not lead to AF as a commercial product.…”

“…The reaction conditions were optimised to quench the mixture even if some starting material still was left. The driving force for the rearrangement is formation of a more stable conjugate system in 6 (-C 3 …”