Cyclo(L-Phe-L-Pro) shows antifungal and broad spectrum antibacterial activities, it exhibits activity against methicillin-resistant S. aureus ATCC 43300 and Enterococcus raffinosus, with low toxicity against human hepatoma HepaRG cells.

We have isolated a Lactobacillus plantarum strain (MiLAB 393) from grass silage that produces broad-spectrum antifungal compounds, active against food- and feed-borne filamentous fungi and yeasts in a dual-culture agar plate assay. METHODS AND RESULTS: Fusarium sporotrichioides and Aspergillus fumigatus were the most sensitive among the molds, and Kluyveromyces marxianus was the most sensitive yeast species. No inhibitory activity could be detected against the mold Penicillium roqueforti or the yeast Zygosaccharomyces bailii. An isolation procedure, employing a microtiter well spore germination bioassay, was devised to isolate active compounds from culture filtrate. Cell-free supernatant was fractionated on a C(18) SPE column, and the 95% aqueous acetonitrile fraction was further separated on a preparative HPLC C(18) column. Fractions active in the bioassay were then fractionated on a porous graphitic carbon column. The structures of the antifungal compounds Cyclo(L-Phe-L-Pro), cyclo(L-Phe-trans-4-OH-L-Pro) and 3-phenyllactic acid (L/D isomer ratio, 9:1), were determined by nuclear magnetic resonance spectroscopy, mass spectrometry, and gas chromatography. MIC values against A. fumigatus and P. roqueforti were 20 mg ml(-1) for Cyclo(L-Phe-L-Pro) and 7.5 mg ml(-1) for phenyllactic acid. CONCLUSIONS: Combinations of the antifungal compounds revealed weak synergistic effects. The production of the antifungal cyclic dipeptides Cyclo(L-Phe-L-Pro) and cyclo(L-Phe-trans-4-OH-L-Pro) by lactic acid bacteria is reported here for the first time.

3705-26-8

C14H16N2O2

244.29

(< 1 mg/ml refers to the product slightly soluble or insoluble )
Powder: -20°C for 3 years
In solvent: -80°C for 2 years