A new cinnamoylphenethylamine derivative from a Mongolian Allium species, Allium carolinianum.

A new cinnamoylphenethylamine derivative, compound 1, was isolated as the main HPLC peak after partitioning the methanol extract of bulbs of a Mongolian onion species, Allium carolinianum DC. The chemical structure of this substance was determined by spectroscopic analysis including MS, and 1D and 2D NMR. Compound 1 showed weak cytotoxic activity in the murine leukemia cell line P388.

[Antimicrobial activity of fosfomycin against beta-lactamase-producing methicillin-sensitive Staphylococcus aureus and methicillin-sensitive coagulase-negative staphylococci].

Antimicrobial activity of fosfomycin (FOM), cefazolin (CEZ), cefmetazole (CMZ), cefotiam (CTM) and piperacillin (PIPC) against clinical isolates of methicillin-sensitive Staphylococcus aureus (MSSA) (beta-lactamase-producing or non-producing) and methicillin-sensitive coagulase-negative Staphylococci (MSCNS) (beta-lactamase-producing or non-producing) were determined to make clear the differences in antimicrobial activity of FOM and beta-lactam antibiotics. The antimicrobial activity of PIPC against beta-lactamase-producing strains of MSSA was lower than that against non-producing ones, judging from the distribution patterns of susceptibility of the strains to PIPC. There were no differences in the antimicrobial activity of FOM, CEZ and CMZ for the producing and non-producing strains. The activity of FOM against MSCNS was comparable to that against MSSA, although those of CEZ, CMZ, CTM and PIPC were decreased. FOM, CEZ, CMZ and CTM showed bactericidal activity against TH4278 (MIC [microgram/ml]: FOM, 1; CEZ, 0.5; CMZ, 1; CTM, 0.5; PIPC, 1) of beta-lactamase-producing MSSA at 1 microgram/ml for 6 h, but PIPC did not at the same condition. FOM and CMZ at MIC suppressed regrowth of the strain, but CEZ, CTM and PIPC did not. In conclusion, FOM, which is not affected by beta-lactamase, demonstrated strong bactericidal activity at low concentration against the beta-lactam-resistant strains due to beta-lactamase production.

[Activity of fosfomycin against Escherichia coli O157:H7--morphological changes and production of Shiga toxins].

We examined the effects of fosfomycin (FOM), norfloxacin (NFLX), kanamycin (KM), chloramphenicol (CP), and ampicillin (ABPC) on the morphology of E. coli O157:H7, and the accumulation (cell fraction) and release (medium fraction) of Shiga toxins (Stxs: Stx1 and Stx2) in E. coli O157:H7 three hours after treatment with the antibiotics. For each drug, 16 MIC was used for measurement of the activity at a high drug concentration and 1/4 MIC at a low concentration. At 16 MIC, cell wall synthesis inhibitors, FOM and ABPC, strongly induced lysis of the cell of E. coli KU3342, a strain of E. coli O157:H7. The release of Stx1 was observed, but there was no accumulation of Stxs. Nucleic acid synthesis inhibitor NFLX and protein synthesis inhibitor KM induced partial lysis and short filamentation of the cell, and the accumulation and release of Stxs were low. No morphological change was observed after treatment with protein synthesis inhibitor CP, but the accumulation and release of Stxs by CP were low. At 1/4 MIC, FOM induced strong lysis of the cell, and the release of Stx1 was observed, but there was no accumulation of Stxs. ABPC and NFLX had weak lytic reaction, but induced filamentation of the cell, and the accumulation and release of Stxs were observed. In particular, NFLX significantly induced accumulation and release of Stx2. KM and CP had no effect on the morphology of the cells, and the accumulation of Stx1 was not observed, but there was no release of Stxs. The above-mentioned results support the clinical efficacy of FOM in the control of enterohoemorhagic E. coli infections.