The oxazolidinone antibacterial agent DuP 105 does not act on cell wall biosynthesis or on a beta-lactamase.

(S)-3-(4-Methylsulfinylphenyl)-5-(acetamidomethyl)oxazolidinone (DuP 105; 1, R = CH3SO, R' = Ac), one of a new class of antibacterial agents, is shown to be devoid of inactivation and inhibitory properties toward bacterial cell wall biosynthesis and toward a beta-lactamase. This is consistent with the idea that this class of compounds acts by a route different from that of the beta-lactam antibiotics.