ent-Thiamphenicol (ent-Dextrosulphenidol) is a enantiomer of Thiamphenicol. Thiamphenicol , a methyl-sulfonyl derivative of Chloramphenicol, is a broad-spectrum antimicrobial antibiotic. Thiamphenicol acts by binding to the 50S ribosomal subunit, leading to inhibition of protein synthesis and bacteriostatic effect (against Gram-negative , Gram-positive aerobic and anaerobic bacteria ).