Benzylpenilloic acid is a metabolite of benzylpenicillin. It is produced by hydrolysis of when beta-lactam ring of benzylpenicillin. Along with some other metabolites of penicillin, benzylpenilloic acid is responsible for the allergic reaction to beta-lactam antibiotic. It is a component of a minor determinant mixture (MDM) reagent which is used to evaluate sensitivity to penicillin in the clinic.

Aphidicolin, a tetracyclic diterpenoid obtained from the culture filtrates of Cephalosporium aphidicola and other fungi, inhibits the growth of eukaryotic cells and of certain animal viruses (SV40, Herpes and Vaccinia viruses) by selectively inhibiting the cellular replicative DNA polymerase alpha or the viral-induced DNA polymerases. The arrest of cellular or viral growth is thus due to inhibition of cellular or viral replicative DNA synthesis without interference with mitochondrial DNA synthesis, RNA, protein and nucleic acid precursors synthesis or other major metabolic pathways. The inhibition of all sensitive eukaryotic DNA polymerases by aphidicolin is competitive with respect to dCTP. Aphidicolin has thus proved extremely useful in elucidating the functional role of DNA polymerase alpha in nuclear DNA replication, of DNA polymerase gamma in mitochondrial DNA synthesis and both DNA polymerases beta and alpha in DNA repair synthesis. An important laboratory application of aphidicolin is the synchronization of the cell cycle of eukaryotic cells both in culture and in vivo. The properties of aphidicolinhave recently aroused considerable interest for its possible exploitation in al practice. The mechanism of action of this drug suggests in fact that it may be useful for controlling excessive cell proliferation in patients with cancer, psoriasis or other dermatitis with little or no adverse effect upon non-multiplying cells.

SNX-2112, a novel 2-aminobenzamide inhibitor of heat shock protein 90 (Hsp90) was discovered by Serenex. This drug was investigated for treatment of different cancer cell lines, including hepatocellular carcinoma cells, breast cancer cells and in combination with 5-fluorouracil in esophageal cancer. However, subsequent development has been discontinued due to ocular toxicity as identified in a phase I study.

Plevitrexed is an orally bioavailable, small molecule, non-polyglutamatable, antifolate quinazoline derivative thymidine synthetase inhibitor with potential antineoplastic activity. This compound belongs to the class of organic compounds known as hippuric acids, which consist of a benzoyl group linked to the N-terminal of a glycine. Plevitrexed is transported into the cell via the physiological reduced folate carrier (RFC) system. Intracellularly, this agent selectively binds to the folate binding site of thymidylate synthase and inhibits thymidine synthesis, which may result in DNA synthesis inhibition and apoptosis. Plevitrexed has been investigated for use/treatment in pancreatic cancer, solid tumors, gastric cancer, lung cancer, and colorectal cancer.