Isatin (2,3-Indolinedione) is an endogenous MAO inhibitor.

Hydralazine hydrochloride (Apresoline) is the hydrochloride salt of hydralazine, a phthalazine derivative with antihypertensive and potential antineoplastic activities. Hydralazine alters intracellular calcium release and interferes with smooth muscle cell calcium influx, resulting in arterial vasodilatation. This agent also inhibits the phosphorylation of myosin protein and chelation of trace metals required for smooth muscle contraction, resulting in an increase in heart rate, stroke volume, and cardiac output. In addition to its cardiovascular effects, hydralazine inhibits DNA methyltransferase, which may result in inhibition of DNA methylation in tumor cells.

Furazolidone (Furoxone), a nitrofuran derivative, inhibits AML1-ETO transformed cells with IC50 value of 12.7 μM. It is antibacterial and antiprotozoal activity,

1,4-Naphthoquinone (P-Naphthoquinone) was used as a potential inhibitor of monoamine oxidase and DNA topoisomerase activities[2]. It was also used to inhibit the acetyltransferase activity[1].

Allylthiourea (Thiosinamine), a metabolic inhibitor, specifically suppresses ammonia oxidation.

Linezolid (PNU-100766), the first of the oxazolidinone class, is a synthetic antibiotic used for the therapy of infections resulted from multi-resistant bacteria including methicillin-resistant Staphylococcus aureus (MRSA) and streptococcus. The drug takes effect as the inhibitor of the initiation of bacterial protein synthesis.

Rosmarinic acid (Labiatenic acid) is widely found in plants and has antioxidant, anti-inflammatory, and antibacterial activities. It inhibits MAO-A, MAO-B, and COMT with IC50 of 50.1, 184.6, and 26.7 μM respectively.

Harmine (Telepathine) is an alkaloid isolated from seeds of Peganum harmala.