N‑Nitrosonornicotine (NNN) is a nitrosamine compound. It is produced by nitrosation of nicotine during the curing, aging, processing, and smoking of tobacco. About half of the NNN originates in the unburnt tobacco, whereas the remainder is formed during burning. NNN is reasonably anticipated to be a human carcinogen based on sufficient evidence of carcinogenicity from studies in experimental animals. NNN induces deleterious mutations in oncogenes and tumor suppression genes by forming DNA adducts, which could be considered as tumor initiation. Meanwhile, the binding of NNN to the nicotinic acetylcholine receptor promotes tumor growth by enhancing and deregulating cell proliferation, survival, migration, and invasion, thereby creating a microenvironment for tumor growth.

3-Indoleacrylic acid (IAA) is a natural auxin from lentil roots. 3-Indoleacrylic acid (IAA) induces transcription of genes under the control of the trpE promoter, including a family of proteins that contain nuclear localization signals. IAA also transcriptionally activates gene expression in plants. Trans-beta-Indoleacrylic acid (IAA) binds with moderately high affinity to the dimeric protein, trp aporepressor from Escherichia coli. 3-Indoleacrylic acid inhibits the growth of mycelia of Neurospora crassa and causes the cells to accumulate indoleglycerol phosphate.

Nile red (9-diethylamino-5H-benzo[alpha]phenoxazine-5-one) is an excellent vital stain for the detection of intracellular lipid droplets by fluorescence microscopy and flow cytofluorometry. It has environment-sensitive fluorescence. Nile red is intensely fluorescent in a lipid-rich environment while it has minimal fluorescence in aqueous media. Better selectivity for cytoplasmic lipid droplets can be obtained when the cells are viewed with yellow-gold fluorescence (450-500 nm excitation; >528 nm emission) rather than red fluorescence (515-560 nm excitation; >590 nm emission). Nile red is strongly fluorescent, but only in a hydrophobic environment.

5,5-dimethyl-1-pyrroline-N-oxide (DMPO), a highly reactive and short-lived compound, which is a commonly used as a spin trap that reacts with radicals. It can control intracellular nitroso-redox balance by scavenging ROS and donating NO. Experiments with bovine aortic endothelial cells have shown that post-treatment with DMPO of oxidatively challenged cells reversed eNOS dysfunction and could have pharmacological implications in the treatment of cardiovascular diseases. Besides DMPO can reacts with the amino acid- and DNA base-derived radicals to form protein- and DNA-DMPO nitroxide radical adducts, respectively. These adducts then decay to form very stable product macromolecule-DMPO-nitrone and can be detected by mass spectrometry, NMR or immunochemistry by the use of anti-DMPO nitrone antibodies. Thus Anti-DMPO antibodies can be used to determine the distribution of free radicals in cells and tissues and even in living animals and this may have a main role for the understanding the role of free radicals in biochemistry, medicine, and toxicology.

Geldanamycin, an antimicrobial compound, was purified in 1970 from the culture filtrates of Streptomyces hygroscopicus var. geldanus var. nova. Geldanamycin is moderately active in vitro against protozoa, bacteria, and fungi. It also has an antineoplastic effect against some cancer cells growing in culture. Molecular studies revealed the binding of geldanamycin to members of the heat shock protein 90 (HSP90) family of molecular chaperones. Interference with the function of these HSPs seems to be the major mechanism of action of geldanamycin.