Theophylline (1,3-Dimethylxanthine) is a methyl xanthine derivative from tea with diuretic, smooth muscle relaxant, bronchial dilation, cardiac, and central nervous system stimulant activities. It inhibits the 3', 5'-cyclic nucleotide phosphodiesterase that degrades cyclic AMP, thus potentiating the actions of agents that act through adenylyl cyclases and cyclic AMP.

4-Phenylbutyric acid (Benzenebutyric acid) is a histone deacetylase (HDAC) inhibitor and an endoplasmic reticulum stress (ERS) inhibitor. 4-Phenylbutyric acid can be used to treat urea cycle disorders.

Parthenolide ((-)-Parthenolide) is a natural sesquiterpene lactone that is an NF-κB inhibitor and also specifically inhibits HDAC1 protein, but is inactive against other class I/II HDACs. Parthenolide has anti-inflammatory, anti-tumor, and anti-viral activities.

Theophylline monohydrate (Quibron) appears to inhibit phosphodiesterase and prostaglandin production, regulate calcium flux and intracellular calcium distribution, and antagonize adenosine. Theophylline monohydrate is a natural alkaloid derivative of xanthine isolated from the plants Camellia sinensis and Coffea arabica. Physiologically, this agent relaxes the bronchial smooth muscle, produces vasodilation (except in cerebral vessels), stimulates the CNS, stimulates the cardiac muscle, induces diuresis, and increases gastric acid secretion; it may also suppress inflammation and improve contractility of the diaphragm.