Icariin (Ieariline) belongs to the flavonol glycoside group of natural products, can inhibit PDE5 and PDE4 activity (IC50=432/73.50 μM), is also a PPARα activator. Icariin can increase cardiovascular and cerebrovascular blood flow, promote hematopoiesis, immunity and bone metabolism.

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.

Indomethacin (Indomethacin) is a COX1 and COX2 inhibitor (IC50=18/26 nM) with blood-brain barrier permeability and non-selectivity. Indomethacin is a non-steroidal anti-inflammatory agent with anti-tumor and anti-infective activity.

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.

Isoprenaline hydrochloride (NCI-c55630) is a potent beta-adrenergic agonist with the peripheral vasodilator, bronchodilator, and cardiac stimulating properties.

Roflumilast (APTA 2217) is an orally available, long-acting inhibitor of phosphodiesterase (PDE) type 4 (PDE4), with anti-inflammatory and potential antineoplastic activities. Upon administration, roflumilast and its active metabolite roflumilast N-oxide selectively and competitively bind to and inhibit PDE4, which leads to an increase of both intracellular levels of cyclic-3', 5'-adenosine monophosphate (cAMP) and cAMP-mediated signaling.

Phloretin (NSC-407292) is a well-known inhibitor of eukaryotic urea transporters, blocks VacA-mediated urea and ion transport. Phloretin is a dihydrochalcone, a type of natural phenols. It can be found in apple tree leaves and the Manchurian apricot. It promotes potent antioxidative activities in peroxynitrite scavenging and the inhibition of lipid peroxidation. It has been found to inhibit the growth of several cancer cells and induce apoptosis of B16 melanoma and HL60 human leukemia cells.

Vardenafil hydrochloride is a New Phosphodiesterase Type 5(PDE5) Inhibitor, in the Treatment of Erectile Dysfunction in Men With Diabetes