Guanosine 3′,5′-cyclic monophosphate (cGMP) is a cyclic nucleotide derived from guanosine triphosphate (GTP). Cyclic GMP is a cellular regulatory agent that acts as a second messenger. Its levels increase in response to a variety of signals (acetylcholine, insulin, oxytocin). cGMP is involved in the regulation of kinases G. cGMP binds to sites on the regulatory units of protein kinase G (PKG) and activates the catalytic units, enabling them to phosphorylate their substrates. cGMP is a common regulator of ion channel conductance, glycogenolysis, and cellular apoptosis. It also relaxes smooth muscle tissues. In blood vessels, relaxation of vascular smooth muscles lead to vasodilation and increased blood flow. cGMP is a secondary messenger in phototransduction in the eye. In the photoreceptors of the mammalian eye, the presence of light activates cGMP phosphodiesterase 5 (PDE5), which degrades cGMP. The sodium ion channels in photoreceptors are cGMP-gated, so degradation of cGMP causes sodium channels to close, which leads to the hyperpolarization of the photoreceptor's plasma membrane and ultimately to visual information being sent to the brain. Mutations in the cGMP phosphodiesterase cause defects in cGMP metabolism leading to retinal disease. Inhibition of cGMP degrading PDE5 by its selective inhibitor sildenafil induced migraine without aura in 10 of 12 migraine patients and in healthy subjects.

Lobeline,(+)- is unnatural enantiomer of Lobeline. Lobeline is the main active alkaloid constituent of Lobelia inflata, a plant sometimes called “Indian tobacco” because it was initially used by Indians of North America as a tobacco substitute. The crude extract is toxic but has been widely recommended for treatment of respiratory illnesses such as asthma, bronchitis, pneumonia, and whooping cough.

Arginyl-Glycyl-Aspartic Acid is a tripeptide composed of L-arginine, glycine, and L-aspartic acid, used as a biochemical tool in the study of cellular recognition. Arginylglycylaspartic acid hows great affinity for the integrin receptors and Arg-Gly-Asp tripeptide motif can be used for Peptide-Based Target Drug Delivery of anticancer agents. The tripeptide Arg-Gly-Asp (RGD) is an important protein sequence in the binding of proteins to cell surfaces. The RGD motif was identified in fibronectin, vitronectin, osteopontin, collagens, thrombospondin, fibrinogen, and von Willebrand factor. Many adhesive extracellular matrix, blood, and cell surface proteins recognize the RGD sequence for cell attachment.