MPDE5 is an enzyme derived from phosphodiesterases, present in various tissues, including rods and cones of the retina, and belongs to the large family of cyclic nucleotide PDEs that catalyze the hydrolysis of cAMP and cGMP. It exists in human colonocytes and intestinal tissue. Besides,  the increase of intracellular cGMP levels in these cells following GCC activation can regulate its activity.

PDE5 inhibitors are vasodilators that block the degradation of cyclic GMP by PDE5 in smooth muscle cells lining blood vessels that supply various tissues. As a result, These drugs dilate the corpus cavernosum, promote erection through sexual stimulation, and can treat erectile dysfunction (ED). Additionally, PDE5 inhibitors prolong the action of cGMP by inhibiting its degradation by PDE5 enzymes throughout the body. In the penis, PDE5 inhibitors enhance the action of cGMP, leading to longer erections and greater sexual satisfaction. However, PDE5 inhibitors do not cause erections in the absence of sexual stimulation. In addition to their hemodynamic effects, PDE5 inhibitors have anti-inflammatory, antioxidative, antiproliferative, and metabolic properties in several experiments.

TPN729 is a selective PDE5 inhibitor for erectile dysfunction research.

TPN729 is a selective phosphodiesterase type 5 (PDE5) inhibitor with an IC₅₀ value of 2.28 nM. Besides, it can affect erectile function and can be used for the research of erectile dysfunction. TPN729 (1.25, 2.5, 5.0 mg/kg; 1 dose) increased intracavernous pressure/blood pressure ratio (ICP/BP) at all time points at the 5.0 mg/kg dose, 75, 90, 105 and 120 at the 2.5 mg/kg dose Increased intracavernous pressure/blood pressure ratio in minutes. It can dose-dependently increase the maximum intracavernous pressure (ICP) and ICP/blood pressure (BP). Moreover, TPN729 (5.0 μg/kg; iv, once) significantly increases intracavernous pressure and intracavernous pressure/blood pressure ratio in male beagle dogs.

In conclusion, TPN729 is a selective phosphodiesterase type 5 (PDE5) inhibitor useful in the study of erectile dysfunction.

References:

[1] Zhen Wang, et al. J Sex Med. 2013 Nov;10(11):2790-7.

[2] Sharon A Huang, et al.  P T. 2013 Jul;38(7):407-19.