PDE5A and Alzheimer disease: These derivatives exhibit diverse pharmacological activities, including anti-inflammatory, anti-atherogenic, anti-Alzheimer’s disease, antitumor, and antifungal activities via a variety of mechanisms, such as inhibiting cyclooxygenase-2 (COX-2), acetylcholine (AChE), phosphodiesterase 4B (PDE4B), phosphodiesterase 5 (PDE5), or topoisomerases (Topos).