title: Synthesis of pyrazolo[4,3-e][1,2,4]triazine sulfonamides, novel  Sildenafil analogs with tyrosinase inhibitory activity.
abstract: Tyrosinase is a multifunctional, glycosylated and copper-containing oxidase which catalyzes the first two steps in mammalian melanogenesis and is responsible for enzymatic browning reactions in damaged fruits during post-harvest handling and processing. Neither hyperpigmentation in human skin nor enzymatic browning in fruits are desirable. These phenomena have encouraged researchers to seek new potent tyrosinase inhibitors for use in foods and cosmetics. This article surveys tyrosinase inhibitors, newly discovered from natural and synthetic sources. The inhibitory strength is comparable to that of the standard inhibitor kojic acid. Also their inhibitory mechanisms are discussed. The new obtained compounds were also tested as PDE5 inhibitors and did not show significant inhibitory effect.
authors.affiliation: Department of Chemistry, Siedlce University of Natural Sciences and Humanities, 3-go Maja 54, 08-110 Siedlce, Poland. Electronic address: mmojzych@yahoo.com.
authors.forename: Mariusz
authors.initials: M
authors.lastname: Mojzych
authors.affiliation: Institute of Organic Chemistry with Centre of Phytochemistry, G. Bonchev Str. 9, Sofia 1113, Bulgaria.
authors.forename: Aleksandar
authors.initials: A
authors.lastname: Dolashki
authors.affiliation: Interfacultary Institute for Biochemistry, Hoppe-Seyler-Str.4, 72076 Tubingen, Germany.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Voelter
mesh_terms: D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D015394:Molecular Structure; D014442:Monophenol Monooxygenase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D010879:Piperazines / Q000737:chemistry* / Q000494:pharmacology; D011687:Purines / Q000737:chemistry / Q000494:pharmacology; D011720:Pyrazoles / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D000068677:Sildenafil Citrate; D013329:Structure-Activity Relationship; D013449:Sulfonamides / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D014227:Triazines / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D004791:Enzyme Inhibitors; D010879:Piperazines; D011687:Purines; D011720:Pyrazoles; D013449:Sulfonamides; D014227:Triazines; D000068677:Sildenafil Citrate; D014442:Monophenol Monooxygenase