title: Spectrophotometric determination of acidity constants of 4-dedimethylamino sancycline (Col-3), a new antitumor drug.
abstract: A spectrophotometric technique was used to determine the acidity constants of 4-dedimethylamino sancycline (Col-3), a new antitumor drug. The apparent pKa values of Col-3 in 0.5% methanol aqueous media at approximately 25 degrees C with a constant ionic strength of 0.2 were calculated manually and graphically to be 5.64 +/- 0.17 (pKa1) and 8.35 +/- 0.07 (pKa2). In addition, the computer program SQUAD was used to confirm Col-3 pKa values. The pKa values obtained by SQUAD were pKa1 5.63 +/- 0.14 and pKa2 8.39 +/- 0.04. These results are in agreement with the tetracycline-like structure of Col-3.
authors.affiliation: Department of Pharmaceutical Technology, Prince of Songkla University, Songkhla, Thailand.
authors.forename: S
authors.initials: S
authors.lastname: Pinsuwan
authors.forename: F A
authors.initials: FA
authors.lastname: Alvarez-Núñez
authors.forename: S E
authors.initials: SE
authors.lastname: Tabibi
authors.forename: S H
authors.initials: SH
authors.lastname: Yalkowsky
mesh_terms: D000970:Antineoplastic Agents / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D013053:Spectrophotometry; D013752:Tetracycline / Q000737:chemistry*; D013754:Tetracyclines
chemical_list: D000970:Antineoplastic Agents; D013754:Tetracyclines; C117155:tetracycline CMT-3; D013752:Tetracycline