title: The Hydractinia echinata test-system. III: Structure-toxicity relationship study of some azo-, azo-anilide, and diazonium salt derivatives.
abstract: Structure-toxicity relationships for a series of 75 azo and azo-anilide dyes and five diazonium salts were developed using Hydractinia echinata (H. echinata) as model species. In addition, based on these relationships, predictions for 58 other azo-dyes were made. The experimental results showed that the measured effectiveness Mlog(1/MRC50) does not depend on the number of azo groups or the ones corresponding to metobolites, but it is influenced by the number of anilide groups, as well as by the substituents' positions within molecules. The conformational analysis pointed out the intramolecular hydrogen bonds, especially the simple tautomerization of quinoidic (STOH) or aminoidic (STNH2) type. The effectiveness is strongly influenced by the "push-pull" electronic effect, specific to two hydroxy or amino groups separated by an azo moiety (double alternate tautomery, (DAT), to the -COOH or -SO3H groups which are located in ortho or para position with respect to the azo group. The levels of the lipophylic/hydrophilic, electronic and steric equilibriums, pointed out by the Mlog(1/MRC50) values, enabled the calculation of their average values Clog(1/MRC50) ("Köln model"), characteristic to one derivative class (class isotoxicity). The azo group reduction and the hydrolysis of the amido/peptidic group are two concurrent enzymatic reactions, which occur with different reaction rates and mechanisms. The products of the partial biodegradation are aromatic amines. No additive or synergic effects are noticed among them.
authors.affiliation: Institute of Chemistry Timisoara of the Romanian Academy, B-dul Mihai Viteazul 24, RO-300223 Timişoara, Romania. lchi@gmx.de.
authors.forename: Sergiu Adrian
authors.initials: SA
authors.lastname: Chicu
authors.affiliation: Department of Clinical Laboratory and Sanitary Chemistry, "Vasile Goldis" University, 1 Feleacului Str., Arad 310396, Romania. melania.munteanu@uvvg.ro.
authors.forename: Melania
authors.initials: M
authors.lastname: Munteanu
authors.affiliation: Faculty of Medicine, "V. Babes" University of Medicine and Pharmacy, 2 Eftimie Murgu, 300041 Timisoara, Romania. citu.ioana@umft.ro.
authors.forename: Ioana
authors.initials: I
authors.lastname: Cîtu
authors.affiliation: Faculty of Pharmacy, "V. Babes" University of Medicine and Pharmacy, 2 Eftimie Murgu, 300041 Timisoara, Romania. codrutasoica@umft.ro.
authors.forename: Codruta
authors.initials: C
authors.lastname: Soica
authors.affiliation: Faculty of Pharmacy, "V. Babes" University of Medicine and Pharmacy, 2 Eftimie Murgu, 300041 Timisoara, Romania. cadehelean@umft.ro.
authors.forename: Cristina
authors.initials: C
authors.lastname: Dehelean
authors.affiliation: Faculty of Pharmacy, "V. Babes" University of Medicine and Pharmacy, 2 Eftimie Murgu, 300041 Timisoara, Romania. trandafirescu.cristina@umft.ro.
authors.forename: Cristina
authors.initials: C
authors.lastname: Trandafirescu
authors.affiliation: Institute of Chemistry Timisoara of the Romanian Academy, B-dul Mihai Viteazul 24, RO-300223 Timişoara, Romania. timofei@acad-icht.tm.edu.ro.
authors.forename: Simona
authors.initials: S
authors.lastname: Funar-Timofei
authors.affiliation: Faculty of Pharmacy, "V. Babes" University of Medicine and Pharmacy, 2 Eftimie Murgu, 300041 Timisoara, Romania. ionescu.daniela@umft.ro.
authors.forename: Daniela
authors.initials: D
authors.lastname: Ionescu
authors.affiliation: Faculty of Pharmacy, "V. Babes" University of Medicine and Pharmacy, 2 Eftimie Murgu, 300041 Timisoara, Romania. simu.georgeta@umft.ro.
authors.forename: Georgeta Maria
authors.initials: GM
authors.lastname: Simu
mesh_terms: D000818:Animals; D001391:Azo Compounds / Q000737:chemistry* / Q000633:toxicity*; D037402:Hydrozoa / Q000187:drug effects*; D013329:Structure-Activity Relationship; D018675:Toxicity Tests / Q000379:methods*
chemical_list: D001391:Azo Compounds