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A series of Zn, Mn, Fe, Co, and Ni complexes ([MX2L], X = Cl, OAc) of the novel di-(2-picolyl)amine ligand L with an antioxidant 2,6-di-tert-butylphenol pendant were synthesized and characterized by elemental analysis, IR, multinuclear NMR spectroscopy, MALDI-TOF mass spectrometry and the molecular structures of [ZnCl2L] and [MnCl2L] were established by X-ray crystallography. The chemical oxidation of complexes with a 2,6-di-tert-butylphenol fragment to the phenoxyl radicals was studied by means of ESR method. The antioxidant radical scavenging activity of the complexes was measured spectrophotometrically using a DPPH-test and linoleic acid peroxidation. The electron transfer reactions were examined in CUPRAC tests and as the inhibition of an enzymatic reaction involving the generation of a reactive oxygen species (superoxide radical-anion) by xanthine oxidase. The lipoxygenase (LOX) inhibition activity of the studied compounds was evaluated. The in vitro biological experiments were performed by using rat brain homogenates. The role of the phenol fragment and metal was found to be essential in antioxidant activity.

Three sister species of rough periwinkles, viz. Littorina saxatilis (Olivi 1792), L. arcana (Hannaford Ellis 1978) and L. compressa (Jeffreys 1865) from the Barents Sea (Russia), the White Sea (Russia) and the Norwegian Sea (Norway) were studied. The identification of two sibling species L. saxatilis and L. arcana is often difficult as both species have extremely similar shell morphology and reproductive systems. Only mature females can be unambiguously distinguished, with a jelly gland present in female L. arcana, but which is replaced by a brood pouch containing developing embryos in L. saxatilis. No clear-cut diagnostic features have been found to discriminate between males or juveniles of the two species. The very first diagnostic DNA marker (DNA fragment A2.8, 271 bp length) for L. arcana and L. saxatilis separation was developed. The marker was derived from apparently species-specific L. arcana DNA fragments obtained via Random Amplified Polymorphic DNA (RAPD) analysis. This fragment was cloned and sequenced, whereupon specific primers were designed and the amplification was surveyed in a large number of morphologically well-identified females of both species. Subsequently, the specific DNA marker was used for the identification of male L. arcana and partners in copulating pairs. In this way, we obtained evidence of possible interspecific hybridization between the sibling species L. arcana and L. saxatilis living in sympatry in natural populations: the presence of A2.8 fragment in 12% of morphologically well identified L. saxatilis females and its absence in 14% of morphologically well identified L. arcana females. The A2.8 fragment never amplified in L. saxatilis from sites without L. arcana. The A2.8 fragment did not amplify in L. compressa, not even in microsympatric populations, and we did not observe interspecific copulations between L. arcana and L. compressa.

ABSTRACT:The organotin compounds R