Cyclic adenosine monophosphate (cAMP)-induced potentiation of synaptic responses in Helix neurons

[Evaluation of cytotocicity and efficiency of antioxidant protection of hydrophilic derivatives of 2,4,6-trialkylphenols in Escherichia coli cells]

The effects of five new derivatives of 2,6-dialkyl-4-propylphenole containing in para-radical different ionogenic groups (-SO3Na, -S-SO3Na, -S-(NH2)2Cl) in the presence and in the absence of hydrogen peroxide on the survival of E. coli AB1157 cells and its isogenic strain defective in repair enzyme genes were studied. Cell survival treated with hydrogen peroxide was remarkably increased in the presence of (3-(3,5-dimethyl-4-hydroxyphenyl)propyl)-1-sulphonate of sodium (Cl). Replacement of methyl ortho-radicals in the structure of Cl for tret-buthyl or cyclohexyl groups led to a decrease of the compounds ability to protect the cells from exogenic hydrogen peroxide. Between derivatives of 2,6-di-tret-buthylphenol the compound with thiosulphonate group demonstrated properties comparable with those for its sulphonate analog, then a chloride of isotiurone at concentration 3 mM completely suppressed the growth of cells in presence and in the absence of H2O2. Compound Cl may be considered as most perspective for detail analysis as antioxidant.

Biological activity and receptor binding properties of some C-terminally modified analogues of FMRFamide

The functional role of the C-terminal amide group (-CONH2) of the molluscan regulatory peptide FMRFamide has been examined in two sets of analogues based on FnLKFamide and FnLRFamide (nL = norleucine). In each series the amide group was replaced by -CONHCH3, -CON(CH3)2, -CONHNH2, -COOCH3, -CH2OH, and -COOH. The analogues were tested for their ability to bind to receptors in membranes from Helix aspersa circumoesophageal ganglia and for their biological effects on the isolated Helix heart. The results indicate i) that agonist activity, but not binding to the receptor, requires the presence of the amide carbonyl group; ii) the hydrogen atoms of the amide group are not essential either for binding or for agonist activity (the mono- and dimethylamides were more effective than the parent compounds on both counts); iii) the is more effective an agonist than is the amide in stimulating Helix heart.