Enkephalin fragments and analogues: Design and activity

DEVELOPMENT OF THE MRI CONTRAST MEDIA: NEW ORIGINAL CHELATES Gd-COMPLEXES. V_V~Panov.S.Egorova. O.Vetmv, D.Mosealev, A.Gladky, I.Shabunin, E.Bolotova, K.Popov, T.Akhadov, N.Shimanovsky, P.Sergeev Department of the Molecular Phannacology~ Medico-biology Faculty, The Moscow State Medical University, B.Pirogovskaya 9, Moscow, 119021, Russia. ]~rpose.The aim was to study 3 new original chelates Gd-complexes (GdC) and Gd-DTPA applaying as the base of MRI-Contrast Media (MRCM) with different ways of admissions in compare with Magnevist (Schering. Germany). ~aterials and methods. All ~H spiu-lattiee relaxation time (Tx)measurements were obtained on the original tH MR-relaxometer. We studied the tH T~relaxation efficiency (T~RE) Of GdC in the phosphate buffer solutions (pI-I=7.4)and the T~ of brain, liver, kidneys, blood and heart at diffemet time after the tail vein of white rats injection of Gd-EDF, Gd-TPED, Gd-DTPA and Maguevist; and after oral admission - for the Gd-TGEID. The T~RE was calculated using the next expression: (1/T~n~°dC~d~=i°")/(1/T~b~f°'~~C,~i,,io.). I=TtRE.(C~C/CW,~), where C°deand Cw~'- whole GdC and water molecular concentration. The T~RE is undepending on the GdC concentration and the type of equipment. In tissues T~RE was evaluated by Wl~rr: Wleff=(l]Tl after GdC ~dmi~.ion)/(1/Tl'~efor¢C,dC admi~0n).l. The acute toxicity was tested by standart methods. Iggsults.All of our GdC had very low acute toxicity (but it was quit higher than the Magnevist acute toxicity). In the buffer solution Gd-TGEID, Gd-EDF and Gd-TPED had shownmorehigh T~RE than the Magnevist (Gd-DTPA T~REwas the same). For the Gd-TPED had been observed the pharmacokinetics in blood and all organs similar to the Magnevist: maximmn of the W~~eewas measured at 10-15 min after the Gd-TPED admission. Gd-EDF and Gd-DTPA shown maximum of the WI'n at 15-20 rain. But the W. °~rof those GdC in blood and kidneys was more higher (at 8-12 time) than in heart, brain and liver, tn brain, liver, kidneys, blood and heart we observed exeled of Gd-TPED, Gd-DTPA in compare with Magnevist. For the Gd-TGEID the Wt'~ maximum was in liver and lddi~eys at 4 h, in heart at 3 h when the WI°~ in blood was not observed. The maximum of the Gd-TGEID W~(oral admission) and of the Magnevist WSr(intravenous injection) ifi the fiver and kidneys was the same. Conclusion. All new Gd-complexes had provided decreasing efficiency of the Tt in solution and rats tissues (similar to the Magnevist or higher) with low toxicity. So, all of them are perspective as the base of the new MRCM.

ENKEPHALIN FRAGMENTS AND ACTIVITY

AND ANALOGUES:

DESIGN

N. Pencheva Institute of Physiology, Bulg. Acad. Sci., Acad. G. Bonchev str., bl. 23, 1113 Sofia, Bulgaria Structure-activity relationships were studied through the opioid potency of enkephalin fragments and analogues. A series of 10 diand tripeptides situated before and after the Gly-Gly bond were examined on guinea-pig ileum (GPI) longitudinal preparations. TyrD-Ala hydraside (1 pM-0.1 raM) and Tyr-Gly- hydraside (10 nM-1 mM) showed agonistic potency, while G!y-Phe-OMe/manifested non-competitive antagonistic activity with a pA2 value comparable with those of synthetic opioid blockers. This poses the question of the metabolic role of opioid-active fragments. The enkephalin analogues are a result of modifications important for the affinity and selectivity of the respective l igands: i.e. substitution at position 2 and alterations in the COOH terminal. The li and $ properties of these ligands were determined in GPI and mouse vas deferens (MVD) preparations. The MVD assay was performed with respect to the purinergic and adrenergic components of electrically-evoked responses. The lengthening of the enkephalin chain suggested that terminal COOH changes are without harm for ~t potency, but are detrimental for potency. Substitution of Gly2 by D-aminoacids or by more hydrophilic residues increased the potency of the respective ligands at both I~ and ~ receptors but changed their selectivity. Cyssulphonamide = substitution in the molecule of native enkephalins yielded potent and selective $ ligands. The present results revealed structure-activity relationships which could be useful for designing peptides of pharmacological and biochemical interest.

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BINDING OF ROENGEN CONTRAST MEDIA WITH MAIN HUMAN BLOOD PLASMA PROTEINS STUDIED BY 1H AND ~C HIGH RESOLUTION NMR SPECTROSCOPY. V.Panov, A.Stepanyants, O.Vetrov, M.Kxasnova, I.Schipanova, L.Sibeldina, T.Akhadov, N.Slumanovsky, P.Sergeev Department of the Molecular Pharmacology, Medico-biology Faculty, The Moscow State Medical University, B.Pirogovskaya, Moscow, 119021, Russia. Purpose. The weak, readily reversible interactions of 6 ionic and 3 nonionic organic three-iodinecontaning Roentgen Contrast Media (RCM) - with different organotropizm - and main fractions of human blood plasma proteins (serum albumin (HSA), fibrinogen, alfa-, beta- and gamma-globulins) were investigated using differential changes of relaxation times in IH and ~3C nuclear magnetic resonance (NMR) spectra (in compare), Methods and material. All 1H NMR spectra were obtained using Vadan Associated HA 100 and ~3C- using Varian Gemini 300 (both - Varian, USA) high resolution NMR spectrometers. The valnes of IH 1/T~ (it was assumed that T2 ~ T 1) given for various NMR peaks were obtained from the spectral line widths using the formula I/T2=YI(W~i2) where W m is the line width at one-half maximum peak height, z3CT~given for various NMR peaks were obtained using inversion-recovery sequence. We investigated values of ~H 1/Tz and t3C T~ for various NMR peaks of 6 ionic RCM: 2 oral cholecystographyc, 2 intravenous cholecystograpfiyc, 2 intravenous angiourograpfiyc; and 3 nonionic RCM before and after 30 min incubation in solutions with different concentrations of human blood plasma proteins. Original calculation method of NMR relaxation data interpretation was used. Results. Nonidenlic increasing of ~H 1/T2 and a~C l/T1 of different RCM NMR peaks after RCM incubation with different blood plasma proteins were revealed. Conclusion. Interaction with human blood plasma proteins decreased in a row: cholecystographyc oral andintravenous RCM, ionic and nonionie angiourographyc RCM (correlation coefficients with RCM toxicity, osmotic efficiency and lipophifity wereis about 0,79-0,88). Affinity of RCM to human blood plasma Proteins decreased in a row: beta-globufins, alfa-globulins, HSA, fibrinogen, gamma-globulins. Nonionic RCM had more high affinity to gamma-globulins. Interaction of RCM with human blood plasma proteins Increased when there is no chemical group in 5 site of benzol ring. 3 model of RCM binding sites configuration (with hydrophobie forces) on proteins surface were elaborated.

ELONGATED ANALOGUES OF NEUROTOXIN ODAP: STRUCTURE-ACTMTY STUDIES. ~ , Dumpis M.A. Institute of Experimental Medicine, acad Paviov t2, 197376 St.Petersburg, Russia. ODAP (3N-oxalyI.L-2,3-diaminopropionic acid) is one of the rare examples of orally active agonisls of AMPA typ~ receptors of excitatory amino acids (EAA). The ODA.~ analogues wilh elongated or modified oxalyl moiety, namely 3N-mgtonyt- (MaDAP), 3N-succinyl- (SuDAP), 3N-glutaryl (GIDAP) and 3N.phthalamoy[- (PtDAP) .derivatives, were synthesized, All new compounds showed the ability I0 interact wilh the EAA receptors. The increase of the distance ibetween the terminal carbo~cy'lic groups reduced the excitatory activily (MaDAP and SuDAP) and finally led to the compounds (GIDAP and PIDAP), that showed the properties of the NMDA type antagonists. The conformational analysiq of new compounds and some known F_..AAagonists and antagonists explained lhe reasons of these changes. Somq therapeutical applications of the new compounds as~ analgetics are discussed.