Volume 50, Issue 7-8

1,2-Dihydroxymintlactone (1), a new monoterpene possessing nematicidal activity was isolated as a minor metabolite from the culture filtrate of the Basidiomycete Cheimonophyllum candidissimum , a fungus that previously has yielded nematicidal sesquiterpenes. The structure was determined by spectroscopic methods.

Reactive coenzyme analogues ω-(3-diazoniumpyridinium)alkyl adenosine diphosphate were prepared by reaction of ω-(3-aminopyridinium)alkyl adenosine diphosphate with nit­rous acid. In these compounds the nicotinamide ribose is substituted by hydrocarbon chains of varied lengths (n-ethyl to n-pentyl). The diazonium compounds are very unstable and decompose rapidly at room temperature. They show a better stability at 0 °C. L actate and alcohol dehydrogenase do not react with any of the analogues. Glyceraldehyde-3-phosphate dehydrogenase reacts rapidly with the diazonium pentyl compound. Decreasing the length of the alkyl chain significantly decreases the inactivation velocity. 3α,20β-Hydroxysteroid dehydrogenase reacts at 0 °C with the ethyl homologue and slowly with the propyl compound. The butyl-and pentyl analogues do not inactivate at 0 °C. Tests with 14 C -labeled 2-(3-diazoniumpyridinium)ethyl adenosine diphosphate show that complete loss of enzyme activity results after incorporation of 2 moles of inactivator into 1 mole of tetrameric enzyme. 4-(3-Acetylpyridinium)butyl 2 ′-phospho-adenosine diphosphate, a structural analogue of NADP + , was prepared by condensation of adenosine-2,3-cyclophospho-5′-phosphomorpholidate with (3-acetylpyridinium)butyl phosphate, followed by hydrolysis of the cyclic phosphoric acid ester with 2 ′:3′-cyclonucleotide-3′-phosphodiesterase. Because of the redox potential (-315 mV) and the distance between the pyridinium and phosphate groups, this analogue is a hydrogen acceptor and its reduced form a hydrogen donor in tests with alcohol dehyd roge­nase from Thermoanaerobium brockii. The reduced form of the coenzyme analogue also is a hydrogen donor with glutathione reductase. With other NADP + -dependent dehydrogenases the com pound has been show n to be a competitive inhibitor against the natural coenzyme. The acetyl group reacts with bromine to form the bromoacetyl group. This reactive bromoacetyl analogue is a specific active-site directed irreversible inhibitor of isocitrate dehydrogenase.

To clarify whether the structure of sporopollenin varies during pollen development FTIR and 13 C NMR spectroscopic analyses of Tulipa and Cucurbita sporopollenin from three different developmental stages were carried out. The spectra of sporopollenin obtained from an early, a middle postmeiotic and the mature stage have been compared. The assumption that sporopollenin mainly consists of long chain aliphatics with varying amounts of aromatics is corroberated by our results. Only slight changes in sporopollenin structure could be recognized during pollen wall development of Cucurbita maxima. In contrast to this the spectra of Tulipa sporopollenin of the three developmental stages exhibited significant differences concerning the aliphatic and aromatic components.

We have shown in molecular basis that alcoholic tea aroma is mainly formed by endogenous enzymatic hydrolysis of glycosidic aroma precursors during manufacturing. Amounts of alcoholic aroma precursor and glycosidase activity in each part of the tea shoot ( Camellia sinensis var. sinensis cv Yabukita and a hybrid of var. assamica & var. sinensis cv Izumi) were indirectly measured by means of a crude enzyme assay. The aroma precursors were abundant in young leaves and decreased as the leaf aged. Glycosidase activity also decreased as leaves aged, but was high in stems.

It has been shown that catalase immobilized on graphite and soot undergoes an oxidationreduction transformation. Some results on the effect of the potential sweep rate, temperature and pH on this transformation are presented. On the basis of the relationship established, it has been proved that the redox transformation is related to the iron in the heme of the active center of the enzyme and takes place with a transfer of one electron.

Two mutants of the cyanobacterium Anabaena variabilis impaired in the utilization or formation of molecular hydrogen have been obtained by nitroso-guanidine mutagenesis. Cul­tures of both mutants did not show alterations in the growth characteristics or in the hetero­cysts frequency but evolved molecular hydrogen from nitrogenase with enhanced rates. Ac­tivity measurements in extracts showed that one mutant (PK84) did not perform Na 2 S 2 O 4- dependent H 2 -formation and was, therefore, unable to express an active bidirectional hydro­genase. Both mutants (PK84, PK 17R) were characterized by lower activity of phenazine-methosulphate-dependent H 2 -uptake when extracts were assayed from younger cultures. In older cells, particularly when grown with nitrate in the medium , this H 2 -uptake activity was, how ever, enhanced. Both mutants are likely affected in regulatory hydrogenase genes. The mutant PK84 offers perspectives for potential applications in solar energy conversion programs.

Nicotiana tabacum was grown with a CO 2 -content in the atmosphereof 350 ppm and 700 ppm. After three weeksof growth in the respective atmospherewe were able to show that chloroplasts from plants grown under 700 ppm CO 2 exhibited an 18% higher photosystem I-mediatedelectron transport activity. Furthermore, we were able to show that in plants grown under the higher CO 2 -concentration the peptide composition of photosystem I had been quantitatively changed. It appeared that the CPI-peptides were increased, whereasthe LHCPI peptides were decreased. Corresponding to this change in the peptide composition the ratio chlorophyll/carotenoids/protein changes from 1:0.16:3.6 in the control plants to 1:0.23:5 in the “CO 2 -plants”. The chlorophyll a/b ratio changes from 1.9 in the control plants to 2.3 in the “CO 2 plants”. Furthermore, the carotenoid composition appears to be changed, β-carotene increases by 60% as expected from the increased CPI-content. The xanthophylls lutein, violaxanthin, neoxanthin and zeaxanthin increase also but to a lesser extent. Using specific antisera to lipids, we were able to show that photosystem I contains only the membrane lipids monogalactosyldiglyceride and phosphatidylglycerol. Both lipids are specifically bound in a restricted number onto peptides of the photosystem I complex. Both lipids differ with respect to their binding strength on the peptides of photosystem I. The changes in the peptide and lipid composition were established by chemical analyses and by immunological techniques (Western blot) using monospecific antisera to the photosystem I peptides, to the chloroplast lipids as well as to the chloroplast carotenoids. From the quantitative and qualitative analyses of the peptides, carotenoids and lipids, the molecular distribution of the carotenoids and lipids in the CPI and LHCPI complex of photosystem I was established.

Plants of Phaseolus vulgaris L. were exposed to mists consisting of distilled water at pH 5.6 (control) or H 2 SO 4 + HNO 3 (molar ratio 1.5:1) in distilled water at pH 4.5, 3.0 and 2.3. At the end of 21-days treatment the growth of the plants in height was not reduced: however, significant changes were detected in the mineral nutrient content and partitioning in plant organs. Treatments at pH 2.3 led to greatly decreased Ca and K content and increased S. N and P content in the leaves. In the roots the most significant increases occurred in the levels of P, S, N, K. Ca, and Mg, in the stems in the levels of N, S and P.

Quinidine (QUIN) is one of the most important and efficient antiarrhythmic drugs (AAD). It belongs to class I. which are the drugs that exert their action at the level of the sodium channels in the membrane of the myocard. Several hypotheses support the idea that the molecular mechanism of action of the AAD is via nonspecific interactions with phospholipids sited in the neighborhood of the channels. In order to probe the validity of these hypotheses, QUIN was made to interact with the phospholipids dimyristoylphosphadidylcholine (DMPC) and dimyristoylphosphatidylethanolamine (DMPE). These interactions were performed in a hydrophobic and a hydrophilic medium under a wide range of molar ratios. The resulting products were analyzed by X-ray diffraction. QUIN solutions were also made to interact with DMPC liposomes, which were studied by fluorescent spectroscopy. Finally, human erythrocytes which were incubated with QUIN solutions were observed by scanning electron microscopy. The results of these experiments proved that QUIN indeed interacted with phos­pholipid bilayers.

The mode of membrane attachment of the Rieske iron -sulfur proteins from cytochrome b 6 ƒ complex of pea thylakoids and from cytochrome bc 1 complex of yeast mitochondria has been studied using biochemical approaches. The relative sensitivity of the Rieske protein to trypsin in the thylakoid membrane shows that all trypsin sites of the Rieske protein are on the lumen side of the thylakoid membrane. In contrast to cytochrome / the chloroplast Rieske protein was extracted from thylakoids using chaotropic agents (NaSCN, urea), an alkaline pH and relatively low concentrations of Trinon X-100. The cytochrome bc 1 complex Rieske protein from mitochondrial membranes of yeast was also released by NaSCN and alkaline treatment. The results presented here led us to the conclusion, that the mitochondrial and chloroplast Rieske proteins are extrinsic and that their association with the rest of the complex involves hydrophobic interactions.

Nodules of Rhizobium leguminosarum bv. phaseoli in symbiosis with Phaseolus vulgaris were compared with regard to their nitrogenase activity and activities of enzymes involved in the removal of O2 ·- and H 2 O 2 as well as total ascorbate content. Activities of catalase (EC 1.11.1.6), ascorbate peroxidase (EC 1.11.1.11), and total ascorbate content were consist­ently higher in nodules inhabited by bacterial strains with higher nitrogenase activity. Values for superoxide dismutase (EC 1.15.11), and guaiacol peroxidase activity did not differ for the bacterial strains compared. On the other hand, when different plant cultivars were inoculated with the same bacterial strain, high nitrogenase activity did not correlate with a higher activ­ity of the oxygen scavenging enzyms or a higher content of total ascorbate. In this case, values for guaiacol peroxidase activity were greatly enhanced in nodules with lower nitrogen­ ase activity. This may be part of a hypersensitive reaction of the plant cultivar against the bacterial symbiotic partner. Inhibition of catalase activity in the nodules by addition of triazole to the nutrient solution did not alter nitrogenase activity within the first nine hours after addition. It can be concluded that the activity of catalase, ascorbate peroxidase, and superoxide dismutase is not generally coupled to nitrogenase activity in root nodules of P. vulgaris.

A number of free radical generating systems were used to investigate the antioxidant properties and structure-activity relationships of a series of monohydroxylated and dihydrox­ylated flavones. Ortho-dihydroxylated flavones showed the highest inhibitory activity on en­ zymic and non-enzymic microsomal lipid peroxidation as well as on peroxyl radical scaveng­ing. Most flavones were weak scavengers of hydroxyl radical, while ortho-dihydroxylated flavones interacted with superoxide anion generated by an enzymic system or by human neutrophils. This series of compounds did not exert cytotoxic effects on these cells. Scaveng­ing of superoxide and peroxyl radicals may determ ine the antioxidant properties of these active flavones.

When model membranes are prepared by ultrasonic treatment of polyunsaturated phos­pholipids, radical production can induce a partial degradation of the polyunsaturated fatty acyl chains and the formation of lipid hydroperoxides. A suitable antioxidant employed dur­ing liposome preparation is able to protect them against lipid peroxidation. This work con­tains the results of studies on egg lecithin liposomes with incorporated antioxidants that were supposed to play the protective role mentioned. As it has been shown the antioxidant com pounds used ensured a 40-60% , i.e., satisfactory protection of liposomes after 30 min sonication. Possible practical applications are discussed.

The serum and red blood cell (RBCs) disposition of epirubicin (EPR) after intravenous bolus injection without and with coadministered quinine (QUI) was investigated in patients undergoing a cyclic chemotherapy with EPR. QUI possesses a statistical significant influence on the EPR serum concentrations and, as a consequence, on the pharmacokinetic parameters for the initial distribution phase of EPR. Within the first 15 min after administration, EPR was distributed from the central compartiment distinctly faster in compare to the control, when QUI was preadministered (t 1/2 = 6 min for the control group and t 1/2 = 3 min with QUI; -46% , p < 0.05). Yet, in the beta-phase when drug-elimination predominates, no statistical significant influence of QUI in regard to EPR serum and RBC concentrations could be observed. Half-life of elimination was 9.5 h for the control group and 8.6 h for the QUI group (-10% ). The mean initial serum concentration (c 0 ) was reduced significantly by QUI from 7359 ± 506 ng/ml to 4351 ± 1682 ng/ml (-42 % . p < 0.005). Furthermore. QUI caused a reduction of the serum bioavailability of EPR (expressed as AUC 0-24 -values) from 3404 ± 1008 ng/ml × h to 2359 ± 1073 ng/ml × h (-3 1 % , p < 0.05). Vd and Vdß were increased at about 90% and the mean total body clearance was accelerated from 45.3 to 148.7 ml/min, but due to the large standard deviations the calculated difference for these parameters was not statistically significant. In the observed time interval of 24 h, the red blood cell coefficient of distribution k RBC of EPR was lower if QUI was coadministered (k RBC = 1.25 ± 0.12 for the control group k RBC = 1.15 ± 0.13 under QUI; p < 0.04). The results point out that QUI induces an accelerated distribution of EPR from the blood into the tissue and that QUI additionally may have influence on the red-blood cell partitioning of EPR.

The iron(III) compounds with several aminocarboxylate chelates containing an aryl or furan substituent exhibit high activity in enhancement of the reactivity of hydrogen peroxide, leading to facile hydroxylation at benzene ring, and to degradation of furan ring, but no such activity was observed for the corresponding Al(III) compounds. These results were inter­preted in terms of the molecular orbital consideration, and lack of the activity of the Al(III) complexes was attributed to lack of electrophilic nature of the peroxide adduct due to the absence of a d-orbital: this may explain the fact that there were no tumors in Al-NTA (nitrilotriacetic acid)-treated rats. Based on the facts observed in this study, the decreased function of iron(III) ions for synthesizing neurotransmitters in the brain was assumed to be one of the possible origin for the neurotoxicity by injection of the Al(III) salts in vivo.

Juvenile hormone analogues were tested for their lytic activity on Trypanosoma cruzi Chagas, 1909 blood tripomastigotes cultivated in vitro. The results indicated that the carbamate 4 and the phenoxyphenol derivative 1 are considered good candidates for blood sterilization. The compounds were also assayed for inhibition of development of parasites in infected mice showing a moderated degree of activity.

1. With the combined oxalate-pyroantimonate method we determined the subcellular distribution of calcium in the photoreceptor cells of the crayfish Orconectes limosus. 2. The calcium antimonate deposits were identified with the electron microscope. Energydispersion X -ray analysis verified that the electron dense deposits contained calcium and antimony. 3. Calcium antimonate deposits were found in the submicrovillar cisternae, mitochondria, multivesicular bodies, and pigment granules, as well as in the cytoplasm . 4. The calcium deposits in the cytoplasm of the retinula cell and in the pigment granules were reduced after incubation of the retinae in a solution with a lowered calcium concentration and even more after we permeabilized the plasma membrane with the saponin β-escin. 5. We suppose that the calcium -storing pigment granules participate in the regulation of the cytosolic calcium concentration of the crayfish photoreceptor cells.

The flavonoid aglycones excreted by aerial parts of three Viguiera species have been analyzed. One of them is a rare natural product. So far unpublished NMR data are reported for three flavones. Each species of V. sec­tion Hypargyrea exhibits a distinctive flavonoid profile based on different patterns of methoxylation, but the taxonomic section as a whole is not characaterized by any distinctive characters of its flavonoid chemistry.