Synthesis of novel nitric oxide (NO)-releasing esters of timolol

A novel class of timolol derivatives with nitric oxide (NO)-donating moieties achieved chemical stability yet under physiologically relevant conditions released timolol and NO. Hindered esters A were designed and synthesized, whose ‘triggered’ release relied on enzymatic hydrolysis of the nitrate ester in A to B, that in turn cyclized to liberate timolol.     

New syntaxa for the prodrome of Italian vegetation

The aim of this study is to provide new syntaxa for the Italian vegetation checklist. For the class Rhamno–Prunetea which includes the class Paliuretea the new alliance Rhamno saxatilis–Paliurion spinae-christi is described, that is included in the order Paliuretalia spinae-christi with a central-western Mediterranean and sub-Mediterranean distribution. Otherwise, the more thermophilous Paliurus spina-christi vegetation is included in the new suballiance named as Oleo sylvestris–Paliurenion spinae-christi within the alliance Oleo–Ceratonion of the class Quercetea ilicis. For the class Trifolio–Geranietea medii, a new alliance named Hyperico calabricae–Asphodelion macrocarpi is proposed here.     

Fluorescent, internally quenched, peptides for exploring the pH-dependent substrate specificity of cathepsin B.

Cathepsin B is a cysteine protease that in tumor tissues is localized in both acidic lysosomes and extracellular spaces. It can catalyze the cleavage of peptide bonds by two mechanisms: endoproteolytic attack with a pH optimum around 7.4, and attack from the C-terminus with a pH optimum at 4.5-5.5. In this work, seven fluorescent, internally quenched, decapeptides have been synthesized using the prototypical cathepsin B selective substrate Z-Phe-Arg-AMC as a lead, and used to identify the structural factors determining the susceptibility of peptides to hydrolysis at acidic and neutral pH values. Each peptide differs from the others in one amino acid (residue 6) and contains a highly fluorescent Nma group linked to the alpha-amino function of the N-terminal Orn residue and a Dnp group linked to the side chain of the Lys(8) residue acting as a quencher. Proteolytic cleavage was monitored by measuring the increase of fluorescence at 440 nm upon excitation at 340 nm, and the cleavage sites were determined by HPLC followed by ESI-MS analysis. Peptides containing Ala or Phe at position 6 are good substrates for the enzyme at both pH 5.0 and 7.4. By contrast, those containing Glu, Asp, Lys or Val are not cleaved at all by cathepsin B at pH 7.4, and are poorly hydrolyzed at pH 5.0. These findings provide new information for the rational design of cathepsin B-activated peptide-containing anticancer drugs.     

Ion-binding and pharmacological properties of Tyr6 and Tyr9 antamanide analogs.

In order to investigate the antiproliferative properties of antamanide, we have synthesized and studied two antamanide analogs where the phenylalanine residue in positions 6 or 9 is substituted by tyrosine, their corresponding linear forms and the cyclic and linear des Phe5,Phe6-Tyr9-analogs. Antamanide and its biologically active synthetic analogs are able to form highly stable complexes with metal ions, particularly Na+, K+ and Ca2+. We studied the ion-binding properties of the Tyr-antamanide analogs by CD and Tb3+ -mediated fluorescence in acetonitrile. In this medium the far-and near-UV CD spectra of the neat Tyr6-antamanide analog are very similar to that of the parent cyclic decapeptide. Substantial differences occur on the contrary in the CD spectra of the neat Tyr9-antamanide, particularly in the regions at 220 nm and 270-290 nm. In acetonitrile, as already found for antamanide, the interaction with the above-mentioned metal ions always produces evident changes in the far- and near-UV CD spectra of both analogs. On the contrary, the CD spectra of the linear deca- and octa- and of the cyclic octa-analogs are affected by the presence of metal ions only in the near-UV region. In the same solvent the Tb3+ -mediated fluorescence spectra of all the synthetic peptides are remarkably affected by the addition of ions. On the basis of the spectral total changes, by using either or both the spectroscopic techniques, it has been possible to determine the ion binding constants for all the linear and cyclic Tyr-antamanide analogs and to compare them with that of the parent peptide. The antitoxic and antiproliferative activities of these antamanide analogs have been tentatively correlated to their ion-binding properties. A preliminary account of this work was given in (1).     

Biodemoraphy and genetics of the Berba of Benin

Genetic structure of the Berba of Benin was studied on the basis of biodemographic data and ABO, RH, MNS, KEL, JK, FY, ACP1, ADA, AK1, CA2, ESD, GLO1, G6PD, PGD, PGM1 (subtypes and thermostability), PGM2, PGP, SODA, HBα, HBβ, HBδ, BF, C3, and Hp gene frequencies. Comparisons were carried out with other populations of Benin and of sub-Sahara Africa. Correspondence analysis revealed genetic differentiation among the three main groups of populations who inhabit sub-Saharan Africa: Bushmen-Hottentots, Pygmies, and Negroes. The genetic differentiation of the Negroes in relation to their linguistic affiliation and geographic localization was evident. The first group included the populations belonging to the Bantoid subfamily of the Nigritic linguistic stock living in southern Africa; in the second subcluster the populations of central-eastern Africa were localized, and the third subcluster included the populations living in the West. © 1996 Wiley-Liss, Inc.     

Innate Olfactory Responses of <Emphasis Type="Italic">Asobara japonica</Emphasis> Toward Fruits Infested by the Invasive Spotted Wing Drosophila

Insect parasitoids are often manipulated to improve biological control programs for various arthropod pests. Volatile compounds can be a relevant cue used by most parasitoid hymenoptera for host or host microhabitat location. Here, we studied olfactory responses of the braconid Asobara japonica Belokobylskij, an Asiatic endoparasitoid of the invasive pest Drosophila suzukii (Matsumura), toward its host and host substrates. Adult A. japonica displayed an innate attraction to undescribed volatile cues from infested host fruits irrespectively of the juvenile rearing experience, i.e. they respond to a novel cue subsequently used for microhabitat selection. These data suggest that A. japonica parasitoids mass-reared on artificial diet and factitious host (D. melanogaster) can successfully locate their hosts. Naïve female parasitoids did not show a preference towards any of the tested host media. However, the enforced adult experience with the rearing host medium modified the olfactory preference patterns toward non-natal host fruits. These findings provide evidence of associative learning during the adult stage of A. japonica, and demonstrate its plasticity in exploiting the volatiles from various fruits infested by D. suzukii.