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The continuous flow telescoped synthesis of 1,1-cyclopropane aminoketones was achieved by optimizing the photocyclization of 1,2-diketones to 2-hydroxycylobutanones (HCBs) and their reaction with aryl- and alkylamines, via tandem condensation C4-C3-ring contraction reaction. With the achieved operational conditions, we were able to obtain a library of cyclopropylamines with good chemical yields, high productivity, and short residence times.

2,8-Dithia-5-aza-2,6-pyridinophane ( L1 ) has been used as a receptor unit in the construction of the conjugated redox chemosensor 5-ferrocenylmethyl-2,8-dithia-5-aza-2,6-pyridinophane ( L3 ). In order to further explore the coordination chemistry of L1 , and comparatively, that of its structural analogue 2,11-dithia-5,8-diaza-2,6-pyridinophane ( L2 ), featuring two secondary nitrogen atoms in the macrocyclic unit, the crystal structures of the new synthesised complexes [Pb( L1 )(ClO 4 ) 2 ]·½CH 3 CN, [Cu( L2 )](ClO 4 ) 2 ·CH 3 CN and [Cd( L2 )(NO 3 )]NO 3 were determined by X-ray diffraction analysis. The electrochemical response of L3 towards the metal ions Cu 2+ , Zn 2+ , Cd 2+ , Hg 2+ , and Pb 2+ was investigated by cyclic voltammetry (CV) in CH 2 Cl 2 /CH 3 CN 0.25:1 ( v / v ) mixture. Upon addition to L3 of increasing amounts of the aforementioned metal cations, the wave corresponding to the Fc + /Fc redox couple of the un-complexed L3 was gradually replaced by a new reversible wave at more positive potentials and corresponding to the Fc + /Fc redox couple of the complexed ligand. The maximum anodic shift of the ferrocene oxidation wave is observed in the presence of Pb 2+ (230 mV), to which corresponds a reaction coupling efficiency (RCE) value as large as 7.9 × 10 3 . The response selectivity of L3 is discussed in reference to the optical selectivity observed for conjugated chemosensors featuring L1 as receptor unit and different fluorogenic fragments as signalling units., Competing Interests: The authors declare no conflicts of interest.

Tyrosinase, a key protein in the biosynthesis of melanin pigments, is crucial in determining skin pigmentation. Inhibiting tyrosinase activity is a promising approach for treating conditions related to excessive pigmentation. For the synthesis of more potent tyrosinase inhibitors, we combined two approaches, para-substitution and lipophilicity, to enhance the inhibitory properties of ( E )-2-(4-hydroxybenzylidene)hydrazine-1-carbotiamide, whose enzyme inhibitory properties have been previously demonstrated. The newly synthesized compounds showed potent inhibition activity against tyrosinase in the micromolar concentration range. The synthesised compounds were up to 41 times more effective than kojic acid. In addition to this biological activity, all molecules were evaluated for their sun protection factor to determine their photoprotective effects. All the compounds showed higher efficacy than reference compounds, used as sunscreens in photoprotective preparations. All compounds were noncytotoxic at the concentration required to inhibit tyrosinase activity. With the aim of defining the potential binding modes and the kind of interactions between the studied molecules and the catalytic site of mushroom tyrosinase, molecular docking simulations were also performed.

By studying the structures of (μ-1,4,10,13-tetrathia-7,16-diazacyclooctadecane)bis[iodidopalladium(II)] diiodide penta(diiodine), [Pd 2 I 2 (C 12 H 26 N 2 S 4 )](I) 2 ·5I 2 or [Pd 2 I 2 ([18]aneN 2 S 4 )](I) 2 ·(I 2 ) 5 , and 4,7,13,16,21,24-hexaoxa-1,10-diazoniabicyclo[8.8.8]hexacosane triiodide iodide hemipenta(diiodine) dichloromethane monosolvate, C 18 H 38 N 2 O 6 2+ ·I 3 - ·I - ·2.5I 2 ·CH 2 Cl 2 or [H 2 ([2.2.2]cryptand)](I 3 )(I)(I 2 ) 2.5 ·CH 2 Cl 2 , we confirm the structural variety of extended polyiodides achievable upon changing the shape, charge and dimensions of the cation template, by altering the synthetic strategy adopted and/or the experimental conditions. Although it is still often difficult to characterize discrete [I 2m+n ] n- polyiodides higher than I 3 - on the basis of structural parameters, such as I-I bond distances, FT-Raman spectroscopy appears to identify them as aggregates of I 2 , I - and (symmetric or slightly asymmetric) I 3 - building blocks linked by I...I interactions of varying strengths. However, because FT-Raman spectroscopy carries no information about the topological features of extended polyiodides, the two techniques should therefore be applied in combination to enhance the analysis of this kind of compounds., (open access.)

4,4'-(Disulfanedi-yl)dipyridinium chloride triiodide, C 10 H 10 N 2 S 2 2+ ·Cl - ·I 3 - , ( 1 ) was synthesized by reaction of 4,4'-di-pyridyl-disulfide with ICl in a 1:1 molar ratio in di-chloro-methane solution. The structural characterization of 1 by SC-XRD analysis was supported by elemental analysis, FT-IR, and FT-Raman spectroscopic measurements., (© Podda et al. 2024.)

Long afterglow phosphors constitute an emerging class of compounds with wide application in several fields, from photonic to dosimetry, solar energy storage and photocatalysis. In this study, we synthesized and thoroughly characterized a new class of persistent emitting materials, Ca 3 Ga 4 O 9 : xBi 3+ , yZn 2+ , zTb 3+ . Through the utilization of X-ray and Raman spectroscopy, as well as optical measurements including static and time-resolved luminescence, thermoluminescence, and phosphorescence, the effects of the Tb concentration on the optical and structural properties of the material has been deeply studied. A suitable mechanism was proposed to account for the long afterglow emission, wherein Tb3+ and Bi3+ ions occupying the Ca2+ sites serve as recombination centers, facilitating the generation of oxygen defects. Zn 2+ in the Ga 3+ sites, contribute to the charge balance and generates hole traps in the matrix. The enduring phosphorescence persists for over 3 h following the cessation of UV irradiation, discernible to the naked eye in low-light conditions., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Author(s).)

The reactivity between bis(pyridin-2-yl)diselane o Py 2 Se 2 and ditellane o Py 2 Te 2 (L1 and L2, respectively; o Py=pyridyn-2-yl) and I 2 /Br 2 is discussed. Single-crystal structure analysis revealed that the reaction of L1 with I 2 yielded [(HL1 + )(I - )⋅5/2I 2 ] ∞ (1) in which monoprotonated cations HL1 + template a self-assembled infinite pseudo-cubic polyiodide 3D-network, while the reaction with Br 2 yielded the dibromide H o PySe II Br 2 (2). The oxidation of L2 with I 2 and Br 2 yielded the compounds H o PyTe II I 2 (3) and H o PyTe IV Br 4 (6), respectively, whose structures were elucidated by X-ray diffraction analysis. FT-Raman spectroscopy measurements are consistent with a 3c-4e description of all the X-Ch-X three-body systems (Ch=Se, Te; X=Br, I) in compounds 2, 3, H o PyTe II Br 2 (5), and 6. The structural and spectroscopic observations are supported by extensive theoretical calculations carried out at the DFT level that were employed to study the electronic structure of the investigated compounds, the thermodynamic aspects of their formation, and the role of noncovalent σ-hole halogen and chalcogen bonds in the X⋅⋅⋅X, X⋅⋅⋅Ch and Ch⋅⋅⋅Ch interactions evidenced structurally., (© 2023 The Authors. Chemistry - An Asian Journal published by Wiley-VCH GmbH.)

Ammonium N -(pyridin-2-ylmethyl)oxamate (AmPicOxam), synthesized from O -methyl- N -(pyridin-2-ylmethyl)oxamate, was spectroscopically and structurally characterized and assayed as a novel precursor for the protection and consolidation of carbonate stone substrates. An in-depth characterization of treated and untreated biomicritic limestone and white Carrara marble samples was carried out by means of SEM microscopy, X-ray powder diffraction, helium pycnometry, determination of water transport properties, and pull-off tests. The improved solubility (1.00 M, 16.5% w / w ) of the title compound with respect to ammonium oxalate (0.4 M, 5% w / w ) results in the formation of a thicker protective coating of calcium oxalate (CaOx) dihydrate (weddellite) on marble and biomicrite samples after the treatment with 5% and 12% w / w water solutions, producing a reduction in the stone porosity and increased cohesion. Theoretical calculations were carried out at the DFT level to investigate both the electronic structure of the N -(pyridin-2-ylmethyl)oxamate anion and the hydrolysis reaction leading from AmPicOxam to CaOx.

The third-order nonlinear optical (NLO) properties of a series of platinum diimine-dithiolate complexes [Pt(N^N)(S^S)] were investigated by means of Z -scan measurements, revealing second hyperpolarizability values up to 10 -29 esu, saturable absorption properties, and nonlinear refractive behaviour, which were rationalized also by means of DFT calculations.

The experimental structural features of chalcogen bonding (ChB) interactions in over 34,000 linear fragments R-Ch⋯A (Ch = S, Se, Te; R = C, N, O, S, Se, Te; A = N, O, S, Se, Te, F, Cl, Br, I) were analyzed. The bond distances d R-Ch and the interaction distances d Ch⋯A were investigated, and the functions δ R-Ch and δ Ch⋯A were introduced to compare the structural data of R-Ch⋯A fragments involving different Ch atoms. The functions δ R-Ch and δ Ch⋯A were calculated by normalizing the differences between the relevant bond d R-Ch and ChB interaction d Ch⋯A distances with respect to the sum of the relevant covalent ( r cov R + r cov Ch ) and the van der Waals (vdW) radii ( r vdW Ch + r vdW A ), respectively. A systematic comparison is presented, highlighting the role of the chalcogen involved, the role of the R atoms covalently bonded to the Ch, and the role of the A species playing the role of chalcogen bond acceptor. Based on the results obtained, an innovative approach is proposed for the evaluation and categorization of the ChB strength based on structural data.

A series of new complexes of general formula [Au III (N^N)Br 2 ](PF 6 ) (N^N = 2,2'-bipyridine and 1,10-phenanthroline derivatives) were prepared and characterized by spectroscopic, electrochemical, and diffractometric techniques and tested against Gram-positive and Gram-negative bacterial strains ( Staphylococcus aureus , Streptococcus intermedius , Pseudomonas aeruginosa , and Escherichia coli ), showing promising antibacterial and antibiofilm properties.

The reactivity of 1,1'-bis(3-methyl-4-imidazolin-2-selone)methane ( L1 ) and 1,2-bis(3-methyl-4-imidazolin-2-selone)ethane ( L2 ) toward I 2 has been explored in MeCN under different experimental conditions and compared with that in CH 2 Cl 2 . The compounds [ L1' ](I) 2 ( I ), [ L1 I] n (I) n ( II ), [ L1 (μ-Se)](I) 2 ·1/2H 2 O ( III ), [ L1 I](I 3 )·2I 2 ( IV ), and [ L2 ](I) 2 ·MeCN ( V ) were obtained and characterized. X-ray diffraction analyses point out an ionic nature for these compounds, which is presumably favored by the polarity of the solvent used. In particular, [ L1 I] n (I) n ( II ) represents the first example of an iodonium complex of imidazoline-2-selone derivatives, while [ L1 (μ-Se)](I) 2 ·1/2H 2 O ( III ) represents a unique example of a dicationic [RSeSeSeR] triselane. Density functional theory calculations have allowed us to better understand the nature of the obtained compounds and to justify their formations in polarizing reaction conditions rather than in low polar solvents.

The reaction of the complex [Au(phen)Br 2 ](PF 6 ) (phen = 1,10-phenanthroline) with molecular dibromine afforded {[Au(phen)Br 2 ](Br 3 )} ∞ ( 1 ). Single crystal diffraction analysis showed that the [Au(phen)Br 2 ] + complex cations were bridged by asymmetric tribromide anions to form infinite zig-zag chains featuring the motif ···Au-Br···Br-Br-Br···Au-Br···Br-Br-Br···. The complex cation played an unprecedented halogen bonding (XB) donor role engaging type-I and type-II XB noncovalent interactions of comparable strength with symmetry related [Br 3 ] - anions. A network of hydrogen bonds connects parallel chains in an infinite 2D network, contributing to the layered supramolecular architecture. DFT calculations allowed clarification of the nature of the XB interactions, showing the interplay between orbital mixing, analyzed at the NBO level, and electrostatic contribution, explored based on the molecular potential energy (MEP) maps of the interacting synthons., Competing Interests: The authors declare no conflicts of interest.

The photoconducting properties of platinum diimine-dithiolate complex [Pt(bipy)(Naph-edt)] (1; bipy = 2,2'-bipyridine; Naph-edt2- = 2-naphthylethylene-1,2-dithiolate) were investigated. DFT calculations on a model assembly with four complex units suggest that the high external quantum efficency measured on a prototype photodetector correlates with the intermolecular character of electronic excitations in the visible region.

The reactivity of thiomorpholinium P -(4-methoxyphenyl)- N -thiomorpholin-amidodithiophosphonate ( S-MorH + ₂)(S-Mor-adtp - ) and morpholinium P -(4-methoxyphenyl)- N -morpholin-amidodithiophosphonate (O-MorH + ₂)(O-Mor-adtp - ) towards nickel (II) dichloride hexahydrated is presented and the hydrolysis of the relevant metal complexes investigated. The hydrolytic products (S-MorH + ₂)₂ [Ni(dtp)₂]²- and (O-MorH + ₂)₂[Ni(dtp)₂]²- were characterized by means of FT-IR, 1 H, and 31 P NMR and XRD and the experimented P-N cleavage investigated and elucidated by means of DFT calculations. The antimicrobial activity of the neutral nickel complex [Ni(S-Mor-adtp)₂] was tested against a set of Gram-positive and Gram-negative bacteria alongside with its nanodispersion in a silica matrix. The complex [Ni(S-Mor-adtp)₂] did not show antibacterial activity, whilst the nano-dispersed sample [Ni(S-Mor-adtp)₂]_SiO₂ demonstrated inhibition to growth of Staphylococcus aureus . The nanocomposites were fully characterized by means of XRPD, TGA, SEM and dinitrogen sorption techniques.

The reaction between differently substituted borasiloxanes and 2,5-bis(3-pyridylethynyl)thiophene provided the first example of luminescent borasiloxane-based chiral helices held together by N-B bonds. The starting building blocks and the helices were fully characterized, and the nature of the N-B bond rationalized by means of theoretical calculations.

The reaction of the bis(1,2-dithiolene) complex [Pd(Me 2 timdt) 2 ] ( 1 ; Me 2 timdt •- = monoreduced 1,3-dimethyl-2,4,5-trithioxoimidazolidine) with Br 2 yielded the complex [Pd(Me 2 timdt)Br 2 ] ( 2 ), which was reacted with Na 2 mnt (mnt 2- = 1,2-dicyano-1,2-ethylenedithiolate) to give the neutral mixed-ligand complex [Pd(Me 2 timdt)(mnt)] ( 3 ). Complex 3 shows an intense solvatochromic near-infrared (NIR) absorption band falling between 955 nm in DMF and 1060 nm in CHCl 3 (ε = 10700 M -1 cm -1 in CHCl 3 ). DFT calculations were used to elucidate the electronic structure of complex 3 and to compare it with those of the corresponding homoleptic complexes 1 and [Pd(mnt) 2 ] ( 4 ). An in-depth comparison of calculated and experimental structural and vis-NIR spectroscopic properties, supported by IEF-PCM TD-DFT and NBO calculations, clearly points to a description of 3 as a dithione-dithiolato complex. For the first time, a broken-symmetry (BS) procedure for the evaluation of the singlet diradical character (DC) of heteroleptic bis(1,2-dithiolene) complexes has been developed and applied to complex 3 . The DC, predominant for 1 ( n D C = 55.4%), provides a remarkable contribution to the electronic structures of the ground states of both 3 and 4 , showing a diradicaloid nature ( n D C = 24.9% and 27.5%, respectively). The computational approach developed here clearly shows that a rational design of the DC of bis(1,2-ditiolene) metal complexes, and hence their linear and nonlinear optical properties, can be achieved by a proper choice of the 1,2-dithiolene ligands based on their electronic structure.

Metal bis(1,2-dithiolene) complexes belonging to the class [Ni(Ar-edt) 2 ] x - [Ar-edt 2- = arylethylene-1,2-dithiolate; Ar = phenyl, ( 1 x - ), 2-naphthyl ( 2 x - ); x = 0 and 1] were fully characterized by NMR, UV-visible-near-infrared (UV-vis-NIR), diffuse reflectance, and FT-IR spectroscopy, as well as cyclic voltammetry and single-crystal X-ray diffraction analysis. These complexes have emerged as new photoconducting materials that allowed for the development of a prototype of photodetectors with response in the vis-NIR region. The photodetecting devices showed in some cases quantum efficiencies orders of magnitude higher than those of previously reported 1,2-dithiolene systems.

The reactions of 2,4-bis(4-methoxyphenyl)-1,3-dithio-2,4-diphosphetane-2,4-disulfide (Lawesson's Reagent, LR) with benzylamine (BzNH 2 ) and 4-phenylbutylamine (PhBuNH 2 ) yield benzylammonium P -(4-methoxyphenyl)- N -benzyl-amidodithiophosphonate (BzNH 3 )(BzNH-adtp) and 4-phenylbutylammonium P -(4-methoxyphenyl)- N -(4-phenylbutyl)-amidodithiophosphonate (PhBuNH 3 )(PhBuNH-adtp). The relevant nickel complexes [Ni(BzNH-adtp) 2 ] and [Ni(PhBuNH-adtp) 2 ] and the corresponding hydrolysed derivatives (BzNH 3 ) 2 [Ni(dtp) 2 ] and (PhBuNH 3 ) 2 [Ni(dtp) 2 ] were prepared and fully characterized. The antimicrobial activity of the aforementioned amidodithiophosphonates against a set of Gram-positive and Gram-negative pathogen bacteria was evaluated, and [Ni(BzNH-adtp) 2 ] and [Ni(PhBuNH-adtp) 2 ] showed antiproliferative activity towards Staphylococcus aureus and Staphylococcus haemolyticus strains. density functional theory (DFT) calculations were performed to shed some light on the activity of reported compounds related to their tendency towards P-N bond cleavage.

Proline-rich peptides are a unique group of antimicrobial peptides that exert their activity selectively against Gram-negative bacteria through an apparently non-membranolytic mode of action that is not yet well understood. We have investigated the mechanism underlying the antibacterial activity of the proline-rich cathelicidin Bac7 against Salmonella enterica and Escherichia coli. The killing and membrane permeabilization kinetics as well as the cellular localization were assessed for the fully active N-terminal fragment Bac7(1-35), its all-D enantiomer and for differentially active shortened fragments. At sub-micromolar concentrations, Bac7(1-35) rapidly killed bacteria by a non-lytic, energy-dependent mechanism, whereas its D-enantiomer was inactive. Furthermore, while the L-enantiomer was rapidly internalized into bacterial cells, the D-enantiomer was virtually excluded. At higher concentrations (>or=64 microM), both L- and D-Bac7(1-35) were instead able to kill bacteria also via a lytic mechanism. Overall, these results suggest that Bac7 may inactivate bacteria via two different modes of action depending on its concentration: (i) at near-MIC concentrations via a mechanism based on a stereospecificity-dependent uptake that is likely followed by its binding to an intracellular target, and (ii) at concentrations several times the MIC value, via a non-stereoselective, membranolytic mechanism.

Ten peptides from 13 to 35 residues in length and covering the whole sequence of the Pro-rich peptide Bac7 were synthesized to identify the domain responsible for its antimicrobial activity. At least 16 residues of the highly cationic N-terminal sequence were required to maintain the activity against Gram-negative bacteria. The fragments Bac7(1-35) and, to a lesser extent, Bac7(1-16) proved active against a panel of antibiotic-resistant clinical isolates of Gram-negative bacteria, with the notable exception of Burkholderia cepacia. In addition, when tested against fungi, the longer fragment was also active against collection strains and clinical isolates of Cryptococcus neoformans, but not towards clinical isolates of Candida albicans.

Imidazolium trans-imidazoledimethylsulphoxidetrachlororuthenate (NAMI-A) was tested in vitro on the pro-adhesive properties, evaluated as resistance to trypsin treatment, which is a bona fide measure of adhesion strength, of KB and HeLa carcinoma cell lines and on human polymorphonuclear neutrophils (HPMN). NAMI-A increased the pro-adhesive activity of KB cells at 0.001 mM concentration, after few minutes incubation and this effect was not influenced by the vehicle used for cell challenge, neither did it depend on NAMI-A concentration or on temperature. The same effect occurred on HeLa cells at 0.01 mM NAMI-A. This effect, detected at concentrations up to 100 times lower than those necessary to block cells at the G(2)-M premitotic phase of cell cycle, or to inhibit matrix metalloproteinase release or cell invasion, was not related to ruthenium uptake by tumour cells. HeLa cells and healthy HPMN, following short exposure to 0.1 mM NAMI-A, assumed a different shape, with the extrusion of filopodia (HeLa) and of large lamellopodia (HPMN), which increased their interactions with the substrate. This effect was attributed to stabilisation, altered turnover and sensitivity to cytochalasin D of actin filaments. Provided that adhesion is associated with cell motility and invasion, these data suggest that NAMI-A may exert antimetastatic properties at concentrations lower than those observed in the lungs at the end of a conventional intraperitoneal treatment in vivo.

Exposure of the nonsteroidal anti-inflammatory drug suprofen (SUP) to UV-radiation results in the formation of radicals, reactive oxygen species (ROS), photodecarboxylated products and photoadducts with biomacromolecules. Using an ex vivo pigskin explant model, we investigated whether topical coapplication of the water-soluble antioxidants vitamin C (Lascorbic acid, ASC), N-acetyl-L-cysteine (NAC) or L-cysteine ethylester (CYSET) with SUP reduced ultraviolet A (UVA)-induced decomposition of SUP. UVA-induced changes in antioxidant bioavailability in the stratum corneum and epidermis were also studied. Epidermal bioavailability of SUP in sham-irradiated pigskin increased 2.2- to 4.1-fold after the lowest antioxidant doses (P < 0.05). As compared with no applied antioxidant, increasing doses of all tested antioxidants resulted in increased levels of SUP and decreased levels of photoproducts (P < 0.05). A maximal protection against SUP photodegradation of 70% was found after an ASC dose of 1 micromol/cm2; these values were 60% for a NAC dose of 10 micromol/cm2 and 50% for a CYSET dose of 5 micromol/cm2. Skin antioxidant levels increased with increasing applied dose (P < 0.05); the bioavailability of CYSET was approximately three-fold lower than that of ASC and NAC. UVA exposure resulted in 30-50% consumption of the topically applied ASC or NAC in the stratum corneum, whereas CYSET was not consumed. In conclusion, the topically applied water-soluble antioxidants ASC, NAC and CYSET protect against UVA-induced decomposition of SUP by scavenging radicals and ROS. Coapplication of these antioxidants may therefore be an effective way to reduce or prevent the phototoxic effects of SUP in vivo.

Topically applied antioxidants constitute an important group of protective agents against skin damage induced by ultraviolet radiation. The current study was performed to investigate whether a recently developed ex vivo pig skin model was suitable for short-term studies of the mechanism(s) of UVB-radiation-induced skin damage; the protective effect of topical application of alpha-tocopherol, l-ascorbic acid, alpha-lipoic acid, glutathione ethylester and N-acetylcysteine was tested. Increasing doses of the antioxidants were applied topically on ex vivo pig skin explants and allowed to penetrate for 60 min. Epidermal antioxidant bioavailability was measured before and 60 min after exposure to an ultraviolet B (UVB) radiation of 7.5 kJ/m2. Cell viability (trypan blue dye exclusion) and apoptosis were measured 48 h later in isolated keratinocytes. UVB-radiation-induced epidermal lipid peroxidation was determined immediately after exposure of the skin to a UVB dose of 28 kJ/m2. All antioxidants tested became bioavailable in pig skin epidermis, and none of them were depleted after UVB-radiation exposure. Increasing doses of the antioxidants tested decreased UVB-radiation-induced cell death and apoptosis. The highest doses of antioxidants prevented UVB-radiation-induced lipid peroxidation; alpha-lipoic acid only tended to decrease lipid peroxidation. In conclusion, a single topical dose of the above antioxidants on ex vivo pig skin can reduce UVB-radiation-induced oxidative stress and lipid peroxidation and thereby reduce apoptotic stimuli and cell death. Furthermore, the ex vivo pig skin model was a useful tool for testing compounds for their antioxidant activity.

Pro-rich antimicrobial peptides are a group of linear peptides of innate immunity isolated from mammals and invertebrates, and characterised by a high content of proline residues (up to 50%). Members of this group are predominantly active against Gram-negative bacterial species which they kill by a non-lytic mechanism, at variance with the majority of the known antimicrobial peptides. Evidence is accumulating that the Pro-rich peptides enter the cells without membrane lysis and, once in the cytoplasm, bind to, and inhibit the activity of specific molecular targets essential to bacterial growth, thereby causing cell death. This mode of action makes these peptides suitable for drug development efforts. In addition to antibacterial action, PR-39, one of the better characterised Pro-rich peptides from mammals, exerts other potentially exploitable biological activities, such as induction of syndecan expression in mesenchymal cells and inhibition of the NADPH oxidase activity of neutrophils, suggesting a role of this peptide in wound repair and inflammation. PR-39 also exerts a protective effect in various animal models of ischemia-reperfusion injury, preventing the post-ischemic oxidant production, and is a potent inducer of angiogenesis both in vitro and in vivo. Although the physiological relevance of all these effects has not yet been established, the above observations underscore the therapeutic potential of this peptide in a number of complex processes such as inflammation, wound repair, ischemia-reperfusion injury, and angiogenesis.

Based on the high level of identity among human, mouse, and rat MRP1 protein sequence, we produced a specific polyclonal antibody (MRP1-A23) against a synthetic polypeptide covering the C-terminus of the human protein. Western blot analysis showed a reactivity against human MRP1 similar to that obtained with the monoclonal QCRL1 antibody. Differently from other available antibodies against human MPR1, MRP1-A23 also detected both rat and mouse MRP1. No cross-reactivity was observed with either human or mouse MRP2 while MRP1-A23 weakly cross-reacted with rat MRP2 in the protein region ranging from 1512 to 1533 amino acids. These data indicate that MRP1-A23 allows specific MRP1 detection in both human and rodent tissues and may provide an important tool in the study of MRP1 expression and function in both experimental and clinical materials., (Copyright 2001 Academic Press.)