Cationic antimicrobial peptides (CAMPs) are a promising alternative to treat multidrug-resistant bacteria, which have developed resistance to all the commonly used antimicrobial, and therefore represent a serious threat to human health. One of the major drawbacks of CAMPs is their sensitivity to proteases, which drastically limits their half-life. Here we describe the design and synthesis of three nine-residue CAMPs, which showed high stability in serum and broad spectrum antimicrobial activity. As for all peptides a very low selectivity between bacterial and eukaryotic cells was observed, we performed a detailed biophysical characterization of the interaction of one of these peptides with liposomes mimicking bacterial and eukaryotic membranes. Our results show a surface binding on the DPPC/DPPG vesicles, coupled with lipid domain formation, and, above a threshold concentration, a deep insertion into the bilayer hydrophobic core. On the contrary, mainly surface binding of the peptide on the DPPC bilayer was observed. These observed differences in the peptide interaction with the two model membranes suggest a divergence in the mechanisms responsible for the antimicrobial activity and for the observed high toxicity toward mammalian cell lines. These results could represent an important contribution to unravel some open and unresolved issues in the development of synthetic CAMPs.

relevant role. They can be transformed into methyl esters for production of biodiesel or functionalized to produce surfactants, plasticizers, monomers, and new solvents [2,3]. These include cis-9-octadecenoic acid (oleic acid, OA in Scheme 1), which is a very interesting raw material, since it is renewable, inexpensive, and available in different geographical areas.Its most common transformations are epoxidation, hydroxylation, and oxidative cleavage of the double bond. The latter reaction is particularly interesting because it selectively produces azelaic acid (AA) and pelargonic acid (PA) (Scheme 1).Azelaic acid has important applications in textiles (polyesters and polyamides) and pharmaceuticals (antiacne). Industrially, oxidative cleavage of the double bond is carried out by ozonolysis [4]. However, use of ozone and molecular oxygen at high temperatures represents a serious drawback of this process, since these oxidants present combustion hazards. It is therefore required to find new processes that meet the standards of sustainability.A valid alternative is hydrogen peroxide, because it is capable of oxidizing with excellent atom economy and is safer than gaseous reactants [5]. Many of the known strategies couple H 2 O 2 with catalytic systems such as RuO 2 , Na 3 PO 4 {[WO(O 2 ) 2 ]}, H 2 WO 4 /Co(OAc) 2 , and Re 2 O 7 [6][7][8][9][10][11][12][13][14][15][16]. These synthetic routes (path i of Scheme 1) typically include a first step of dihydroxylation that gives 9,10-dihydroxystearic acid (DSA). In a second step (ii) a new catalyst is introduced, either in the same reaction environment [14] or on the purified diol [15], for oxidative cleavage of the CH(OH)-CH(OH) bond.Recently, an efficient one-pot strategy (iii in Scheme 1) was proposed with a catalyst based on the quaternary ammonium salt Q 3 {PO 4 [WO(O 2 ) 2 ] 4 } [17]. Even in this case, there are some disadvantages, namely high catalyst Abstract This work describes two sustainable methods for production and purification of azelaic acid (AA) to replace the current process of ozonolysis of oleic acid (OA). The first proceeds in two steps, coupling smooth oxidation of OA to 9,10-dihydroxystearic acid (DSA) with subsequent oxidative cleavage by sodium hypochlorite. An alternative methodology is also proposed, using a chemocatalytic system consisting of H 2 O 2 /H 2 WO 4 for direct oxidative cleavage of the double bond of OA at 373 K. A convenient technique for separation and purification of azelaic acid is also proposed.

Two transglutaminase-mediated modifications of the rat epididymal spermatozoon surface were demonstrated in vitro. Transglutaminase was effective in promoting the binding of spermidine to the sperm. Moreover, the enzyme, by reacting with one of the major proteins secreted by the rat seminal vesicle epithelium, produced a modified form of the protein with a higher molecular weight and the capability of binding to the sperm cells. A specific physiological role for the enzyme, bringing about modifications of the rat sperm surface in the seminal fluid environment, is suggested.

Antimicrobial peptides are promising candidates as future therapeutics in order to face the problem of antibiotic resistance caused by pathogenic bacteria. Myxinidin is a peptide derived from the hagfish mucus displaying activity against a broad range of bacteria. We have focused our studies on the physico-chemical characterization of the interaction of myxinidin and its mutant WMR, which contains a tryptophan residue at the N-terminus and four additional positive charges, with two model biological membranes (DOPE/DOPG 80/20 and DOPE/DOPG/CL 65/23/12), mimicking respectively Escherichia coli and Pseudomonas aeruginosa membrane bilayers. All our results have coherently shown that, although both myxinidin and WMR interact with the two membranes, their effect on membrane microstructure and stability are different. We further have shown that the presence of cardiolipin plays a key role in the WMR-membrane interaction. Particularly, WMR drastically perturbs the DOPE/DOPG/CL membrane stability inducing a segregation of anionic lipids. On the contrary, myxinidin is not able to significantly perturb the DOPE/DOPG/CL bilayer whereas interacts better with the DOPE/DOPG bilayer causing a significant perturbing effect of the lipid acyl chains. These findings are fully consistent with the reported greater antimicrobial activity of WMR against P. aeruginosa compared with myxinidin.

A broad biophysical analysis was performed to investigate the molecular basis of the neuroprotective action of Curcuma longa extracts in Alzheimer’s disease. By combining circular dichroism and electron paramagnetic resonance experiments with molecular modeling calculations, the minor components of Curcuma longa extracts, such as demethoxycurcumin (2, DMC), bisdemethoxycurcumin (3, BDMC) and cyclocurcumin (4, CYC), were analyzed in a membrane environment mimicking the phospholipid bilayer. Our study provides the first evidence on the relative role of single curcuminoids interacting with Aβ-peptide. When the CYC and curcumin metabolite tetrahydrocurcumin (5, THC) were inserted into an anionic lipid solution, a significant modification of the Aβ CD curves was detected. These data were implemented by EPR experiments, demonstrating that CYC reaches the inner part of the bilayer, while the other curcuminoids are localized close to the membrane interface. Computational studies provided a model for the curcuminoid-Aβ interaction, highlighting the importance of a constrained “semi-folded” conformation to interact with Aβ analogously to the pattern observed in α-helical coiled-coil peptide structures. This combined approach led to a better understanding of the intriguing in vitro and in vivo activity of curcuminoids as anti-Alzheimer agents, paving a new path for the rational design of optimized druggable analogues.

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The effect of the 665-683 fragment of the HIV fusion glycoprotein 41, corresponding to the MPER domain of the protein and named gp41MPER, on the microscopic structure and mesoscopic arrangement of palmitoyl oleoyl phosphatidylcholine (POPC) and POPC/sphingomyelin (SM)/cholesterol (CHOL) lipid bilayers is analyzed. The microscopic structuring of the bilayers has been studied by Electron Spin Resonance (ESR) spectroscopy, using glycerophosphocholines spin-labelled in different positions along the acyl chain. Transitions of the bilayer liquid crystalline state have been also monitored by Differential Scanning Calorimetry (DSC). Changes of the bilayers morphology have been studied by determining the dimension of the liposomes through Dynamic Light Scattering (DLS) measurements. The results converge in showing that the sample preparation procedure, the bilayer composition and the peptide/lipid ratio critically tune the lipid response to the peptide/membrane interaction. When gp41MPER is added to preformed liposomes, it positions at the bilayer interface and the lipid perturbation is limited to the more external segments. In contrast, if the peptide is mixed with the lipids during the liposome preparation, it assumes a trans-membrane topology. This happens at all peptide/lipid ratios for fluid POPC bilayers, while in the case of rigid POPC/SM/CHOL membranes a minimum ratio has to be reached, thus suggesting peptide self-aggregation to occur. Peptide insertion results in a dramatic increase of the lipid ordering and bilayer stiffening, which reflect in significant changes in liposome average dimension and distribution. The biological implications of these findings are discussed.

A Ca2+-dependent, transglutaminase-like activity has been detected both free in the human seminal plasma and bound on the spermatozoon surface. A marked variability of the two enzymatic activities in the semen of different normal subjects was observed; but limited changes occurred in various ejaculates of the same individual. Moreover, we report evidence of the ability of several seminal plasma proteins to act as acyl donor substrates for endogenous transglutaminase, whereas human ejaculated spermatozoa have been shown to possess polyamine-binding sites specifically involved in transglutaminase-catalyzed reactions. It is postulated that semen transglutaminase may play a role in suppressing sperm antigenicity and in the male gamete's acquiring biological features of a fully differentiated and fertile cell.