Development of a neuromedin U–human serum albumin conjugate as a long‐acting candidate for the treatment of obesity and diabetes. Comparison with the PEGylated peptide

Neuromedin U (NMU) is an endogenous peptide implicated in the regulation of feeding, energy homeostasis, and glycemic control, which is being considered for the therapy of obesity and diabetes. A key liability of NMU as a therapeutic is its very short half‐life in vivo. We show here that conjugation of NMU to human serum albumin (HSA) yields a compound with long circulatory half‐life, which maintains full potency at both the peripheral and central NMU receptors. Initial attempts to conjugate NMU via the prevalent strategy of reacting a maleimide derivative of the peptide with the free thiol of Cys34 of HSA met with limited success, because the resulting conjugate was unstable in vivo. Use of a haloacetyl derivative of the peptide led instead to the formation of a metabolically stable conjugate. HSA–NMU displayed long‐lasting, potent anorectic, and glucose‐normalizing activity. When compared side by side with a previously described PEG conjugate, HSA–NMU proved superior on a molar basis. Collectively, our results reinforce the notion that NMU‐based therapeutics are promising candidates for the treatment of obesity and diabetes. Copyright © 2013 European Peptide Society and John Wiley & Sons, Ltd.     

Relative potency of the forms of GnRH and their analogs on LH release in sea bass

The in vivo and in vitro potency of native and modified forms of gonadotropin releasing hormone (GnRH) to release luteotropic hormone (LH) was studied in sea bass Dicentrarchus labrax in particular the hypothalamic fish‐specific sea bream GnRH form (sbGnRH) and the general mesoencephalic form chicken GnRH‐II (cGnRH‐II). The potencies of the natives and their analogs (GnRHas) were referred to that of [D‐Ala⁶, Pro⁹Net]‐mGnRHa (LHRHa) at equivalent doses. Analogs of the native peptides [D‐Arg⁶, Pro⁹Net]‐cGnRH‐II, [D‐Ala⁶, Pro⁹Net]‐cGnRH‐II, [D‐Trp⁶, Pro⁹Net]‐sbGnRH and [D‐Ala⁶, Pro⁹Net]‐sbGnRH were effective in inducing in vivo LH release (at 15 µg kg^?1 body mass), exhibiting longer lasting activity than their corresponding native forms. Injection of sbGnRH and cGnRH‐II provoked a small but significant peak of circulating LH at 1·5 h after treatment (a.t.) decreasing down to basal levels at 4 h a.t. [D‐Arg⁶, Pro⁹Net]‐cGnRH‐II, [D‐Ala⁶, Pro⁹Net]‐cGnRH‐II and [D‐Ala⁶, Pro⁹Net]‐mGnRHa evoked a higher and a more sustained elevation of LH, peaking at 12 h a.t. and returning to basal levels between 48 and 72 h a.t. [D‐Trp⁶, Pro⁹Net]‐sbGnRH and [D‐Ala⁶, Pro⁹Net]‐sbGnRH also induced a significant surge of LH in plasma at 4 h a.t. turning to the basal levels at 24 h a.t. These rises, however, were of less amplitude and duration than the observed after treatment with cGnRH‐II analogs and [D‐Ala⁶, Pro⁹Net]‐mGnRHa. The in vitro stimulation of dispersed pituitary cells with the different native and modified forms of GnRH resulted in a dose‐dependent increase in the quantity of LH released at 24 h a.t. [D‐Arg⁶, Pro⁹Net]‐cGnRH‐II and [D‐Ala⁶, Pro⁹Net]‐cGnRH‐II induced the highest response of LH in vitro release followed by salmon GnRH (sGnRH), [D‐Ala⁶, Pro⁹Net]‐mGnRHa and [D‐Trp⁶, Pro⁹Net]‐sbGnRH. The lowest activity was exhibited by sbGnRH. Collectively, the in vitro biological activity (compared by their EC₅₀) can be ordered as follows: [D‐Arg⁶, Pro⁹Net]‐cGnRH‐II > [D‐Ala⁶, Pro⁹Net]‐cGnRH‐II > sGnRH > [D‐Ala⁶, Pro⁹Net]‐mGnRHa > [D‐Trp⁶, Pro⁹Net]‐sbGnRH > [D‐Ala⁶, Pro⁹Net]‐sbGnRH > cGnRH‐II > sbGnRH.     

Brain Pharmacokinetics of Non‐Imidazole Biphenyl H3 Receptor Antagonists: a Liquid Chromatography/Electrospray‐Mass Spectrometry and ex vivo Binding Study in Rats

In the present article, we report on the kinetics of brain penetration in rats of the H3R antagonist 1,1′‐[1,1′‐biphenyl‐4,4′‐diylbis(methylene)]bis‐[piperidine] ( 1 ), which had shown a favorable in vitro pharmacological profile and in vivo potency in preventing scopolamine‐induced amnesia. Two different approaches were employed: high‐performance liquid chromatography/electrospray‐mass spectrometry (HPLC/ESI‐MS) and ex vivo binding against the labeled agonist [³H]‐(R)‐α‐methylhistamine ([³H]RAMHA). Starting from the structure of 1 , the rigid piperidine ring was replaced by a flexible dipropylamino group (see 2 ) or by a morpholino ring (see 3 ), endowed with lower basicity. The effect of replacement on rat plasma and brain disposition in the 24 h after administration was analyzed. High (μM ) and persistent concentrations of 1 were found in rat plasma, while plasma levels were significantly lower (range: 0–200 nM ) for the other two derivatives. This could be explained, among other factors, by the higher stability, observed for 1 , to liver metabolic cleavage. The applied chemical modulation had an important effect on in vivo brain disposition, as, despite the comparable physico‐chemical properties, 2 did not show the tendency to accumulate within the brain, as stated by its brain vs. plasma concentration ratios, if compared to 1 . These structure? property relationships should be taken into account in the pharmacokinetic optimization of new series of H3 receptor antagonists.     

PDZ domains of RseP are not essential for sequential cleavage of RseA or stress‐induced σE activation in vivo

The Escherichia coli σ^E extracytoplasmic stress response monitors and responds to folding stress in the cell envelope. A protease cascade directed at RseA, a membrane‐spanning anti‐σ that inhibits σ^E activity, controls this critical signal‐transduction system. Stress cues activate DegS to cleave RseA; a second cleavage by RseP releases RseA from the membrane, enabling its rapid degradation. Stress control of proteolysis requires that RseP cleavage is dependent on DegS cleavage. Recent in vitro and structural studies found that RseP cleavage requires binding of RseP PDZ‐C to the newly exposed C‐terminal residue (Val148) of RseA, generated by DegS cleavage, explaining dependence. We tested this mechanism in vivo. Neither mutation in the putative PDZ ligand‐binding regions nor even deletion of entire RseP PDZ domains had significant effects on RseA cleavage in vivo, and the C‐terminal residue of DegS‐processed RseA also little affected RseA cleavage. Indeed, strains with a chromosomal rseP gene deleted for either PDZ domain and strains with a chromosomal rseA V148 mutation grew normally and exhibited almost normal σ^E activation in response to stress signals. We conclude that recognition of the cleaved amino acid by the RseP PDZ domain is not essential for sequential cleavage of RseA and σ^E stress response in vivo.     

Development and stability of bacteriocin resistance in Campylobacter spp

Aims: Several bacteriocins (BCNs) that were identified from chicken commensal bacteria dramatically reduced Campylobacter colonization in poultry and are being directed toward on‐farm control of this important foodborne human pathogen. A recent study has shown that BCN resistance in Campylobacter jejuni is very difficult to develop in vitro. In this study, in vivo development and stability of BCN resistance in Campylobacter was examined. Methods and Results: Chickens infected with Camp. jejuni NCTC 11168 were treated with BCN E‐760 at the dose of 5 mg kg^?1 body weight day^?1 via oral gavages for three consecutive days, which selected BCN‐resistant (BCN^r) mutants in the treated birds. However, all the in vivo‐selected mutants only displayed low levels of resistance to BCN (MIC = 2–8 mg l^?1) when compared to parent strain (MIC = 0·5 mg l^?1). Inactivation of CmeABC efflux pump of the BCN^r mutants led to increased susceptibility to BCN (8–32 fold MIC reduction). Three different BCN^rCampylobacter strains (in vitro‐ or in vivo‐derived) were examined for the stability of BCN resistance using both in vitro and in vivo systems. The low level of BCN resistance in these strains was not stable in vitro or in vivo in the absence of BCN selection pressure. Conclusions: Usage of BCN E‐760 only selected low‐level BCN^rCamp. jejuni mutants in vivo, and the low‐level BCN resistance was not stable in vitro and in vivo. Significance and Impact of the Study: The study provides helpful information for risk assessment of the future practical application of the anti‐Campylobacter BCNs in animals.     

A potent neuromedin U receptor 2-selective alkylated peptide

Neuromedin U (NMU) mediates various physiological functions via NMUR1 and NMUR2 receptors. NMUR2 has been considered a promising treatment option for diabetes and obesity. Although NMU-8, a shorter peptide, has potent agonist activity for both receptors, it is metabolically unstable. Therefore, NMU-8 analogs modified with long-chain alkyl moieties via a linker were synthesized. An octadecanoyl analog (17) with amino acid substitutions [αMePhe¹⁹, Nle²¹, and Arg(Me)²⁴] and a linker [Tra-γGlu-PEG(2)] dramatically increased NMUR2 selectivity, with retention of high agonist activity. Subcutaneous administration of 17 induced anorectic activity in C57BL/6J mice. Owing to its high metabolic stability, 17 would be useful in clarifying the physiological role and therapeutic application of NMU.     

Angiotensin II restricted analogs with biological activity in the erythrocytic cycle of Plasmodium falciparum

The anti‐plasmodial activity of conformationally restricted analogs of angiotensin II against Plasmodium gallinaceum has been described. To observe activity against another Plasmodium species, invasion of red blood cells by Plasmodium falciparum was analyzed. Analogs restricted with lactam or disulfide bridges were synthesized to determine their effects and constraints in the peptide–parasite interaction. The analogs were synthesized using tert‐butoxycarbonyl and fluoromethoxycarbonyl solid phase methods, purified by liquid chromatography, and characterized by mass spectrometry. Results indicated that the lactam bridge restricted analogs 1 (Glu‐Asp‐Arg‐Orn ‐Val‐Tyr‐Ile‐His‐Pro‐Phe) and 3 (Asp‐Glu‐Arg‐Val‐Orn ‐Tyr‐Ile‐His‐Pro‐Phe) showed activity toward inhibition of ring formation stage of P. falciparum erythrocytic cycle, preventing invasion in about 40% of the erythrocytes. The disulfide‐bridged analog 10 (Cys‐Asp‐Arg‐Cys ‐Val‐Tyr‐Ile‐His‐Pro‐Phe) was less effective yet significant, showing a 25% decrease in infection of new erythrocytes. In all cases, the peptides presented no pressor activity, and hydrophobic interactions between the aromatic and alkyl amino acid side chains were preserved, a factor proven important in efficacy against P. gallinaceum. In contrast, hydrophilic interactions between the Asp¹ carboxyl and Arg² guanidyl groups proved not to be as important as they were in the case of P. gallinaceum, while interactions between the Arg² guanidyl and Tyr⁴ hydroxyl groups were not important in either case. The β‐turn conformation was predominant in all of the active peptides, proving importance in anti‐plasmodial activity. This approach provides insight for understanding the importance of each amino acid residue on the native angiotensin II structure and a new direction for the design of potential chemotherapeutic agents. Copyright © 2014 European Peptide Society and John Wiley & Sons, Ltd.     

A simple protocol to characterize bacterial cell‐envelope lipoproteins in a native‐like environment

Physiological conditions in living cells are strictly regulated to allow, optimize, and coordinate biological processes. The bacterial cell envelope is the compartment where the communication with the external environment takes place. This involves membrane proteins, key players in many biological processes that ensure bacterial survival. The biochemical characterization of membrane proteins, either integral, lipidated or peripheral is challenging due to their mixed protein‐lipid nature, making it difficult to purify and obtain considerable amounts of samples. In contrast to integral membrane proteins, lipidated proteins are usually purified as truncated soluble versions, neglecting the impact of the membrane environment. Here we report a simple and robust protocol to characterize bacterial lipidated proteins in spheroplasts from Escherichia coli using a β‐lactamase as a model. The Metallo‐β‐lactamase NDM‐1 is an enzyme anchored to the inner leaflet of the outer membrane of Gram‐negative bacteria. Kinetic parameters and stability of the lipidated NDM‐1 and the soluble unbound version (NDM‐1 C26A) were measured in spheroplasts and periplasm, respectively. These studies revealed that membrane anchoring increases the K_M of the enzyme, consequently decreasing the catalytic efficiency, while not affecting its kinetic stability. This approach can be used to characterize lipidated proteins avoiding the purification step while mimicking its native environment. This approach also helps in filling the gap between in vitro and in vivo studies.     

Peptide hormone isoforms: N‐terminally branched PYY3–36 isoforms give improved lipid and fat‐cell metabolism in diet‐induced obese mice

The prevalence of obesity is increasing with an alarming rate worldwide and there is a need for efficacious satiety drugs. PYY3–36 has been shown to play a role in hypothalamic appetite regulation and novel analogs targeting the Y2 receptor have potential as drugs for the treatment of obesity. We have designed a series of novel PYY3–36 isoforms, by first adding the dipeptide Ile–Lys N‐terminal to the N^α of Ser‐13 in PYY13–36 and then anchoring the N‐terminal segment, e.g. PYY3–12, to the new Lys N^ε‐amine. We hypothesized that such modifications would alter the folding of PYY, due to changes in the turn motif, which could change the binding mode to the Y receptor sub‐types and possibly also alter metabolic stability. In structure‐affinity/activity relationship experiments, one series of PYY isoforms displayed equipotency towards the Y receptors. However, an increased Y2 receptor potency for the second series of PYY isoforms resulted in enhanced Y receptor selectivity compared to PYY3–36. Additionally, acute as well as chronic mice studies showed body‐weight‐lowering effects for one of the PYY isoforms, which was also reflected in a reduction of circulating leptin levels. Interestingly, while the stability and pharmacokinetic profile of PYY3–36 and the N‐terminally modified PYY3–36 analogue were identical, only mice treated with the branched analogue showed marked increases in adiponectin levels as well as reductions in non‐esterified free fatty acids and triglycerides. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd.     

Effect of N-nitroso-N-methylurea on viability and mutagenic response of repair-deficient strains of Escherichia coli

Various E. coli mutants, deficient in DNA repair, differed in their response to increasing concentrations of N-nitroso-N-methylurea (NMU).Loss of viability due to exposure to NMU was greatest in those strains with a reduced capacity for repair of single-strand breaks. Viability of wild-type and uvrA^? strains was not affected by NMU concentrations up to 3.0 mM. Some loss of viability occurred, at the higher NMU concentrations, in both strains carrying exrA^? while strains carrying uvrA^?polA^? or recA^? were the most sensitive. The results support the hypothesis that the lethal effect of NMU on repair-deficient E. coli was due to its ability to induce single-strand breaks.Induction of mutations by NMU was observed in all the strains used and the results suggested that NMU damage per se was the major mutational event. The dose response curve for induction of revertants by NMU was, however, influenced by the repair system(s) present. The number of revertants scored at the higher NMU concentrations was greater in those strains lacking the recA and polA dependent repair functions than in the wild-type strain. However, at NMU concentrations below 2.0 mM the numbers of revertants induced in exrA^? carrying strains, prossessing accurate rec-dependent repair, were lower than the comparable wild-type values. The evidence suggests that the uvrA gene product also acts on some, possibly non-mutagenic, types of NMU damage and that error-prone repair of these lesions increases the number of potential revertants.     

Design,synthesis and biological activity of flavonoid derivatives as selective agonists for neuromedin U 2 receptor

Central neuromedin U 2 receptor (NMU2R) plays important roles in the regulation of food intake and body weight. Identification of NMU2R agonists may lead to the development of pharmaceutical agents to treat obesity. Based on the structure of rutin, a typical flavonoid and one of the NMU2R agonists we previously identified from an in-house made natural product library, 30 flavonoid derivatives have been synthesized and screened on a cell-based reporter gene assay. A number of compounds were found to be selective and highly potent to NMU2R. For example, the EC₅₀ value of compound NRA 4 is very close to that of NMU, the endogenous peptide ligand of NMU2R. Structure–activity relationship analysis revealed that a 3-hydroxyl group in ring C and a 2′-fluoride group in ring B were essential for this class of compounds to be active against NMU2R.     

Ghrelin—a novel generation of anti‐obesity drug: design,pharmacomodulation and biological activity of ghrelin analogues

Ghrelin is a unique bioactive peptide with respect to both the structure and its biological function. This 28‐amino acid peptide is modified with an n‐octanoyl group at serine‐3, and accordingly is the only lipidated biologically active peptide hormone known so far. Ghrelin binds to the so‐called ghrelin or GHS receptor, a member of the class A of G‐protein coupled receptors, which leads to Ca²⁺ release intracellularly due to the activation of the Gq‐system. Interestingly, the ghrelin receptor shows a significant constitutive activity which means that in addition to agonists and antagonists, inverse agonists play an important role in receptor modulation. In this review, the major activities of ghrelin are summarized with a strong focus on the regulation of food intake. So far reported agonists, antagonists and inverse agonists are shown and structure activitiy relationships are discussed. Furthermore, the application of ghrelin ligands as novel anti‐obesity drugs is outlined and the state of the art in this field is summarized. Copyright © 2009 European Peptide Society and John Wiley & Sons, Ltd.     

Non‐invasive imaging of allogeneic transplanted skin graft by 131I‐anti‐TLR5 mAb

Although ¹⁸F‐fluorodeoxyglucose (¹⁸F‐FDG) uptake can be used for the non‐invasive detection and monitoring of allograft rejection by activated leucocytes, this non‐specific accumulation is easily impaired by immunosuppressants. Our aim was to evaluate a ¹³¹I‐radiolabelled anti‐Toll‐like receptor 5 (TLR5) mAb for non‐invasive in vivo graft visualization and quantification in allogeneic transplantation mice model, compared with the non‐specific radiotracer ¹⁸F‐FDG under using of immunosuppressant. Labelling, binding, and stability studies were performed. BALB/c mice transplanted with C57BL/6 skin grafts, with or without rapamycin treatment (named as allo‐treated group or allo‐rejection group), were injected with ¹³¹I‐anti‐TLR5 mAb, ¹⁸F‐FDG, or mouse isotype ¹³¹I‐IgG, respectively. Whole‐body phosphor‐autoradiography and ex vivo biodistribution studies were obtained. Whole‐body phosphor‐autoradiography showed ¹³¹I‐anti‐TLR5 mAb uptake into organs that were well perfused with blood at 1 hr and showed clear graft images from 12 hrs onwards. The ¹³¹I‐anti‐TLR5 mAb had significantly higher graft uptake and target‐to‐non‐target ratio in the allo‐treated group, as determined by semi‐quantification of phosphor‐autoradiography images; these results were consistent with ex vivo biodistribution studies. However, high ¹⁸F‐FDG uptake was not observed in the allo‐treated group. The highest allograft‐skin‐to‐native‐skin ratio (A:N) of ¹³¹I‐anti‐TLR5 mAb uptake was significantly higher than the ratio for ¹⁸F‐FDG (7.68 versus 1.16, respectively). ¹³¹I‐anti‐TLR5 mAb uptake in the grafts significantly correlated with TLR5 expression in the allograft area. The accumulation of ¹³¹I‐IgG was comparable in both groups. We conclude that radiolabelled anti‐TLR5 mAb is capable of detecting allograft with high target specificity after treatment with the immunosuppressive drug rapamycin.     

Ferric ions inhibit proteolytic processing of progastrin

The gastrointestinal hormone gastrin is generated from an 80 amino acid precursor (progastrin) by cleavage after dibasic residues by prohormone convertase 1. Phosphorylation of Ser₇₅ has previously been suggested, on the basis of indirect evidence, to inhibit cleavage of progastrin after Arg₇₃Arg₇₄. Gastrins bind two ferric ions with high affinity, and iron binding is essential for the biological activity of non-amidated gastrins in vitro and in vivo. This study directly investigated the effect of iron binding and of serine phosphorylation on the cleavage of synthetic progastrin-derived peptides. The affinity of synthetic progastrin_55–80 for ferric ions, and the rate of cleavage by prohormone convertase 1, were not affected by phosphorylation of Ser₇₅. In contrast, in the presence of ferric ions the rate of cleavage of both progastrin_55–80 and phosphoSer₇₅progastrin_55–80 by prohormone convertase 1 was significantly reduced. Hence iron binding to progastrin may regulate processing and secretion in vivo, and regulation may be particularly important in diseases with altered iron homeostasis.     

Inhibition of inflammation and oxidative stress by an imidazopyridine derivative X22 prevents heart injury from obesity

Inflammation and oxidative stress plays an important role in the development of obesity‐related complications and cardiovascular disease. Benzimidazole and imidazopyridine compounds are a class of compounds with a variety of activities, including anti‐inflammatory, antioxidant and anti‐cancer. X22 is an imidazopyridine derivative we synthesized and evaluated previously for anti‐inflammatory activity in lipopolysaccharide‐stimulated macrophages. However, its ability to alleviate obesity‐induced heart injury via its anti‐inflammatory actions was unclear. This study was designed to evaluate the cardioprotective effects of X22 using cell culture studies and a high‐fat diet rat model. We observed that palmitic acid treatment in cardiac‐derived H9c2 cells induced a significant increase in reactive oxygen species, inflammation, apoptosis, fibrosis and hypertrophy. All of these changes were inhibited by treatment with X22. Furthermore, oral administration of X22 suppressed high‐fat diet‐induced oxidative stress, inflammation, apoptosis, hypertrophy and fibrosis in rat heart tissues and decreased serum lipid concentration. We also found that the anti‐inflammatory and anti‐oxidative actions of X22 were associated with Nrf2 activation and nuclear factor‐kappaB (NF‐κB) inhibition, respectively, both in vitro and in vivo. The results of this study indicate that X22 may be a promising cardioprotective agent and that Nrf2 and NF‐κB may be important therapeutic targets for obesity‐related complications.     

Molecular characterization of the ligand–receptor interaction of the neuropeptide Y family

Neuropeptide Y (NPY), peptide YY (PYY) and pancreatic polypeptide (PP) belong to the NPY hormone family and activate a class of receptors called the Y‐receptors, and also belong to the large superfamily of the G‐protein coupled receptors. Structure–affinity and structure–activity relationship studies of peptide analogs, combined with studies based on site‐directed mutagenesis and anti‐receptor antibodies, have given insight into the individual characterization of each receptor subtype relative to its interaction with the ligand, as well as to its biological function. A number of selective antagonists at the Y₁‐receptor are available whose structures resemble that of the C‐terminus of NPY. Some of these compounds, like BIBP3226, BIBO3304 and GW1229, have recently been used for in vivo investigations of the NPY‐induced increase in food intake. Y₂‐receptor selective agonists are the analog cyclo‐(28/32)‐Ac‐[Lys²⁸‐Glu³²]‐(25–36)‐pNPY and the TASP molecule containing two units of the NPY segment 21–36. Now the first antagonist with nanomolar affinity for the Y₂‐receptor is also known, BIIE0246. So far, the native peptide PP has been shown to be the most potent ligand at the Y₄‐receptor. However, by the design of PP/NPY chimera, some analogs have been found that bind not only to the Y₄‐, but also to the Y₅‐receptor with subnanomolar affinities, and are as potent as NPY at the Y₁‐receptor. For the characterization of the Y₅‐receptor in vitro and in vivo, a new class of highly selective agonists is now available. This consists of analogs of NPY and of PP/NPY chimera which all contain the motif Ala³¹‐Aib³². This motif has been shown to induce a 3₁₀‐helical turn in the region 28–31 of NPY and is suggested to be the key motif for high Y₅‐receptor selectivity. The results of feeding experiments in rats treated with the first highly specific Y₅‐receptor agonists support the hypothesis that this receptor plays a role in the NPY‐induced stimulation of food intake. In conclusion, the selective compounds for the different Y‐receptor subtypes known so far are promising tools for a better understanding of the physiological properties of the hormones of the NPY family and related receptors. Copyright © 2000 European Peptide Society and John Wiley & Sons, Ltd.     

Synthesis and properties of cyclic gomesin and analogues

Gomesin (Gm) was the first antimicrobial peptide (AMP) isolated from the hemocytes of a spider, the Brazilian mygalomorph Acanthoscurria gomesiana. We have been studying the properties of this interesting AMP, which also displays anticancer, antimalarial, anticryptococcal and anti‐Leishmania activities. In the present study, the total syntheses of backbone‐cyclized analogues of Gm (two disulfide bonds), [Cys(Acm)^2,15]‐Gm (one disulfide bond) and [Thr^2,6,11,15,d ‐Pro⁹]‐Gm (no disulfide bonds) were accomplished, and the impact of cyclization on their properties was examined. The consequence of simultaneous deletion of pGlu¹ and Arg¹⁶‐Glu‐Arg¹⁸‐NH₂ on Gm antimicrobial activity and structure was also analyzed. The results obtained showed that the synthetic route that includes peptide backbone cyclization on resin was advantageous and that a combination of 20% DMSO/NMP, EDC/HOBt, 60 °C and conventional heating appears to be particularly suitable for backbone cyclization of bioactive peptides. The biological properties of the Gm analogues clearly revealed that the N‐terminal amino acid pGlu¹ and the amidated C‐terminal tripeptide Arg¹⁶‐Glu‐Arg¹⁸‐NH₂ play a major role in the interaction of Gm with the target membranes. Moreover, backbone cyclization practically did not affect the stability of the peptides in human serum; it also did not affect or enhanced hemolytic activity, but induced selectivity and, in some cases, discrete enhancements of antimicrobial activity and salt tolerance. Because of its high therapeutic index, easy synthesis and lower cost, the [Thr^2,6,11,15,d ‐Pro⁹]‐Gm analogue remains the best active Gm‐derived AMP developed so far; nevertheless, its elevated instability in human serum may limit its therapeutic potential. Copyright © 2012 European Peptide Society and John Wiley & Sons, Ltd.     

Synthesis of β‐Ketoamide Curcumin Analogs for Anti‐Diabetic and AGEs Inhibitory Activities

Two different series of novel β‐ketoamide curcumin analogs enriched in biological activities have been synthesized. The synthesized compounds were screened for their in vitro anti‐diabetic and AGEs inhibitory activities and exhibited potent to good anti‐diabetic and AGEs inhibitory activities. The molecular docking study was also performed with the α‐amylase enzyme.     

Design of novel artemisinin‐like derivatives with cytotoxic and anti‐angiogenic properties

Artemisinins are plant products with a wide range of medicinal applications. Most prominently, artesunate is a well tolerated and effective drug for treating malaria, but is also active against several protozoal and schistosomal infections, and additionally exhibits anti‐angiogenic, anti‐tumorigenic and anti‐viral properties. The array of activities of the artemisinins, and the recent emergence of malaria resistance to artesunate, prompted us to synthesize and evaluate several novel artemisinin‐like derivatives. Sixteen distinct derivatives were therefore synthesized and the in vitro cytotoxic effects of each were tested with different cell lines. The in vivo anti‐angiogenic properties were evaluated using a zebrafish embryo model. We herein report the identification of several novel artemisinin‐like compounds that are easily synthesized, stable at room temperature, may overcome drug‐resistance pathways and are more active in vitro and in vivo than the commonly used artesunate. These promising findings raise the hopes of identifying safer and more effective strategies to treat a range of infections and cancer.