Search

Sambucus nigra L. (Caprifoliaceae) is wide spread in temperate and sub-tropical zones. The consumption of its berries has been associated with health benefits especially for its high content of natural antioxidants such as polyphenols, in particular anthocyanins. In this work we investigated the polyphenolic composition and the in vitro antioxidant activities (ABTS, DPPH, BCB and FRAP-ferrozine (FRAP-FZ) assays) of S. nigra berries, collected in four different Sicilian areas (Italy). Elderberries are considered one of the fruits with highest anthocyanins content, the amount of phenolic compounds, other than anthocyanins, is approximately 1.5 times greater than the latter. The LC–MS analyses have revealed an opposite trend in the polyphenols pattern in Sicilian populations. Moreover, a statistical correlation was found between cyanidin-3- sambubioside-5-glucoside and antioxidant activity evaluated by FRAP-FZ and ABTS assays. In conclusion, Sicilian S. nigra berries are appealing for its antioxidant potential and for its particularly high content of anthocyanins.

Hypericum hircinum L. is a shrub traditionally used in some Mediterranean areas as a remedy for several diseases, mainly linked to the airway apparatus. In this work, an ethanolic extract prepared from aerial parts of plants collected in Sardinia (Italy), and six fractions isolated by a chromatographic separation of the extract, were evaluated for their antioxidant activity using three in vitro assays. Based on the ethnobotanical use of the plant and in view of the emerging role that enzymes belonging to matrix metalloproteinases (MMPs) play in the pathogenesis of some respiratory diseases, the effect of the crude extract and of several fractions on in-vitro collagenase activity was also evaluated. Results show that the ethanolic extract and fractions containing quercetin, chlorogenic acid, and 5,7,3′,5′-tetrahydroxyflavanone, a component recently identified in this species, are endowed with the highest free radical scavenging activity. Conversely, fractions containing shikimic acid as the main component did not show this property. The crude extract was able to inhibit in-vitro collagenase activity with an IC50 value of 156 μg/mL. A Lineaweaver–Burk plot, built to obtain the kinetic parameters of the enzymatic reaction, revealed that the inhibitory mechanism is non-competitive. Single fractions were also evaluated for their inhibitory activity on collagenase; fractions mainly containing flavonols and the substituted flavanone showed the highest inhibitory effect. Thus, H. hircinum can be considered as a new natural source of molecules able to inhibit enzymes of the MMP family, which could enter as active ingredients in wrinkle-care cosmetics.

A novel antimicrobial peptide, anoplin, was purified from the venom of the solitary wasp Anoplius samariensis. The sequence was mostly analyzed by mass spectrometry, which was corroborated by solid-phase synthesis. Anoplin, composed of 10 amino acid residues, Gly-Leu-Leu-Lys-Arg-Ile-Lys-Thr-Leu-Leu-NH2, has a high homology to crabrolin and mastoparan-X, the mast cell degranulating peptides from social wasp venoms, and, therefore, can be predicted to adopt an amphipathic alpha-helix secondary structure. In fact, the circular dichroism (CD) spectra of anoplin in the presence of trifluoroethanol or sodium dodecyl sulfate showed a high content, up to 55%, of the alpha-helical conformation. A modeling study of anoplin based on its homology to mastoparan-X supported the CD results. Biological evaluation using the synthetic peptide revealed that this peptide exhibited potent activity in stimulating degranulation from rat peritoneal mast cells and broad-spectrum antimicrobial activity against both Gram-positive and Gram-negative bacteria. Therefore, this is the first antimicrobial component to be found in the solitary wasp venom and it may play a key role in preventing potential infection by microorganisms during prey consumption by their larvae. Moreover, this peptide is the smallest among the linear alpha-helical antimicrobial peptides hitherto found in nature, which is advantageous for chemical manipulation and medical application.

The molecular structure of human uropepsin, an aspartic proteinase from the urine produced in the form of pepsinogen A in the gastric mucosa, has been determined by molecular replacement using human pepsin as the search model. Crystals belong to space group P2(1)2(1)2(1), with unit-cell parameters a = 50.99, b = 75.56, c = 89.90 A. Crystallographic refinement led to an R factor of 0.161 at 2.45 A resolution. The positions of 2437 non-H protein atoms in 326 residues have been determined and the model contains 143 water molecules. The structure is bilobal, consisting of two predominantly beta-sheet lobes which, as observed in other aspartic proteinases, are related by a pseudo-twofold axis. A model of the uropepsin-pepstatin complex has been constructed based on the high-resolution crystal structure of pepsin complexed with pepstatin.

Inflammatory peptides display different types of post-transcriptional modifications, such as C-terminal amidation, that alter their biological activity. Here we describe the structural and molecular dynamics features of the mast cell degranulating peptide, eumenine mastoparan-AF (EMP-AF-NH(2)), found in the venom of the solitary wasp, and of its carboxyl-free C-terminal form (EMP-AF-COO(-)) characterized by a reduced activity. Circular dichroism indicates that both peptides switch from a random coil conformation in water to a helical structure in TFE and SDS micelles. NMR data, in 30% TFE, reveal that the two peptides fold into an alpha-helix spanning most of their length, while they differ in terms of molecular rigidity. To understand the origins of the conformational flexibility observed in the case of EMP-AF-COO(-), a 5 ns MD simulation was carried out for each peptide, in an explicit water/TFE environment. The results show that the two peptides differ in an H-bond between Leu14 NH(2) and the backbone carbonyl of Ile11. The loss of that H-bond in EMP-AF-COO(-) leads to a significant modification of its structural dynamics. In fact, as evidenced by essential dynamics analysis, while EMP-AF-NH(2) exists mainly as a rigid structure, EMP-AF-COO(-) presents two helical stretches that fluctuate in some sort of independent fashion. We conclude that the diverse biological activity of the two peptides is not simply due to the reduction of the net positive charge, as generally suggested, but also to a structural perturbation of the amphipathic alpha-helix that affects their ability to perturb the cell membrane.

Mastoparans are tetradecapeptides found to be the major component of vespid venoms. A mastoparan toxin isolated from the venom of Anterhynchium flavomarginatum micado has been crystallized and X-ray diffraction data collected to 2.7 A resolution using a synchrotron-radiation source. Crystals were determined to belong to the space group P6(2)22 (P6(4)22). This is the first mastoparan to be crystallized and will provide further insights into the conformational significance of mastoparan toxins with respect to their potency and activity in G-protein regulation.

Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2014-02-26T17:19:10Z No. of bitstreams: 1 WOS000076672000015.pdf: 496595 bytes, checksum: f665690bee8811b10e98bd4de3959f2c (MD5) Made available in DSpace on 2014-02-26T17:19:11Z (GMT). No. of bitstreams: 1 WOS000076672000015.pdf: 496595 bytes, checksum: f665690bee8811b10e98bd4de3959f2c (MD5) Previous issue date: 1998-10-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T13:49:22Z No. of bitstreams: 1 WOS000076672000015.pdf: 496595 bytes, checksum: f665690bee8811b10e98bd4de3959f2c (MD5) Made available in DSpace on 2014-05-20T13:49:22Z (GMT). No. of bitstreams: 1 WOS000076672000015.pdf: 496595 bytes, checksum: f665690bee8811b10e98bd4de3959f2c (MD5) Previous issue date: 1998-10-01 Aspartic protease (EC 3.4.23) make up a widely distributed class of enzymes in animals, plants, microbes and, viruses. In animals these enzymes perform diverse functions, which range from digestion of food proteins to very specific regulatory roles. In contrast the information about the well-characterized aspartic proteases, very little is known about the corresponding enzyme in urine. A new aspartic protease isolated from human urine has been crystallized and X-ray diffraction data collected to 2.45 Angstrom resolution using a synchrotron radiation source. Crystals belong to the space group P2(1)2(1)2(1) the cell parameters obtained were a=50.99, b=75.56 and c=89.90 Angstrom. Preliminary analysis revealed the presence of one molecule in the asymmetric unit. The structure was determined using the molecular replacement technique and is currently being refined using simulated annealing and conjugate gradient protocols. UNESP, Inst Biociencias Letras & Ciências Exatas, Dept Fis, BR-15054000 Sao Jose do Rio Prieto, SP, Brazil FMTM Uberaba, Fac Med Triangulo Mineiro, Dept Bioquim Celular & Biofis, BR-38015050 Uberlandia, MG, Brazil UNESP, IB, Dept Fis & Biofis, Botucatu, SP, Brazil UNESP, Inst Biociencias Letras & Ciências Exatas, Dept Fis, BR-15054000 Sao Jose do Rio Prieto, SP, Brazil UNESP, IB, Dept Fis & Biofis, Botucatu, SP, Brazil