Study of tensiometric properties,microbiological and collagen content in nile tilapia skin submitted to different sterilization methods

Tissue bioengineering development is a global concern and different materials are studied and created to be safe, effective and with low cost. Nile Tilapia skin had shown its biological potential as covers for the burn wound. This study evaluates the tilapia skin histological, collagen properties and tensiometric resistance, after treatment by different sterilization methods. Tilapia skin samples were submitted to two sterilization processes: (1) chemical, which consisted in two 2% chlorhexidin baths, followed by sequential baths in increasing glycerol concentrations; and (2) radiation, when glycerolized skin samples were submitted to gamma radiation at 25, 30 and 50 kGy. Microscopic analyzes were performed through Haematoxylin–eosin and Picrosirius Red under polarized light. For tensiometric analysis, traction tests were performed. Glycerol treated skin presented a discrete collagen fibers disorganization within the deep dermis, while irradiated skin did not show any additional change. Throughout the steps of chemical sterilization, there was a higher proportion of collagen with red/yellow birefringence (type I) in the skin samples up to the first bath in chlorhexidin, when compared to samples after the first two glycerol baths (P < 0.005). However, there was no difference in relation to total collagen between groups. In irradiated skin, there was a larger total collagen preservation when using until 30 kGy (P < 0.005). Tensiometric evaluation did not show significant differences in relation to maximum load in the groups studied. We concluded that chemical and radiation (25 and 30 kGy) are efficient methods to sterilize Nile Tilapia skin without altering its microscopic or tensiometric characteristics.     

Bioassay-guided fractionation of pterocarpans from roots of Harpalyce brasiliana Benth

Pterocarpans, a special kind of isoflavonoids possessing two contiguous benzofuran and benzopyran rings, have been reported as possessing several biological activities. In order to isolate and identify the active principles possibly responsible for the stronger activity of the EtOH extract from roots of Harpalyce brasiliana on the antimitotic assay using sea urchin egg development, a bioassay-guided fractionation was performed. Six bioactive pterocarpan derivatives: 4'-dehydroxycabenegrin A-I, leiocarpin, medicarpin, cabenegrins A-I and A-II, and maackiain were isolated from the chloroform fraction of H. brasiliana extract. Leiocarpin was the most active on the sea urchin egg assay with IC(50) values ranging from 0.1 to 1.2 microg/mL, followed by 4'-dehydroxycabenegrin A-I. The isolated compounds were also tested for cytotoxicity against tumor cell lines in cultures, where 4'-dehydroxycabenegrin A-I was the most active, followed by leiocarpin. Additionally, some studies on the structure-activity relationship of these pterocarpans are suggested.     

Studies on the cytotoxic activity of synthetic 2H-azirine-2-azetidinone compounds

2-Azetidinones and 2H-azirines show antibacterial and cytotoxic activities, however the biological properties of molecules containing both 2H-azirine and 2-azetidinone functions in the same structure had never been evaluated before. In the present study, two 2H-azirine-2-azetidinones (1 and 2) and three 2H-azirines (3-5) were synthesized from 2-formyl-3-phenyl-2H-azirine-N-arylimines with diphenylketene. The compounds were assayed for antibacterial and cytotoxic activities. None of them showed antibacterial activity on the tested strains, but both 2H-azirine-2-azetidinones showed cytotoxicity against four tumor cell lines (HL-60, leukemia; HCT-8, colon cancer; MDA-MB-435, melanoma; and SF-295, CNS). The IC₅₀ values of 1 ranged from 1.1 to 10.5 μM and from 3.8 to 26.6 μM for 2. The mechanism of cell growth inhibition of 1 and 2 towards HL-60 cell line was also investigated. Membrane damage, cell viability, DNA synthesis inhibition and morphological changes were evaluated. The preliminary findings suggested that 1 and 2 induce apoptosis.     

Pro-apoptotic activity of lipidic α-amino acids isolated from Protopalythoa variabilis

Lipidic α-amino acids (LAAs) have been described as non-natural amino acids with long saturated or unsaturated aliphatic chains. In the continuing prospect to discover anticancer agents from marine sources, we have obtained a mixture of two cytotoxic LAAs (1a and 1b) from the zoanthid Protopalythoa variabilis. The anti-proliferative potential of 14 synthetic LAAs and 1a/1b were evaluated on four tumor cell lines (HCT-8, SF-295, MDA-MB-435, and HL-60). Five of the synthetic LAAs showed high percentage of tumor cell inhibition, while 1a/1b completely inhibited tumor cell growth. Additionally, apoptotic effects of 1a/1b were studied on HL-60 cell line. 1a/1b-treated cells showed apoptosis morphology, loss of mitochondrial potential, and DNA fragmentation.     

Form and function of grass ring patterns in arid grasslands: the role of abiotic controls

Ring-shaped growth patterns commonly occur in resource-limited arid and semi-arid environments. The spatial distribution, geometry, and scale of vegetation growth patterns result from interactions between biotic and abiotic processes, and, in turn, affect the spatial patterns of soil moisture, sediment transport, and nutrient dynamics in aridland ecosystems. Even though grass ring patterns are observed worldwide, a comprehensive understanding of the biotic and abiotic processes that lead to the formation, growth and breakup of these rings is still lacking. Our studies on patterns of infiltration and soil properties of blue grama (Bouteloua gracilis) grass rings in the northern Chihuahuan desert indicate that ring patterns result from the interaction between clonal growth mechanisms and abiotic factors such as hydrological and aeolian processes. These processes result in a negative feedback between sediment deposition and vegetation growth inside the bunch grass, which leads to grass die back at the center of the grass clump. We summarize these interactions in a simple theoretical and conceptual model that integrates key biotic and abiotic processes in ring formation, growth and decline.     

Synthetic Chalcone Derivatives as Inhibitors of Cathepsins K and B,and Their Cytotoxic Evaluation

A series of chalcone derivatives, 1 – 15 , were prepared by Claisen? Schmidt condensation and evaluated for their cytotoxicities on tumor cell lines and also against proteolytic enzymes such as cathepsins B and K. Of the compounds synthesized, (E)‐3‐(3,4‐dimethoxyphenyl)‐1‐phenylprop‐2‐en‐1‐one ( 12 ), (E)‐3‐(4‐chlorophenyl)‐1‐phenylprop‐2‐en‐1‐one ( 13 ), (E)‐3‐(4‐methoxyphenyl)‐1‐phenylprop‐2‐en‐1‐one ( 14 ), and (E)‐3‐(4‐nitrophenyl)‐1‐phenylprop‐2‐en‐1‐one ( 15 ) showed significant cytotoxicities. The most effective compound was 15 , which showed high cytotoxic activity with an IC₅₀ value lower than 1 μg/ml, and no selectivity on the tumor cells evaluated. Substituents at C(4) of ring B were found to be essential for cytotoxicity. In addition, it was also demonstrated that some of these chalcones are moderate inhibitors of cathepsin K and have no activity against cathepsin B.     

Cytotoxicity and genotoxicity of ingenamine G isolated from the Brazilian marine sponge Pachychalina alcaloidifera

Marine sponges belonging to the order Haplosclerida are one of the more prolific sources of new natural products possessing various biological activities. The present study examined the cytotoxic and genotoxic potential of ingenamine G, an alkaloid isolated from the Brazilian marine sponge Pachychalina alcaloidifera. Ingenamine G displayed a moderate cytotoxic activity against human proliferating lymphocytes evaluated by the MTT assay (IC(50) 15 microg/mL). The hemolytic assay showed that ingenamine G cytotoxic activity was not related to membrane disruption. The comet assay and chromosome aberration analysis were applied to determine the genotoxic and clastogenic potential of ingenamine G, respectively. Cultured human lymphocytes were treated with 5, 10, 15 and 20 microg/mL of ingenamine G during the G(1), G(1)/S, S (pulses of 1 and 6 h), and G(2) phases of the cell cycle. All tested concentrations were cytotoxic, reduced significantly the mitotic index, and were clastogenic in all phases of the cell cycle, especially in S phase. While an increase in DNA-strand breaks was observed starting with the concentration corresponding to the IC(50). The presence of genotoxicity and polyploidy during interphase and mitosis, respectively, suggests that ingenamine G at high concentrations is clastogenic and indirectly affects the construction of mitotic fuse.     

Relationship between oviposition,virulence gene expression and parasitism success in <Emphasis Type="Italic">Cotesia typhae</Emphasis> nov. sp. parasitoid strains

Studying mechanisms that drive host adaptation in parasitoids is crucial for the efficient use of parasitoids in biocontrol programs. Cotesia typhae nov. sp. (Fernández-Triana) (Hymenoptera: Braconidae) is a newly described parasitoid of the Mediterranean corn borer Sesamia nonagrioides (Lefebvre) (Lepidoptera: Noctuidae). Braconidae are known for their domesticated bracovirus, which is injected with eggs in the host larva to overcome its resistance. In this context, we compared reproductive success traits of four Kenyan strains of C. typhae on a French and a Kenyan populations of its host. Differences were found between the four strains and the two most contrasted ones were studied more thoroughly on the French host population. Parasitoid offspring size was correlated with parasitism success and the expression of bracovirus virulence genes (CrV1 and Cystatin) in the host larva after parasitism. Hybrids between these two parasitoid strains showed phenotype and gene expression profiles similar to the most successful parental strain, suggesting the involvement of dominant alleles in the reproductive traits. Ovary dissections revealed that the most successful strain injected more eggs in a single host larva than the less successful one, despite an equal initial ovocyte number in ovaries. It can be expected that the amount of viral particles increase with the number of eggs injected. The ability to bypass the resistance of the allopatric host may in consequence be related to the oviposition behaviour (eggs allocation). The influence of the number of injected eggs on parasitism success and on virulence gene expression was evaluated by oviposition interruption experiments.     

Cytotoxic activity of a dichloromethane extract and fractions obtained from Eudistoma vannamei (Tunicata: Ascidiacea)

This study consists of the bioassay-guided fractionation of the dichloromethane extract from Eudistoma vannamei and the pharmacological characterization of the active fractions. The dried hydromethanolic extract dissolved in aqueous methanol was partitioned with dichloromethane and chromatographed on a silica gel flash column. The anti-proliferative effect was monitored by the MTT assay. Four of the latest fractions, numbered 14 to 17, which held many chemical similarities amongst each other, were found to be the most active. The selected fractions were tested for viability, proliferation and death induction on cultures of HL-60 promyeloblastic leukemia cells. The results suggested that the observed cytotoxicity is related to apoptosis induction.