Levels of lipid peroxidation in hepatopancreas (HP), gill (G), and hemolymph (HYM) of stone violaceous crab Platyxanthus orbignyi (Milne Edwards and Lucas (1843)) were performed to examine the effect of short exposure to air. After four hours animals were collected, 14 from exposure to air and 10 from seawater were dissected and their lipid peroxidation (LPO) levels were evaluated using the ferrous oxidation-xylenol orange (FOX) method, in gill, hepatopancreas, and hemolymph. The total mortality of those crabs was evaluated after seven hours at 22 ± 1 °C on exposure to air conditions. Levels of LPO in hepatopancreas (female/male = 4.68 ± 1.60/5.12 ± 1.59 Eq-H2O2/g wet tissue) and hemolymph (female/male = 1.48 ± 1.42/1.28 ± 1.06 Eq-H2O2/g wet tissue) displayed no significant differences, in contrast, gills displayed significant differences (male/female = 5.63 ± 0.83/4.63 ± 0.44 Eq-H2O2/g wet tissue, p < 0.05). The results showed that air exposure in the short term in this study induces a different response in oxidative stress levels and damage could be accompanied by accumulation of peroxide lipids (LOOH). These results suggest that different organs can show different responses to oxidative stress between male and female crabs to this species.

The field of nanotechnology had enormous developments, resulting in new methods for the controlled synthesis of a wide variety of nanoscale materials with unique properties. Efficient methods such as thermal decomposition for efficient size control have been developed in recent years for the synthesis of oleic acid (OA)-coated magnetite (Fe3O4) nanoparticles (MNP-OA). These nanostructures can be a source of pollution when emitted in the aquatic environment and could be accumulated by vulnerable marine species such as crustaceans. In this work, we synthesized and characterized MNP-OA of three different diameters (5, 8, and 12 nm) by thermal decomposition. These nanoparticles were remarkably stable after treatment with high affinity iron chelators (calcein, fluorescent desferrioxamine, and fluorescent apotransferrin); however, they displayed pro-oxidant activity after being challenged with ascorbate under two physiological buffers. Free or nanoparticle iron displayed low toxicity to four types of hepatopancreatic cells (E, R, F, and B) of the mangrove crab Ucides cordatus; however, they were promptly bioavailable, posing the risk of ecosystem disruption due to the release of excess nutrients.

The mangrove crab Ucides cordatus is a bioindicator of aquatic contamination. In this work, the iron availability and redox activity of saccharide-coated mineral iron supplements (for both human and veterinary use) and ferrocene derivatives in Saline Ucides Buffer (SUB) medium were assessed. The transport of these metallodrugs by four different hepatopancreatic cell types(embryonic (E), resorptive (R), fibrillar (F), and blister (B)) of U.cordatus were measured. Organic coated iron minerals (iron supplements) were stable against strong chelators (calcein and transferrin). Ascorbic acid efficiently mediated the release of irononly from ferrocene compounds, leading to redox-active species. Ferrous iron and iron supplements were efficient in loading ironto all hepatopancreatic cell types.In contrast, ferrocene derivatives were loaded only in F and B cell types. Acute exposition to the iron compounds resulted in cell viability of 70–95%, and to intracellular iron levels as high as 0.40μmol L−1 depending upon the compound and the cell line. The easiness that iron from iron metallodrugs was loaded/transported into U.cordatus hepatopancreatic cells reinforces a cautionary approach to the widespread disposal and use of highly bioavailable iron species as far as the long-term environmental welfare is concerned.

Cell-impermeant iron chelator desferrioxamine (DFO) can have access to organelles if appended to suitable vectors. Mitochondria are important targets for the treatment of iron overload-related neurodegenerative diseases. Triphenylphosphonium (TPP) is a delocalized lipophilic cation used to ferry molecules to mitochondria. Here we report the synthesis and characterization of the conjugate TPP–DFO as a mitochondrial iron chelator. TPP–DFO maintained both a high affinity for iron and the antioxidant activity when compared to parent DFO. TPP–DFO was less toxic than TPP alone to A2780 cells (IC50 = 135.60 ± 1.08 and 4.34 ± 1.06 μmol L⁻¹, respectively) and its native fluorescence was used to assess its mitochondrial localization (Rr = +0.56). These results suggest that TPP–DFO could be an interesting alternative for the treatment of mitochondrial iron overload e.g. in Friedreich’s ataxia.

Crustaceans are frequently used as bioindicators, and changes in their metabolism at the hepatopancreas (HP) level are often followed in these studies. The HP is the site of digestion, absorption, nutrient storage, and toxic metal detoxification, enabling crabs to survive in metal contaminated regions. Cellular damage and high lipid peroxidation (LPO) levels have been found in crab populations under high cadmium (Cd) concentrations. The aim of this work was to separate and characterize the HP cells of the stone crab Menippe frontalis from the Pacific Ocean, Perú (5° 5' 21″ S-81° 6' 51″ W) and to measure the cellular viability and LPO after exposure to the non-essential metal Cd. The HP cells were dissociated by magnetic stirring, with posterior separation by sucrose gradient at concentrations of 10, 20, 30, and 40%. We found the same cell types that were described for other species (e.g., Ucides cordatus, Atlantic Ocean, Brazil). High cellular viability against 1 mmol L(-1) of Cd was observed for resorptive (R) cells in 20% sucrose layer (88 ± 8%, *P < 0.05, ANOVA), and blister (B) cells in the 40% sucrose layers (92 ± 7%, *P < 0.05, ANOVA). Cd (1 mmol L(-1)) caused an increase in LPO levels, suggesting that crabs from polluted areas can be affected by toxic metals, generating a physiological stress. The gradient sucrose methodology can be used for different species and results in a similar separation, viability, and cellular identification. The results are a starting point for toxic metal studies for species distributed across different geographic coordinates.

Desferrioxamine (DFO) is a bacterial siderophore with a high affinity for iron, but low cell penetration. As part of our ongoing project focused on DFO-conjugates, we synthesized, purified, characterized and studied new mtDFOs (DFO conjugated to the Mitochondria Penetrating Peptides TAT49-57, 1A, SS02 and SS20) using a succinic linker. These new conjugates retained their strong iron binding ability and antioxidant capacity. They were relatively non toxic to A2780 cells (IC50 40–100 μM) and had good mitochondrial localization (Rr +0.45 –+0.68) as observed when labeled with carboxy-tetramethylrhodamine (TAMRA) In general, mtDFO caused only modest levels of mitochondrial DNA (mtDNA) damage. DFO-SS02 retained the antioxidant ability of the parent peptide, shown by the inhibition of mitochondrial superoxide formation. None of the compounds displayed cell cycle arrest or enhanced apoptosis. Taken together, these results indicate that mtDFO could be promising compounds for amelioration of the disease symptoms of iron overload in mitochondria.

Crustaceans found in metal contaminated regions are able to survive and the authors decided to investigate the physiological mechanisms involved by comparing populations from contaminated and non-contaminated areas. The objective of the present study was to measure the cellular transport of a non-essential metal (Cd, cadmium), in gills (G) and hepatopancreas (H) of Ucides cordatus, together with cell membrane fluidity, metallothionein levels (MT) and lipid peroxidation (LPO). The two populations compared were from a polluted (P) and a non-polluted (NP) mangrove area of São Paulo State, Brazil. The authors found, for the first time, a larger Cd transport in G and in H cells from crabs living in P mangrove areas. The cells also had lower plasma membrane fluidity, increased LPO and less MT compared to NP regions. The authors also found larger amounts of Cd in intracellular organelles of G from crabs in P regions, but not in H. Therefore, in polluted areas, these animals showed higher Cd transport, lower plasma membrane fluidity and storage of Cd intracellularly in G cells, while H cells used metallothionein as their main line of defense. The implications for these findings suggest that crabs from polluted areas can accumulate Cd more easily compared to crabs from non-polluted areas, probably because of an impairment of the regulatory mechanisms of membrane transport. This article is protected by copyright. All rights reserved

Iron metallodrugs comprise mineral supplements, anti-hypertensive agents and, more recently, magnetic nanomaterials, with both therapeutic and diagnostic roles. As biologically-active metal compounds, concern has been raised regarding the impact of these compounds when emitted to the environment and associated ecotoxicological effects for the fauna. In this work we assessed the relative stability of several iron compounds (supplements based on glucoheptonate, dextran or glycinate, as well as 3,5,5-trimethylhexanoyl (TMH) derivatives of ferrocene) against high affinity models of biological binding, calcein and aprotransferrin, via a fluorimetric method. Also, the redox-activity of each compound was determined in a physiologically relevant medium. Toxicity toward Artemia salina at different developmental stages was measured, as well as the amount of lipid peroxidation. Our results show that polymer-coated iron metallodrugs are stable, non-redox-active and non-toxic at the concentrations studied (up to 300 µM). However, TMH derivatives of ferrocene were less stable and more redox-active than the parent compound, and TMH-ferrocene displayed toxicity and lipid peroxidation to A. salina, unlike the other compounds. Our results indicate that iron metallodrugs based on polymer coating do not present direct toxicity at low levels of emission; however other iron species (eg. metallocenes), may be deleterious for aquatic organisms. We suggest that ecotoxicity depends more on metal speciation than on the total amount of metal present in the metallodrugs. Future studies with discarded metallodrugs should consider the chemical speciation of the metal present in the composition of the drug.

There has been a growing interest in the use of micelles with nanofiber geometry as nanocarriers for hydrophobic drugs. Here we show that the conjugate of penetratin, a cell-penetrating peptide (CPP) with blood-brain barrier (BBB) permeability, and deferasirox (DFX), a hydrophobic iron chelator, self-assembles to form micelles at a very low concentration (∼15 mg/L). The critical micelle concentration (CMC) was determined, and the micelles were used for solubilizing curcumin, a hydrophobic anti-neurodegenerative drug, for successful delivery across RBE4 cells, a BBB model. Transmission Electron Microscope images of the curcumin-loaded micelles confirmed the formation of nanofibers. These results indicate the potential of CPP-drug conjugates for use as nanocarriers.

Membrane pathway for intracellular cadmium (Cd(2+)) accumulation is not fully elucidated in many organisms and has not been studied in crab gill cells. To characterize membrane Cd(2+) transport of anterior and posterior gill cells of Ucides cordatus, a hypo-hyper-regulating crab, a change in intracellular Cd(2+) concentration under various experimental conditions was examined by using FluoZin, a fluorescent probe. The membrane Cd(2+) transport was estimated by the augmentation of FluoZin fluorescence induced by extracellular application of CdCl2 and different inhibitors. Addition of extracellular calcium (Ca(2+)) to the cells affected little the fluorescence of FluoZin, confirming that Cd(2+) was the main ion increasing intracellular fluorescence. Ca(2+) channels blockers (nimodipine and verapamil) decreased Cd(2+) influx as well as vanadate, a Ca(2+)-ATPase blocker. Chelating intracellular Ca(2+) (BAPTA) decreased Cd(2+) influx in gill cells, while increasing intracellular Ca(2+) (caffeine) augmented Cd influx. Cd(2+) and ATP added at different temporal conditions were not effective at increasing intracellular Cd(2+) accumulation. Ouabain (Na(+)/K(+)-ATPase inhibitor) increased Cd(2+) influx probably through a change in intracellular Na and/or a change in cell membrane potential. Routes of Cd(2+) influx, a non-essential metal, through the gill cell plasma membrane of crabs are suggested.

Desferrioxamine (DFO) is a potent iron chelator used in the treatment of iron overload (IO) disorders. However, due to its low cell permeability and fast clearance, DFO administration is usually prolonged and of limited use for the treatment of IO in tissues such as the brain. Caffeine is a safe, rapidly absorbable molecule that can be linked to other compounds to improve their cell permeability. In this work, we successfully prepared and described DFO-caffeine, a conjugate with iron scavenging ability, antioxidant properties and enhanced permeation in the HeLa cell model.

Deferasirox (DFX), an orally active and clinically approved iron chelator, is being used extensively for the treatment of iron overload. However, its water insolubility makes it cumbersome for practical use. In addition to this, the low efficacy of DFX to remove brain iron prompted us to synthesize and evaluate a DFX-TAT(47-57) peptide conjugate for its iron chelation properties and permeability across RBE4 cell line, an in vitro model of the blood-brain barrier. The water-soluble conjugate was able to remove labile iron from buffered solution as well as from iron overloaded sera, and the permeability of DFX-TAT(47-57) conjugate into RBE4 cells was not affected compared to parent deferasirox. The iron bound conjugate was also able to translocate through the cell membrane.

Iron overload causes progressive and sometimes irreversible damage due to accelerated production of reactive oxygen species. Desferrioxamine (DFO), a siderophore, has been used clinically to remove excess iron. However, the applications of DFO are limited because of its inability to access intracellular labile iron. Cell penetrating peptides (CPPs) have become an efficient delivery vector for the enhanced internalization of drugs into the cytosol. We describe, herein, an efficient method for covalently conjugating DFO to the CPPs TAT(47–57) and Penetratin. Both conjugates suppressed the redox activity of labile plasma iron in buffered solutions and in iron-overloaded sera. Enhanced access to intracellular labile iron compared to the parent siderophore was achieved in HeLa and RBE4 (a model of blood-brain-barrier) cell lines. Iron complexes of both conjugates also had better permeability in both cell models. DFO antioxidant and iron binding properties were preserved and its bioavailability was increased upon CPP conjugation, which opens new therapeutic possibilities for neurodegenerative processes associated with brain iron overload.

Ucides cordatus (Linnaeus, 1763) is a hypo-hyper-regulating mangrove crab possessing gills for respiratory and osmoregulatory processes, separated in anterior and posterior sections. They also have hepatopancreas, which is responsible for digestion and absorption of nutrients and detoxification of toxic metals. Each of these organs has specific cells that are important for in vitro studies in cell biology, ion and toxic metals transport. In order to study and characterize cells from gills and hepatopancreas, both were separated using a Sucrose Gradient (SG) from 10 to 40% and cells in each gradient were characterized using the vital mitochondrial dye DASPEI (2-(4-dimethylaminostyryl)-N- ethylpyridinium iodide) and Trichrome Mallory’s stain. Both in 20 and 40% SG for gill cells and 30% SG for hepatopancreatic cells, a greater number of cells were colored with DASPEI, indicating a larger number of mitochondria in these cells. It is concluded that the gill cells present in 20% and 40% SG are Thin cells, responsible for respiratory processes and Ionocytes responsible for ion transport, respectively. For hepatopancreatic cells, the 30% SG is composed of Fibrillar cells that possess larger number of membrane ion and nutrient transporters. Moreover, the transport of toxic metal cadmium (Cd) by isolated hepatopancreatic cells was performed as a way of following cell physiological integrity after cell separation and to study differences in transport among the cells. All hepatopancreatic cells were able to transport Cd. These findings are the first step for further work on isolated cells of these important exchange epithelia of crabs, using a simple separation method and to further develop successful in vitro cell culture in crabs.

The gills contain essential cells for respiration and osmoregulation, whereas the hepatopancreas is the site of digestion, absorption, and nutrients storage. The aim of this work was to separate and characterize gill and hepatopancreatic cells of the mangrove crab, Ucides cordatus. For gills, the methodology consisted of an enzymatic cellular dissociation using Trypsin at 0.5%, observation of cellular viability with Tripan Blue, and separation of cells using discontinuous sucrose gradient at concentrations of 10%, 20%, 30%, and 40%. The hepatopancreatic cells were dissociated by magnetic stirring, with posterior separation by sucrose gradient at the same concentrations above. For gills, a high cellular viability was observed (92.5±2.1%), with hemocyte cells in 10% sucrose layer (57.99 ± 0.17%, *P < 0.05), principal cells in the 20% sucrose layer (57.33 ± 0.18, *P < 0.05), and thick cells and pillar cells in the 30% and 40% sucrose layers, respectively (39.54 ± 0.05%, *P < 0.05; and 41.81 ± 0.04%, *P < 0.05). The hepatopancreatic cells also showed good viability (79.22 ± 0.02%), with the observation of embryonic (E) cells in the 10% sucrose layer (67.87 ± 0.06%, **P < 0.001), resorptive (R) and fibrillar (F) cells in the 20% and 30% sucrose layers (44.71 ± 0.06%, **P < 0.001, and 43.25 ± 0.01%, *P < 0.05; respectively), and blister (B) cells in the 40% sucrose layer (63.09 ± 0.03%, **P < 0.001). The results are a starting point for in vitro studies of heavy metal transport in isolated cells of the mangrove crab U. cordatus, subjected to contamination by metals in the mangrove habitat where they are found.