Search Results (91)

Brown macroalgae are a valuable source of bioactive polysaccharides, particularly alginates and fucoidans, with significant potential for cosmetic and pharmaceutical applications. In this study, polysaccharides were extracted from four species (Padina pavonica, Sargassum ilicifolium, S. latifolium, and Turbinaria decurrens) collected along the Djibouti coastline. Structural characterization by FT-IR and ¹H-NMR revealed pronounced interspecific variability. Alginates displayed distinct mannuronate/guluronate (M/G) ratios, with Sargassum latifolium showing the highest and T. decurrens the lowest, reflecting differences in polymer composition and structural flexibility. Fucoidan spectra exhibited characteristic sulfate bands at 1217–1220 and 840 cm⁻¹, with lower transmission values for T. decurrens indicating a relatively higher degree of sulfation. Biological assays demonstrated that alginate extracts exhibited moderate antioxidant activity, whereas fucoidans showed significantly stronger radical scavenging (DPPH) and ferric reducing (FRAP) capacities, in some cases comparable to vitamin C. Fucoidans also displayed potent inhibition of skin-aging enzymes, with elastase inhibition reaching 62.1% for P. pavonica and tyrosinase inhibition peaking at 63% for S. ilicifolium at 0.5 mg/mL. These results highlight the critical role of structural features, particularly sulfation patterns, in determining biological activity. Overall, Djiboutian brown algal polysaccharides combine antioxidant and enzyme inhibitory properties, confirming their potential as multifunctional and sustainable marine-derived ingredients for cosmetic formulations. Full article

New N-benzoyl-l-homoserine lactone derivatives bearing a meta-fluorosulfonyl or a meta-methylsulfonyl group have been designed, synthesized and evaluated as quorum sensing (QS) inhibitors. Docking simulations involving the structure of several targeted LuxR-type receptors suggested that a sulfonyl substituent on the benzene ring can trigger interactions within the binding site, possibly consistent with either covalent SuFEx reaction targeting a tyrosine residue or competitive interaction with additional hydrogen bonding. Biological evaluation of the two meta- methyl or fluorosulfonyl-benzoyl acylhomoserine lactone (AHL) analogs as LuxR-regulated quorumsensing inhibitors showed a significant effect for the fluorosulfonyl derivative with an IC₅₀ value of 15 ± 2 µM, while the methylsulfonyl was found to be a weak inhibitor. The stability of the fluorosulfonyl derivative was confirmed by kinetic studies based on ¹⁹F NMR experiments. Investigations dedicated to defining the mechanism of action, either covalent or competitive, were achieved through experiments including inhibition assays without or with pre-incubation in the bacterial medium, and LC/MS analysis with the ExpR protein. The results strongly suggest that the type of inhibition is a competitive one. Full article

Background/Objectives: In Brazil, quilombos—African-descendant resistance communities—emerged during slavery and persisted beyond its abolition. The state of Paraná, in Southern Brazil, is home to 86 quilombos, yet their genetic diversity remains entirely unexplored, and little is known about their subcontinental African origins. Methods: To explore the demographic history of these communities and the reach of the Transatlantic Slave Trade in Southern Brazil, we analyzed Y and mitochondrial DNA haplotypes in samples from two quilombo communities from Paraná, Feixo (n = 117) and Restinga (n = 47). Results: Our findings reveal a significant African maternal ancestry in both communities, with Feixo exhibiting 35% and Restinga showing a striking 78.72% of maternal haplogroups of African origin. Feixo’s mtDNA haplotypes display affinities with Bantu-speaking populations from Central-Western and Southeastern Africa (such as Angola, Congo, and Mozambique), whereas those found in Restinga are more closely aligned with lineages frequent in Western Africa. Y-chromosome data reveal 39.4% and 25% African paternal ancestry in Feixo and Restinga, respectively, with most African chromosomes assigned to haplogroup E1b1b1-M35, which has a broad frequency across eastern Africa. Conclusions: These results offer novel insights into the history of the African diaspora in a previously unstudied Brazilian region, suggesting African sources—including underdocumented Eastern/Southern lineages—and contributing useful new clues to their broader within-Africa affinities. Full article

Sea mayweed (Tripleurospermum maritimum L. syn. Matricaria maritima) is a halophytic species widely distributed along the Atlantic shoreline. Unlike other Tripleurospermum species, the chemical composition and biological activities of this halophyte have received no attention. Here, a hydroalcoholic extract of sea mayweed leaves was evaluated for in vitro antioxidant (DPPH, ABTS, and FRAP bioassays), anti-inflammatory (NO reduction in RAW 264.7 macrophages), anti-diabetic (alpha-glucosidase inhibition), neuroprotective (inhibition of acetylcholinesterase), and skin protective (tyrosinase, melanogenesis, elastase, and collagenase inhibition) activities. Solid–liquid partition chromatography of the extract and NMR characterization of its fractions allowed the identification of some major compounds, including fructo-oligosaccharides in the MeOH_20% fraction, a new carbohydrate called tripleurospermine (1), 3-5-dicaffeoylquinic acid (2) in the MeOH_40% fraction, and matricaria lactone (3) in the MeOH_80% fraction. MeOH₄₀ fraction exhibited strong antioxidant, anti-tyrosinase (thus skin-whitening potential), and anti-glycosidase activities (anti-diabetic potential), whereas MeOH_80% fraction showed anti-inflammatory and anti-diabetic potential. Overall, our results suggest that sea mayweed may have dietary or medicinal uses due to its biochemical composition and bioactivities. Full article

The appearance of spin-induced ferroelectric polarization in the so-called type-II multiferroic materials has received a lot of attention. The nature and mechanisms of such polarization were intensively studied using perovskite rare-earth manganites, RMnO₃, as model systems. Later, multiferroic properties were discovered in some RFeO₃ perovskites and possibly in some RCrO₃ perovskites. However, R₂NiMnO₆ double perovskites have ferromagnetic structures that do not break the inversion symmetry. It was found recently that more complex magnetic structures are realized in A-site-ordered quadruple perovskites, RMn₃Ni₂Mn₂O₁₂. Therefore, they have the potential to be multiferroics. In this work, dielectric properties in magnetic fields up to 9 T were investigated for such perovskites as RMn₃Ni₂Mn₂O₁₂ with R = Ce to Ho and for BiMn₃Ni₂Mn₂O₁₂. The samples with R = Bi, Ce, and Nd showed no dielectric anomalies at all magnetic fields, and the dielectric constant decreases with decreasing temperature. The samples with R = Sm to Ho showed qualitatively different behavior when the dielectric constant started increasing with decreasing temperature below certain temperatures close to the magnetic ordering temperatures, T_N. This difference could suggest different magnetic ground states. The samples with R = Eu, Dy, and Ho still showed no anomalies on the dielectric constant. On the other hand, peaks emerged at T_N on the dielectric constant in the R = Sm sample from about 2 T up to the maximum available field of 9 T. The Gd sample showed peaks on dielectric constant at T_N between about 1 T and 7 T. Transition temperatures increase with increasing magnetic fields for R = Sm and decrease for R = Gd. These findings suggest the presence of magnetic-field-induced multiferroic states in the R = Sm and Gd samples with intermediate ionic radii. Dielectric properties at different magnetic fields are also reported for Lu₂NiMnO₆ for comparison. Full article

Prematurity is associated with a higher risk of developing short- and long-term metabolic complications. However, the concrete mechanisms are not yet fully understood. The purpose of this study was to characterize early urinary metabolic adaptations linked to preterm birth. Urine samples collected at one month of age were compared between extremely and very preterm neonates (<32 weeks gestation) (n = 45) and term newborns (n = 96). Liquid chromatography coupled to mass spectrometry (LC-MS) and nuclear magnetic resonance (NMR) techniques were both applied and analyzed independently. Univariate analysis and multivariate analyses were utilized to assess the impact of preterm birth on the metabolites identified. Multiblock analysis was further used to evaluate the effect of prematurity on biological functions. A profound impact of prematurity was observed. Both experimental groups differed in the concentrations of 240 metabolites from the LC-MS dataset and 52 from the NMR one. Multivariate analyses confirmed a significant and important separation between groups. Finally, multiblock analysis identified six major biological outcomes affected by preterm birth: nitrogen metabolism, growth, neurochemical metabolism, microbiota metabolism, cell defense, and metabolic alterations. Most of the observed variations exhibited biological plausibility and were consistent with reported health complications associated with preterm birth. In conclusion, preterm birth is linked to a specific fingerprint in the urinary metabolome, reflecting metabolic adaptations in multiple systems occurring at one month of age. Full article

Two nitrogen-modified mesoporous MCM-41-type silicas were synthesized by the sol–gel route and post-grafting surface modification procedure, obtaining an aminopropyl-modified MCM-41 (denoted MCM-41-N) and an aminoethyl-aminopropyl-modified MCM-41 (denoted MCM-41-NN). Hexavalent chromium removal from acidified water by adsorption and reduction to Cr(III) on the solid mesophases was analyzed. The modified silicas were characterized by powder X-ray diffraction (XRD), Fourier transformed infrared spectra (FT-IR), nitrogen adsorption–desorption measurements at −196 °C, X-ray photoelectron spectroscopy (XPS), ²⁹Si solid state Nuclear Magnetic Resonance (²⁹Si-RMN), and thermogravimetric analysis (TGA). Both samples exhibited very high capacities for decreasing Cr(VI) concentrations in water, according to the Langmuir isotherm model: 129.9 mg·g⁻¹ for MCM-41-N and 133.3 mg·g⁻¹ for MCM-41-NN. The chromium speciation in the supernatant after 24 h indicates that MCM-41-N had a higher capacity to reduce Cr(VI) to the less toxic Cr(III) species than MCM-41-NN: 92.9% vs. 72.5% when the initial Cr(VI) concentration was 10 mg·g⁻¹. These differences were related to the different capacity of nitrogen atoms in MCM-41-N and MCM-41-NN to interact with the surrounding surface silanols which are required for the chemical reduction in the hexavalent species to take place, as evidenced by FT-IR and XPS analysis. Also, the Cr(III)/Cr(VI) atomic ratios on the solid’s surfaces were higher for MCM-41-N. These results highlight the characteristics that nitrogen atoms incorporated into silica matrices must possess in order to maximize the transformation of Cr(VI) into the trivalent species, thereby reducing the generation of toxic waste harmful to living organisms. Full article

The complex dielectric permittivity has been studied with the waves of millimeter wavelength for rare earth manganate and titanate and LiCoPO₄ and LiNi_0.5Co_0.5PO₄ orthophosphate composites. The measurements are carried out at frequencies of 26 to 38 GHz via measurements of transmission and reflection coefficients through a plate. A special method on how to extract the real and imaginary parts of dielectric permittivity is applied. Discussion is conducted on a nonmonotonic type of the frequency dependences for both real and imaginary parts of permittivity, and it has been shown that relaxation is non-Debye. The Cole–Cole, Havriliak–Negami, and Kohlrausch–Williams–Watts models cannot also explain the nonmonotonic frequency dependence of the real part of dielectric permittivity. Investigation of the structure and phase composition of nanocomposites has been carried out. Full article

Background/Objectives: Antimicrobial resistance represents a critical global health challenge that has been exacerbated by the significant decline in antibiotic development. Natural product-based drugs, particularly plant-derived phenolic compounds, offer promising alternatives to conventional antibiotics. This study aimed to isolate and characterize a novel phenolic compound from Bacopa procumbens, a Mexican perennial repent plant that is widespread in the Mexican valley and produces a variety of saponins, gastrodin derivatives, and phenolic acids, and to evaluate its antibacterial potential against clinically relevant pathogens. Methods: The hydroalcoholic extraction of B. procumbens was followed by liquid–liquid partitioning with ethyl acetate. The resulting fraction underwent chromatographic separation and purification. The structural elucidation of the isolated compound was performed using thin-layer chromatography (TLC), high-performance liquid chromatography (HPLC), mass spectrometry (MS-EI), and nuclear magnetic resonance (NMR) techniques. Antimicrobial activity was assessed via a microdilution assay against five bacterial strains, including drug-resistant Staphylococcus species and Gram-negative pathogens. Results: A novel phenolic compound, 5-(p-hydroxybenzoyl) shikimic acid (5pHSA), was isolated and characterized. The compound demonstrated moderate antibacterial activity against methicillin-resistant Staphylococcus haemolyticus and Escherichia coli (minimum inhibitory concentration (MIC) = 100 μg/mL) but showed limited efficacy against Staphylococcus aureus, MRSA, and Klebsiella pneumoniae (MIC > 100 μg/mL). Comparative analysis with the previously isolated compound ProcumGastrodin A revealed structure–activity relationships where the higher lipophilicity of PG-A was correlated with enhanced antimicrobial activity. Conclusions: This study establishes 5pHSA as a novel phenolic compound with moderate antibacterial properties. The findings highlight the importance of molecular polarity and structural complexity in determining antimicrobial efficacy, offering valuable insights into the development of phenolic, acid-based antimicrobial agents to address the growing challenge of antimicrobial resistance. Full article

Urban solid waste (USW) is a promising alternative source of valuable chemical compounds. It is considered an adsorbent material due to its chemical structure, porosity and electronic charge available to form chemical bonds and can be recovered or transformed for use in bioprocesses and industrial applications. This is the case with cigarette butts (CBs), which consist of thousands of substances that can be chemically converted for various purposes. This work showed high efficiency in the production of cellulose mass from the recycling of CBs, a patented technology in operation at the company Poiato Recicla—SP. The lignin-like solid (LLS)—a material obtained from the recycling of cigarette butts (CBs) by catalytic transfer hydrogenation (CTH), under non-rigorous conditions—showed high efficiency in its conversion into molecules of great interest. In the bio-oil obtained, characterized by analyses such as GCMS and RMN 2D HSQC, a mixture of predominantly hydrocarbons (many of them with cyclic and/or branched chains) was identified in almost all the experiments. This method demonstrates the potential of the TCH process for SSLs and completes the recycling chain designed for CBs, promoting their complete conversion into chemical compounds of greater interest. Full article

Hospital-acquired infections (HAIs) previously focused mainly on multidrug-resistant (MDR) bacteria, with less attention on viruses. The COVID-19 pandemic highlighted the importance of controlling viral infections. Human rhinoviruses (HRVs) are among the viruses responsible for HAIs. HRVs are non-enveloped viruses that infect the upper airways after airborne or direct transmission. Due to their lack of a membrane envelope, HRVs exhibit moderate resistance to commonly applied alcoholic disinfectants. Therefore, there is a significant need to develop alternative disinfection and hand sanitation strategies to control HRV infections in healthcare settings without posing a risk to human health. The antimicrobial activity and safety of rhamnolipids and rhamnolipids nano-micelles (RMN) against MDR-bacteria and several viruses, including SARS-CoV-2, were confirmed recently. Also, we previously demonstrated the superior antimicrobial activity of RMN over rhamnolipids. In the current study, molecular docking demonstrated the weak interactions of rhamnolipids with HRV-1A (minor group) compared to HRV-14 (major group), suggesting a superior antiviral activity of rhamnolipids towards major group rhinoviruses. To biologically validate these data, RMN was prepared and characterized, and then antiviral activity against HRV-16 (major group) and HRV-1B (minor group) infection of HeLa cells was assessed. RMN showed a complete inhibition of HRV-16 infection with recovery of 100% of HeLa cell viability. In contrast, only partial inhibition of HRV-1B infection with approximately 50% protection against infection was observed. Therefore, RMN might be recommended as a disinfectant and/or a hand sanitizer component to control the spread of RVs in hospital care settings or elsewhere to reduce the incidence of respiratory infections. Full article

A site-ordered quadruple perovskites, AA′₃B₄O₁₂, can have 3d transition metals at A′ and B sites, and show complex magnetic interactions and behavior. Additional complexity appears when B site-ordered arrangements are realized in AA′₃B₂B′₂O₁₂. In this work, A site-ordered quadruple perovskites, RMn₃Ni₂Mn₂O₁₂ with R = Bi, Ce, and Ho, were prepared by a high-pressure, high-temperature method at about 6 GPa and about 1500 K. The R = Bi and Ce samples were found to crystallize in space group Im-3 with a disordered distribution of Ni²⁺ and Mn⁴⁺ cations in one B site. On the other hand, the R = Ho sample crystallized in space group Pn-3 and showed partial ordering of Ni²⁺ and Mn⁴⁺ cations between two B sites. The structural data (and bond valence sums) suggest that cerium has the oxidation state +3, which is unusual for such perovskites. Magnetic properties were investigated by magnetic susceptibility and specific heat measurements, which showed the presence of one magnetic transition near 36 K for R = Bi; there was evidence for the presence of two magnetic transitions near 27 K and 33 K for R = Ce, and near 10 K and 36 K for R = Ho. Curie–Weiss parameters were estimated for all samples from high-temperature magnetic measurements up to 750 K. The total effective magnetic moment for R = Ce also suggests the presence of Ce³⁺. A magnetic field of 90 kOe had the largest effect on the specific heat of the R = Ho sample, and almost no effects on the specific heat of the R = Bi sample. Full article

Leishmania amazonensis, a cause of cutaneous leishmaniasis in Brazil, is a neglected disease with toxic and inconsistently effective treatments. The parasite’s survival depends on managing oxidative stress, making redox-regulating enzymes potential therapeutic targets. Geopropolis, a resinous product from native stingless bees, shows promising antiparasitic effects. This study aims to evaluate the anti-L. amazonensis activity of geopropolis produced by Melipona bicolor, M. marginara, M. mondury, and M. quadrifasciata (two samples), targeting enzymes responsible for the parasite’s redox balance. Ethanol extracts of geopropolis produced by each bee (BCRL, MRGT, MNDY, MNDA(1), and MNDA(2), respectively) were analyzed for total phenolics and flavonoids. Promastigotes and axenic amastigotes were treated with various extract concentrations, and parasite viability was assessed using the resazurin reduction method. Cytotoxicity was tested on peritoneal macrophages, RAW 264.7, VERO cell lines (MTT assay), and erythrocytes (hemolysis assay). Additionally, mitochondrial dehydrogenase activity, reactive oxygen species (ROS) production, the inhibition of recombinant arginase, and autophagic activity were also evaluated in treated parasites. MRGT showed the highest levels of phenolics (762 mg GAE/g) and flavonoids (345 mg QE/g). MDRY was more effective against promastigote and axenic amastigote forms (IC₅₀ = 168 and 19.7 µg/mL, respectively). MRGT showed lower cytotoxicity against RAW 264.7 and VERO (CC₅₀ = 654 µg/mL and 981 µg/mL, respectively). Erythrocytes exhibited reduced sensitivity to MNDA(2) (HC₅₀ = 710 µg/mL). The activity of dehydrogenases and LiARG was reduced by treating the parasites with the extracts following the induction of ROS and autophagic activity. These results highlight geopropolis extracts as a source of substances with anti-L. amazonensis activity capable of inducing oxidative stress on the parasite. Full article

This study focuses on developing innovative and eco-friendly purification methods for the isolation of bioactive compounds derived from Padina pavonica, a brown abundant macroalga in Djibouti. Three distinct fractions, obtained via liquid-liquid extraction (LLE_FAE), solid-phase extraction (SPE_WE50), and flash chromatography (FC_EtOH20), were selected based on their high phenolic content and antioxidant activities. All fractions were also evaluated for their anti-ageing potential by assessing their ability to inhibit two vital skin-ageing enzymes, tyrosinase and elastase. Structural analysis by ¹H-¹³C HMBC NMR and LC-MS revealed a selectivity of phlorotannins depending on the purification methods. The LLE_FAE fraction exhibited greater structural complexity, including compounds such as phloroglucinol, diphlorethol/difucol, fucophlorethol and bifuhalol, which likely contribute to its enhanced bioactivity compared to the fractions obtained by FC_EtOH20 and SPE_WE50, which were also active and enriched only in phloroglucinol and fucophlorethol. These findings highlight the impact of purification techniques on the selective enrichment of specific bioactive compounds and demonstrated the interest of FC or SPE in producing active phlorotannin-enriched fractions. These two purification methods hold strong potential for innovative cosmeceutical applications. Results are discussed regarding the use of P. pavonica as a promising marine resource in Djibouti to be used for the development of cosmetic industry. Full article

The Spanish Merino is the most significant sheep breed globally due to its economic and cultural importance in human history. It has also had a substantial influence on the development of other Merino and Merino-derived breeds. Historical sources indicate that crossbreeding to produce finer, higher-quality wool was already taking place in the south of the Iberian Peninsula during the Roman era. This evidence suggests that individuals with a racial pattern very similar to that of the modern Merino may have already existed on the peninsula. The presence of the skeletal remains of these animals at various human settlements dated to the late fourth and third millennia BC could provide insights into the genomics of these ancestral sheep. This study analyses ancient DNA extracted from nine skeletal remains from three archaeological sites in Southern Iberia, dated to the third millennium BC. The samples were sequenced and aligned with the ovine genome. The genetic distances observed among the samples indicate a closer relationship between several animals from the Marinaleda (Seville) and Grañena Baja (Jaén) sites. The study of the slaughter/death age profiles identified at La Minilla (La Rambla, Córdoba) suggests an approach centred on meat exploitation, while the data from Marinaleda (Seville) and Grañena Baja (Jaén) indicate the potential exploitation of secondary resources. A review of the composition of these small ruminant herds could provide insights into the type of secondary resource exploitation that may have been prioritised. Our aim is to investigate the presence of distinct production systems, differentiating between those aimed primarily at meat use and those focused on secondary products. This is the first approach to exploring the genetic evidence for sheep livestock related to its productive use during this period and in this geographical area. Full article