Unveiling the capacity of bioaugmentation application, in comparison with biochar and rhamnolipid for TPHs degradation in aged hydrocarbons polluted soil

Persistent, aged hydrocarbons in soil hinder remediation, posing a significant environmental threat. While bioremediation offers an environmentally friendly and cost-effective approach, its efficacy for complex contaminants relies on enhancing pollutant bioavailability. This study explores the potential of immobilized bacterial consortia combined with biochar and rhamnolipids to accelerate bioremediation of aged total petroleum hydrocarbon (TPH)-contaminated soil. Previous research indicates that biochar and biosurfactants can increase bioremediation rates, while mixed consortia offer sequential degradation and higher hydrocarbon mineralization. The present investigation aimed to assess whether combining these strategies could further enhance degradation in aged, complex soil matrices. The bioaugmentation (BA) with bacterial consortium increased the TPHs degradation in aged soil (over 20% compared to natural attenuation - NA). However, co-application of BA with biochar and rhamnolipid higher did not show a statistically prominent synergistic effect. While biochar application facilitated the maintenance of hydrocarbon degrading bacterial consortium in soil, the present study did not identify a direct influence in TPHs degradation. The biochar application in contaminated soil contributed to TPHs adsorption. Rhamnolipid alone slightly increased the TPHs biodegradation with NA, while the combined bioaugmentation treatment with rhamnolipid and biochar increased the degradation between 27.5 and 29.8%. These findings encourage further exploration of combining bioaugmentation with amendment, like biochar and rhamnolipid, for remediating diverse environmental matrices contaminated with complex and aged hydrocarbons.

Desulfurization of thiosemicarbazones: the role of metal ions and biological implications

Thiosemicarbazones are biologically active substances whose structural formula is formed by an azomethine, an hydrazine, and a thioamide fragments, to generate a R2C=N-NR-C(=S)-NR2 backbone. These compounds often act as ligands to generate highly stable metal-organic complexes. In certain experimental conditions, however, thiosemicarbazones undergo reactions leading to the cleavage of the chain. Sometimes, the breakage involves desulfurization processes. The present work summarizes the different chemical factors that influence the desulfurization reactions of thiosemicarbazones, such as pH, the presence of oxidant reactants or the establishment of redox processes as those electrochemically induced, the effects of the solvent, the temperature, and the electromagnetic radiation. Many of these reactions require coordination of thiosemicarbazones to metal ions, even those present in the intracellular environment. The nature of the products generated in these reactions, their detection in vivo and in vitro, together with the relevance for the biological activity of these compounds, mainly as antineoplastic agents, is discussed.

Perchlorate-induced structural diversity in thiosemicarbazone-copper(II) complexes provides insights to understand the reactivity in acid and basic media

The use of perchlorato ancillary ligands, with relatively low coordinating ability, nicely illustrates a rich structural diversity in thiosemicarbazonecopper(II), TSC-Cu(II), systems. Five compounds with formulae {[CuL(OH2)][CuL(OClO3)]}n·nClO4·2nH2O (1), [{CuL(OClO3)}2] (2), [Cu(HL)(OClO3)2(OH2)]...

Conversion of a double-tetranuclear cluster silver helicate into a dihelicate via a rare desulfurization process

We show the first example of a bisthiosemicarbazone silver double-tetranuclear cluster helicate [Ag4L2]2 obtained by electrochemical synthesis which undergoes a rare desulfurization process giving rise to a cationic silver dihelicate [Ag2(H2L)2]SO4.

Phyllosilicate-content influence on the spectroscopic properties and antioxidant capacity of Iberian Cretaceous clays

Kaolinite-rich Cretaceous clay sediment samples from Burgos (Spain) have been analyzed by elemental analysis, X-ray fluorescence, inductively coupled plasma mass spectrometry, X-ray diffraction and different spectroscopic techniques, as Fourier Transform Infrared, ultraviolet-visible and electron paramagnetic resonance. The clay sediment samples mainly contain quartz, muscovite and kaolinite. Different radicals, as A- and B-Centers in kaolinite and organic paramagnetic species, are detected. An illite/kaolinite FTIR band ratio parameter (IKB) is proposed to infer the illite/kaolinite proportion, which can be useful to graphically visualize the iron-substituted Al(III) sites. Studies of the activity as scavengers of DPPH and ABTS radicals show that samples with a larger amount of orthorhombic Fe(III) ions replacing Al(III) ions exhibit a higher antioxidant capacity.

Anticancer activity of a new copper(II) complex with a hydrazone ligand. Structural and spectroscopic characterization, computational simulations and cell mechanistic studies on 2D and 3D breast cancer cell models

We report here the synthesis, crystal structure, characterization and anticancer activity of a copper(ii)-hydrazone complex, [Cu(MeBHoVa)(H2O)2](NO3) (for short, CuHL), against human breast cancer cells on monolayer (2D) and spheroids/mammospheres (3D). The solid-state molecular structure of the complex has been determined by X-ray diffraction methods. The conformational space was searched and geometries were optimized both in the gas phase and including solvent effects by computational methods based on DFT. The compound has been characterized in the solid state and in solution by spectroscopic (FTIR, Raman, UV-vis) methods. The results were compared with those obtained for the hydrazone ligand and complemented with DFT calculations. Cell viability assays on MCF7 (IC50(CuHL) = 1.7 ± 0.1 μM, IC50(CDDP) = 42.0 ± 3.2 μM) and MDA-MB-231 (IC50(CuHL) = 1.6 ± 0.1 μM, IC50(CDDP) = 131.0 ± 18 μM) demonstrated that the complex displays higher antitumor activity than cisplatin (CDDP) on 2D and 3D human breast cancer cell models. Molecular docking and molecular dynamics simulations showed that CuHL could interacts with DNA, inducing a significant genotoxic effect on both breast cancer cells from 0.5 to 1 μM. On the other hand, CuHL increases the ROS production and induces cell programmed death on breast cancer cells at very low micromolar concentrations (0.5-1.0 μM). Moreover, the compound decreased the amount of breast CSCs on MCF7 and MDA-MB-231 cells reducing the percentage of CD44+/CD24-/low cells from 0.5 to 1.5 μM. In addition, CuHL overcame CDDP with an IC50 value 65-fold lower against breast multicellular spheroids ((IC50(CuHL) = 2.2 ± 0.3 μM, IC50(CDDP) = 125 ± 4.5 μM)). Finally, CuHL reduced mammosphere formation capacity, hence affecting the size and number of mammospheres and showing that the complex exhibits antitumor properties on monolayer (2D) and spheroids (3D) derived from human breast cancer cells.

Thiosemicarbazone-metal complexes exhibiting cytotoxicity in colon cancer cell lines through oxidative stress

Colorectal cancer is the third most common type of cancer and has a high incidence in developed countries. At present, specific treatments are being required to allow individualized therapy depending on the molecular alteration on which the drug may act. The aim of this project is to evaluate whether HPTSC and HPTSC* thiosemicarbazones (HPTSC = pyridine-2-carbaldehyde thiosemicarbazone and HPTSC* = pyridine-2-carbaldehyde 4N-methylthiosemicarbazone), and their complexes with different transition metal ions as Cu(II), Fe(III) and Co(III), have antitumor activity in colon cancer cells (HT-29 and SW-480), that have different oncogenic characteristics. Cytotoxicity was evaluated and the involvement of oxidative stress in its mechanism of action was analyzed by quantifying the superoxide dismutase activity, redox state by quantification of the thioredoxin levels and reduced/oxidized glutathione rate and biomolecules damage. The apoptotic effect was evaluated by measurements of the levels of caspase 9 and 3 and the index of histones. All the metal-thiosemicarbazones have antitumor activity mediated by oxidative stress. The HPTSC*-Cu was the compound that showed the best antitumor and apoptotic characteristics for the cell line SW480, that is KRAS gene mutated.

Synthesis, characterization, DFT calculations and anticancer activity of a new oxidovanadium(iv) complex with a ligand derived from o-vanillin and thiophene

New vanadium complex was synthesized and fully characterized showing promising anticancer activity on triple negative breast cancer cells.

Cu(ii) and Zn(ii) complexes with a poly-functional ligand derived from o-vanillin and thiophene. Crystal structure, physicochemical properties, theoretical studies and cytotoxicity assays against human breast cancer cells

New ML₂ complexes were extensively characterized showing stability in solution and promising anti-tumoral results, particularly for CuL2.

Influence of Three Commercial Graphene Derivatives on the Catalytic Properties of a Lactobacillus plantarum α-l-Rhamnosidase When Used as Immobilization Matrices

The modification of carbon nanomaterials with biological molecules paves the way toward their use in biomedical and biotechnological applications, such as next-generation biocatalytic processes, development of biosensors, implantable electronic devices, or drug delivery. In this study, different commercial graphene derivatives, namely, monolayer graphene oxide (GO), graphene oxide nanocolloids (GOCs), and polycarboxylate-functionalized graphene nanoplatelets (GNs), were compared as biomolecule carrier matrices. Detailed spectroscopic analyses showed that GO and GOC were similar in composition and functional group content and very different from GN, whereas divergent morphological characteristics were observed for each nanomaterial through microscopy analyses. The commercial α-l-rhamnosidase RhaB1 from the probiotic bacterium Lactobacillus plantarum, selected as a model biomolecule for its relevant role in the pharma and food industries, was directly immobilized on the different materials. The binding efficiency and biochemical properties of RhaB1-GO, RhaB1-GOC, and RhaB1-GN composites were analyzed. RhaB1-GO and RhaB1-GOC showed high binding efficiency, whereas the enzyme loading on GN, not tested in previous enzyme immobilization studies, was low. The enzyme showed contrasting changes when immobilized on the different material supports. The effect of pH on the activity of the three RhaB1-immobilized versions was similar to that observed for the free enzyme, whereas the activity-temperature profiles and the response to the presence of inhibitors varied significantly between the RhaB1 versions. In addition, the apparent K_m for the immobilized and soluble enzymes did not change. Finally, the free RhaB1 and the immobilized enzyme in GOC showed the best storage and reutilization stability, keeping most of their initial activity after 8 weeks of storage at 4 °C and 10 reutilization cycles, respectively. This study shows, for the first time, that distinct commercial graphene derivatives can influence differently the catalytic properties of an enzyme during its immobilization.

Selectivity of a thiosemicarbazonatocopper(ii) complex towards duplex RNA. Relevant noncovalent interactions both in solid state and solution

Thiosemicarbazones and their metal derivatives have long been screened as antitumor agents, and their interactions with DNA have been analysed. Herein, we describe the synthesis and characterization of compounds containing [CuL]⁺ entities (HL = pyridine-2-carbaldehyde thiosemicarbazone) and adenine, cytosine or 9-methylguanine, and some of their corresponding nucleotides. For the first time, crystal structures of adenine- and 9-methylguanine-containing thiosemicarbazone complexes are reported. To the best of our knowledge, the first study on the affinity thiosemicarbazone-RNA is also provided here. Experimental and computational studies have shown that [CuL(OH₂)]⁺ entities at low concentration intercalate into dsRNA poly(rA)·poly(rU) through strong hydrogen bonds involving uracil residues and π-π stacking interactions. In fact, noncovalent interactions are present both in the solid state and in solution. This behaviour diverges from that observed with DNA duplexes and creates an optimistic outlook in achieving selective binding to RNA for subsequent possible medical applications.

The mechanism of the Cu2+[12-MCCu(Alaha)-4] metallacrown formation and lanthanum(iii) encapsulation

Formation of Cu²⁺[12-MC-4] metallacrown from Cu(ii) and α-alaninehydroxamic acid involves the Cu₂L²⁺ species as the fundamental intermediate. La³⁺ encapsulation, giving La³⁺[15-MC-5], occurs through the intermediacy of the Cu[12-MC-4]La complex.

Structure, magnetic properties and nuclease activity of pyridine-2-carbaldehyde thiosemicarbazonecopper(II) complexes

New complexes of formulae [Cu(HL(2))(H(2)O)(NO(3))](NO(3)) (1), [{Cu(L(1))(tfa)}(2)] (2), [{Cu(L(1))}(2)(pz)](ClO(4))(2) (3) and {[{Cu(L(1))}(2)(dca)](ClO(4))}(n) (4), where HL(1)=pyridine-2-carbaldehyde thiosemicarbazone, HL(2)=pyridine-2-carbaldehyde 4N-methylthiosemicarbazone, Htfa=trifluoroacetic acid (CF(3)COOH), pz=pyrazine (C(4)H(4)N(2)) and dca=dicyanamide [N(CN)(2)](-), have been synthesized and characterized. The crystal structures of these compounds are built up of monomers (1), dinuclear entities with the metal centers bridged through the non-thiosemicarbazone coligand (2 and 3) and 1D chains of dimers (4). In all the cases, square-pyramidal copper(II) ions are present, except for the square-planar ones in 3. Magnetic measurements show antiferromagnetic couplings in 2, 3 and 4. The susceptibility data were fitted by the Bleaney-Bowers' equation for copper(II) dimers derived from H=-2JS(1)S(2) being the obtained J/k values -4.8, -4.3 and -5.1K for compounds 2-4, respectively. The magnetic susceptibility of the already known [{Cu(HL(1))(tfa)}(2)](tfa)(2) compound has been also measured for the first time. The J/k value is -0.3K, lower than that in 2. The nuclease activity of 3 and 4 has been analyzed.

Dinuclear CoII/GdIII and CoIII/GdIII complexes derived from hexadentate Schiff bases: synthesis, structure, and magnetic properties

Two heterodimetallic complexes of formulae [LCo(MeOH)Gd (NO3)3] (1) and [LCo(AcO)2Gd(NO3)2] (2) (H2L = 1,3-bis[(3-methoxysalicylidene)amino]-2,2'-dimethylpropane) have been synthesized and characterized. The structure of 1 consists of discrete dinuclear entities. The cobalt(II) ion exhibits a square-pyramidal geometry, in which the basal plane is formed by the N2O2 set of the inner Schiff base site and the apical position is occupied by the methanol oxygen atom. The gadolinium(III) ion is ten-coordinate to three bidentate nitrate groups and the four oxygen atoms of the Schiff base. The phenolate oxygen atoms act as a bridge between both metal ions. Complex 2 is also formed by isolated dinuclear species. The cobalt(III) ion shows a distorted octahedral geometry in which the equatorial plane is formed by the N2O2 set of the Schiff base, and the axial positions are occupied by two oxygen atoms from both acetate groups. The gadolinium(III) ion is ten-coordinate to two bidentate nitrate groups, two oxygen atoms of the acetate groups, and the four oxygen atoms of the Schiff base. The metal ions are bridged through both the phenolate oxygen and the acetate groups, the latter acting as mu 2 ligands. Magnetic measurements on compound 1 allowed, for the first time, a quantitative evaluation of the J(Co,Gd) ferromagnetic interaction parameter (J = 0.90 cm-1). The CoII zero-field splitting has to be taken into account to fit the experimental data at low temperature (D = 4.2 cm-1). In complex 2, the magnetically isolated gadolinium center obeys a Curie law.

Evidence of desulfurization in the oxidative cyclization of thiosemicarbazones. Conversion to 1,3,4-oxadiazole derivatives

The addition of pyridine-2-carbaldehyde 4N-methylthiosemicarbazone (C8H10N4S) to an aqueous solution of copper(II) nitrate yields [[Cu(C8H9N4S)(NO3)]2] (1). This complex consists of centrosymmetric dinuclear entities containing square-pyramidal copper(II) ions bridged through the sulfur thioamide atoms. The oxidation of 1 with KBrO3 or KIO3 gives rise to a compound with formula [[Cu(C8H8N4O)(H2O)2(SO4)]2]*2H2O (2) (C8H8N4O = 2-methylamino-5-pyridin-2-yl-1,3,4-oxadiazole). The structure of 2 is made up of centrosymmetric dimers where the copper(II) ions exhibit a distorted octahedral coordination and are connected by the oxadiazole moiety. The metal ions in 2 can be removed by addition of K4[Fe(CN)6], and then the oxadiazole ligand can be isolated and recrystallized as (C8H8N4O)*3H2O (3).

Biological activity of complexes derived from thiophene-2-carbaldehyde thiosemicarbazone. Crystal structure of [Ni(C(6)H(6)N(3)S(2))(2)]

The crystal structure of [Ni(L(III))(2)] (1), where HL(III)=thiophene-2-carbaldehyde thiosemicarbazone, consists of monomeric entities where the nickel(II) ions exhibit distorted square planar geometry. The two bidentate thiosemicarbazone ligands are centrosymmetric. C...S van der Waals' links and nonbonded intramolecular interactions are present in the structure. The biological activity of 1 is compared to that of the free ligand, and the cobalt(III) (2) and copper(II) (3) derivatives. The observed order of cytotoxicity against melanoma B16F10 and Friend erythroleukemia cells is: 1< or =ligand<2<3. A structure-activity correlation using Extended-Hückel MO calculations is described.

Biological activity of complexes derived from pyridine-2-carbaldehyde thiosemicarbazone

Biological studies on [Fe(L)2](NO3).0.5H2O (1), [Fe(L)2][PF6] (2), [Co(L)2](NCS) (3), [Ni(HL)2]Cl2.3H2O (4) and Cu(L)(NO3) (5), where HL=C7H8N4S, pyridine-2-carbaldehyde thiosemicarbazone, have been carried out. The crystal structure of compound 3 has been solved. It consists of discrete monomeric cationic entities containing cobalt(III) ions in a distorted octahedral environment. The metal ion is bonded to one sulfur and two nitrogen atoms of each thiosemicarbazone molecule. The thiocyanate molecules act as counterions. The copper(II) and iron(III) complexes react with reduced glutathione and 2-mercaptoethanol. The reaction of compound 1 with the above thiols causes the reduction of the metal ion and bis(thiosemicarbazonato)iron(II) species are obtained. The redox activity, and in particular the reaction with cell thiols, seems to be related to the cytotoxicity of these complexes against Friend erithroleukemia cells and melanoma B16F10 cells.

Synthesis and spectroscopic properties of copper(II) complexes derived from thiophene-2-carbaldehyde thiosemicarbazone. Structure and biological activity of [Cu(C6H6N3S2)2]

The synthesis, structure and spectroscopic properties on complexes with the formula [Cu(Lm)2] (1) and Cu(NO3)2(HLm)2 (2), where HLm = thiophene-2-carbaldehyde thiosemicarbazone, have been developed. The molecular structure of compound 1 consists of monomeric entities. The copper(II) ions exhibit distorted square-planar geometry with both bidentate thiosemicarbazone ligands placed in a centrosymmetric way. Metal to ligand pi-backdonation is proposed to explain several structural and spectroscopic features in these complexes. The EPR spectra of compound 1 show an orthorhombic g tensor indicating the presence of weak magnetic exchange interactions. The reaction of compound 1 with glutathione causes the reduction of the metal ion and the substitution of the thiosemicarbazone ligand by the thiol ligand. This mechanism seems to be related to the cytotoxicity of this complex against Friend Erithroleukemia cells (FLC) and melanome B16F10 cells.