Preparation of LCST regulable DES-lignin-g-PNVCL thermo-responsive polymer by ARGET-ATRP.

To expand the field of high-value utilization of lignin. The degraded deep eutectic solvent lignin-grafted poly (N-Vinyl caprolactam) (DES-lignin-g-PNVCL) was synthesized by modified DES-lignin and NVCL via the combination of activators regenerated by electron transfer-atom transfer radical polymerization (ARGET-ATRP). Fourier transform infrared spectroscopy (FT-IR), 1H NMR, X-ray electron spectroscopy (XPS), dynamic light scattering (DLS), differential scanning calorimeter (DSC) were used to characterize the structure and performance of DES-lignin-g-PNVCL. The results indicated that the PNVCL and DES-lignin-g-PNVCL were successfully prepared by ARGET-ATRP. The lowest critical solution temperature (LCST) of PNVCL was 35.75 °C. Due to different strength of hydrogen bond, different energies were required, so the LCST of the polymer can be regulated. When the molar ratio of phenolic hydroxyl group in degraded DES-lignin to 2-bromoisobutyryl bromide (BiBB) was increased from 1:1 to 1:7, the grafting rate of DES-lignin-Br was increased from 32.87% to 60.84%, and the LCST of DES-lignin-g-PNVCL was decreased from 47.98 °C to 27.88 °C. The LCST of DES-lignin-g-PNVCL was increased from 30.98 °C to 44.64 °C when the addition amount of DES-lignin-Br was increased from 20 mg to 200 mg. The LCST of DES-lignin-g-PNVCL was increased from 27.20 °C to 39.86 °C when the ratio of DMF/water was increased from 1:4 to 4:1. The LCST of DES-lignin-g-PNVCL was decreased from 52.10 °C to 31.02 °C when the concentration of DES-lignin-g-PNVCL was increased from 0.5 mg/mL to 2.5 mg/mL. The equation represented the relationship between LCST and influencing factors was obtained, the good predictability provided a tactics for preparing desired LCST thermo-responsible polymer.

Temperature and pH-responsive nano-hydrogel drug delivery system based on lysine-modified poly (vinylcaprolactam).

BACKGROUND: Smart materials capable of responding to external stimuli are noteworthy candidates in designing drug delivery systems. In many of the recent research, temperature and pH have been recognized as the main stimulating factors in designing systems for anti-cancer drugs delivery systems. PURPOSE: In this study, thermo and pH-responsive character of a nano-carrier drug delivery platform based on lysine modified poly (vinylcaprolactam) hydrogel conjugated with doxorubicin was assessed. METHODS: Poly (vinylcaprolactam) cross-linked with poly (ethyleneglycol) diacrylate was prepared via RAFT polymerization, and the prepared structure was linked with lysine through ring-opening. The anti-cancer drug doxorubicin, was linked to lysine moiety of the prepared structure via Schiff-base reaction. The prepared platform was characterized by 1HNMR and FT-IR, while molecular weight characterization was performed by size exclusion chromatography. The temperature-responsive activity was evaluated using differential scanning calorimetry and dynamic light scattering. In vitro release pattern in simulated physiologic pH at 37°C was compared with acidic pH attributed to tumor site and elevated temperature. The anticancer efficiency of the drug-conjugated structure was evaluated in breast cancer cell line MCF-7 in 24 and 48 h, and cell uptake assay was performed on the same cell line. CONCLUSION: According to the results, well-structure defined smart pH and temperature responsive nano-hydrogel was prepared. The enhanced release rates are observed at acidic pH and elevated temperature. We have concluded that the doxorubicin-conjugated nanoparticle results in higher cellular uptakes and more cytotoxicity.

Glucose-Sensitive Nanoparticles Based On Poly(3-Acrylamidophenylboronic Acid-Block-N-Vinylcaprolactam) For Insulin Delivery.

BACKGROUND: Compared with random copolymers, block copolymerization is easier to prepare for nanoparticles with core-shell structure, and they will have better glucose sensitivity and higher insulin loading. PURPOSE: In our study, insulin-loaded poly (3-acrylamidophenylboronic acid-block-N-vinyl caprolactam) p(AAPBA-b-NVCL) nanoparticles were successfully prepared and were glucose-sensitive, which could effectively lower the blood sugar levels within 72 hrs. METHODS: The polymer of p(AAPBA-b-NVCL) was produced by reversible addition-fragmentation chain transfer polymerization based on different ratios of 3-acrylamidophenylboronic acid (AAPBA) and N-vinylcaprolactam (NVCL), and its structure was discussed by Fourier transform infrared spectroscopy and 1H-nuclear magnetic resonance . Next, the polymer was manufactured into the nanoparticles, and the characteristics of nanoparticles were detected by dynamic light scattering, lower critical solution temperature, and transmission electron microscopy. After that, the cell and animal toxicity of nanoparticles were also investigated. RESULTS: The results demonstrated that p(AAPBA-b-NVCL) was successfully synthesized, and can be easily self-assembled to form nanoparticles. The new nanoparticles included monodisperse submicron particles, with the size of the nanoparticle ranged between 150 and 300nm and are glucose- and temperature-sensitive. Meanwhile, insulin can be easily loaded by p(AAPBA-b-NVCL) nanoparticles and an effective sustained release of insulin was observed when the nanoparticles were placed in physiological saline. Besides, MTT assay revealed that cell viability was more than 80%, and mice demonstrated no negative impact on blood biochemistry and heart, liver, spleen, lung, and kidney after intraperitoneal injection of 10 mg/kg/d of nanoparticles. This suggested that the nanoparticles were low-toxic to both cells and animals. Moreover, they could lower the blood sugar level within 72h. CONCLUSION: Our research suggested that these p(AAPBA-b-NVCL) nanoparticles might have the potential to be applied in a delivery system for insulin or other hypoglycemic proteins.

Amylose-Coated Biohybrid Microgels by Phosphorylase-Catalyzed Grafting-From Polymerization.

Herein, the synthesis of amylose-coated, temperature-responsive poly(N-vinylcaprolactam) (VCL)-based copolymer microgels by enzyme-catalyzed grafting-from polymerization with phosphorylase b from rabbit muscle is reported. The phosphorylase is able to recognize the oligosaccharide maltoheptaose as primer and attach glucose units from the monomer glucose-1-phosphate to it, thereby forming amylose chains while releasing inorganic phosphate. Therefore, to enable the phosphorylase-catalyzed grafting-from polymerization of glucose-1-phosphate from the PVCL-based microgels, the maltoheptaose primer is covalently attached to the microgel in the first synthesis step. This is realized by adding N-(2-aminoethyl)methacrylamide (AEMAA) as a comonomer to the PVCL microgel to integrate primary amino groups and subsequent coupling of maltoheptaonolactone. Both the PVCL/AEMAA microgel as well as the obtained microgel-maltoheptaose construct are characterized in detail by dynamic light scattering, electrophoretic mobility measurements, IR spectroscopy, and atomic force microscopy. From the microgel-maltoheptaose construct, the grafting-from polymerization of glucose-1-phosphate is performed by the addition of phosphorylase b. Atomic force microscopy images clearly demonstrate the formation of an amylose shell around the microgels. The developed amylose-coated microgels open up promising application possibilities, for example, as colloidal scavengers, since amylose helices can serve as host molecules for inclusion of hydrophobic guest molecules.

Microfluidic fabrication of biocompatible poly(N-vinylcaprolactam)-based microcarriers for modulated thermo-responsive drug release.

Various thermo-responsive polymers have been developed for controlled drug delivery upon the local application of external heat. The development of thermo-responsive polymers with high biocompatibility and tunable thermo-sensitivity is crucial for safe and efficient therapeutic application. In this study, thermo-responsive drug carriers featuring tunable thermo-sensitivities were synthesized using biocompatible poly(N-vinyl caprolactam) (PVCL) and stop-flow lithography. The PVCL-based particles showed selective drug release depending on temperature, illustrating their feasibility for on-demand controlled drug delivery. The volume phase transition temperature (VPTT) of the PVCL-based particles can be adjusted to vary from room temperature to body temperature by controlling their monomer compositions. In addition, modulated drug release was achieved by constructing multicompartments of different thermo-sensitivities within the PVCL particles. To accomplish thermo-responsive anticancer therapy, doxorubicin (DOX) was encapsulated into the PVCL particles as an anticancer drug. The DOX-loaded PVCL particles exhibited both thermo-responsive drug release and anticancer activity. This study demonstrates that thermo-responsive PVCL particles are highly promising carriers for safe and targeted anticancer therapy.

Hydrogen Gas-Mediated Deoxydehydration/Hydrogenation of Sugar Acids: Catalytic Conversion of Glucarates to Adipates.

The development of a system for the operationally simple, scalable conversion of polyhydroxylated biomass into industrially relevant feedstock chemicals is described. This system includes a bimetallic Pd/Re catalyst in combination with hydrogen gas as a terminal reductant and enables the high-yielding reduction of sugar acids. This procedure has been applied to the synthesis of adipate esters, precursors for the production of Nylon-6,6, in excellent yield from biomass-derived sources.

Production of dodecanedioic acid via biotransformation of low cost plant-oil derivatives using Candida tropicalis.

Dodecanedioic acid (DDA) is highly useful to the chemical industry as a versatile precursor for producing the polyamide nylon-6,12, which is used for many technical applications, such as heat and chemical-resistant sheaths. However, DDA synthesis has several drawbacks, such as high energy input and cost-intensive removal of by-products. Therefore, alternative bio-based production routes are required due to increasing industrial demand for green chemicals and renewable products. Candida tropicalis converts petrochemical-based n-dodecanes to the corresponding dicarboxylic acids by targeted functionalization. To increase sustainability of the DDA production process, we tested dodecanoic acid methyl ester, which can be easily obtained from transesterification of coconut oil, in whole-cell biotransformation by C. tropicalis. By modifying selected process parameters, a final DDA concentration of 66 g/L was achieved using a highly reliable, small-scale bioreactor system. Crucial process development included a gradual pH shift, an optimized substrate feeding strategy, and monitoring the transcriptional profile.

Synthesis and characterization of poly(N-vinylcaprolactam)-based spray-dried microparticles exhibiting temperature and pH-sensitive properties for controlled release of ketoprofen.

Poly(N-vinylcaprolactam) (PNVCL) and poly(N-vinylcaprolactam-co-acrylic acid) (poly(NVCL-co-AA)) were synthesized by solution-free radical polymerization and displayed thermo-responsive behavior, with lower critical solution temperatures (LCSTs) of 35 °C and 39 °C, respectively. The incorporation of AA unities made the poly(NVCL-co-AA) sensitive to both pH and temperature. They were exploited in this work in preparing microparticles loaded with ketoprofen via spray-drying to modulate the drug release rate by changing pH or temperature. The interaction between polymer and drug was studied using X-ray diffractometry, Raman spectrometry and scanning electron microscopy (SEM). The biocompatibility of pure polymers, free ketoprofen as well as the spray-dried particles was demonstrated in vitro by low cytotoxicity and a lack of nitric oxide production in macrophages at concentrations as high as 100 µg/ml. The release profile of ketoprofen was evaluated by in vitro assays at different temperatures and pH values. Drug diffusion out of PNVCL's hydrated polymer network is increased at temperatures below the LCST. However, when poly(NVCL-co-AA) was used as the matrix, the release of ketoprofen was primarily controlled by the pH of the medium. These results indicated that PNVCL and the novel poly(NVCL-co-AA) could be promising candidates for pH and temperature-responsive drug delivery systems.

Multifaceted thermoresponsive poly(N-vinylcaprolactam) coupled with carbon dots for biomedical applications.

A fluorescent thermoresponsive polymer consisting of poly(N-vinylcaprolactam) (PVCL) coupled with carbon dots (CDs) (PVCL-CDs) was synthesized by reacting a carboxyl-terminated PVCL derivative with CDs via N-hydroxysuccinimide and N-(3-(dimethylamino)propyl)-N-ethylcarbodiimide hydrochloride coupling. The temperature-dependent fluorescence properties of this material were studied for biomedical applications. Fluorescence quenching in PVCL-CDs was observed above the lower critical solution temperature (LCST) due to thermo-induced aggregation of the PVCL chains. This fluorescent thermoresponsive PVCL-CDs showed good biocompatibility and was demonstrated as a thermometer for sensing intracellular temperatures and also as a marker for bioimaging. In addition, PVCL-CDs showed a significant fluorescence turn-on response to proteins above the LCST, which allows for the utilization of this material in biosensors. Thus, PVCL-CDs, with its tuneable size, low cytotoxicity, good photostability, ease of bioconjugation, and resistance to metabolic degradation, is a novel material for biomedical applications.

Metabolic Engineering toward Sustainable Production of Nylon-6.

Nylon-6 is a bulk polymer used for many applications. It consists of the non-natural building block 6-aminocaproic acid, the linear form of caprolactam. Via a retro-synthetic approach, two synthetic pathways were identified for the fermentative production of 6-aminocaproic acid. Both pathways require yet unreported novel biocatalytic steps. We demonstrated proof of these bioconversions by in vitro enzyme assays with a set of selected candidate proteins expressed in Escherichia coli. One of the biosynthetic pathways starts with 2-oxoglutarate and contains bioconversions of the ketoacid elongation pathway known from methanogenic archaea. This pathway was selected for implementation in E. coli and yielded 6-aminocaproic acid at levels up to 160 mg/L in lab-scale batch fermentations. The total amount of 6-aminocaproic acid and related intermediates generated by this pathway exceeded 2 g/L in lab-scale fed-batch fermentations, indicating its potential for further optimization toward large-scale sustainable production of nylon-6.

Effect of the molecular architecture on the thermosensitive properties of chitosan-g-poly(N-vinylcaprolactam).

A series of thermoresponsive copolymers based on chitosan-g-poly(N-vinylcaprolactam) were synthesized by amidation reaction using 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride as coupling reagent. The effect of molecular architecture on the thermoresponsive properties of the graft copolymers solutions was studied by varying the chain length of the grafted poly(N-vinylcaprolactam), PVCL, (in the range from 4 to 26 kDa) and the spacing between grafted chains onto the chitosan backbone. The most interesting characteristic of these copolymers is their solubility in water at temperatures below their lower critical solution temperature (LCST). These solutions presented a LCST between 36 and 44 °C, which decreases with the spacing and length of grafted PVCL chains onto the chitosan backbone, in contrast with the limited decrease of the LCST of PVCL above a critical M¯n value around 18 kDa. This behavior offers tangible possibilities for the preparation and application of sensitive bioactive formulations and "smart" drug delivery systems.

Preparation of Polyamide-6 Submicrometer-Sized Spheres by In Situ Polymerization.

Polyamide-6 (PA6) submicron-sized spheres are prepared by two steps: (1) anionic ring-opening polymerization of ε-caprolactam in the presence of poly(ethylene glycol)-block-poly-(propylene glycol)-block-poly(ethylene glycol)(PEG-b-PPG-b-PEG) and (2) separation of PA6 spheres by dissolving PEG-b-PPG-b-PEG from the prepared blends. The PA6 microspheres obtained are regular spherical, with diameter ranging from 200 nm to 2 µm and narrow size distribution, as confirmed by scanning electron microscopy. By comparison with PA6/PS and PA6/PEG systems, it is denominated that the PEG blocks in PEG-b-PPG-b-PEG can effectively reduce the surface tension of PA6 droplets and further decrease the diameter of the PA6 microspheres. The PPG block in PEG-b-PPG-b-PEG can prevent the PA6 droplets coalescing with each other, and isolated spherical particles can be obtained finally. The phase inversion of the PA6/PEG-b-PPG-b-PEG blends occurs at very low PEG-b-PPG-b-PEG content; the PEG-b-PPG-b-PEG phase can be removed by water easily. The whole experiment can be finished in a short time (approximately in half an hour) without using any organic solvents; it is an efficient strategy for the preparation of submicron-sized PA6 microspheres.

Comparison of LCST-transitions of homopolymer mixture, diblock and statistical copolymers of NIPAM and VCL in water.

The LCST-transitions of linear, well-defined polymers of N-isopropylacrylamide (NIPAM) and N-vinylcaprolactam (VCL), including a homopolymer mixture, diblock and statistical copolymers, in water are explored and compared by applying turbidity and FTIR measurements in combination with two-dimensional correlation spectroscopy (2Dcos). Only one transition is observed in all polymer systems, suggesting a dependent aggregation of poly(N-isopropylacrylamide) (PNIPAM) and poly(N-vinylcaprolactam) (PVCL) parts in the phase transition processes. With the help of 2Dcos analysis, it is discovered that the hydrophobic interaction among C-H groups is the driving force for simultaneous collapse of the two distinct thermo-responsive segments. Additionally, the delicate differences within the LCST-transitions thereof have been emphasized, where the phase separation temperatures of the homopolymer mixture and the diblock copolymer are close while that of the statistical copolymer is relatively higher. Moreover, both diblock and statistical copolymers exhibit rather sharp phase transitions while the homopolymer mixture demonstrates a moderately continuous one.

Phase separation of aqueous poly(2-dimethylaminoethyl methacrylate-block-N-vinylcaprolactams).

Details of the phase separation of the poly(N-vinylcaprolactam) (PVCL) homopolymers and block copolymers of PVCL and poly(2-dimethylaminoethyl methacrylate) (PDMAEMA) were studied in aqueous buffer solutions. Phase separation occurred at either one or two temperatures depending on pH. The lower critical solution temperature of PVCL can be fine-tuned by varying the molecular weight of the block, whereas the phase separation temperature of the PDMAEMA block is strongly dependent on pH. The enthalpies of the collapse of the PVCL homopolymer and PVCL-b-PDMAEMA block copolymers were measured and show that the blocks phase separate independently upon heating. PVCL is known to bind amphiphilic cations, and correspondingly, according to light scattering, the block copolymers dissolve as single molecules but also form aggregates at room temperature. At temperatures above the cloud points of both blocks, only homogeneous large aggregates were observed. Zeta potential measurements confirmed that, upon heating, PDMAEMA blocks turn out from the collapsed PVCL globule toward the aqueous phase.

Polymeric micelles for GSH-triggered delivery of arsenic species to cancer cells.

Arsenic trioxide (ATO), dissolved in water as arsenous acid or inorganic arsenite (As(III)), is an effective chemotherapeutic agent against acute promyelocytic leukemia (APL). It has been under investigation as a potential treatment for a variety of solid tumors although with much poorer efficacy than for APL. The toxicity of As(III) and its derivatives is a common concern that has limited its use. The objective of the current study was to develop a polymeric micelle drug delivery system for efficient and controlled delivery of trivalent arsenicals to solid tumor cells. A polymeric micelle-based drug delivery system can potentially extend the duration of drug circulation in blood, restrict access of encapsulated drug to normal tissues, achieve tumor targeted drug delivery, enhance drug accumulation in the tumor area, and trigger drug release at tumor sites if designed properly. These, in turn, can lead to an improved therapeutic index for the polymeric micellar formulation of arsenic species compared to their free form. Towards this goal, a biodegradable block copolymer with pendent thiol groups on the hydrophobic block, i.e., methoxy poly(ethylene oxide)-block-poly[α-(6-mecaptohexyl amino)carboxylate-ε-caprolactone] [PEO-b-P(CCLC6-SH)], was synthesized and used for conjugation of a trivalent arsenical, phenylarsine oxide (PAO), to free thiol groups on the polymer backbone. PAO-loaded micelles had refined size distribution with an average diameter of 150 nm as evidenced by dynamic light scattering (DLS) in water. Prepared polymeric micelles were characterized for the level of PAO conjugation using inductively coupled plasma mass spectrometry (ICP-MS). The results showed 65% of total free thiols were conjugated to PAO providing an arsenic/polymer loading content of ~2.5 wt%. In vitro release study suggests prolonged release of PAO from its polymeric micellar carrier, which was accelerated in the presence of glutathione (GSH). Cytotoxicity studies against MDA-MB-435 cells show that the IC50 of PEO-b-P(CCLC6-S-PAO) is not significantly different from that of free PAO. The results indicate that PEO-b-P(CCLC6-SH) is a promising carrier for successful arsenic delivery for cancer therapy.

Poly(N-vinyl caprolactam) grown on nanographene oxide as an effective nanocargo for drug delivery.

This study evaluated graphene oxide functionalized covalently with poly N-vinyl caprolactam (GO-PVCL) via in situ atomic transfer radical polymerization (ATRP), as a nano-cargo carrier for the efficient delivery of drugs into cells. Water-soluble GO-PVCL exhibited excellent stability in physiological solutions. An anti-cancer drug, camptothecin (CPT), was then loaded onto GO-PVCL with a high payload (20%) through π-π stacking and hydrophobic interactions, and its release could be controlled by varying the pH. PVCL grafted onto GO offers an additional advantage of targeted delivery according to temperature. GO-PVCL showed no obvious toxicity, whereas the CPT-loaded GO-PVCL showed high potency in killing cancer cells in vitro. The drug transportation mechanism was found to be energy-dependent endocytosis. Overall, this study revealed GO-PVCL to be a promising drug delivery vector with high biocompatibility, solubility and stability in physiological solutions, and good payload capacity owing to its small size, low cost, large specific area, ready scalability, and useful non-covalent interactions. This material is expected to be a novel material propitious for biomedical applications.

Initiated chemical vapor deposition of thermoresponsive poly(N-vinylcaprolactam) thin films for cell sheet engineering.

Poly(N-vinylcaprolactam) (PNVCL) is a thermoresponsive polymer known to be nontoxic, water soluble and biocompatible. Here, PNVCL homopolymer was successfully synthesized for the first time by use of a one-step vapor-phase process, termed initiated chemical vapor deposition (iCVD). Fourier transform infrared spectroscopy results showed that radical polymerization took place from N-vinylcaprolactam monomers without damaging the functional caprolactam ring. A sharp lower critical solution temperature transition was observed at 31°C from the iCVD poly(N-vinylcaprolactam) (PNVCL) film. The thermoresponsive PNVCL surface exhibited a hydrophilic/hydrophobic alteration with external temperature change, which enabled the thermally modulated attachment and detachment of cells. The conformal coverage of PNVCL film on various substrates with complex topography, including fabrics and nanopatterns, was successfully demonstrated, which can further be utilized to fabricate cell sheets with aligned cell morphology. The advantage of this system is that cells cultured on such thermoresponsive surfaces could be recovered as an intact cell sheet by simply lowering the temperature, eliminating the need for conventional enzymatic treatments.

Oxidation of primary amines to oximes with molecular oxygen using 1,1-diphenyl-2-picrylhydrazyl and WO3/Al2O3 as catalysts.

The oxidative transformation of primary amines to their corresponding oximes proceeds with high efficiency under molecular oxygen diluted with molecular nitrogen (O2/N2 = 7/93 v/v, 5 MPa) in the presence of the catalysts 1,1-diphenyl-2-picrylhydrazyl (DPPH) and tungusten oxide/alumina (WO3/Al2O3). The method is environmentally benign, because the reaction requires only molecular oxygen as the terminal oxidant and gives water as a side product. Various alicyclic amines and aliphatic amines can be converted to their corresponding oximes in excellent yields. It is noteworthy that the oxidative transformation of primary amines proceeds chemoselectively in the presence of other functional groups. The key step of the present oxidation is a fast electron transfer from the primary amine to DPPH followed by proton transfer to give the α-aminoalkyl radical intermediate, which undergoes reaction with molecular oxygen and hydrogen abstraction to give α-aminoalkyl hydroperoxide. Subsequent reaction of the peroxide with WO3/Al2O3 gives oximes. The aerobic oxidation of secondary amines gives the corresponding nitrones. Aerobic oxidative transformation of cyclohexylamines to cyclohexanone oximes is important as a method for industrial production of ε-caprolactam, a raw material for Nylon 6.

Synthesis and antimycobacterial activity of calpinactam derivatives.

Synthesis of calpinactam 1, a fungal antimycobacterial metabolite, utilizing solid-phase peptide synthesis is described. To explore the structure-activity relationships of 1, its derivatives with different amino acids were also synthesized on the basis of the same synthetic strategy. These derivatives were examined for antimycobacterial activity against Mycobacterium smegmatis. Among them, only peptide 6d having d-Ala in place of d-Glu showed moderate activity.

Synthesis, characterization and biological studies of new antimony(III) halide complexes with ω-thiocaprolactam.

Three new antimony(III) halide complexes (SbX(3), X=Cl, Br and I) with the heterocyclic thione ω-thiocaprolactam (1-azacycloheptane-2-thione, (Hthcl)) of formulae {[SbCl(2)(µ(2)-Cl)(Hthcl)(2)](n)} (1), {[(SbBr(2)(µ(2)-Br)(Hthcl)(2))(2)]} (2) and {[(SbI(2)(µ(2)-I)(Hthcl)(2))(2)]} (3) were synthesized from the reaction of antimony(III) halides with ω-thiocaprolactam in 1:2 stoichiometry. The complexes were characterized by elemental analysis, FT-IR spectroscopy, (1)H, (13)C NMR spectroscopy and Thermal Gravimetry-Differential Thermal Analysis (TG-DTA). Crystal structures of the ligand ω-thiocaprolactam and its complexes 1-3 were determined with single crystal X-ray diffraction analysis. Complexes 1-3 and ω-thiocaprolactam were evaluated for their in vitro cytotoxic activity against leiomyosarcoma (LMS) and human breast adenocarcinoma (MCF-7) tumor cell lines. Antimony complexes 1-3 exhibit strong antiproliferative activity against both cell lines tested. The higher such activity was found for 3 with IC(50) values of 0.12±0.04 µM (LMS) and 0.76±0.16 µM (MCF-7) which are 60 and 10 times respectively, stronger than that of cisplatin. The influence of these complexes 1-3 and ω-thiocaprolactam upon the catalytic peroxidation of linoleic acid to hyperoxolinoleic acid by the enzyme lipoxygenase (LOX) was kinetically and theoretically studied. The results were shown negligible inhibitory activity of 1-3 against LOX.