Engineering Semicarbazide-Bearing Polypeptide Conjugates for Efficient Tumor Chemotherapy and Imaging of Tumor Metastasis

Polypeptide materials offer scalability, biocompatibility, and biodegradability, rendering them an ideal platform for biomedical applications. However, the preparation of polypeptides with specific functional groups, such as semicarbazide moieties, remains challenging. This work reports, for the first time, the straightforward synthesis of well-defined methoxy-terminated poly(ethylene glycol)-b-polypeptide hybrid block copolymers (HBCPs) containing semicarbazide moieties. This synthesis involves implementing the direct polymerization of environment-stable N-phenoxycarbonyl-functionalized α-amino acid (NPCA) precursors, thereby avoiding the handling of labile N-carboxyanhydride (NCA) monomers. The resulting HBCPs containing semicarbazide moieties enable facile functionalization with aldehyde/ketone derivatives, forming pH-cleavable semicarbazone linkages for tailored drug release. Particularly, the intracellular pH-triggered hydrolysis of semicarbazone moieties restores the initial semicarbazide residues, facilitating endo-lysosomal escape and thus improving therapeutic outcomes. Furthermore, the integration of the hypoxic probe (Ir(btpna)(bpy)2 ) into the pH-responsive nanomedicines allows sequential responses to acidic and hypoxic tumor microenvironments, enabling precise detection of metastatic tumors. The innovative approach for designing bespoke functional polypeptides holds promise for advanced drug delivery and precision therapeutics.

Design and Synthesis of Novel Betulin Derivatives Containing Thio-/Semicarbazone Moieties as Apoptotic Inducers through Mitochindria-Related Pathways

Two new series of betulin derivatives with semicarbazone (7a-g) or thiosemicarbazone (8a-g) groups at the C-28 position were synthesized. All compounds were evaluated for their in vitro cytotoxicities in human hepatocellular carcinoma cells (HepG2), human breast carcinoma cells (MCF-7), human lung carcinoma cells (A549), human colorectal cells (HCT-116) and normal human gastric epithelial cells (GES-1). Among these compounds, 8f displayed the most potent cytotoxicity with an IC₅₀ value of 5.86 ± 0.61 μM against MCF-7 cells. Furthermore, the preliminary mechanism studies in MCF-7 cells showed that compound 8f could trigger the intracellular mitochondrial-mediated apoptosis pathway by losing MMP level, which was related with the upregulation of Bax, P53 and cytochrome c expression; the downregulation of Bcl-2 expression; activation of the expression levels of caspase-3, caspase-9, cleaved caspase-3 and cleaved caspase-9; and an increase in the amounts of intracellular reactive oxygen species. These results indicated that compound 8f may be used as a valuable skeleton structure for developing novel antitumor agents.

Design, synthesis and insecticidal activity of novel semicarbazones and thiosemicarbazones derived from chalcone

Thirty semicarbazone and thiosemicarbazone derivatives (2a-w and 4a-g) from chalcones containing furan and thiophene ring were designed and synthesized. They were characterized by IR, ¹H NMR, ¹³C NMR and HRMS. The crystal structure of compound 2r was characterized by single crystal X-ray diffraction. It crystallizes in the monoclinic system with space group P2₁/c. The insecticidal activity of the synthesized compounds was screened against Leucania separata and Pieris rapae using beta-cypermethrin as the comparative standard. The results displayed that most of them had remarkable insecticidal activity. Among them, compounds 2e-g showed better activity than beta-cypermethrin against L. separata and P. rapae. Compound 2p also possessed a better activity than beta-cypermethrin against P. rapae. The insecticidal activities of these compounds have been reported for the first time.

Novel Steroidal 5α,8α-Endoperoxide Derivatives with Semicarbazone/Thiosemicarbazone Side-chain as Apoptotic Inducers through an Intrinsic Apoptosis Pathway: Design, Synthesis and Biological Studies

A series of novel steroidal 5α,8α-endoperoxide derivatives bearing semicarbazone (7a–g) or thiosemicarbazone (7h–k) side chain were designed, synthesized and evaluated for their cytotoxicities in four human cancer cell lines (HepG2, HCT-116, MCF-7, and A549) using the MTT assay in vitro. The results showed that compound 7j exhibited significant cytotoxic activity against HepG2 cells (IC₅₀ = 3.52 μM), being more potent than ergosterol peroxide. Further cellular mechanism studies in HepG2 cells indicated that compound 7j triggered the mitochondrial-mediated apoptosis by decreasing mitochondrial membrane potential (MMP), which was associated with up-regulation of Bax, down-regulation of Bcl-2, activation levels of the caspase cascade, and formation of reactive oxygen species (ROS). The above findings indicated that compound 7j may be used as a promising skeleton for antitumor agents with improved efficacy.

Interplay between Polymorphism and Isostructurality in the 2-Fur- and 2-Thenaldehyde Semi- and Thiosemicarbazones

The four compounds, namely: 5-nitro-2-furaldehyde thiosemicarbazone (1); 5-nitro-2-thiophene thiosemicarbazone (2); 5-nitro-2-furaldehyde semicarbazone (3); and 5-nitro-2-thiophene semicarbazone (4) were synthesized and crystallized. The three new crystal structures of 1, 2, and 4 were determined and compared to three already known crystal structures of 3. Additionally, two new polymorphic forms of 1 solvate were synthesized and studied. The influence of the exchange of 2-thiophene to 2-furaldehyde as well as thiosemicarbazone and semicarbazone on the self-assembly of supramolecular nets was elucidated and discussed in terms of the formed synthons and assemblies accompanied by Full Interaction Maps analysis. Changes in the strength of IR oscillators caused by the molecular and crystal packing effects are described and explained in terms of changes of electron density.

Semicarbazone Derivatives Bearing Phenyl Moiety: Synthesis, Anticancer Activity, Cell Cycle, Apoptosis-Inducing and Metabolic Stability Study

A series of semicarbazone derivatives bearing phenyl moiety were synthesized and evaluated for the vitro anticancer activities in four human cancer cell lines (human colon cancer (HT29), human neuro-blastoma (SK-N-SH), human breast cancer (MDA-MB-231), and human gastric cancer (MKN45)). Biological evaluation led to the identification of 11q and 11s, which showed excellent anticancer activities against tested cancer cell lines with IC₅₀ values ranging from 0.32 to 1.57 µM, respectively, while exhibiting weak cytotoxicity on the normal cells (human umbilical vein endothelial cell (HUVEC)). Flow cytometric assay for cell cycle and apoptosis revealed that 11q and 11s caused an arrest in the Sub-G1 cell cycle and inhibited proliferation of cancer cells by inducing apoptosis in a dose-dependent manner. Further enzymatic assay suggested that 11q and 11s could significantly activated procaspase-3 to caspase-3. Metabolic stability study indicated that 11q and 11s showed moderate stability in vitro in human and rat liver microsomes. In view of promising pharmacological activities of 11q and 11s, which had emerged as the valuable lead for further development in the treatment for cancer.

Viscoelastic Oxidized Alginates with Reversible Imine Type Crosslinks: Self-Healing, Injectable, and Bioprintable Hydrogels

Bioprinting techniques allow for the recreation of 3D tissue-like structures. By deposition of hydrogels combined with cells (bioinks) in a spatially controlled way, one can create complex and multiscale structures. Despite this promise, the ability to deposit customizable cell-laden structures for soft tissues is still limited. Traditionally, bioprinting relies on hydrogels comprised of covalent or mostly static crosslinks. Yet, soft tissues and the extracellular matrix (ECM) possess viscoelastic properties, which can be more appropriately mimicked with hydrogels containing reversible crosslinks. In this study, we have investigated aldehyde containing oxidized alginate (ox-alg), combined with different cross-linkers, to develop a small library of viscoelastic, self-healing, and bioprintable hydrogels. By using distinctly different imine-type dynamic covalent chemistries (DCvC), (oxime, semicarbazone, and hydrazone), rational tuning of rheological and mechanical properties was possible. While all materials showed biocompatibility, we observed that the nature of imine type crosslink had a marked influence on hydrogel stiffness, viscoelasticity, self-healing, cell morphology, and printability. The semicarbazone and hydrazone crosslinks were found to be viscoelastic, self-healing, and printable-without the need for additional Ca2+ crosslinking-while also promoting the adhesion and spreading of fibroblasts. In contrast, the oxime cross-linked gels were found to be mostly elastic and showed neither self-healing, suitable printability, nor fibroblast spreading. The semicarbazone and hydrazone gels hold great potential as dynamic 3D cell culture systems, for therapeutics and cell delivery, and a newer generation of smart bioinks.

Crystal structure and Hirshfeld surface analysis of (E)-1-[(4,7-di-methyl-quinolin-2-yl)methyl-idene]semicarbazide dihydrate

In the title compound, C13H14N4O·2H2O, the organic mol-ecule is almost planar. In the crystal, the mol-ecules are linked by O-H⋯O, N-H⋯O and O-H⋯N hydrogen bonds, forming a two-dimensional network parallel to (10). Hirshfeld surface analysis and two-dimensional fingerprint plots indicate that the most important contributions to the crystal packing are from H⋯H (55.4%), H⋯O/O⋯H (14.8%), H⋯C/C⋯H (11.7%) and H⋯N/N⋯H (8.3%) inter-actions.

The use of dialdehyde starch derivatives in the phytoremediation of soils contaminated with heavy metals

Products of the reaction between dialdehyde starch and Y-NH2 compounds (e.g. semicarbazide or hydrazine) are effective ligands for metal ions. The usefulness of these derivatives was tested in the experiment, both in terms of the immobilization of heavy metal ions in soil and the potential application in phytoextraction processes. The experimental model comprised maize and the ions of such metals as: Zn(II), Pb(II), Cu(II), Cd(II), and Ni(II). The amount of maize yield, as well as heavy metal content and uptake by the aboveground parts and roots of maize, were studied during a three-year pot experiment. The results of the study indicate the significant impact of heavy metals on reduced yield and increased heavy metal content in maize. Soil-applied dialdehyde starch derivatives resulted in lower yields, particularly disemicarbazone (DASS), but in heavy metal-contaminated soils they largely limited the negative impact of these metals both on yielding and heavy metal content in plants, particularly dihydrazone (DASH). It was demonstrated that the application of dihydrazone (DASH) to a soil polluted with heavy metals boosted the uptake of Zn, Pb, Cu, and Cd from the soil, hence there is a possibility to use this compound in the phytoextraction of these metals from the soil. Decreased Ni uptake was also determined, hence the possibility of using this compound in the immobilization of this metal. The study showed that dialdehyde starch disemicarbazone was ineffective in the discussed processes.

Crystal structures of crotonaldehyde semicarbazone and crotonaldehyde thiosemicarbazone from X-ray powder diffraction data

Crotonaldehyde semicarbazone {systematic name: (E)-2-[(E)-but-2-en-1-yl-idene]hydrazinecarboxamide}, C5H9N3O, (I), and crotonaldehyde thio-semi-carba-zone {systematic name: (E)-2-[(E)-but-2-en-1-yldene]hydra-zinecarbo--thio-amide}, C5H9N3S, (II), show the same E conformation around the imine C=N bond. Compounds (I) and (II) were obtained by the condensation of crotonaldehyde with semicarbazide hydro-chloride and thio-semicarbazide, respectively. Each mol-ecule has an intra-molecular N-H⋯N hydrogen bond, which generates an S(5) ring. In (I), the crotonaldehyde fragment is twisted by 2.59 (5)° from the semicarbazide mean plane, while in (II) the corresponding angle (with the thio-semicarbazide mean plane) is 9.12 (5)°. The crystal packing is different in the two compounds: in (I) inter-molecular N-H⋯O hydrogen bonds link the mol-ecules into layers parallel to the bc plane, while weak inter-molecular N-H⋯S hydrogen bonds in (II) link the mol-ecules into chains propagating in [110].

Structure-Activity Relationship of Semicarbazone EGA Furnishes Photoaffinity Inhibitors of Anthrax Toxin Cellular Entry

EGA, 1, prevents the entry of multiple viruses and bacterial toxins into mammalian cells by inhibiting vesicular trafficking. The cellular target of 1 is unknown, and a structure-activity relationship study was conducted in order to develop a strategy for target identification. A compound with midnanomolar potency was identified (2), and three photoaffinity labels were synthesized (3-5). For this series, the expected photochemistry of the phenyl azide moiety is a more important factor than the IC50 of the photoprobe in obtaining a successful photolabeling event. While 3 was the most effective reversible inhibitor of the series, it provided no protection to cells against anthrax lethal toxin (LT) following UV irradiation. Conversely, 5, which possessed weak bioactivity in the standard assay, conferred robust irreversible protection vs LT to cells upon UV photolysis.