This work reports the preparation of amino acid-functionalized CQDs from citric acid by facile hydrothermal synthesis. The prepared N-doped CQDs exhibited excellent optical, physical, and chemical properties, and the differences were observed among the six different amino acids used as nitrogen dopants (Leu, Trp, Lys, Arg, Ala, His). Compared to the blank sample (without the addition of amino acids), N-doped CQDs have shown significantly higher quantum yield, also demonstrating the potential in metal ion sensing. The highest quantum yield of 36.45%, with a peak excitation/emission of 340/406 nm, was achieved using citric acid and amino acid Leu (CQD@Leu), treated at temperature of 180 °C during 9 h. The prepared samples were investigated toward metal ion selectivity (Ca²⁺, Cu²⁺, Fe³⁺, K⁺, Hg²⁺, Mg²⁺, Al³⁺, Mn²⁺, and Na⁺), and the CQD@Leu showed a selective and sensitive response upon the addition of Fe³⁺ ions. Therefore, CQD@Leu was selected for further investigation in Fe³⁺ detection in the model system and real well water samples. A developed model was described by a logistic function with a good coefficient of determination of R² = 0.9982, while the linear range was determined in the concentration range from 0.3 mol dm⁻³ to 30 mol dm⁻³, with a determined limit of detection of LOD = 1.77 ± 0.01 mol dm⁻³ and limit of quantification of LOQ = 5.89 ± 0.04 mol dm⁻³. Furthermore, the results of the in vitro cytotoxicity test (MTT) with normal and tumor cell lines (MRC-5, HeLa, NCI-H358, and CaCo-2) clearly demonstrate the excellent biocompatibility of CQD@Leu.

Cell culture models are of central importance for the investigation of cellular metabolism, proliferation and stress responses. In this study, the effects of different concentrations of glucose (1 g/L vs. 4.5 g/L) and fetal bovine serum (FBS; 5%, 10%, 15%) on viability, mitochondrial function and autophagy are investigated in four human cell lines: MRC-5, HeLa, Caco-2 and SW-620. Cells were cultured in defined media for 72 h, and viability was assessed by LDH release, mitochondrial membrane potential using Rhodamine 123, ATP content by luminescence and autophagy activity by dual fluorescence staining. The results showed that HeLa and SW-620 cancer cells exhibited increased proliferation and mitochondrial activity under high glucose conditions, while low glucose media resulted in decreased ATP content and increased membrane permeability in HeLa cells. MRC-5 fibroblasts and Caco-2 cells showed greater resilience to nutrient stress, with minimal changes in LDH release and consistent proliferation. Autophagy was activated under all conditions, with a significant increase only in selected cell-medium combinations. These results highlight the importance of medium composition in influencing cellular bioenergetics and stress responses, which has implications for cancer research, metabolic disease modelling and the development of serum-free culture systems for regenerative medicine.

Syntheses of 6-halogen-substituted benzothiazoles were performed by condensation of 4-hydroxybenzaldehydes and 2-aminotiophenoles and subsequent O-alkylation with appropriate halides, whereas 6-amidino-substituted benzothiazoles were synthesized by condensation of 5-amidino-2-aminothiophenoles and corresponding benzaldehydes. While most of the compounds from non-substituted and halogen-substituted benzothiazole series showed marginal antiproliferative activity on tested tumor cell lines, amidino benzazoles exhibited stronger inhibitory activity. Generally, imidazolyl benzothiazoles showed pronounced and nonselective activity, with the exception of 36c which had a strong inhibitory effect on HuT78 cells (IC₅₀ = 1.6 µM) without adverse cytotoxicity on normal BJ cells (IC₅₀ >100 µM). Compared to benzothiazoles, benzimidazole structural analogs 45a–45c and 46c containing the 1,2,3-triazole ring exhibited pronounced and selective antiproliferative activity against HuT78 cells with IC₅₀ < 10 µM. Moreover, compounds 45c and 46c containing the methoxy group at the phenoxy unit were not toxic to normal BJ cells. Of all the tested compounds, benzimidazole 45a with the unsubstituted phenoxy central core showed the most pronounced cell growth inhibition on THP1 cells in the nanomolar range (IC₅₀ = 0.8 µM; SI = 70). QSAR models of antiproliferative activity for benzazoles on T-cell lymphoma (HuT78) and non-tumor MDCK-1 cells elucidated the effects of the substituents at position 6 of benzazoles, demonstrating their dependence on the topological and spatial distribution of atomic mass, polarizability, and van der Waals volumes. A notable cell cycle perturbation with higher accumulation of cells in the G₂/M phase, and a significant cell increase in subG0/G1 phase were found in HuT78 cells treated with 36c, 42c, 45a–45c and 46c. Apoptotic morphological changes, an externalization of phosphatidylserine, and changes in the mitochondrial membrane potential of treated cells were observed as well.

The aim of this study was to explore the mechanism of antitumor effect of (E)-6-morpholino-9-(styrylsulfonyl)-9H-purine (6-Morpholino-SPD) and (E)-6-amino-9-(styrylsulfonyl)-9H-purine (6-Amino-SPD). The effects on apoptosis induction, mitochondrial potential, and accumulation of ROS in treated K562 cells were determined by flow cytometry. The RT-PCR method was used to measure the expression of Akt, CA IX, caspase 3, and cytochrome c genes, as well as selected miRNAs. Western blot analysis was used to determine the expression of Akt, cytochrome c, and caspase 3. The results demonstrate the potential of the tested derivatives as effective antitumor agents with apoptotic-inducing properties. In leukemic cells treated with 6-Amino-SPD, increased expression of caspase 3 and cytochrome c genes was observed, indicating involvement of the intrinsic mitochondrial pathway in the induction of apoptosis. Conversely, leukemic cells treated with 6-Morpholino-SPD showed reduced expression of these genes. The observed downregulation of miR-21 by 6-Morpholino-SPD may contribute to the induction of apoptosis and disruption of mitochondrial function. In addition, both derivatives exhibited increased expression of Akt and CA IX genes, suggesting activation of the Akt/HIF pathway. However, the exact mechanism and its relations to the observed overexpression of miR-210 need further investigation. The acceptable absorption and distribution properties predicted by ADMET analysis suggest favorable pharmacokinetic properties for these derivatives.

This study investigates two sulfonylpurine derivatives, Pur-6-NH2-SS and Pur-6-Mor-SS, which contain amino and morpholino substituents, for their anticancer potential in 2D and 3D models of human cervical adenocarcinoma (HeLa) cells. Cell cycle distribution, apoptosis, mitochondrial membrane potential, and ROS accumulation were evaluated by flow cytometry. Both Pur-6-NH2-SS and Pur-6-Mor-SS reduced the proportion of cells in the G0/G1 phase (to 39.65 ± 5.59% and 28.25 ± 1.20%, respectively) when compared with untreated cells. Pur-6-NH2-SS additionally increased the proportion of cells in the S phase (7.41 ± 0.32%), whereas Pur-6-Mor-SS increased the number of cells in subG0 (21.05 ± 6.15%). Additionally, Pur-6-NH2-SS triggered early apoptosis in 79.6 ± 8.5% of cells, accompanied by mitochondrial membrane depolarisation in 64.3 ± 9.0%. In comparison, Pur-6-Mor-SS elicited an even stronger apoptotic response, inducing early apoptosis in 87.4 ± 15.6% of cells and mitochondrial membrane potential disruption in 86.8 ± 9.0%, relative to untreated cells. RT-PCR analysis assessed the expression of key regulators, including miR-21, miR-210, and genes involved in survival and stress-response pathways (Akt, CAIX, caspase-3, and cytochrome C). In the 2D model, both derivatives increased CAIX, Akt, and Cyp C expression compared with untreated cells. In contrast, p53 expression remained unchanged in Pur-6-NH2-SS-treated cells and was slightly decreased in Pur-6-Mor-SS-treated cells. Casp3 expression was slightly elevated following Pur-6-NH2-SS treatment and remained nearly unchanged in Pur-6-Mor-SS-treated cells. In the 3D model, Pur-6-NH2-SS exerted a stronger inhibitory effect on CAIX, Akt, p53, Cyp C, and Casp3 expression than Pur-6-Mor-SS, which showed weaker inhibition overall. Both derivatives had a comparable impact on miR-21 and miR-210 expression in 2D and 3D HeLa models. These findings provide mechanistic insight into amino- and morpholino-substituted sulfonylpurine derivatives and highlight how 2D and 3D tumour models influence drug response, offering a basis for further development of purine-based anticancer agents.