3,5-Disubstituted hydantoin (1,3-imidazolidinedione) derivatives 5a-h wereprepared by base induced cyclization of the corresponding N-(1-benzotriazolecarbonyl)-L-and D-amino acid amides 4a-h. Compounds 5a-h were evaluated for their cytostatic andantiviral activities. Among all the compounds evaluated, 3-benzhydryl-5-isopropylhydantoin (5a) showed a weak but selective inhibitory effect against vaccinia virus (EC₅₀ =16 μg/mL; selectivity index: 25). 3-Cyclohexyl-5-phenyl hydantoin (5g) showed inhibitoryactivity against cervical carcinoma (HeLa, IC₅₀ = 5.4 μM) and breast carcinoma (MCF-7,IC₅₀ = 2 μM), but also cytotoxic effects towards human normal fibroblasts (WI 38). On thecontrary, the 3-benzhydryl-5-phenyl substituted hydantoin derivative 5h showed moderateinhibitory activity towards HeLa, MCF-7, pancreatic carcinoma (MiaPaCa-2), lungcarcinoma (H 460) and colon carcinoma (SW 620) (IC₅₀ = 20−23 μM), but no effect on WI38.

The plant hormone auxin is the key regulator of plant growth and development. Auxin regulates transcription of plant genes by targeting degradation of transcriptional repressor proteins Aux/IAA. While there are many reports describing its potential to modulate human cell functions, the majority are based on auxin action following enzymatic activation. A study focused on auxin alone and its antiproliferative potential, with emphasis on modulation of the cell cycle, has not been performed. Therefore, we analyzed tumor growth inhibitory effects and the cell-cycle perturbations of natural (IAA, IBA) and synthetic (NAA, 2,4-D) auxins. All derivatives showed cytostatic effects on selected human tumor cell lines. The cell-cycle analysis revealed that IAA and 2,4-D induce strong G1 arrest, along with a drastic decrease in the percentage of S-phase cells in MCF-7 cell line. This phenomenon demonstrates that auxins may have novel, unexploited antitumor potential and should be further investigated.

The photophysical properties and photochemical reactivities of a series of bis-naphthols 4a–4e and bis-anthrols 5a and 5e were investigated by preparative irradiation in CH₃OH, fluorescence spectroscopy and laser flash photolysis (LFP). Methanolysis taking place via photodehydration (bis-naphthols: Φ_R = 0.04–0.05) is in competition with symmetry breaking charge separation (SB-CS). The SB-CS gave rise to radical ions that were detected for 4a and 4e by LFP. Photodehydration gave quinone methides (QMs) that were also detected by LFP (λ_max = 350 nm, τ ≈ 1–2 ms). In the aqueous solvent, excited state proton transfer (ESPT) competes with the abovementioned processes, giving rise to naphtholates, but the process is inefficient and can only be observed in the buffered aqueous solution at pH > 7. Since the dehydration of bis-naphthols delivers QMs, their potential antiproliferative activity was investigated by an MTT test on three human cancer cell lines (NCI-H1299, lung carcinoma; MCF-7, breast adenocarcinoma; and SUM159, pleomorphic breast carcinoma). Cells were treated with 4 or 5 with or without irradiation (350 nm). An enhancement of the activity (up to 10-fold) was observed upon irradiation, which may be associated with QM formation. However, these QMs do not cross-link DNA. The activity is most likely associated with the alkylation of proteins present in the cell cytoplasm, as evidenced by photoinduced alkylation of bovine and human serum albumins by 4a.