Background: Acridine and thiourea derivatives are important compounds in medicinal chemistry due to their diverse biological properties including anticancer and antimicrobial effects. However, literature reveals some side effects associated with use of acridines. It is suggested that hybrid molecules may reduce the side effects and enhance the beneficial properties due to synergistic activity. The objectives of the present study are to synthesize and evaluate the anticancer and antimicrobial properties of new hybrids of acridine thiosemicarbazides derivatives. Results: The structures of the synthesized compounds 4a–4e were elucidated by MS and NMR spectra. In antimicrobial assay, Compound 4c exhibited potent antimicrobial activity compared to the other four compounds. In anticancer studies, we observed that compounds 4a, 4b, 4d and 4e exhibited high cytotoxicity against the MT-4 cell line, with IC50 values of 18.42 ± 1.18, 15.73 ± 0.90, 10.96 ± 0.62 and 11.63 ± 0.11 μM, respectively. The evaluation of anticancer effects, and the associated mechanism reveals that, the anticancer activities may be related to Topo I inhibitory activity, apoptosis and cell-cycle. Molecular docking studies revealed that the presence of planar naphtho-fused rings and a flexible thiourea group together, could improve DNA-intercalation and inhibition of DNA-Topo I activity. Conclusions: The results of this study demonstrate that the rational design of target derivatives as novel antimicrobial or antitumor leads is feasible.

A new coumarin-acridone fluorescent probe S was designed and synthesized, and the structure was confirmed with 1H/13C NMR spectrometry, single-crystal X-ray diffraction, and high-resolution mass spectrometry. This probe has high sensitivity and selectivity for Fe3+ over other testing metal ions at 420 or 436 nm in acetonitrile–MOPS (3-Morpholinopropanesulfonic Acid) buffer solution (20.0 μM, pH = 6.9, 8:2 (v/v)). Under physiological conditions, the probe displayed satisfying time stability with a detection limit of 1.77 µM. In addition, probe S was successfully used to detect intracellular iron changes through a fluorescence-off mode, and the imaging results of cells and zebrafish confirmed their low cytotoxicity and satisfactory cell membrane permeability, as well as their potential biological applications.

Robustic acid is reported to be a bioactive compound, isolated from the medicinal plant Dalbergia benthamii Prain. Ten alkyl and benzyl derivatives (2a–2j) of robustic acid were designed and synthesized based on molecular docking approaches. The biological activities of most of the synthesized compounds (such as 2g, 2h, and 2i) were closely consistent with the docking results. In particular, 4‐O‐phenylpropyl substituted compound 2g displayed potent topoisomerase I inhibitory activity as well as cytotoxicity against SMMC‐7721, HepG2, and HeLa cell lines. Further biological testing suggests that compound 2g acted mainly by an arrest of the tumor cells in G1 phase of the cell cycle and suppressed cell proliferation by inducing apoptosis. The findings of this study are encouraging with respect to potential utilization of these compounds as new topoisomerase I inhibitors.