Synthesis of anthraquinone-connected coumarin derivatives via grindstone method and their evaluation of antibacterial, antioxidant, tyrosinase inhibitory activities with molecular docking, and DFT calculation studies.

Anthraquinones and coumarins have excellent pharmacological activities and are an important class of natural plant metabolites with various biological activities. In this study, anthraquinone-9,10-dione and coumarin derivatives were combined to develop a novel anthraquinone-connected coumarin-derivative sequence. The synthesised novel anthraquinone-connected coumarin derivatives () were screened for antibacterial, antioxidant, and tyrosinase inhibitory activities. The antibacterial activities of the synthesised compounds () were tested against both gram-positive and gram-negative bacteria. Specifically, compound was more active against than ciprofloxacin. With regard to antioxidant activity, compound (50.68 % at 100 μg/mL) was highly active compared to the other compounds, whereas it was less active than the standard BHT (76.74 % at 100 μg/mL). In terms of compound (9.31 ± 0.45 μg/mL) was highly active against tyrosinase inhibitory activity compared with kojic acid (10.42 ± 0.98 μg/mL). In the molecular docking study, compound had a higher docking score (-8.8 kcal mol) than kojic acid (-1.7 kcal mol). DFT calculations were performed to determine the energy gap of highly active compound (ΔE = 0.11) and weakly active compound (ΔE = 0.12). In this study, we found that every molecule displayed significant antibacterial, antioxidant, and tyrosinase inhibitory properties. Based on these reports, compounds and may act as multi-target agents.