© 2021 Elsevier B.V.In this study, the fluorescent probe property of a bis indole compound (5,14-dimethyl-5,6,7,8,9,14-hexahydroindolo [2 ', 3′: 3,4] cycloocta [1,2-b] indole), a Caulerpin derivative, which is a member of the indole family, was investigated. For this purpose, firstly, the fluorescence character of the molecule was investigated by absorption and fluorescence spectroscopy techniques in both solvent and surfactant environments. Afterwards, the cytotoxicity of the molecule was tested on the human colon cancer HT-29 cells and breast cancer MCF-7 cells as well as mouse fibroblast 3T3-L1 cells. After determining that the molecule has no cytotoxic effect against all the tested cell lines by 100 µM, the cell staining feature of the probe was examined. The obtained data showed us that the molecule, whose confocal microscopy images were taken at 360 nm excitation wavelength, stained the cell cytoplasm. In addition, optical absorption spectra, oscillator strength (f), transition configuration and transition characteristics of the Ars-In in different solvents were investigated at the theoretical level using Time Dependent-Density Functional Theory (TD-DFT). In conclusion, these results confirm that this indole derivative molecule could be evaluated as an effective fluorescence probe for biological systems.