Ethanolic Extract of <i>Salvia officinalis</i> Leaves Affects Viability, Survival, Migration, and the Formation and Growth of 3D Cultures of the Tumourigenic Murine HPV-16+-Related Cancer Cell Line

<i>Salvia officinalis</i> (SO) is one of the most widely used plants in traditional medicine worldwide. In the present study, the effect of an ethanolic extract of <i>S. officinalis</i> leaves on hallmarks of cancer of HPV-16-positive cancer tumorigenic cells, TC-1, was analyzed in vitro. Phytochemical and spectroscopic analysis were performed. Additionally, the extract’s flavonoid content, reducing iron, and antioxidant capacity were determined. In regard to the in vitro tests, the cytotoxic activity and its effect on the replicative capacity and on the cell migration of TC-1 cells were analyzed by viability and clonogenic, survival, and wound healing assays. The effect of a pre-treatment or treatment on 3D culture formation, growth, and reversion capacity was also examined. The results of the phytochemical analysis allowed the detection of tannins, saponins, steroids, and flavonoids. The flavonoids content was found to be 153.40 ± 10.68 µg/mg of extract. Additionally, the extract exhibited an antioxidant capacity and a ferric-reducing capacity of around 40% compared to the ascorbic acid. Thin layer chromatographic (TLC) analysis and spectroscopic tests showed the presence of compounds similar to quercetin and catechin flavonoids in the extract. In the in vitro assays, the SO extract induced in a concentration-dependent way changes in cell morphology, the decrease of cell viability, survival, and migration. At a concentration of 125 µg/mL, the extract inhibited spheroid formation, reduced their growth, and affected their reversion to 2D. Ethanolic extract of <i>S. officinalis</i> leaves had inhibitory effects on hallmarks of the cancer line HPV-16+. This suggests that the phytochemicals present in it may be a source of chemotherapeutics against cervical cancer.