RESUMEN
Medical research explores plant extracts' properties to obtain potential anticancer drugs. The present study aims to formulate, develop, and characterize the bioadhesive oral films containing Usnea barbata (L.) dry ethanol extract (F-UBE-HPC) and to investigate their anticancer potential for possible use in oral cancer therapy. The physicochemical and morphological properties of the bioadhesive oral films were analyzed through Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Atomic Force Microscopy (AFM), thermogravimetric analysis (TG), and X-ray diffraction techniques. Pharmacotechnical evaluation (consisting of the measurement of the specific parameters: weight uniformity, thickness, folding endurance, tensile strength, elongation, moisture content, pH, disintegration time, swelling rate, and ex vivo mucoadhesion time) completed the bioadhesive films' analysis. Next, oxidative stress, caspase 3/7 activity, nuclear condensation, lysosomal activity, and DNA synthesis induced by F-UBE-HPC in normal blood cell cultures and oral epithelial squamous cell carcinoma (CLS-354) cell line and its influence on both cell types' division and proliferation was evaluated. The results reveal that each F-UBE-HPC contains 0.330 mg dry extract with a usnic acid (UA) content of 0.036 mg. The bioadhesive oral films are thin (0.093 ± 0.002 mm), reveal a neutral pH (7.10 ± 0.02), a disintegration time of 118 ± 3.16 s, an ex vivo bioadhesion time of 98 ± 3.58 min, and show a swelling ratio after 6 h of 289 ± 5.82%, being suitable for application on the oral mucosa. They displayed in vitro anticancer activity on CLS-354 tumor cells. By considerably increasing cellular oxidative stress and caspase 3/7 activity, they triggered apoptotic processes in oral cancer cells, inducing high levels of nuclear condensation and lysosomal activity, cell cycle arrest in G0/G1, and blocking DNA synthesis. All these properties lead to considering the UBE-loaded bioadhesive oral films suitable for potential application as a complementary therapy in oral cancer.