Optimizing bioactive compounds extraction and cell viability effect of Tithonia diversifolia (Hemsl.) A. Gray dry flower extracts

Context: Tithonia diversifolia (Hemsl.) A. Gray, a species native to Mexico and Central America, is widely distributed across tropical and subtropical regions of Central America, South America, Africa, Asia, and Oceania. Aims: To characterize and optimize the dried flowers of T. diversifolia, focusing on their physicochemical properties, the extraction process, and the viability of HaCaT cells treated with the most effective extract. Methods: The dried flowers of T. diversifolia were analyzed for various physicochemical parameters, including loss on drying, particle size, moisture content, pH, total ash, acid-insoluble ash, and extractable matter. A factorial design (Design of Experiments, DoE) was employed to evaluate and optimize the extraction process based on the contents of total phenolic compounds and flavonoids, determined via colorimetric analysis. The extraction conditions investigated included drug-to-solvent ratios (1:20 and 1:10) and maceration durations (1 and 7 days). The HaCaT cell viability assay was conducted using the extract that was identified as optimal. Results: The physicochemical properties of the dried flowers conformed to the standards set by the Brazilian Pharmacopeia. The optimal extraction conditions for maximizing total phenolic and flavonoid content were a drug-to-solvent ratio of 1:10 and a maceration period of one day. The selected extract, at a concentration of 0.1 mg/mL, exhibited no cytotoxic effects on HaCaT cells after 24 hours of exposure. Conclusions: The application of DoE effectively enhanced the interpretability of the experimental results. The observed cell viability following 24 and 72 hours of extract exposure suggests a potential regenerative effect of the extract on human epithelial (HaCaT) cells.