Objectives: This study analyzed the antiproliferative potential of Eugenia uniflora L. leaf extracts against cervical cancer and non-cancerous cell lines. Methods: The extracts were prepared by maceration using hexane (EUH), dichloromethane (EUD), and ethyl acetate (EUA). Their cytotoxic potential was evaluated through MTT assays, wound healing assays, and flow cytometry. To identify classes of secondary metabolites, total phenolic and flavonoid contents were quantified using spectrophotometric methods, and individual metabolites were tentatively identified by LC-MS/MS. Results: EUH, EUD. and EUA exhibited cytotoxicity in HeLa cells, with IC₅₀ values of 63.03 μg/mL, 33.79 μg/mL, and 38.38 μg/mL, respectively. Due to their lower IC₅₀ values, the EUD and EUA fractions were selected for further investigation. EUA and EUD inhibited cell migration at all the time points tested and altered the cell cycle. Twenty-eight compounds were tentatively identified in E. uniflora L. leaf extracts based on the interpretation of their fragmentation patterns and molecular formulas obtained from mass spectrometry. Conclusions: The EUD and EUA extracts appear to modulate the metabolism of cervical cancer cells, leading to cell cycle arrest and inhibition of cell migration. Flavonoids and other phenolic compounds are likely responsible for these observed biological effects.

Over the past decades, natural products have been a primary source of anticancer agents. Naphthoquinones, a large class of secondary metabolites, exhibit known anticancer activity. Thionaphthoquinones, which are naphthoquinones with added thiol groups, have demonstrated similar potential to their precursors. Cervical cancer is the third most common and fourth most lethal type of cancer among women worldwide. This study aimed to investigate the antiproliferative activity of new bis-thionaphthoquinones in cervical cancer cells. Five new molecules (D1-D5) were synthesized via multicomponent reaction and characterized by mass spectrometry, infrared spectroscopy, and nuclear magnetic resonance. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay was used to evaluate antiproliferative activity in HeLa and NIH3T3 cells. Flow cytometry was employed to analyze deoxyribonucleic acid (DNA) fragmentation. PharmMapper was utilized for target fishing. Among the tested molecules, bis-thionaphthoquinone D4 exhibited the highest potency and selectivity, with a half maximal inhibitory concentration (IC50) of 42.7 μM and a selectivity index of 2.05. Additionally, it also induced DNA fragmentation, suggesting its potential to induce cell death. Carbonic anhydrase II was identified as the most likely target for D4. Therefore, bis-thionaphthoquinone D4 demonstrated both potency and selectivity, making it a promising drug candidate for the treatment of cervical cancer.

Oral squamous cell carcinoma (OSCC) is the most prevalent malignancy of the head and neck region, and current chemotherapeutic regimens, based largely on platinum compounds, are limited by low selectivity and severe adverse effects. Aiming to identify selective cytotoxic agents from the Brazilian Atlantic Forest, we screened seventeen ethanolic extracts derived from ten plant species collected in Restinga ecosystems (Myrciaria floribunda, Myrcia amazonica, Myrsine parvifolia, Myrcia ovata, Pilocarpus spicatus, Eugenia sulcata, Eugenia pruniformis, Ocotea indecora, Ocotea notata, and Ocotea pulchella) against the OSCC cell line SCC-9 and primary human gingival fibroblasts. Among the active extracts, those from M. floribunda leaves and stem were the most potent and selective, with IC₅₀ values of 78.7 and 56.9 µg/mL and selectivity indices of 7.14 and 6.80, respectively. Liquid–liquid partitioning of the stem extract yielded an ethyl acetate fraction (MfEA) that was further evaluated against a panel of eight tumor cell lines and against primary fibroblasts, displaying IC₅₀ values ranging from 9.4 to 92.7 µg/mL and selectivity indices between 6.1 and 60.5. Chemical profiling of MfEA by UPLC-DAD-QTOF-ESI-HRMS/MS tentatively annotated gallic and ellagic acids, hydrolyzable tannins, and pentacyclic triterpenoids, several of which have individually been reported to exhibit antitumor activity. In SCC-9 cells, MfEA induced morphological hallmarks of apoptosis, activated effector caspases-3/7, increased the sub-G0/G1 population, and promoted phosphatidylserine externalization, without a detectable increase in H₂O₂ levels. MfEA exhibited negligible hemolytic activity (<3%) and, in C57BL/6 mice, an estimated intraperitoneal LD₅₀ close to 200 mg/kg, with full tolerability at 100 mg/kg. Together, these findings identify the ethyl acetate fraction from Myrciaria floribunda as a promising lead from the Brazilian Restinga for further anticancer drug development.