Phytochemical Study and Cytotoxic Properties of Hydroalcoholic Extracts of Epilobium parviflorum Schreb.: In Silico and In Vitro Insights

Epilobium parviflorum Schreb. is a medicinal plant used traditionally against inflammatory disorders whose cytotoxic potential is still incompletely revealed. The current study investigates the phytochemical composition and in vitro cytotoxic activity of four hydroalcoholic extracts prepared from the aerial parts of E. parviflorum by using maceration and Soxhlet extraction. The extracts were characterized in terms of total phenolic, flavonoid and tannins composition and LC-MS was used to identify its individual polyphenols. Their biological effects were assessed against four cancer cell lines (A375 melanoma, HT-29 colorectal adenocarcinoma, PANC-1 pancreatic carcinoma and SK-OV-3 ovarian adenocarcinoma cells), while using HaCaT keratinocytes as healthy cells in order to assess selectivity. Cell viability, cytoskeletal and nuclear morphology, mitochondrial respiration and network pharmacology were further investigated. A complex phenolic profile was revealed, with hyperoside being identified as the main component in all extracts while the extraction parameters strongly influenced the recovery of various phenolic compounds. All extracts reduced cancer cell viability in a dose-dependent manner after 24 h exposure, with the most pronounced effects observed at 720 and 1000 μg/mL, while HaCaT cells were left relatively unaffected. The morphological assessment indicated nuclear condensation, fragmentation and cytoskeletal disruption following the application of extracts. Moreover, high-resolution respirometry showed reduced oxidative phosphorylation and electron transfer system capacity thus indicating that early mitochondrial dysfunction may contribute to the cytotoxic effects. Network pharmacology revealed that ERBB2, CTNNB1, HSP90AA1 and HDAC6 might act as molecular targets in melanoma. Thus, these findings support the hypothesis that E. parviflorum hydroalcoholic extracts, particularly the 40% ethanol Soxhlet extract, may serve as important sources of bioactive phytocompounds with antiproliferative and apoptotic properties.