Molecular Profiling and Selective Pro-Apoptotic Activity of a Pruning-Derived Lavandula dentata Leaf-Surface Extract in Colorectal Cancer Cells

Lavandula dentata is a medicinal and aromatic plant rich in specialised secondary metabolites, but the biomedical potential of leaf-surface metabolites recovered from pruning biomass remains poorly investigated. In this study, a pruning-derived leaf-surface extract of L. dentata was obtained by brief acetone immersion followed by n-hexane partitioning. Its chemical profile was investigated by ultra-high-performance liquid chromatography coupled with high-resolution tandem mass spectrometry analysis combined with feature-based molecular networking, which revealed an enrichment in methoxylated flavonoids and pentacyclic triterpenes, including oleanane- and ursane-like derivatives. The biological activity of the extract was evaluated in HCT116 colorectal cancer cells, MDA-MB-231 triple-negative breast cancer cells, and HaCaT keratinocytes. After 24 h treatment, the extract selectively reduced HCT116 cell viability in a concentration-dependent manner, with an IC50 of 27.8 ± 1.049 μg/mL, whereas MDA-MB-231 and HaCaT cells were less sensitive. Mechanistic analyses in HCT116 cells showed increased early and late apoptotic populations, mitochondrial membrane depolarisation, and enhanced cleavage of caspase-9, caspase-3, and PARP. These findings indicate that a chemically profiled L. dentata leaf-surface extract selectively impairs colorectal cancer cell survival by activating mitochondria-mediated apoptosis. The study also supports the valorisation of pruning-derived aromatic plant biomass as a source of bioactive natural products with potential biomedical relevance.