Chemical Characterization and In Vitro Biological Activities of Essential Oil from Oxalis corniculata L. Collected in the Ecuador Highlands

Oxalis corniculata L. is an ethnobotanically recognized plant in Ecuador. Although its bioactive extracts have been investigated, the chemical and biological properties of its essential oil (OcEO) remain unexplored. This study aimed to characterize the chemical profile of OcEO and evaluate its in vitro antioxidant, antimicrobial, and cytotoxic properties. Aerial parts of O. corniculata were collected and hydrodistilled to obtain the OcEO. Its phytochemical profile was characterized using GC-MS and GC-FID. Antioxidant capacity was measured via DPPH, ABTS, and FRAP assays. Antimicrobial activity against Klebsiella pneumoniae, Acinetobacter baumannii, and Candida albicans was evaluated by determining the minimum inhibitory concentration (MIC) and zone of inhibition (ZOI). Cytotoxicity was assessed on MCF-7, HCT-116, and MRC-5 cell lines using the MTT assay, determining the IC50 and Selective Cytotoxicity Index (SCI). The GC-MS and GC-FID analysis identified or tentatively identified 24 constituents (accounting for 93.2% of the total oil composition), predominantly sesquiterpenes (54.96%), with β-caryophyllene (24.71%) and germacrene D (14.62%) as the major components. OcEO showed moderate complementary chemical antioxidant and antimicrobial effects, being most active against K. pneumoniae (MIC: 0.56 mg/mL) and C. albicans (MIC: 2.24 mg/mL). Furthermore, OcEO evidenced selective cytotoxicity against tumor cells, particularly against HCT-116 (IC50: 8.19 mg/mL; SCI: 4.52). In conclusion, OcEO exhibits potential in vitro antioxidant, antimicrobial, and cytotoxic properties, providing preliminary evidence to support future research on this Ecuadorian essential oil.