Composition of Volatiles, Phytochemical Analysis, Antioxidant and Anticancer Activity of Euryops floribundus Ne.Br. Leaves (Asteraceae)

<i>Euryops floribundus</i> has traditionally been recognized for its therapeutic benefits, although its pharmacological potential has not been fully explored. This study investigated the leaves of <i>E. floribundus</i> for volatile compounds, in vitro anticancer potential, antioxidant activity, and phytochemical composition using standard methods. Terpenoids, flavonoids, glycosides, tannins, saponins, and steroids were identified using qualitative screening. FTIR analysis verified that the functional groups corresponded to bioactive substances. Methanol, ethanol, and aqueous extracts showed dose-dependent 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity. Nitric oxide scavenging activity ranged from 7.2% to 22.5% at 2500 μg/mL. GC-MS profiling of essential oils revealed monoterpenes as the primary constituents (60%), with sabinene (27.86%) and terpinen-4-ol (13.63%) as major chemicals. Significant antiproliferative effects were shown by ethanol and methanol extracts against DU-145, PC-3, and SK-UT-1 cancer cell lines with cell viability inhibition ranging from 82.6% to 85.6%, and IC₅₀ values ranging from 1.7 ± 0.02 to 2.7 ± 0.03 µg/mL. These findings support the potential therapeutic uses of <i>E. floribundus</i> leaves and necessitate additional bioassay-guided research since they indicate that the leaves are rich in bioactive phytochemicals with antioxidant and anticancer activities.