Phytochemical composition and bioactivities of Saudi endemic Reseda pentagyna essential oils

Reseda pentagyna, a medicinal plant native to Saudi Arabia, has little scientific evidence of its phytochemical composition and biological capabilities. Despite its potential therapeutic benefits, the Resedaceae family has received little research attention. The purpose of this study was to analyze the phytochemical composition of R. pentagyna leaves essential oil (RPLEO) from Abha, Saudi Arabia, and evaluate its antioxidant, antibacterial, antidiabetic, and cytotoxic effects. The essential oils (EOs) were extracted via hydro-distillation and yielded 4.75 ± 1.75 (W/V). GC-MS analysis showed a robustly dominated monoterpenoid composition, mainly carvacrol (21.59%) as the predominant compound, followed by thymol (3.62%) and other phenolic constituents. RPLEO exhibits high antioxidant activity (DPPH IC50 = 80.13 ± 1.53 µg/mL, ABTS IC50 = 92.72 ± 1.34 µg/mL), which explains the high TPC (141.30 mg GAE/g) and TFC (88.34 mg QAE/g). Furthermore, RPLEO showed an antibacterial activity against Gram-negative pathogens (MIC = 6.25–12.50 µg/mL). It also showed notable antidiabetic potential by inhibiting α-amylase (IC50 = 82.31 µg/mL) and α-glucosidase (IC50 = 87.49 µg/mL) enzymes. Furthermore, it induced considerable cytotoxicity against HepG2 (IC50 = 112.34 µg/mL) and MCF-7 (IC50 = 126.34 µg/mL) cells, confirmed by the upregulation of pro-apoptotic markers (caspase-3, -8, -9, Bax) and downregulation of anti-apoptotic markers (Bcl-2, Bcl-xL). This study provides the first comprehensive analysis of RPLEO, demonstrating significant bioactivity. Further investigations, including compound isolation, in vivo validation, and clinical translation, are recommended to fully realize its medicinal potential.