Phytochemical constituents, antioxidant activity and toxicity potential of Phlomis olivieri Benth.

Background and objectives: Phlomis olivieri Benth. (Lamiaceae) is a medicinal plant widely distributed in Iran. In the present study, we have investigated the phytochemical constituents, antioxidant activity and general toxicity potential of the aerial parts of this species. Methods: Silica gel (normal and reversed phases) and Sephadex LH-20 column chromatographies were used for isolation of compounds from methanol-soluble portion (MSP) of the total extract obtained from P. olivieri aerial parts. The structures of isolated compounds were elucidated using 1H-NMR, 13C-NMR and UV spectral analyses. Antioxidant activity and general toxicity potential of MSP were also evaluated in DPPH free radical-scavenging assay and brine shrimp lethality test (BSLT), respectively. Results: One caffeoylquinic acid derivative, chlorogenic acid (1), one iridoid glycoside, ipolamiide (2), two phenylethanoid glycosides, phlinoside C (3) and verbascoside (5), along with two flavonoids, isoquercetin (4) and naringenin (6) were isolated and identified from MSP. The MSP exhibited considerable antioxidant activity in DPPH method (IC50; 50.4 ± 4.6 µg/mL), compared to BHT (IC50; 18.7 ± 2.1 µg/mL), without any toxic effect in BSLT at the highest tested dose (1000 µg/mL). Conclusion: the results of the present study introduce P. olivieri as a medicinal plant with valuable biological and pharmacological potentials.