NATURAL MEDICINE NOTE Free-radical-scavenging principles from Phlomis caucasica Abbas Delazar Æ Araz Sabzevari Æ Mahdi Mojarrab Æ Hossein Nazemiyeh Æ Solmaz Esnaashari Æ Lutfun Nahar Æ Seied Mehdi Razavi Æ Satyajit Dey Sarker Received: 3 March 2008 / Accepted: 18 April 2008 / Published online: 17 May 2008 Ó The Japanese Society of Pharmacognosy and Springer 2008 Abstract Seven free-radical-scavenging phenolic com- pounds including five flavonoids, rutin (1), chrysoeriol 7- O-rutinoside (2), kaempferol 3-O-glucoside (3), chrysoe- riol 7-O-glucoside (4) and naringenin (5), and two phenylethanoid glycosides, forsythoside B (6) and acteo- side (7) were isolated from the methanol extract of the aerial parts of the Iranian medicinal plant Phlomis cauca- sica by reversed-phase preparative high-performance liquid chromatography (HPLC), and the structures of these compounds were elucidated by spectroscopic means. The free-radical-scavenging properties of 1–7 were assessed by 2,2-diphenyl-1-picryl hydrazyl (DPPH) assay. Among these compounds, forsythoside B (6) and acteoside (7) were found to be the most potent antioxidants with the RC 50 values of 4.97 and 4.27 lg/ml, respectively. Keywords Phlomis caucasic Á Lamiaceae Á Phenylethanoid Á Flavonoid Á Antioxidant Phlomis caucasica Rech. (family: Lamiaceae) is one of the 17 endemic Iranian species of the genus Phlomis [1]. This plant grows abundantly in the Yam area located in east Azerbaijan province of Iran. A number of Phlomis species have been used in Iranian traditional medicine as a stimulant and tonic and to treat pains, respiratory tract infections, diabetes and wounds [2, 3]. P. caucasica has been used in the treatment of throat infections. Whereas the genus Phlomis is known to produce a variety of compounds including, terpenoids, iridoids, phe- nylethanoids, phenylpropanoids and flavonoids [2], no phytochemical investigation on P. caucasica has ever been carried out before. As a part of our ongoing phytochemical and bioactivity studies on plants from Iranian flora [4–16], we report on the isolation and identification of seven antioxidant phenolic compounds (1–5), and two phenylethanoid glyco- sides (6–7) from the aerial parts of P. caucasica and also on their free-radical-scavenging properties in the 2,2-diphenyl- 1-picryl hydrazyl (DPPH) assay. The dried and ground aerial parts of P. caucasica (100 g) were Soxhlet extracted, successively, with n-hexane, dichloromethane and methanol (1.1 L each). All these extracts were separately concentrated using a rotary evapo- rator at a maximum temperature of 45°C to yield 1.2, 0.72, and 13.9 g of dried n-hexane, dichloromethane (DCM) and methanol extracts, respectively. The methanol (MeOH) extract (2 g) was subjected to Sep-Pack fractionation (Sep- Pak, C 18 cartridge; 10 g) using a step gradient of MeOH– water mixture (10:90, 20:80, 40:60, 60:40, 80:20 and 100:0). The preparative reversed-phase high-performance liquid chromatography (HPLC) analysis (Shim Pak Prep-ODS column 10 lm, 250 mm 9 21.2 mm; mobile phase: 0– 50 min gradient 30–50% MeOH in water; 50–62 min, iso- cratic MeOH 50% in water; flow-rate 20 ml/min; detection at 248 nm) of the 40% methanolic Sep-Pack fraction (283 mg) resulted in isolation of four compounds: 6 (14 mg, retention time: 20.5 min), 7 (23.2 mg, t R = 22 min), 1 (15.7 mg, t R = 30 min) and 2 (13 mg, t R = 32 min). The A. Delazar Á A. Sabzevari Á M. Mojarrab Á H. Nazemiyeh Á S. Esnaashari School of Pharmacy and Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz, Iran L. Nahar Á S. D. Sarker (&) School of Biomedical Sciences, University of Ulster, Cromore Road, Coleraine BT52 1SA, Co. Londonderry, UK e-mail: s.sarker@ulster.ac.uk S. M. Razavi Department of Biology, Faculty of Science, Mohagegeh Ardabili University, Ardabil, Iran 123 J Nat Med (2008) 62:464–466 DOI 10.1007/s11418-008-0255-y