Research Journal of Pharmacognosy (RJP) 4(4), 2017: 57-64 Received: 7 May 2017 Accepted: 5 July 2017 Original article Phytochemical analysis and antioxidative properties of Centaurea albonitens S. Hamedeyazdan1,2, F. Niroumand3, F. Fathiazad2* 1Drug Applied Research Centre, Tabriz University of Medical Sciences, Tabriz, Iran. 2Department of Pharmacognosy, Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran. 3Student Research Committee, Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran. Abstract Background and objectives: The genus Centaurea from the Asteraceae family is one of the most widely distributed plant genera worldwide that has been extensively used in folk medicine for hundreds of years. The present study is the first investigation about the principal constituents of Centaurea albonitens Turrill which is native to Iran. Methods: The aerial parts of C. albonitens were extracted via maceration. Phytochemical analysis of the methanol extract was carried out via different chromatography approaches like HPLC, SPE and preparative TLC. Structures of the purified compounds were revealed through spectral analysis from 1D and 2D NMR including DQF-COSY, HSQC and DEPT in comparison with the relative data in published reports. Subsequently, the antioxidant property of the extract was evaluated via scavenging the free DPPH radicals. In addition, the total phenolic and flavonoid contents of the extract were ascertained based on Folin-Ciocalteu and colorimetric aluminum chloride methods, correspondingly. Results: Analysis of the extract yielded in the isolation and identification of arctiin and apigenin-4'-O-rhamnoside. Moreover, the antioxidant assessment determined IC50 value of 389.9 µg/mL for the plant extract in DPPH assay. The total phenolics and flavonoids content of the plant extract were 2.87 g gallic acid equivalent and 0.28 g quercetin equivalent both in 100 g dried plant material. Conclusion: The findings of this study introduce C. albonitens as a suitable source for isolation of lignans (like arctiin). Keywords: apigenin-4'-O-rhamnoside, arctiin, Asteraceae, Centaurea albonitens, lignans Introduction Plants of Asteraceae family have been valuable well. Flora Iranica [3] has reported 28 growth natural remedy resources for most nations. The situ for different species of Centaurea. It is of genus Centaurea (Asteraceae) is one of the most note to mention that 74 species from Centaurea widely distributed plant genera worldwide. The such as C. bachtiarica, C. lachnopus, C. aziziana, number of taxa included in this genus ranges C. ustulata, C. pterocaula, C. imperialis, C. from 500 to 600 globally [1]. Turkey is the most pabotii, C. hyrcanica are native to Iran [4]. abundant habitat for Centaurea species [2] while Different species of genus Centaurea have been Iran has been accepted as one of the major extensively used in folk medicine for hundreds of centers of diversity for the genus Centaurea, as years [5] as wound healing, antidiabetic, anti- © Available at: http://rjpharmacognosy.ir Copy right 2014 by the Iranian Society of Pharmacognosy *Corresponding author: [email protected], Tel: +98413-3372250-51, Ext. 240, Fax: +98413-3334798 Hamedeyazdan S. et al. diarrhea, antirheumatic, anti-inflammatory [6], phase-extraction (SPE) on Sep-Pak C18 cartridge choleretic, cholagogue, digestive, stomachic, (10 g, Waters, Ireland) using a step-wise gradient diuretic, astringent, hypotensive, antipyretic, of MeOH-H2O mixture (10:90, 20:80, 40:60, cytotoxic [7] and antibacterial agents [8]. 60:40, 80:20 and 100:0), 200 mL each affording Phytochemical studies on various species of 6 fractions. All fractions were dried under vaccue Centaurea have reported isolation of different using a rotary evaporator at 45 °C. In order to classes of compounds such as flavonoids, obtain the optimum gradient time program of the sesquiterpene lactones, triterpenes and alkaloids, SPE fractions, reversed phase analytical-HPLC along with other secondary metabolites [9]. (Shimadzu, Japan) equipped with a Shim-pack Centaurea albonitens Turrill is one of the seventy ODS column (250 mm ×4.6 mm I.D.) and a four Centaurea species represented in flora of UV/PDA detector was applied. Accordingly, Iran. This species grows as a perennial plant in fraction 3 which was eluted with 40% MeOH- semi-arid habitats at the north-west of Iran, East H2O containing the main compounds was further Azerbaijan province. Regarding the valuable analyzed by preparative-HPLC. Separations were reports on chemical diversity of compounds carried out with a linear gradient of mobile phase, present in different species of the genus 20-50% acetonitrile in water; 50 min; flow rate: Centaurea along with their valuable biological 15 mL/min. Peak fractions with retention time of properties, we decided to study C. albonitens 19.5 min (fraction I) and 21.5 min (fraction II) phytochemicals. It is of note to mention that the were collected according to the chromatogram (figure 1). Additional purification of the two present study is the first phytochemical HPLC fractions I and II were accomplished by investigation on C. albonitens. normal phase preparative thin layer chromatography on silicagel GF . Mobile phase Experimental 254 of ethyl acetate 100: formic acid 11: acetic acid Plant material 11: water 26 was employed for preparative TLC, Aerial parts of C.albonitens were collected yielding compound I (70 mg, Rf~0.5) and during the flowering stage from wild population compound II (56 mg, Rf~0.8). Detection of the growing in Mishudagh, East Azarbaijan, Iran, in spots was fulfilled under UV-Visible light at the June 2015. A voucher specimen (No. 6583) of wavelengths of 254 and 366 nm. The spots were the plant has been deposited at the herbarium of scrapped off the silicagel plates, extracted and the East Azerbaijan research center for eluted with methanol. Eventually, chemical agriculture and natural resources Research and structures of the purified compounds were Education Center, Tabriz, Iran. elucidated via 1D and 2D NMR spectroscopic analyses recorded in DMSO-d6 on a Bruker DRX Extraction, fractionation and isolation 400 MHz NMR spectrometer in accordance with The air-dried ground aerial parts of C. albonitens the obtained experimental data and authentic (450 g) were defatted with petroleum ether and published data. subsequently extracted with chloroform (3×4 L) and methanol (3×4 L) respectively, for 24 h via Determination of in vitro antioxidant activity maceration at room temperature. The crude 1,1-diphenyl-2-picryl-hydrazil (DPPH) was used extracts were filtered, concentrated and dried at to determine the free radical scavenging potential 45 °C using a rotary evaporator (Heidolph, of the MeOH extract. Briefly, 8 mg of DPPH in Germany). The greenish methanol (MeOH) 100 mL MeOH was prepared [10]. The stock extract weighing 6.07% (w/w) was selected for concentration of MeOH extract 1 mg/mL was further evaluation which was kept in an air tight prepared followed by two-fold dilution series (i.e. bottle in a refrigerator until use. Two g of the 5×10-1, 2.5×10-1, 1.25×10-1, 6.25×10-2, 3.13×10-2 dried MeOH extract was fractionated by solid- and 1.56×10-2 mg/mL). 58 RJP 4(4), 2017: 57-64 Phytochemicals from Centaurea albonitens Figure 1. HPLC chromatogram of of fractions Ι and ΙΙ from Sep-Pak 40% with retention times (tR 19.5 and 21.5 min) depicted at different wavelengths of 220, 280 and 330 nm Correspondingly, 5 mL of DPPH solution was Assay for total phenolics content added to 5 mL of each concentration. The The total phenolics content of the MeOH extract mixture was shaken and allowed to stand at room was determined by Folin-Ciocalteau method [12]. temperature for 30 min. Absorbance of the Briefly, 0.5 mL of MeOH extract, 5 mL of Folin- samples were recorded against a blank Ciocalteau 10% (v/v) in distilled water and 4 mL (methanol) at 517 nm using a UV Na2CO3 1 M were all mixed. Following the spectrophotometer (Shimadzu, Japan). The incubation at room temperature for 15 min, the experiments were performed in triplicate and the absorbance was measured by UV-VIS spectrophotometer at 765 nm. The standard average absorption was recorded for each calibration curve of gallic acid was achieved by concentration. The free radical scavenging 25, 50, 100, 200 and 400µg/mL in MeOH: water percentage (I %) was calculated by following (50:50, v/v). The total phenolics content was formula: calculated from the calibration curve of gallic acid. Total phenolics content of MeOH extract I(%) = 100 [(A blank- A sample) / A blank] was mentioned as g gallic acid equivalent per 100 g of dried plant material [13]. IC50 (50% inhibitory concentration), concentration of the MeOH extract reducing 50% Assay for total flavonoid content of the DPPH free radicals, was calculated from The flavonoid content of MeOH extract was the graph of inhibition percentages against determined using colorimetric aluminum chloride different concentration of C. albonitens MeOH method [14]. Briefly, 0.5 mL of the extract, 1.5 extract in mg/mL. Besides, the same procedure mL MeOH, 0.1 mL aluminum chloride (10℅), was practiced with quercetin as the positive 0.1 mL potassium acetate (1M) and 2.8 mL control [11]. distilled water were mixed. Following the 59 Hamedeyazdan S. et al. 2 7 9 mixture incubation at room temperature for 30 H3CO a 3 1 8 min, the absorbance was measured by UV-VIS O 4 6 8' spectrophotometer at 415 nm. The standard 9' H3CO 5 7' calibration curve of quercetin was achieved by O 25, 50, 100, 200 and 400 µg/mL in MeOH. The 1' total flavonoid content was calculated from the 6' 2' calibration curve of quercetin. Total flavonoid 5' 3' content of MeOH extract was mentioned as g 4' OCH3 O quercetin equivalent per 100 g of dried plant 6" O material [15].