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Using high-performance liquid chromatography/mass spectrometry, leaf and petal phenolic profiles of four rose (Rosa) species (R. canina, R. glauca, R. rubiginosa, R. sempervirens) traditionally used for medicinal purposes and three modern rose cultivars (Rosarium Uetersen, Ulrich Brunner Fils, Schwanensee) were determined. An abundance of phenolic constituents was identified: seven different anthocyanins and 31 flavonols in petals; 30 flavonols, 14 phenolic acids, and their derivatives; 15 flavanols; and 20 hydrolysable tannins in leaves. Additionally, petal color was measured with a colorimeter and regression analysis indicated a strong correlation between color parameter a* and total anthocyanin content. The content and composition of phenolic compounds varied significantly among species and cultivars and plant organs investigated. Distinct differences in the distribution of leaf phenolic compounds were observed, especially between Rosa species and modern rose cultivars. In general, leaves of analyzed species were richer in content of most phenolic groups and individual components compared with cultivars. Multivariate statistical analysis clustered the investigated species and cultivars into three distinct groups. Among species, leaves of R. canina stood out with their high and varied phenolic content. Conversely, leaves of the susceptible cultivar Schwanensee appeared most dissimilar as a result of their low levels of phenolic constituents. The genus Rosa contains more than 200 species distributed in Europe, Asia, the Middle East, and North America (Li et al., 2013). The genus is represented by 22 species in the Slovenian flora, among which R. canina, R. glauca, R. rubiginosa, and R. sempervirens are most frequent (Martincic et al., 1999). Numerous rose cultivars are widely planted in gardens and parks for their aesthetic value and native plants are harvested for their fruit and flowers. Medicinal benefits of the genus Rosa have been reported in many studies and specific plant tissue has been used for different purposes (Nowak and Gawlik-Dziki, 2007). Rose hips comprise several biologically active compounds and are famous for their high content of vitamins, particularly vitamin C (Hvattum, 2002; Roman et al., 2013). Fragrance compounds in rose petals are praised in perfumery and food industries (Farooq et al., 2012). Similarly, rose leaves have been used in Chinese and European medicine for centuries as ingredients in common cold remedies (Coruh and Ercisli, 2010; Fenglin et al., 2004). Health-beneficial properties of Rosa leaves may be attributed to their content of phenolics, which are known to possess a wide spectrum of bioactive functions such as antioxidant and antiinflammatory effects (Sroka, 2005). Interspecific variation in the levels of bioactive compounds and their healing potential led to selective harvest of specific rose species for traditional uses. In Slovenia, hips, petals, and leaves of R. canina have been favored for their healing powers, but other indigenous rose species have not been used to the same extent. A number of studies have been published on the phenolic and mineral composition of rose hips in connection to their antioxidant activity (Ghazghazi et al., 2012; Hvattum, 2002; Roman et al., 2013). Petal phenolic antioxidants have also been identified in several rose species and cultivars (Biolley et al., 1994; Cai et al., 2005; Mikanagi et al., 1995; Schmitzer et al., 2010, 2012). However, research on rose leaf polyphenols is still partial and scarce. Different authors report total phenolic content, total flavonoid, or total flavonol aglycone levels in leaf extracts (Ghazghazi et al., 2012; Nowak and Gawlik-Dziki, 2007) of Rosa species, but studies targeted at identification of individual phenolic compounds are limited. The aim of the present study was to identify and quantify phenolic compounds in petals of several indigenous rose species in Slovenia and compare them with the phenolic profiles of certain modern rose cultivars. Moreover, rose leaf phenolic profiles were established and individual phenolic compounds have been identified and quantified for the first time in selected rose species. The qualitative and quantitative differences in leaf phenolic compounds among analyzed rose species and cultivars are discussed. Materials and Methods PLANT MATERIAL. Four rose species: R. glauca (pink flowers), R. canina ssp. canina (white to pale pink flowers), R. sempervirens (white flowers), and R. rubiginosa (pink flowers), and three cultivars: Rosarium Uetersen, Ulrich Brunner Fils (both with pink flowers), and Schwanensee (white flowers with light pink center), were selected for the study. Plants were located at the Botanical Garden and Arboretum Ljubljana (lat. 46.18 N, Received for publication 22 Nov. 2013. Accepted for publication 19 Dec. 2013. This work is part of the program Horticulture No P4-0013-0481 funded by the Slovenian Research Agency. We give special thanks to Dr. Joze Bavcon and Matjaz Mastnak of the Botanical Garden and Arboretum Ljubljana for providing rose samples and many useful information. The work was reviewed by two internal reviewers from the field of study, Dr. Gregor Osterc and Dr. Robert Veberic. Corresponding author. E-mail: vlasta.cunja@bf.uni-lj.si. J. AMER. SOC. HORT. SCI. 139(2):157–166. 2014. 157 long. 14.61 E, altitude 250 m) and leaves and petals for the analysis were sampled in June 2013. Flowers were collected and analyzed in developmental stage fully open flower (Schmitzer et al., 2010) and petal color measurements were recorded. Leaves were collected at their mature stage and only the first three fully expanded leaves on the branch were analyzed. Plant material was frozen in liquid nitrogen and stored at –20 C until further analysis. PETAL COLOR MEASUREMENTS. Flower color was measured by a portable colorimeter (CR-10 Chroma; Minolta, Osaka, Japan) with C illuminant. The colorimeter was calibrated with a white standard calibration plate before use. In the CIE L* a * b* system of color representation, the L* value corresponds to a dark–bright scale and represents the relative lightness with a range from 0 to 100 (0 = black, 100 = white). Color parameters a* and b* extend from –60 to 60; a* negative is for green and a* positive is for red and b* negative is for blue and positive for yellow. The hue angle (h ) is expressed in degrees from 0 to 360, where 0 = red, 90 = yellow, 180 = green, and 270 = blue. Color was measured in the middle of each petal (three replicates per flower; 10 flowers per repetition) to ensure equal measurement conditions. EXTRACTION AND HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY DETERMINATION OF PHENOLIC COMPOUNDS. Flower petals (combined samples consisting of five to 15 flowers) and leaves (combined samples consisting of 10 leaves) were ground to a fine powder with liquid nitrogen and 1 g of powder was extracted with 6 mL methanol containing 3% (v/v) formic acid and 1% (w/v) 2,6-Di-tert-butyl-4-methylphenol (BHT) in an ultrasonic bath for 1 h. Samples were centrifuged for 7 min at 12,000 gn. Supernatant was filtered through a polyamide filter (Chromafil AO-20/25; Macherey-Nagel, Düren, Germany) and transferred to a vial before injection into the high-performance liquid chromatography (HPLC) system. Samples were analyzed using a Thermo Finnigan Surveyor HPLC system (Thermo Scientific, San Jose, CA) with a diode array detector at 280 nm (phenolic acids and their derivatives, hydrolysable tannins, flavanols), 350 nm (glycosides of quercetin, kaempferol, myricetin, and isorhamnetin), and 530 nm (anthocyanins). A HPLC column (150 · 4.6 mm, Gemini 3 mm C18; Phenomenex, Torrance, CA) protected with a Phenomenex security guard column operated at 25 C was used. The injection volume was 20 mL and the flow rate maintained at 0.6 mL min. The elution solvents were aqueous 0.1% formic acid in double-distilled water (A) and 0.1% formic acid in acetonitrile (B). Samples were eluted according to the linear gradient from 5% to 20% B in the first 15 min followed by a linear gradient from 20% to 30% B for 5 min, then an isocratic mixture for 5 min, followed by a linear gradient from 30% to 90% B for 5 min, and then an isocratic mixture for 15 min before returning to the initial conditions (Wang et al., 2002). Phenolics were further identified using a mass spectrometer (LCQ Deca XP MAX; Thermo Scientific) with an electrospray ionization interface operating in negative/ positive ion mode using multiple-stage mass spectrometry (MS) scanning mode from m/z 115 to 1500. The injection volume was 10 mL and the flow rate maintained at 0.6 mL min. Capillary temperature was 250 C, the sheath gas and auxiliary gas were 20 and 8 units, respectively, and the source voltage was 4 kV for negative ionization and 0.1 kV for positive ionization. Spectral data were elaborated using Excalibur software (Thermo Scientific). The identification of compounds was confirmed by comparing retention times and their spectra as well as by adding the standard solution to the sample and by fragmentation. The content of phenolic compounds was assessed from peak areas and quantified with the use of corresponding external standards. For compounds lacking standards, quantification was carried out using similar compounds as standards. Thus, galloylquinic acid, methyl gallate hexoside, digalloyl quinic acid, trigalloyl hexose, digalloyl pentose, ellagic acid hexoside, digalloyl glucose isomer, vescalagin, and compounds with a hexahydroxydiphenic (HHDP) moiety were quantified with the calibration curve of ellagic acid, p-coumaric acid hexoside, cisand trans-5-O-p-coumaroylquinic acid by p-coumaric acid, caffeoyl hexose by caffeic acid, sinapic acid hexoside by sinapic acid, all procyanidins by the standard curve of procyanidin B2, all kaempferol compounds by kaempferol3-glucoside, and quercetin (Q) compounds (except Q-rutinoside, Q-galactoside, Q-glucoside, Q-rhamnoside, Q-arabinofuranoside

Compound Identification of Selected Rose Species and Cultivars: an Insight to Petal and Leaf Phenolic Profiles