Bulgarian Chemical Communications, Volume 51, Special Issue A (pp. 95-100) 2019 Phytochemical profile and in vitro antioxidant activity of Centaurium erythraea Rafn. D. Mihaylova1, R. Vrancheva2, A. Popova3* 1Department of Biotechnology, Technological Faculty/ University of Food Technologies, 26 Maritza Blvd., 4000 Plovdiv, (Plovdiv), Bulgaria 2Department of Analytical Chemistry and Physicochemistry, Technological Faculty/ University of Food Technologies, 26 Maritza Blvd., 4000 Plovdiv, (Plovdiv), Bulgaria 3 Department of Catering and tourism, Econimics Faculty/ University of Food Technologies, 26 Maritsa blvd, 4000 Plovdiv, (Plovdiv), Bulgaria Received January 15, 2019; Revised March 19, 2019 Centaurium erythraea Rafn. (small centaury) is an important medicinal plant from Gentianaceae family, which is used traditionally in the folk medicine as a digestive, stomachic, tonic, depurative, sedative, and antipyretic. It is known with anti-inflammatory and antipyretic effects. The aim of current study was to evaluate and compare the total polyphenol content and antioxidant activity of water (infusion, decoction and microwave) and alcohol (tincture) extracts of Centaurium erythraea. The total flavonoid content, total monomeric anthocyanin content and detailed phenolic acids profile were assessed additionally. The polyphenol content was established to be in range from 1.23 to 12.46 mg GAE/g dw, the total flavonoids from 1.18 to 3.35 mg QЕ/g dw and total monomeric anthocyanins from 1.70 to 6.15 mg/L. In vitro antioxidant activity was evaluated by four common procedures and the highest results were established for the decoction and tincture extracts. The highest phenolic acids profile was disclosed in the small centaury infusion - 2208 µg/g dw. As a result the consumption of the studied C. erythraea extracts could be recommended as a good source of biologically active substances and bio-antioxidants in particular with potential benefit effects. Keywords: Centaurium erythraea, water extract, ethanol extract, antioxidant activity INTRODUCTION phytochemical exploration of this plant species [9, 10]. Thus, the present study aimed at evaluating and Plants are an overall source of antioxidant comparing the total polyphenol content and activity compounds, such as phenolic acids, antioxidant activity of water (infusion, decoction and flavonoids, vitamins and carotenoids that may be microwave treatment) and alcohol (tincture) extracts used as pharmacologically active constituents [1]. In of Centaurium erythraea, relying on widespread, particular, the antioxidant activity is one of the most simple for conduction and consumer-familiar important properties of plant extracts, due to extraction methods. scientists have looked for sources of natural Many researchers have studied the influence of antioxidants to be introduced in many cosmetic, different extraction solvents and techniques on the pharmaceutical and food formulations. The research content of natural antioxidants in extracts. for the new sources of antioxidants in the past Phytochemical compounds, such as phenolic acids, resulted in the extensive studies on medicinal plants flavonoids, tannins and saponins are considered as [2]. The use of herbal drugs and phytonutrients or major secondary metabolites in plants. Phenolic nutraceuticals continues to expand rapidly across the compounds, which possess a broad spectrum of world with many people now resorting to these biochemical activities, represent the largest group products for treatment of various health challenges [11-15]. Interest in these classes of compounds are in different national healthcare settings [3]. due to their pharmacological activities as radical Small centaury (Centaurium erythraea Rafin.) scavengers [16]. Recently, different studies have (Gentianaceae) is a medicinal plant with a long shown that phenols and non-phenolic compounds tradition, being included in the pharmacopoeias of are of great interest to the pharmaceutical industry many European and American countries. for their anti-inflammatory, anti-aging, and Phytochemically it is characterized by the presence antimicrobial benefits, which make them an of terpenoids [4], xanthones [5, 6], and phenolic important source of molecules for new drug acids and their derivatives [4, 7]. It has been used in discovery [17]. One very important step for utilizing human traditional medicine as a digestive, bioactive compounds from plant resources is the stomachic, tonic, depurative, sedative, and extraction process. Selection of the extraction antipyretic [4]. The anti-inflammatory and process itself is an important step for the antipyretic effects of an aqueous extract of the plant standardization of herbal products, as they can be have already been observed experimentally in rats utilized in the removal of desirable soluble [8]. Many research articles deal with the 2019 Bulgarian Academy of Sciences, Union of Chemists in Bulgaria 95 * To whom all correspondence should be sent: E-mail: [email protected] 7 constituents. Due to the wide variations in the tincture, which was prepared with manual agitation structures and polarities of chemical compounds, for a period of seven days, left in the dark, at room extraction from plant products is complex and temperature. The material/solvent ratio used was challenging. The critical extraction parameters 1:10 (w/v). All extracts were filtered after include solvent, time, solid-to-solvent ratio, number preparation and stored at 4 °C without adding any of extractions, temperature, and partial size of the preservatives until analyses. sample material [17]. Selection of the extraction Phytochemical screening solvent depends on the specific nature of the Total Phenolic Content (TPC). The TPC was bioactive compound being targeted. The extraction analyzed following the method of Kujala et al. [23] yield and, consequently, the biological activity of with some modifications. Each extract (0.1 mL) was vegetal extracts can be strongly affected by the mixed with 0.5 mL Folin-Ciocalteu phenol reagent solvent applied [18]. For bioactive compound and 0.4 mL 7.5% Na CO . The mixture was vortexed extraction, different solvents, including organic 2 3 and left for 5 min at 50 ºС. After incubation, the and/or aqueous solutions, have been reported [19]. absorbance was measured at 765 nm. The TPC was Water and ethanol are often recommended for expressed as mg gallic acid equivalents (GAE) per g extract preparation because of their differences in dry weight (dw). polarity. The use of organic solvents for industrial Total flavonoid content. The total flavonoid extractions has several disadvantages, such as: (a) content was evaluated according to the method solvent residue in the product; (b) worker exposure; described by Kivrac et al. [24]. An aliquot of 0.5 mL (c) disposal of waste solvents; and (d) environmental of the sample was added to 0.1 mL of 10 % pollution [20]. Several studies have shown that Al(NO ) , 0.1 mL of 1 mol CH COOK and 3.8 mL ethanol and boiling water are effective for 3 3 3 of ethanol. After incubation at room temperature for polyphenol extraction [21, 22]. 40 min, the absorbance was measured at 415 nm. In this regard, the aim of the present study was to Quercetin was used as a standard and the results explore and compare antioxidant properties, total were expressed as mg QE/g dw. polyphenolic contents and phytochemical profile in Total monomeric anthocyanin content. The total respect of phenolic acids composition of several monomeric anthocyanin content was determined extracts of Centaurium erythraea obtained by water using the pH- differential method [25]. Properly and ethanol (tincture). The main purpose was to diluted samples were mixed with KCl (0.025 mol, highlight the potential biological activity of the pH 1.0) and CH COONa (0.4 mol, pH 4.5) with an extracts and to recommend the most appropriate 3 appropriate dilution factor. Absorbance (A) was technique of extraction among studied. measured using UV-Vis spectrophotometer at 520 .MATERIALS AND METHODS and 700 nm after 15 min incubation at room temperature, and the results were calculated as Plant Material follows: The samples of Centaurium erythraea Rafn. Pers (stems) were obtained from local pharmacy A = (A520 – A700)pH 1.0 – (A520 – A700)pH 4.5 (Plovdiv, Bulgaria) in 2016. The plant parts were The monomeric anthocyanin (MA) pigment dried, ground and stored at ambient temperature in concentration in the samples was calculated as: air-tight containers prior to extraction. Monomeric anthocyanin pigment (mg/liter) = Extraction preparation = (A × MW × DF × 1000)/(ε × 1) Four extraction procedures were performed as follow: with water (infusion, decoction and where M represents the molar mass of cyanidin-3- microwave extraction) and with 70 % ethanol (v/v, glycoside (449.2 g/mol), DF is the dilution factor, ε tincture). is molar extinction coefficient (26,900 L/mol x cm), The infusion was obtained by pouring 2.5 g of and 1 is the cuvette optical path length (10 mm). The plant material with 50 mL water and then, left for 30 final anthocyanin concentration is expressed as min to cool. Water decoction was retrieved by milligram per 1000 mL of sample of cyanidin-3- boiling 2.5 g of plant material in 50 mL solvent for glycoside. 30 min; Microwave-assisted extract (MAE) Determination of antioxidant activity: experiment was carried out in a domestic microwave DPPH assay: The ability of the extracts to donate an oven (LG MB4047C) where 2.5 g of plant material electron and scavenge