Dasha Mihaylova

In the present study the carbohydrate content of aqueous extracts of fresh Portulaca oleracea leaves and stems was assessed in details for the first time. The total phenolic content was appraised and the antioxidant capacity of the obtained by different extraction procedures extracts was evaluated as well. To determine the antioxidant activities of the extracts, several complementary tests were used. The leaves extracts showed the higher results in accordance with the DPPH and the FRAP assays. The present study revealed that the leaves are rich in polyphenolics, and due to the established carbohydrate constituents in both leaves and stems the plant extracts can be used as a natural source of antioxidants in culinary and as ingredient with nutritional value. Carbohydrate content and in vitro antioxidant capacity of different extracts of fresh Bulgarian Portulaca oleracea L.

The Lemon balm (Melissa officinalis L.) is an important aromatic and medicinal plant from Lamiaceae family. Its leaves and essentials oils are used in folk medicine for the treatment of fevers and colds, hyperthyroidism, headaches and toothaches. Melissa officinalis is a rich source of volatile oil, flavonoid glycosides and derivatives of caffeic acid (rosmarinic acid). The aim of current study was to evaluate and compare the polyphenol content and antioxidant activity of infusions prepared from commercially available lemon balm brands on Bulgarian market. The total polyphenol content was established to be in range from 18.17 ± 0.04 to 64.17 ± 0.52 mg GAE/g dw, the total derivatives of caffeic acid from 3.80 ± 0.05 to 21.66 ± 0.10 mg CAE/g dw, caffeic acid content from 0.16 ± 0.01 to 0.97 ± 0.03 mg/g dw and rosmarinic acid between 2.4 ± 0.02 and 23.1 ± 0.5 mg/g dw, respectively. In vitro radical scavenging activity was evaluated by DPPH method (106.31 ± 9.87-553.51 ± 46.04 mM TE/g dw) and the metal reducing antioxidant potential was established by CUPRAC method (321.32 ± 14.39-1476.63 ± 11.32 mM TE/g dw). As a result the consumption of M. officinalis infusions could be recommended as a good preventive and therapeutic source of biologically active substances with potential benefit effects.

The purpose of the present study was to investigate the antioxidant activity and fructans content in ethanol and water extracts of roots of elecampane (lnula helenium L.), a Bulgarian medicinal plant. The extraction procedure included 95 % (v/v) ethanol extraction and subsequent water treatment. The antioxidant activity was evaluated by severa l reliable methods such as DPPH-, ABTS-, FRAP- and CUPRAC­ assays , as well as by total phenolic content. The total fructans and sugars content were determinated by spectrophotomeric, TLC and HPLC-RID methods. The level of fructans in ethanol extracts was 14.1 g/100 g dry weight, as nystose and 1-kestose were only 0.3 g/100 g dry weight, and 0.5 g/100 g dry weight, respectively. The absence of fructooligosacharides and sugars in water extracts after the ethanol pretreatment was established. Inulin content was evaluated to be 31.2 g/100 g dry weight. The metabolites profile of roots revealed their potential application as radical scavengers due...

The rich world of herbs, with thousands of varieties and species, exhibiting multiple biological effects, including antioxidant activity, demands extensive studies. Melissa officinalis L., a representative of the Lamiaceae family, is a well-known herb that has long been used in traditional medicine to treat many disorders, and multiple studies have been conducted to identify its healing properties. The essential oil obtained by microdistillation of aerial parts of Melissa officinalis L. (Bulgarian origin) was analyzed by GC and GC-MS. Thirty-seven compounds were identified, representing 92.27 % of the total oil. The major components were terpenes with citronellal-18.45 %, and geraniol-15.22 % as the dominant representatives. Two water extracts were prepared to evaluate the radical-scavenging ability of M. officinalis-decoction and infusion. The antioxidant activity was determined using four spectrophotometric methods (ABTS, DPPH, FRAP, and CUPRAC). The TEAC values of the herb ranged from 389.52±3.11 μM TE/g DW (DPPH-infusion) to 1228.71±46.07 μM TE/g DW (CUPRAC-decoction). A significant correlation between the total phenolic content and the antioxidant activity was also determined. All obtained results revealed M. officinalis as a potential source of natural antioxidants.

In the present study the antioxidant capacity of aqueous extracts of fresh Bulgarian ramsons’ leaves (Allium ursinum L.), used as a culinary spice, was studied. The purpose of this investigation was to evaluate the impact of decoction on total polyphenolic content (TPC) and antioxidant activity, measured by different reliable methods - ABTS, DPPH and FRAP assays. The extraction was conducted with various durations in order to achieve better extractability of the valuable compounds. Results demonstrated highest levels of antioxidant capacity pursuant to ABTS (7.24 μMTE/g FW), DPPH (1.35 μMTE/g FW) and FRAP- methods (2.79 μMTE/g FW) at 15 min of thermal treatment. The highest total polyphenolics content was evaluated at 30 min of thermal treatment (0.97 mg GAE/g FW). Based on the results the A. ursinum leaves could be recommended as a daily source of biologically active substances of natural origin.

The widespread use of culinary plants for health purposes has increased dramatically due to their great importance to a balanced diet. In this study, different extracts of fresh Malva sylvestris leaves and flowers were investigated for their level of total phenolics, antimicrobial activity against Gram-positive (Bacillus cereus, Staphylococcus aureus ATCC 6538-P), Gram-negative (Escherichia coli ATCC 25922, Escherichia coli ATCC 8739, Salmonella sp. (clinical isolate), Proteus vulgaris J) bacteria, molds (Aspergillus niger, Penicillium sp., Rhizopus sp.) and yeasts (Saccharomyces cerevisiae); and their antioxidant activities using various methodologies: ABTS, DPPH, FRAP, and CUPRAC assays. The total phenolic content was established to be 2.35 ± 0.01 and 0.83 ± 0.05 mg GAE/g fresh plant weight in the decoction extracts of leaves and flowers, respectively. The flowers were found to be more active toward pathogenic microorganisms. The present study revealed that the consumption of this plant would exert several beneficial effects by virtue of their antioxidant and antimicrobial activities.

The content of phenolic acids, flavonoids and total phenolic compounds and the antioxidant capacity of Alchemilla mollis aqueous ethanol extracts were investigated. The antioxidant capacity was determined by four different assays (FRAP, CUPRAC, DPPH and ABTS) and was expressed as mmol Trolox equivalent per dm3 extract. The maximum values of fresh extracts were 382.78 ± 1.16; 363.79 ± 0.74; 247.58 ± 2.26; 308.44 ± 6.74 for FRAP, CUPRAC, DPPH and ABTS assays, respectively. They were observed in variants obtained with 40 to 60% (v/v) aqueous ethanol solutions. The highest concentration of phenolics was detected in extracts obtained with 40 to 70% (v/v) ethanol. The extraction of A. mollis with aqueous ethanol solution higher than 70%, led to the reduction of the phenolics concentration and the antioxidant capacity. A formation of sediments during the storage of the extracts and decreasing in antioxidant capacity and phenolic content was observed. In accordance with the application of the A. mollis extracts in soft drinks without removing the ethanol, the aqueous ethanol solutions with concentration lower than 30% (v/v) is more suitable. Although the extracts obtained with 40 to 70% ethanol have the highest biological value, they add less biologically active components in soft drinks due to the limit of 0.5% ethanol in the nonalcoholic beverages.

The antioxidant capacity of aqueous extracts of fresh leaves of lemon balm (Melissa officinalis L.), used as a medical plant and culinary spice, was studied. The aim of the present study was to measure the effect of extraction time on total phenolic compounds (TPC) and antioxidant activity (ABTS - , DPPH- and FRAP - assays). The obtained results demonstrated highest levels of TPC (5.25 GAE/g fresh plant weight), ABTS (72.04 μMTE/g FW), DPPH (81.55 μMTE/g FW) and FRAP (116.58 μMTE/g FW) at 30 min of thermal treatment. A high correlation between antioxidant capacities of fresh leaves of M. officinalis and their total phenolic contents (R=0.97-0.99) was established.

The aim of the present paper was to investigate the antioxidant capacity and the possible cell structure changes of frozen Chrysanthemum balsamita leaves. The antioxidant activity of the studied aqueous extracts was estimated through ABTS, DPPH, FRAP, and CUPRAC methods. The total phenolic content was assessed as well. The results varied significantly before and after freezing of the plant samples. The total phenolic content of the fresh leaves was established to be 0.59 mg GAE/g PW and 0.68 mg GAE/g PW of the frozen leaves. The microscopic analysis of both fresh and frozen leaves showed changes in the cellular structure which influenced the radical scavenging activity of the frozen Chrysanthemum balsamita plant samples

Pelargonium graveolens, commonly known as rose geranium, is an aromatic and medicinal plant belonging to the Geraniacea family. The aim of the present study was to evaluate the in vitro antioxidant and antibacterial activity of Pelargonium graveolens, as well as to determine the total phenolic content of the studied extracts. Four spectrophotometric assays were used for the radical scavenging ability analysis, namely ABTS, DPPH, CUPRAC, and FRAP. The inhibitory activity of the leaves’ extracts was tested against S. aureus, L. monocytogenes, E. coli and Salmonella.
The total phenolics ranged from 1,65 to 8,23 mg GAE/g FW. Antibacterial activity, whose zone of inhibition varied from 15 mm to 19 mm depending on the extract quantity, was shown only against L. monocytogenes.

The aim of the present study was to investigate the antioxidant activity and the fructan content of
Bulgarian Carduus thoermeri Weinm. flower heads. The antioxidant activity of the extracts was
evaluated by several reliable methods such as 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical
scavenging activity, 2,2′-azinobis-3 ethyl benxothiazoline-6-sulphonic acid (ABTS) cation
decolorization activity assays, the ferric reducing/antioxidant power method (FRAP) and cupric ion
reducing antioxidant capacity assay (CUPRAC) in addition to the total phenolic content evaluation.
The reported results could be considered as first detailed investigation on the sugar and inulin content
of Bulgarian C. thoermeri. The content of inulin in the plant samples was evaluated to be 0.7% dry
weight (dw). In the water extracts besides the fructose, sucrose and nystose, the presence of high
molecular fraction of inulin was determined. Based on the established inulin content the use of infusions
and tinctures from the plant is recommended for improvement of the gastrointestinal tract function as
they may act as potential prebiotics.

The purpose of the present study was to investigate the antioxidant activity and fructans content in ethanol and water extracts of roots of elecampane (Inula helenium L.), a Bulgarian medicinal plant. The extraction procedure included 95% (v/v) ethanol extraction and subsequent water treatment. The antioxidant activity was evaluated by several reliable methods such as DPPH-, ABTS-, FRAP- and CUPRAC-assays, as well as the total phenolic content. In addition, the total fructans and sugar content were determinated by spectrophotomeric, TLC and HPLC-RID methods. The level of fructans in ethanol extracts was 14.1 g / 100 g dry weight, as nystose and 1-kestose were only 0.3 g / 100 g dry weight, and 0.5 g / 100g dry weight, respectively. The absence of fructooligosacharides and sugars in water extracts after the ethanol pretreatment was established. Inulin content was evaluated to be 32 g / 100 g dry weight. The metabolites profile of roots revealed their potential application as radical scavengers due to the presence of polyphenols. Therefore, the root extracts of elecampane could be assumed as a rich source of biologically active substance, in particular dietary fiber with potential prebiotic effect, due to the presence of polysaccharide inulin and fructooligosacharides.

Allium bulgaricum L. is used as a culinary herb and it is a well- known flavouring principle. The antioxidant activity of dry leaves was determined as Trolox equivalent antioxidant capacity (TEAC) using different reliable methods- DPPH, ABTS, FRAP, and CUPRAC assays. Total phenolic contents was determined using a spectrophotometric technique, based on the Folin-Ciocalteau reagent, and calculated as gallic acid equivalents GAE/g DW. The total polyphenolics ranged from 9,01 ± 0,14 to 22,92 ± 0,30 mg GAE/g DW.

Portulaca oleracea (Family Portulacaceae), commonly known as purslane, is a source of many nutrient compounds. In the present stud,y extracts from dry purslane leaves were screened for their radical scavenging ability and total polyphenolic content. The antioxidant activity was measured by using four different reliable assays- DPPH, ABTS, FRAP, and CUPRAC. All samples were tested in order to determine the eventual change of the radical scavenging capacity based on the influence of some technological factors. Significant differences were observed among all obtained extracts.

Culinary plant extracts prepared with 70% ethanol from  three species
Chrysanthemum balsamita L., Melissa officinalis L. and Allium bulgaricum L.
growing in Bulgaria were screened for their in vitro antioxidant activity and total
phenolic compounds content. Samples of fresh plant material were subjected to
heat-reflux extraction and several complementary tests were used in order to
determine the antioxidant activity of the extracts, namely ABTS radical
scavenging, DPPH radical cation decolorization activity, ferric reducing
antioxidant power (FRAP) assay and copper reduction assay (CUPRAC). The total
polyphenolic content of the obtained extracts was executed spectrophotometrically
using the FolinCiocalteus phenol reagent. The concentration of polyphenolics
was established to be in the range from 0.41 ± 0.08 to 2.71 ± 0.15 mg GAE/g fw.
M. officinalisfresh leaves showed the strongest antioxidant activity according to all
performed assays. Based on the results of the present study, it was revealed that the
investigated Bulgarian culinary plants could be considered a potential source of
polyphenolics and thus could be applied as antioxidants of natural origin in
culinary.