Hypoglycemic Effects of Extracts Obtained from Endemic Betonica bulgarica Degen and Neic.

The increasing prevalence of diabetes mellitus, together with the limited access of many patients to conventional antidiabetic drugs and the side effects resulting from their use, are the reason for the ever-increasing need for new agents. One of the most important strategies used in the therapy of this disease is to reduce the postprandial blood glucose level by inhibiting the carbohydrate-degrading enzymes α-amylase and α-glucosidase. The purpose of the present study was to provide in vitro evidence for the potential hypoglycemic effect of leaf and inflorescence aqueous extracts of Bulgarian endemic species Betonica bulgarica Degen and Neic. Total phenolic and flavonoid contents and antioxidant activities were determined by spectrophotometric methods. Qualitative and quantitative determinations of principal phenolic acids and flavonoids were performed using HPLC with a dual absorbance detector. The plant extracts were able to retard the enzymatic breakdown of starch to glucose with 50% inhibiting concentrations of 1.86 mg/mL and 1.54 mg/mL respectively for leaf and flower extract. Some of the plant constituents are proven inhibitors of α-amylase and/or α-glucosidase, but their adsorption on starch seems to be one additional mechanism for the inhibition of glucose release. Combination index analysis carried out with binary mixtures of acarbose and plant extracts showed a tendency toward synergism with an increase in concentrations and level of inhibition.

Chromatographic Profile and Redox-Modulating Capacity of Methanol Extract from Seeds of Ginkgo biloba L. Originating from Plovdiv Region in Bulgaria.

Oxidative stress underlies the pathogenesis of many diseases, which determines the interest in natural substances with antioxidant properties. Ginkgo biloba L. leaves are well known and widely used in the pharmaceutical industry, but the therapeutic properties of the seeds are less studied. This study aimed to identify the chromatographic profile and to evaluate the antioxidant properties of methanol extract from seeds of G. biloba (GBSE). In the GBSE, flavonoids and terpenes were found as terpenes predominated. The GBSE antioxidant capacity determined by 2,2 azino-bis (3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS) and 1-diphenyl-2-picrylhydrazyl (DPPH) methods were equal to 1.34% and 0.58% of the activity of reference substance Trolox, respectively. The results of the ferric reducing antioxidant power method showed that the effect of concentration 1 mg/mL (w/v) GBSE was equal to 7.418 mM FeSO4 used as a standard. The cupric reducing antioxidant capacity activity of the GBSE was found to be 215.39 µmol Trolox/g GBSE and is presented as Trolox equivalent. The metal chelation effect of 1 mg/mL (w/v) GBSE was equal to that obtained for 0.018 mM EDTA. In conclusion, GBSE showed a good ability to neutralize ABTS and DPPH radicals and could have a beneficial effect in pathological conditions with oxidative stress etiology.

Phytochemical Constituents and Pharmacological Potential of Tamus communis Rhizomes.

Tamus communis L. is a plant distributed in a number of geographical areas whose rhizome has been used for centuries as an anti-inflammatory and analgesic remedy. This review aims to summarize the current knowledge of the chemical composition and biological activity of the extracts or individual compounds of the rhizome. The data for the principal secondary metabolites are systematized: sterols, steroidal saponins, phenanthrenes, dihydrophenanthrenes, etc. Results of biological tests for anti-inflammatory action, cytotoxicity, anticholinesterase effect, and xanthine oxidase inhibition are presented. Some open questions about the therapeutic properties of the plant are also addressed.

An experimental study on phytochemical composition and memory enhancing effect of Ginkgo biloba seed extract.

INTRODUCTION: The Ginkgo biloba L. tree is considered as one of the oldest species on Earth. It is known as a "living fossil" dating back approximately 200 million years. Both the leaves and seeds of this tree have been used for millennia in traditional Chinese medicine. AIM: To study the phytochemical profile of Gingko biloba seed extract (GBSE) and its memory enhancing effects. MATERIALS AND METHODS: Liquid chromatography with mass detection (LC-MS) was performed for phytochemical analyses of the extracts. For the in vivo experiments, male Wistar rats were divided randomly into 5 groups (n=8): saline; piracetam;  GBSE 50; 100, and 200 mg/kg b.w. Y-maze, T-maze, step-down passive avoidance and novel object recognition test (NORT) were performed. The observed parameters were: percentage of spontaneous alternations (% SA), working memory index, latency of reaction and recognition index, respectively. Statistical analysis was done using SPSS 19. RESULTS: LC-MS analysis showed the presence of the flavonoids quercetin, kaempferol and isorhamnetin (as aglycones), the ginkgolides A, B, C, J, and bilobalide. In Y-maze task, the groups treated with 50 and 100 mg/kg of GBSE significantly increased the % SA during the memory test compared to saline (p<0.05). In T-maze test, the three experimental groups with GBSE significantly increased the working memory index in comparison with that of the control group (p<0.05). In step-down test, the animals receiving 100 mg/kg b.w. GBSE, notably increased the latency during both retention tests (p<0.05 and p<0.01, respectively). In NORT, only the animals with the middle dose of GBSE ameliorated the recognition index when compared to saline (p<0.05). CONCLUSIONS: GBSE enhances spatial working memory, recognition memory, and short- and long-term recall in naïve rats due to the synergic effects of detected flavonoids and terpene lactones on brain functions. The brain structures involved are probably the hippocampus and prefrontal cortex.

Chemical composition, antioxidant and antimicrobial activity of essential oils from tangerine (Citrus reticulata L.), grapefruit (Citrus paradisi L.), lemon (Citrus lemon L.) and cinnamon (Cinnamomum zeylanicum Blume).

The phytochemical and biological properties of tangerine (Citrus reticulata L.), grapefruit (Citrus paradisi L.), lemon (Citrus lemon L.) and cinnamon (Cinnamomum zeylanicum Blume) essential oils were examined. The chemical composition of the essential oils determined using chromatography analysis revealed that D-limonene and cis-cinnamaldehyde were the main components. The antioxidant and antimicrobial activities of the essential oils have been studied by the DPPH radical-scavenging assay and the disc-diffusion method, respectively. All essential oils had antimicrobial activity against saprophytic (Bacillus subtilis, Penicillium chrysogenum, Fusarium moniliforme, Aspergillus niger, Aspergillus flavus, Saccharomyces cerevisiae) and pathogenic microorganisms (Escherichia coli, Salmonella abony, Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans), with the highest inhibitory activity being observed in cinnamon oil, followed by grapefruit zest oil, tangerine zest oil and lemon zest oil; the MIC ranging from 6 to 60 ppm. In addition, they exhibited high antioxidant activity with the highest antioxidant activity being determined for the grapefruit zest essential oil, followed by the lemon zest essential oil, the tangerine zest essential oil and the cinnamon essential oil. The demonstrated promising results for the antioxidant and antimicrobial activity of the studied essential oils would give reason for their inclusion in the development of bio-preservation strategies for food emulsion preservation.

Production of probiotic wort-based beverages with grapefruit (Citrus paradisi L.) or tangerine (Citrus reticulata L.) zest essential oil addition.

BACKGROUND: In recent years, increasing health awareness in consumers has motivated breweries to expand their beverage ranges with products with increased biological value. The aim of the present research was to develop probiotic wort-based beverages with grapefruit or tangerine zest essential oil addition. METHODS: Wort was produced with 60% Pilsen malt, 20% Vienna malt and 20% Caramel Munich ІІ malt with and without the addition of 0.05% (v/v) grapefruit or tangerine essential oils. It was inoculated with the probiotic yeast strain Saccharomyces cerevisiae var. boulardii Y1. Fermentations were carried out at a constant temperature of 10°C for 5 days. The dynamics of the extract, the alcohol content and the concentration of viable cells were monitored daily. The total phenolic content, phenolic acid and flavonoid phenolic compounds were determined because of their antioxidant activity. The antioxidant activity was determined by radical scavenging assay (DPPH) and ferric reducing antioxidant power (FRAP). A descriptive organoleptic evaluation of the final beverages was performed. RESULTS: The essential oils inhibited yeast growth to some extent at the beginning of the fermentation, even at a concentration of 0.05% (v/v), which resulted in lower alcohol content in the beverages with essential oil addition. Nevertheless, at the end of fermentation the concentration of viable cells was almost equal in all the beverages. Tangerine essential oil addition led to the highest content of phenolics, of which phenolic acids predominated. Therefore, the highest antioxidant activity of the beverage with tangerine essential oil can be ascribed to phenolic acids. The results of the sensorial evaluation also showed that the panel had preference towards the beverage with tangerine essential oil. CONCLUSIONS: The combination of essential oil and the probiotic yeast strain resulted in beverages with higher biological value than the beverages produced with the probiotic strain alone. The results obtained will be used for optimisation of process variables in the production of pilot-scale wort-based probiotic beverages with essential oil addition.

Bio-preservation of chocolate mousse with free and immobilized cells of Lactobacillus plantarum D2 and lemon (Citrus lemon L.) or grapefruit (Citrus paradisi L.) zest essential oils.

BACKGROUND: The bio-preservation of food products using various natural ingredients and metabolites from various types of beneficial microorganisms released during targeted fermentation is a method that simultaneously has a preservative effect on the food product and provides a model of its composition in order to ensure its functional and health properties. This double effect can be achieved by incorporating ingredients with proven preservative and functional effects into the food product, such as essential oils from various plant species and probiotic bacteria. The aim of the present research was to study the synergistic effect of selected probiotic lactic acid bacteria (LAB) and essential oils with high antimicrobial activity against pathogenic and spoilage microorganisms for the bio-preservation of chocolate mousse food emulsion. METHODS: The susceptibility of the selected probiotic strain Lactobacillus plantarum D2 to different concentrations of the selected lemon or grapefruit essential oil was examined using the disc-diffusion method. Nine chocolate mousse variants were prepared with the inclusion of free or immobilized cells of the probiotic strain L. plantarum D2 and/or lemon or grapefruit zest essential oils. The chocolate mousse variants were stored for 20 days in refrigerated conditions, and changes in the concentration of viable lactobacilli cells, the pH and the microbiological purity were monitored in accordance with standard requirements by taking samples on the 0th, 5th, 10th, 15th, and 20th days of storage. An organoleptic evaluation of the chocolate variants was performed on the 0th day. RESULTS: Concentrations of up to 1% lemon or grapefruit essential oil did not affect the growth of the probiotic strain L. plantarum D2, which revealed opportunities for their joint application for the bio-preservation of food emulsions. The obtained chocolate mousse variants were characterized by preserved organoleptic characteristics and microbiological safety. Free or immobilized probiotic L. plantarum D2 cells applied alone or in combination with lemon or grapefruit essential oils provided bio-preservation of the food emulsions, maintaining a high concentration of viable cells (106-107 cfu/g) during storage under refrigerated conditions for 20 days. CONCLUSIONS: The combined application of free or immobilized probiotic LAB and lemon or grapefruit essential oils resulted in better bio-preservation results than in the use of probiotic LAB or essential oils alone, thus suggesting a synergistic effect between the two bio-preservative agents. Moreover, the obtained chocolate mousse emulsions can be classified as functional foods and the chocolate mousse food matrix can successfully be used as a vehicle for delivery of probiotic LAB to a wide range of food consumers. The obtained results and the developed successful bio-preservation strategy for the production of chocolate mousse food emulsions would provide grounds for the future selection of other probiotic lactobacilli strains, essential oils and synergistic combinations of them for the development of successful bio-preservation strategies for other types of food and beverage products.

Cytotoxic effect of Ginkgo biloba kernel extract on HCT116 and A2058 cancer cell lines.

While the pharmacology of Ginkgo biloba leaf extract has been studied extensively, little is known about the pharmacological potential of Ginkgo biloba seeds, although they contain similar active ingredients that are responsible for the therapeutic effects of the leaf extract. In this study we used 70%-methanol Ginkgo biloba kernel extract, quantified its bioactive constituents and tested their cytotoxic effect on two cancer cell lines, A2058 and HCT116, and the non-tumor cell line McCoy-Plovdiv. We studied the biological effect of the extract by real-time analysis in the xCELLigence system, WST-1 assay and LIVE/DEAD viability assay. We show that the extract significantly perturbed the viability of cancer cells in a concentration- and time-dependent manner. In contrast, non-cancerous McCoy-Plovdiv cells sustained their proliferation potential even at high concentrations of the extract. Therefore, we propose that the active constituents of the Ginkgo biloba endosperm extract may interact additively or synergistically to protect against cancer.

Naturally present metal ions in plants could interfere with common antioxidant assays.

Most of the commonly applied assays used to assess antioxidant properties of plant extracts exploit the ability of some biologically active metabolites to participate in oxidation-reduction reactions with metal ions. On the other hand, most plants contain different chelated metal ions whose levels depend on the geographic origin, soil, and environmental pollutions. In this study the levels of redox-active metal ions in three plant sources were measured and extracts of these botanicals were treated with ChelexⓇ - an ion exchanger that is noteworthy for its ability to bind transition metal ions. The original and chelated extracts were subjected to three antioxidant assays based on single electron transfer. The results obtained showed statistically significant differences between the original and Chelex-treated extracts suggesting that the naturally present metal ions could interfere with the results of the three most commonly applied antioxidant methods.•The proposed pre-analytical procedure is simple and does not require special instrumental equipment.•Preliminary depletion of redox active metal ions, namely iron and copper ions could improve reproducibility of the analytical methods.•The method allows a more reliable comparison of antioxidant properties of particular botanical species from different geographic regions.