Enzyme Inhibitory Activities, Phenolic Profile, and in Silico Studies of Sorbus torminalis Tree Bark Methanol Extract.

The different parts of Sorbus torminalis (L.) Crantz are used in traditional medicine for various conditions such as cardiac diseases, cough, and diabetes, indicating its significant medicinal potential. Therefore, the current investigation aimed to reveal the phenolic composition of the poorly studied S. torminalis methanol extract of the bark, as well as its capacity to inhibit enzymes relevant to cardiovascular, neurodegenerative, and metabolic diseases. A total of 28 phenolic components, including 20 procyanidins aglycones (A- and B-type), four procyanidin glycosides, catechin and its glycoside, and two (epi)catechin derivatives, were detected using LC-MS. The contents of total polyphenols (6.22%), total tannins (3.04%), condensed tannins (0.70%), and total flavonoids (0.24 %) were determined spectrophotometrically, highlighting the considerable phenolic richness of the examined plant material. The concentration-dependent ability to inhibit α-amylase (IC50=130 µg/mL), α-glucosidase (IC50=312.13 µg/mL), acetylcholinesterase (IC50=156.46 µg/mL), butyrylcholinesterase (IC50=217.68 µg/mL), and angiotensin-converting enzyme (IC50=36.77 µg/mL) was demonstrated. The in silico approach showed that catechin, procyanidin B2 and C1, S. torminalis bark constituents, can form stable complexes with the target enzymes but with different binding affinity. The results supported the medicinal potential of S. torminalis bark and significantly expanded our knowledge of its chemistry, justifying further research.

Investigation of Anticholinesterase Activity of Chemically Characterised Hieracium s. str. Methanol Extracts and Their Selected Metabolites.

The composition and anticholinesterase activity of the dried MeOH extracts of Hieracium scheppigianum and H. naegelianum underground parts (rhizomes and roots), as well as the anticholinesterase activity of the dried, previously chemically characterised MeOH extracts of the flowering aerial parts of these two and 26 other Hieracium species in the strict sense (s. str.), were investigated. Furthermore, the anticholinesterase activity of 12 selected secondary metabolites of these extracts was evaluated. Using semi-preparative LC-MS, five caffeoylquinic acids and the sesquiterpene lactone crepiside E were isolated from H. scheppigianum underground parts extract. All these compounds were also identified in the underground parts extract of H. naegelianum. Quantitative LC-MS analysis showed that the analysed underground parts extracts were rich in both caffeoylquinic acids (139.77 and 156.62 mg/g of extract, respectively) and crepiside E (126.88 and 116.58 mg/g). In the Ellman method, the tested extracts showed an interesting anti-AChE and/or anti-BChE activity (IC50 =0.56-1.58 mg/mL), which can be explained, at least partially, by the presence of some of their constituents. Among the metabolites tested, the best activity was revealed for the flavonoids apigenin, luteolin and diosmetin, and the sesquiterpene lactone 8-epiixerisamine A (IC50 =68.09-299.37 µM).

Antimicrobial and Cytotoxic Activities of Selected Hieracium L. s. str. (Asteraceae) Extracts and Isolated Sesquiterpene Lactones.

Antimicrobial and cytotoxic activities were tested for dried MeOH extracts of Hieracium calophyllum (CAL), H. coloriscapum (COL), H. pseudoschenkii (PSE), H. valdepilosum (VAL) and H. glabratum (GLA) herbs (flowering aerial parts), their 2 sesquiterpene lactones (SLs) 8-epiixerisamine A and crepiside E, and dried CH2 Cl2 extract of H. scheppigianum (SCH) herb. In microdilution test, extracts showed activity on all tested microorganisms (8 bacteria, 10 fungi). The best effect was exhibited by SCH and CAL on Salmonella Typhimurium (MIC=1.7-2.5 mg/mL MBC=3.4-5.0 mg/mL), and SCH and VAL on Candida albicans (MIC=2.5 mg/mL MFC=5.0 mg/mL). SLs showed notable effect on all tested fungi Aspergillus ochraceus, Penicillium funiculosum, C. albicans and C. krusei (MIC=0.15-0.4 mg/mL MFC=0.3-0.8 mg/mL). In MTT test, extracts inhibited growth of all tested cancer cells (HeLa, LS174 and A549), with the best effect on HeLa (IC50 =148.1 µg/mL for SCH, and 152.3-303.2 µg/mL for MeOH extracts); both SLs were active against HeLa cells (IC50 =46.2 µg/mL for crepiside E and 103.8 µg/mL for 8-epiixerisamine A). Extracts and SLs showed good safety profile on normal MRC-5 cells.

Barks of Three Wild Pyrus Taxa: Phenolic Constituents, Antioxidant Activity, and in Vitro and in Silico Investigations of α-Amylase and α-Glucosidase Inhibition.

Dry MeOH extracts of the twig barks of Pyrus communis subsp. pyraster, P. spinosa and their hybrid P.×jordanovii nothosubsp. velenovskyi, collected in wild in Serbia, were analyzed. By LC/MS, the contents of arbutin (99.9-131.0 mg/g), chlorogenic acid (2.2-6.3 mg/g), catechin (1.0-5.3 mg/g) and total dimeric and trimeric procyanidins (42.2-61.3 mg/g), including procyanidin B2 (8.9-17.2 mg/g), were determined. Colorimetrically, high contents of total phenolics (436.2-533.4 mg GAE/g) and tannins (339.4-425.7 mg GAE/g), as well as strong total antioxidant activities (FRAP values 4.5-5.9 mmol Fe2+ /g), and DPPH (SC50 =6.6-7.1 µg/ml) and hydroxyl radical (SC50 =447.1-727.7 µg/ml) scavenging abilities were revealed. In vitro, all extracts exhibited notable inhibition of α-amylase (IC50 =310.8-617.7 µg/ml) and particularly strong inhibition of α-glucosidase (IC50 =2.1-3.7 µg/ml). Molecular docking predicted that among identified compounds procyanidin B2 is the best inhibitor of these carbohydrate-digesting enzymes. Obtained results showed that the barks of investigated Pyrus hybrid and its parent taxa have similar composition and bioactivity.

Methanol Extracts of 28 Hieracium Species from the Balkan Peninsula - Comparative LC-MS Analysis, Chemosystematic Evaluation of their Flavonoid and Phenolic Acid Profiles and Antioxidant Potentials.

INTRODUCTION: Hieracium s. str. represents one of the largest and most complex genera of flowering plants. As molecular genetics seems unlikely to disentangle intricate relationships within this reticulate species complex, analysis of flavonoids and phenolic acids, known as good chemosystematic markers, promise to be more reliable. Data about pharmacological activity of Hieracium species are scarce. OBJECTIVE: Evaluation of the chemosystematic significance of flavonoids and phenolic acids of methanol extracts of aerial flowering parts of 28 Hieracium species from the Balkans. Additionally, investigation of antioxidant potentials of the extracts. METHODS: Comparative qualitative and quantitative analysis of flavonoids and phenolic acids was performed by LC-MS. Multivariate statistical data analysis included non-metric multidimensional scaling (nMDS), unweighted pair-group arithmetic averages (UPGMA) and principal component analysis (PCA). Antioxidant activity was evaluated using three colorimetric tests. RESULTS: Dominant phenolics in almost all species were luteolin type flavonoids, followed by phenolic acids. Although the investigated Hieracium species share many compounds, the current classification of the genus was supported by nMDS and UPGMA analyses with a good resolution to the group level. Hieracium naegelianum was clearly separated from the other investigated species. Spatial and ecological distances of the samples were likely to influence unexpected differentiation of some groups within H. sect. Pannosa. The vast majority of dominant compounds significantly contributed to differences between taxa. The antioxidant potential of the extracts was satisfactory and in accordance with their phenolics composition. CONCLUSIONS: Comparative LC-MS analysis demonstrated that flavonoids and phenolic acids are good indicators of chemosystematic relationships within Hieracium, particularly between non-hybrid species and groups from the same location. Copyright © 2017 John Wiley & Sons, Ltd.

Chemical Analysis and Investigation of Antimicrobial and Antibiofilm Activities of Prangos trifida (Apiaceae).

Plants of the genus Prangos are intensively investigated as potential new sources of bioactive isolated products. In this work, the chemical composition of volatile constituents (essential oils and headspace volatiles) and dichloromethane extracts, as well as antimicrobial and antibiofilm activities of essential oils and MFDEs (methanol fractions of dichloromethane extracts) of Prangos trifida from Serbia, were investigated. Volatiles of roots, leaves, stems and fruits, and fatty acids and phytosterols in dichloromethane extracts of roots and fruits were analyzed by GC-FID-MS, whereas coumarins in MFDEs by LC-MS and some isolated coumarins by 1H-NMR. Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations/minimum fungicidal concentrations (MBCs/MFCs) of essential oils and MFDEs were determined against 13 microorganisms. Antibiofilm activity was assessed against four microorganisms. Additionally, congo red and ergosterol binding assays were conducted to elucidate selected mechanisms of antibiofilm action in the case of Candida albicans. Total of 52 volatile constituents, 16 fatty acids, eight phytosterols and 10 coumarins were identified. Essential oils demonstrated significant activity, surpassing that of commercial food preservatives, against six tested molds from the Aspergillus, Penicillium and Trichoderma genera, as well as against bacteria Staphylococcus aureus and Bacillus cereus. Most of the oils strongly inhibited the formation of biofilms by S. aureus, Listeria monocytogenes and Escherichia coli. MFDEs exhibited noteworthy effects against B. cereus and the tested Aspergillus species, particularly A. niger, and significantly inhibited C. albicans biofilm formation. This inhibition was linked to a marked reduction in exopolysaccharide production, while antifungal mechanisms associated with ergosterol remained unaffected.

Vaccinium myrtillus L. Leaf Waste as a Source of Biologically Potent Compounds: Optimization of Polyphenol Extractions, Chemical Profile, and Biological Properties of the Extracts.

The aims of the present research include (1) optimization of extraction from Vaccinium myrtillus leaf waste via investigation of plant material:medium ratio, extraction medium, and extraction period, employing extractions at room and high temperatures, or using ultrasound and microwaves (M, HAE, UAE, and MAE, respectively), (2) physicochemical characterization, and (3) investigation of extract biological potential. The statistical analysis revealed that optimal levels of parameters for the greatest polyphenolic yield were a proportion of 1:30 g/mL, ethyl alcohol 50% (v/v) during 2 min of microwave irradiation. By LC-MS analysis, 29 phenolic components were detected; HAE showed the highest richness of almost all determined polyphenols, while chlorogenic acid and quercetin 3-O-glucuronide were dominant. All extracts showed a high inhibition of Staphylococcus aureus growth. The effect of different parameters on extracts' antioxidant capacity depended on the used tests. The extracts also showed a stimulative influence on keratinocyte viability and anti-inflammatory activity (proven in cell-based ELISA and erythrocyte stabilization assays). The extraction procedure significantly affected the extraction yield (MAE ≥ maceration ≥ UAE ≥ HAE), whereas conductivity, density, surface tension, and viscosity varied in a narrow range. The presented research provides evidence on the optimal extraction conditions and technique, chemical composition, and antioxidant, antimicrobial, anti-inflammatory, and keratinocyte viability properties of bilberry extracts for potential applications in pharmacy and cosmetics.

From Aloe vera Leaf Waste to the Extracts with Biological Potential: Optimization of the Extractions, Physicochemical Characterization, and Biological Activities.

In the study, the optimization of the extraction from Aloe vera leaf waste was performed via varying solid-to-solvent ratio, solvent type, extraction time, and technique (maceration, heat-, ultrasound-, and microwave-assisted extractions-HAE, UAE, and MAE, respectively). The optimal extraction conditions for achieving the highest polyphenol content are a 1:30 ratio, 70% ethanol, and 30 min of HAE. Total flavonoid and protein contents were significantly higher in the extract from MAE, while total condensed tannin content was the highest in HAE. LC-MS analysis quantified 13 anthraquinone and chromone compounds. The variations in the FT-IR spectra of the extracts obtained by different extraction procedures are minor. The influence of extraction conditions on the antioxidant ability of the extracts depended on applied antioxidant assays. The extracts possessed medium inhibition properties against Staphylococcus aureus and weak inhibitory activity against Enterococcus feacalis. The extracts had stimulative effect on HaCaT cell viability. Regarding the extraction yield, there was a significant difference between the used extraction techniques (MAE > HAE > maceration and UAE). The presented study is an initial step in the production of polyphenol-rich extracts from A. vera leaf waste aimed to be used for the potential preparation of pharmaceutical and cosmetic formulations for the skin.

Investigation of antihyperalgesic and antiedematous activities of three Hieracium species.

Present study investigated triterpene profile, antihyperalgesic and antiedematous activities of Hieracium scheppigianum flowering aerial parts dichloromethane extract (SCH), and antihyperalgesic and antiedematous activities of previously chemically characterised polyphenol-rich H. glabratum and H. calophyllum flowering aerial parts methanol extracts (GLA and CAL, respectively). α- and ß-Amyrin and their acetates, and lupeol acetate were identified and quantified in SCH by GC-FID and GC-MS. In carrageenan-induced localised inflammation model in rats, SCH and GLA (50-200 mg/kg, p.o.) produced significant and dose-dependent antihyperalgesic effect of 26.9%-56.2% (ED50=163.0 ± 26.5 mg/kg) and 25.3%-51.6% (ED50=211.6 ± 70.6 mg/kg), respectively, and CAL (200 mg/kg, p.o.) exhibited effect of 38.1%. Extracts did not significantly reduce paw edema. SCH and GLA, which demonstrated higher (over 50%) antihyperalgesic efficacy, were tested in a rotarod test (200 mg/kg, p.o.) and no alteration of motor coordination was observed. Also, acute administration of SCH and GLA in mice (2000 mg/kg, p.o.) caused neither mortality nor toxicity.

Sesquiterpene lactones from the methanol extracts of twenty-eight Hieracium species from the Balkan Peninsula and their chemosystematic significance.

Four sesquiterpene lactones (SLs), including three undescribed proline-SL conjugates, the guaianolides calophyllamine A and 8-epiixerisamine A, and the eudesmanolide calophyllamine B, were isolated from the methanol extract of Hieracium calophyllum R. Uechtr. (Compositae) flowering heads. Another known guaianolide, crepiside E, was detected in Hieracium L. species for the first time. Their structures were elucidated using extensive 1D and 2D NMR spectroscopy in combination with HRMS. The isolated SLs were used as external standards for qualitative and quantitative LC-MS analysis of the dry methanol extracts of the flowering aerial parts of 28 Hieracium species from the Balkan Peninsula. Guaianolides were the dominant SLs in 27 species studied. The chemosystematic significance of detected SLs was evaluated using multivariate statistics (PCA, nMDS and UPGMA). Differentiation between the main groups was well supported. All four compounds significantly and equally contributed to the differences between the species. In addition, the eudesmanolide calophyllamine B could be a significant chemosystematic marker for H. sect. Villosa (Griseb.) Gremli s.l. and Glauciformia (Freyn) Zahn-Italica (Fr.) Av. Touv.