Phenolic Compounds Composition of Hypericum perforatum L. Wild-Growing Plants from the Republic of Macedonia

The aim of this study was to provide comprehensive understanding of phenolic compounds composition in roots (RO), non-flower shoots (NFS) and flower shoots (FS) of Hypericum perforatum wild-growing plants from the Republic of Macedonia. Identification of phenolic compounds in plant methanolic extracts was performed by HPLC-DAD/ESI-MS analysis. Chlorogenic acid and 3-p-coumaroylquinic acid were identified in NFS and FS, while 3-feruloylquinic acid was detected in RO and FS extracts. From the group of flavan- 3-ols, (epi)catechin and procyanidins were found in all tested samples, whereas catechin and B-type procyanidin dimer were confirmed in NFS and FS. Four flavonol glycosides (hyperoside, rutin, quercitrin and kaempferol 3-O-rutinoside) were identified in aerial parts. Guaijaverin and kaempferol 3-O-glucoside were exclusively found in NFS. Quercetin, amentoflavone and I3-II8 biapigenin as flavonoid aglycones were detected only in FS extracts. The NFS and FS extracts showed a capability for the accumulation of cyanidin 3-O-glycoside and cyanidin 3-O-rhamnoside, as well for hyperforin and adhyperforin. Naphthodianthrones were represented with pseudohypericin, hypericin and  protopseudohypericin  in  FS, while only hypericin was detected in NFS. Six xanthones, γ-mangostin, 5-O-methyl-2- deprenylrheediaxanthone B, garcinone C, 3,6-dihydroxy-1,5,7-trimethoxy-xanthone, cadensin G and cadensin C were exclusively confirmed in RO extracts. Padiaxanthone was detected in NFS, while dimethylmangiferin in FS extracts. The major finding of this study is the identification of novel xanthones in H. perforatum roots that could be potentially used as bioactive compounds in food and pharmaceutical industry

Phenolic Profile of Dark-Grown and Photoperiod-Exposed Hypericum perforatum

Hypericum perforatum L. is a medicinal plant considered as an important natural source of secondary metabolites with a wide range of pharmacological attributes. Hairy roots (HR) were induced from root segments of in vitro grown seedlings from H. perforatum after cocultivation with Agrobacterium rhizogenes A4. Investigations have been made to study the production of phenolic compounds in dark-grown (HR1) and photoperiod-exposed (HR2) cultures. The chromatographic analysis of phenolic acids, flavonols, flavan-3-ols, and xanthones revealed marked differences between HR1 and HR2 cultures. The production of quinic acid, kaempferol, and seven identified xanthones was increased in HR2. Moreover, HR2 showed a capability for de novo biosynthesis of two phenolic acids (3-p-coumaroylquinic acid and 3-feruloylquinic acid), three flavonol glycosides (kaempferol hexoside, hyperoside, and quercetin acetylglycoside), and five xanthones (tetrahydroxy-one-methoxyxanthone, 1,3,5-trihydroxy-6-methoxyxanthone, 1,3,5,6-tetrahydroxy-2-prenylxanthone, paxanthone, and banaxanthone E). On the other side, HR1 cultures were better producers of flavan-3-ols (catechin, epicatechin, and proanthocyanidin dimers) than HR2. This is the first comparative study on phenolic profile of H. perforatum HR cultures grown under dark and photoperiod conditions

Hydroxylated derivatives of dimethoxy-1,4-benzoquinone as redox switchable earth-alkaline metal ligands and radical scavengers

Benzoquinones (BQ) have important functions in many biological processes. In alkaline environments, BQs can be hydroxylated at quinoid ring proton positions. Very little is known about the chemical reaction leading to these structural transformations as well as about the properties of the obtained hydroxyl benzoquinones. We analyzed the behavior of the naturally occurring 2,6-dimethoxy-1,4-benzoquinone under alkaline conditions and show that upon substitution of methoxy-groups, poly-hydroxyl-derivatives (OHBQ) are formed. The emerging compounds with one or several hydroxyl-substituents on single or fused quinone-rings exist in oxidized or reduced states and are very stable under physiological conditions. In comparison with the parent BQs, OHBQs are stronger radical scavengers and redox switchable earth-alkaline metal ligands. Considering that hydroxylated quinones appear as biosynthetic intermediates or as products of enzymatic reactions, and that BQs present in food or administered as drugs can be hydroxylated by enzymatic pathways, highlights their potential importance in biological systems

Development of a spectrophotometric method for assessment of the relative reactivity of monocarbonyl analogs of curcumin with 2-(dimethylamino)ethanethiol

In order to improve the bioavailability of curcumin, studies have been undertaken to prepare the so-called monocarbonyl analogs of curcumin (MACs) and assess their biological activity. These analogs contain an electrophilic α,β-unsaturated carbonyl moiety (Michael acceptor). Several key biological processes are connected/controlled with thiol alkylation (glutathione, cysteine, cysteine peptide residues). The most likely reaction is the Michael addition between the α,β-unsaturated acceptor and a corresponding thiol. 2,6-Bisarylidenecyclohexanone and 3,5-bisarylidenepiperidin-4-one scaffolds offer convenient tunability of electrophilicity and redox properties of the Michael acceptor by the introduction of various substituents. In this study, several MACs were prepared by Claisen-Schmidt condensation reaction, and their reactivity with 2-(dimethylamino)ethanethiol was evaluated. For this purpose, based on the UV-Vis spectra of the analogs and thiol(s), a proper method for spectrophotometric evaluation of their reactivity with 2-(dimethylamino)ethanethiol was optimized. The relative reactivity of the analogs was 7 > 2 > 5 > 4 > 1 ≈ 6. The developed method is simple, and it can be extended to assess the reactivity of other MACs

Assay of Urinary Excretion of Polyphenols after Ingestion of a Cup of Mountain Tea (Sideritis scardica) Measured by HPLC-DAD-ESI-MS/MS

Flavonoids and phenolic acid metabolites excreted in human urine after ingestion of Sideritis scardica decoction with characterized polyphenolic composition were studied. A feeding study was carried out with 10 human volunteers, and urine samples were collected for 24 h after ingestion of the <i>Sidertis</i> decoction. Polyphenol metabolites were identified and quantified in urine samples by HPLC with tandem mass spectrometric detection. Thirty-one different metabolites of hypolaetin, methylhypolaetin, isoscutellarein, methylisoscutellarein, and apigenin and 32 phenolic acid metabolites were detected and quantified using a method validated for this purpose. The urinary excretion of polyphenol metabolites corresponded to 5% (n/n) of the intake of polyphenols from the <i>Sideritis</i> decoction. Flavonoid metabolites were dominant in urine samples with 87–94% of total polyphenolic metabolites content. The most abundant metabolites were methylhypolaetin and methylisoscutellarein glucuronides. Urinary excretion of isoscutellarein (35.61%) was 10 times higher than that of hypolaetin (3.67%). Apigenin also showed high urinary excretion (32.46%)

HPLC-DAD-ESI/MS monitoring of stilbenes content in Vranec red wines produced with traditional and modern fermentation methods

Quantification of stilbenes was performed on Vranac wines (vintage 2008 and 2009) produced by traditional and modern fermentation methods, applying different enological additions (enzyme, oak chips and grape tannins). Stilbenes, trans-resveratrol and trans-resveratrol-3-glucoside were determined using the HPLC/DAD/ESI-MS and MS/MS technique. Trans-resveratrol ranged from 0.09 to 3.3 mg/L and the trans-resveratrol-3-glucoside was present in a range of 1.13 to 2.6 mg/L. The influence of vintage, fermentation tanks and enological additions was noticed on the content of stilbenes. Wines from vintage 2008 presented higher amount of stilbenes (on average: 1.89 mg/L) compared to the wines from 2009 (on average: 1.59 mg/L) probably because of the difference in the temperature and humidity in both years. Application of modern fermentation tanks (Sifa and Ganimede) followed by additions of enzyme, oak chips and grape tannins resulted in a higher amount of stilbenes. PCA presented grouping of wines according to the applied fermentation method

Biogenic aminies and aroma in Vranec wines from Macedonia and Montenegro and effect of malolactic fermentation on their formation

The control of biogenic amines is becoming increasingly important to the consumers and also to wine producers because of the potential risk of toxicity and the negative impact on sales, trade and export of wine. Biogenic amines are organic nitrogen compounds with low molecular weight which have different origin in the wine. They can be found in the must, can be formed by the yeast during the alcoholic and malolactic fermentation and during wine aging. In this project the content of the biogenic amines and aroma profile of the wine from Vranec variety will be analyzed, produced by addition of malolactic bacteria during different stages of vinification. The analysis of biogenic amines will be performed with liquid chromatography coupled with DAD and MS detector and gas chromatography coupled with ion trap MS and QQQ MS detector. In order to determine the effect of malolactic fermentation on the content of biogenic amines, as well as, on the aroma compounds in wines, malolactic bacteria will be applied before fermentation and after the alcoholic fermentation. The following biogenic amines will be analyzed: tryptamine, putrescine, histamine, phenylethyl amine, tyramine, cadaverine, spermine and spermedine. 1,7 diaminoheptane will be used as an internal standard. The obtained results will be statistically processed, applying Analysis of Variance (ANOVA), Principle Component Analysis (PCA), Cluster Analysis (CA) and Linear Discriminant Analysis (LDA) in order to determine possible differences between the analyzed wines. Implementation of controlled malolactic fermentation is expected to improve aromatic profile of the wine and the overall control of the wine as well

Phenolic Compounds Composition of Hypericum perforatum L. Wild-Growing Plants from the Republic of Macedonia

The aim of this study was to provide comprehensive understanding of phenolic compounds composition in roots (RO), non-flower shoots (NFS) and flower shoots (FS) of Hypericum perforatum wild-growing plants from the Republic of Macedonia. Identification of phenolic compounds in plant methanolic extracts was performed by HPLC-DAD/ESI-MS analysis. Chlorogenic acid and 3-p-coumaroylquinic acid were identified in NFS and FS, while 3-feruloylquinic acid was detected in RO and FS extracts. From the group of flavan- 3-ols, (epi)catechin and procyanidins were found in all tested samples, whereas catechin and B-type procyanidin dimer were confirmed in NFS and FS. Four flavonol glycosides (hyperoside, rutin, quercitrin and kaempferol 3-O-rutinoside) were identified in aerial parts. Guaijaverin and kaempferol 3-O-glucoside were exclusively found in NFS. Quercetin, amentoflavone and I3-II8 biapigenin as flavonoid aglycones were detected only in FS extracts. The NFS and FS extracts showed a capability for the accumulation of cyanidin 3-O-glycoside and cyanidin 3-O-rhamnoside, as well for hyperforin and adhyperforin. Naphthodianthrones were represented with pseudohypericin, hypericin and  protopseudohypericin  in  FS, while only hypericin was detected in NFS. Six xanthones, γ-mangostin, 5-O-methyl-2- deprenylrheediaxanthone B, garcinone C, 3,6-dihydroxy-1,5,7-trimethoxy-xanthone, cadensin G and cadensin C were exclusively confirmed in RO extracts. Padiaxanthone was detected in NFS, while dimethylmangiferin in FS extracts. The major finding of this study is the identification of novel xanthones in H. perforatum roots that could be potentially used as bioactive compounds in food and pharmaceutical industry

NMR Profiling of North Macedonian and Bulgarian Honeys for Detection of Botanical and Geographical Origin

Bulgaria and North Macedonia have a long history of the production and use of honey; however, there is an obvious lack of systematic and in-depth research on honey from both countries. The oak honeydew honey is of particular interest, as it is highly valued by consumers because of its health benefits. The aim of this study was to characterize honeydew and floral honeys from Bulgaria and North Macedonia based on their NMR profiles. The 1D and 2D 1H and 13C-NMR spectra were measured of 16 North Macedonian and 22 Bulgarian honey samples. A total of 25 individual substances were identified, including quinovose, which was found for the first time in honey. Chemometric methods (PCA&mdash;principal component analysis, PLS-DA&mdash;partial least squares discriminant analysis, ANOVA&mdash;analysis of variance) were used to detect similarities and differences between samples, as well as to determine their botanical and geographical origin. Semiquantitative data on individual sugars and some other constituents were obtained, which allowed for the reliable classification of honey samples by botanical and geographical origin, based on chemometric approaches. The results enabled us to distinguish oak honeydew honey from other honey types, and to determine the country of origin. NMR was a rapid and convenient method, avoiding the need for other more time-consuming analytical techniques

New insights into the chemistry of Coenzyme Q-0: A voltammetric and spectroscopic study

Coenzyme Q-0 (CoQ-0) is the only Coenzyme Q lacking an isoprenoid group on the quinoid ring, a feature important for its physico-chemical properties. Here, the redox behavior of CoQ-0 in buffered and non-buffered aqueous media was examined. In buffered aqueous media CoQ-0 redox chemistry can be described by a 2-electron–2-proton redox scheme, characteristic for all benzoquinones. In non-buffered media the number of electrons involved in the electrode reaction of CoQ-0 is still 2; however, the number of protons involved varies between 0 and 2. This results in two additional voltammetric signals, attributed to 2-electrons–1H+ and 2-electrons–0H redox processes, in which mono- and di-anionic compounds of CoQ-0 are formed. In addition, CoQ-0 exhibits a complex chemistry in strong alkaline environment. The reaction of CoQ-0 and OH− anions generates several hydroxyl derivatives as products. Their structures were identified with HPLC/MS. The prevailing radical reaction mechanism was analyzed by electron paramagnetic resonance spectroscopy. The hydroxyl derivatives of CoQ-0 have a strong antioxidative potential and form stable complexes with Ca2+ions. In summary, our results allowmechanistic insights into the redox properties of CoQ-0 and its hydroxylated derivatives and provide hints on possible applications.