Anna Stochmal

Isolation and structure elucidation of flavonoid and phenolic acid glycosides from pericarp of hot pepper fruit Capsicum annuum L.

Hot pepper fruits (Capsicum annuum L.) var. Bronowicka Ostra have been studied with regard to content of flavonoids and other phenolics. Nine compounds were isolated from pericarp of pepper fruits by preparative HPLC. Their structures were identified by chromatographic (analytical HPLC) and spectroscopic (UV, NMR) techniques. Two of the identified compounds, trans-p-ferulylalcohol-4-O-(6-(2-methyl-3-hydroxypropionyl) glucopyranoside and luteolin-7-O-(2-apiofuranosyl-4-glucopyranosyl-6-malonyl)-glucopyranoside were found for the first time in the plant kingdom. Additionally compounds: trans-p-feruloyl-beta-D-glucopyranoside, trans-p-sinapoyl-beta- D-glucopyranoside, quercetin 3-O-alpha-L-rhamnopyranoside-7-O-beta-D-glucopyranoside, luteolin 6-C-beta-D-glucopyranoside-8-C-alpha-L-arabinopyranoside, apigenin 6-C-beta-D-glucopyranoside-8-C-alpha-L-arabinopyranoside and luteolin 7-O-[2-(beta-D-apiofuranosyl)-beta-D-glucopyranoside] were found for the first time in pepper fruit Capsicum annuum L.

Comparative anti-platelet and antioxidant properties of polyphenol-rich extracts from: berries of Aronia melanocarpa, seeds of grape and bark of Yucca schidigera in vitro

The aim of the present study was to investigate and compare the anti-platelet action of extracts from three different plants: bark of Yucca schidigera, seeds of grape and berries of Aronia melanocarpa (chokeberry). Anti-platelet action of tested extracts was compared with action of well characterized antioxidative and anti-platelet commercial monomeric polyphenol–resveratrol. The effects of extracts on platelet adhesion to collagen, collagen–induced platelet aggregation and on the production of in resting platelets and platelets stimulated by a strong platelet agonist–thrombin were studied. The in vitro experiments have shown that all three tested extracts (5–50 µg/ml) rich in polyphenols reduce platelet adhesion, aggregation and generation of in blood platelets. Comparative studies indicate that all three plant extracts were found to be more reactive in reduction of platelet processes than the solution of pure resveratrol. The tested extracts due to their anti-platelet effects may play an important role as components of human diet in prevention of cardiovascular or inflammatory diseases, where blood platelets are involved.

Herbivore-Induced Responses in Alfalfa (Medicago sativa)

The herbivore-induced response of alfalfa (Medicago sativa) was examined through assays with Spodoptera littoralislarvae and analyses of important secondary substances. In food preference experiments, larvae preferred young undamaged alfalfa plants over plants that had been damaged by feeding larvae 5 and 7 days earlier, while no difference in feeding preferences could be detected 1, 9, and 14 days after damage. This suggests a peak in the herbivore induced resistance of alfalfa approximately one week after initial damage. The induced resistance in young plants was also shown to be systemic, while older flowering plants failed to show increased resistance after defoliation. Larvae gained weight slower and had lower pupal mass when fed damaged alfalfa than when fed undamaged alfalfa. Levels of total saponins were increased in foliage of damaged alfalfa, and detailed analyses of specific saponin components revealed doubled concentrations of 3GlcA,28AraRhaXyl medicagenate (medicagenic acid bidesmoside) and 3GlcAGalRha soyasapogenol B (soyasaponin I). Levels of the flavonoid apigenin (as free aglycone) also were increased in herbivore damaged plants. The herbivore-induced response of alfalfa was significantly weaker than that of cotton: S. littoralis larvae given a choice of undamaged cotton and undamaged alfalfa preferred to feed on cotton, whereas preferences shifted towards alfalfa when plants were damaged.

Triterpene saponins and flavonoids in the seeds of Trifolium species

Seeds of 57 species of the genus Trifolium have been studied for the occurrence and concentration of soyasapogenol B glycosides and flavonoids. It was shown that all tested species contained soyasaponin I and in some species astragaloside VIII and/or 22-O-glucoside and 22-O-diglucoside of soyasaponin I were also present. Total concentration of saponins ranged from trace amounts up to 10 mg/g(DM). It was suggested that soyasapogenol B glycosides could be recognized as chemotaxonomic character of Fabaceae family. All but three tested species contained flavonoids. The majority of species contained quercetin as a sole flavonoid or in the mixture with a number of unidentified flavonoid components. Concentration of quercetine in some species was at the level of about 3 mg/g(DM). This high quercetin concentration and soyasaponin occurrence makes the seeds of some Trifolium species a potential source of health beneficial phytochemicals, to be used in human nutrition.

Approach to develop a standardized TLC-DPPH test for assessing free radical scavenging properties of selected phenolic compounds

TLC-DPPH(•) test belongs to a group of frequently performed assays aimed at detection of compounds with desired activity (effect directed analysis). Despite its popularity a standard procedure has not been elaborated so far causing difficulties in comparing results obtained in different laboratories. Thus the aim of the presented research was an approach to develop a standardized procedure for assessing free radical scavenging properties of plant polyphenols. It was observed that specifically positive adsorbent (silica gel) strengthened the observed result of radical-antioxidant reaction, while polar bonded stationary phase CN-silica weakened it. Based on the observed results it was concluded that the TLC-DPPH(•) assay should be preferably performed on the surface of non-specific adsorbents (e.g.: RP-18) with the use of n-hexane for DPPH(•) dissolution. It is also proposed to document the results every 5 min after staining, as they change in time.

Combined effects of elevated CO2 and herbivore damage on alfalfa and cotton

We examined herbivore-induced responses of alfalfa (Medicago sativa) and cotton (Gossypium hirsutum) under different CO2 conditions. Plants were grown under ambient (350 ppm) or elevated (700 ppm) CO2 levels, and were either damaged or undamaged by Spodoptera littoralis larvae. At harvest, growth of undamaged (control) plants was determined, and foliar chemical composition of both undamaged and damaged plants was analyzed. Cotton grew faster overall and showed a greater increase in growth in response to CO2 enrichment than did alfalfa. Elevated CO2 levels increased starch and decreased nitrogen levels in damaged alfalfa and undamaged cotton plants. Alfalfa saponin levels were significantly increased by elevated CO2 and damage. Regarding specific saponins, medicagenic acid bidesmoside (3GlcA,28AraRhaXyl medicagenate) concentrations were reduced by high CO2, whereas zanhic acid tridesmoside (3GlcGlcGlc,23Ara,28AraRhaXylApi Za) levels were unaffected by the treatments. Soyasaponin I (3GlcAGalRha soyasapogenol B) was only detected in minute amounts. Alfalfa flavonoid analyses showed that total flavonoid levels were similar between treatments, although free apigenin increased and apigenin glucoside (7-O-[2-O-feruloyl-β-D-glucuronopyranozyl (1→2)-O-β-D-glucuronopyranozyl]-4′-O-β-D-glucuronopyranozide apigenin) decreased in CO2-enriched plants. In cotton, herbivore damage increased levels of total terpenoid aldehydes, gossypol, hemigossypolone, the heliocides H1 and H4, but not H2 and H3, whereas CO2 enrichment had no effect. These results demonstrate that combined effects of CO2 and herbivore damage vary between plant species, which has implications for the competitive balance within plant communities.

An Extract from Berries of Aronia melanocarpa Modulates the Generation of Superoxide Anion Radicals in Blood Platelets from Breast Cancer Patients

Plant antioxidants protect cells against oxidative stress. Because oxidative stress (measured by different biomarkers) is observed in breast cancer patients, the aim of this study was to establish the effects of a polyphenol-rich extract of Aronia melanocarpa (final concentration of 50 microg/mL, 5 min, 37 degrees C) on superoxide anion radicals (O(2)(-*)) and glutathione (GSH) in platelets from patients with breast cancer and in a healthy group in vitro. Generation of O(2)(-*) in platelets before and after incubation with the extract was measured by cytochrome C reduction. Using HPLC, we determined the level of glutathione in blood platelets. We observed a statistically significant increase of biomarkers of oxidative stress such as O(2)(-*) and a decrease in GSH in platelets from patients with breast cancer compared with the healthy group. We showed that the extract from A. melanocarpa added to blood platelets significantly reduced the production of O(2)(-*) in platelets not only from the healthy group but also from patients with breast cancer. Considering the data presented in this study, we have demonstrated the protective role of the extract from A. melanocarpa in patients with breast cancer in vitro.

Flavonoids from Pinus sylvestris needles and their variation in trees of different origin grown for nearly a century at the same area

Abstract Flavonoids in needles of Scots pine planted in 1912–1914 in Poland from seeds originating from different parts of Europe, were isolated, chemically characterised and analysed by HPLC. It was shown that flavonoid profiles were similar in all tested populations and were different from those previously reported for Scots pine seedlings. They included taxifolin, taxifolin 3′- O -glucoside, quercetin as well as quercetin 3- O -glucoside and 3′- O -glucoside. The quercetin 3- O -glucoside could be found only in a trace amount in all samples and quercetin 3′- O -glucoside appeared in all samples regardless their origin. The relative concentration of taxifolin 3′- O -glucoside, quercetin, taxifolin and total flavonoids showed dependence on the origin of seeds; needles from high latitude populations contained smaller amounts of these compounds. Presented data clearly indicate that Scots pine contain glycosidases specific for glycosylation at C-3′ rather than at C-3. Besides, they indicate that long lasting influence of similar environmental factors is not able to change genetic regulatory systems responsible for flavonoid biosynthesis.

Profiles analysis of proanthocyanidins in the argun nut (Medemia argun—an ancient Egyptian palm) by LC–ESI–MS/MS

Medemia argun is an ancient palm rich in proanthocyanidins (PACs). These polyphenolic compounds are widely distributed in plants and are an integral part of the human diet. A sensitive high-performance liquid chromatography and electrospray ionization mass spectrometry (HPLC-ESI-MS) method in the negative ion mode for sequencing these ubiquitous and highly beneficial antioxidants is described in order to profile different PACs in M. argun nuts. The analytical protocol based on tandem mass spectrometry was used to sequence dimers, trimers, tetramers and pentamers with different A-type, B-type and A/B-type linkages. Diagnostic ions resulting from heterocyclic ring fission and retro-Diels-Alder reaction of flavan-3-ol provided information on the hydroxylation pattern and the type of interflavan bond. The sequences were discovered through ions derived from quinone methide cleavage of the interflavan bond. The identification of PACs linkages through LC-MS(n) eliminates a number of tedious separation steps. The method was successfully applied to give a view of PAC profile in M. argun nuts. M. argun nuts contained 636.88 mg/g PACs (as equivalent of (þ)-catechin). The data obtained in our research show that M. argun is a rich source of hydrolyzable PACs.

Saponins and polar compounds from Trifolium resupinatum

Abstract In addition to the known soyasaponin I, 3- O -[α- l -rhamnopyranosyl(1→2)-β- d -galactopyranosyl(1→2-β- d -glucuronopyranosyl]-22- O -[β- d -glucuronopyranosyl(1→2)-β- d -glucopyranosyl]soyasapogenol B, soyasaponin II, 3- O -β- d -glucopyranosyl sitosterol, 3- O -β- d -glucopyranosyl stigmasterol and 3- O -α- l -arabinopyranosyl-(1→6)-β- d -glucopyranosyl]oct-1-ene-3-ol, the new saponin, 3- O -α- l -rhamnopyranosyl(1→2)-β- d -galactopyranosyl(1→2)-β- d -glucuronopyranosyl]-22- O -β- d -glucopyranosyl soyasapogenol B ( 2 ) was isolated and characterised from the seed saponins fraction of Trifolium resupinatum . The structural determination is based on spectroscopic methods (including DQF-COSY, HETCOR, TOCSY, ROESY and NOEs experiments).