Trifolium pallidum and Trifolium scabrum extracts in the protection of human plasma components

Variability of sinapic acid derivatives during germination and their contribution to antioxidant and anti-inflammatory effects of broccoli sprouts on human plasma and human peripheral blood mononuclear cells

Broccoli sprouts represent a health-promoting food, rich in antioxidant and anti-inflammatory phytochemicals, among which sulfur compounds are most extensively investigated. In this study, the phenolics of broccoli sprouts (Brassica oleracea var. italica'Cezar') were examined for variability during germination and influence on the bioactivity of sprouts. In the sprouts germinated in darkness, 31 compounds were identified by UHPLC-PDA-ESI-MS³ (18 sinapic acid derivatives, 8 glucosinolates, and 5 flavonoids) with sinapoyl components (SADs) prevailing among polyphenols. The total SADs decreased during germination (down to 4.85 mg per g dw in 6-day-sprouts), but the concurrent changes in molecular structures of the leading compounds (sinapine was replaced by sinapate sugar esters and sinapic acid) increased the antioxidant capacity of the sprouts. The glucosinolate-depleted 6-day-sprout extract (34.2 mg SADs per g dw) effectively protected human plasma components against peroxynitrite-induced oxidative damage in vitro (reduced the levels of 3-nitrotyrosine, lipid hydroperoxides and thiobarbituric acid-reactive substances) and enhanced the non-enzymatic antioxidant status of plasma. It also downregulated the release of pro-inflammatory cytokines (TNF-α, IL-6) from LPS-stimulated human peripheral blood mononuclear cells and increased the production of IL-10, an anti-inflammatory mediator. The relevant activity parameters of sinapic acid indicated that SADs might be linked to the observed effects. The results support the application of broccoli sprouts in oxidative stress- and inflammation-related diseases and the role of SADs as their bioactive components next to glucosinolates.

Caffeoylquinic Acids with Potential Biological Activity from Plant In vitro Cultures as Alternative Sources of Valuable Natural Products

BACKGROUND

For a long time, the researchers have been looking for new efficient methods to enhance production and obtain valuable plant secondary metabolites, which would contribute to the protection of the natural environment through the preservation of various plant species, often rare and endangered. These possibilities offer plant in vitro cultures which can be performed under strictly-controlled conditions, regardless of the season or climate and environmental factors. Biotechnological methods are promising strategies for obtaining the valuable plant secondary metabolites with various classes of chemical compounds including caffeoylquinic acids (CQAs) and their derivatives. CQAs have been found in many plant species which are components in the daily diet and exhibit a wide spectrum of biological activities, including antioxidant, immunomodulatory, antihypertensive, analgesic, anti-inflammatory, hepato- and neuroprotective, anti-hyperglycemic, anticancer, antiviral and antimicrobial activities. They have also been found to offer protection against Alzheimer's disease, and play a role in weight reduction and lipid metabolism control, as well as modulating the activity of glucose-6-phosphatase involved in glucose metabolism.

METHODS

This work presents the review of the recent advances in use in vitro cultures of various plant species for the alternative system to the production of CQAs and their derivatives. Production of the secondary metabolites in in vitro culture is usually performed with cell suspension or organ cultures, such as shoots and adventitious or transformed roots. To achieve high production of valuable secondary metabolites in in vitro cultures, the optimization of the culture condition is necessary with respect to both biomass accumulation and metabolite content. The optimization of the culture conditions can be achieved by choosing the type of medium, growth regulators or growth conditions, selection of high-productivity lines or culture period, supplementation of the culture medium with precursors or elicitor treatments. Cultivation for large-scale in bioreactors and genetic engineering: Agrobacterium rhizogenes transformation and expression improvement of transcriptional factor or genes involved in the secondary metabolite production pathway are also efficient strategies for enhancement of the valuable secondary metabolites.

RESULTS

Many studies have been reported to obtain highly productive plant in vitro cultures with respect to CQAs. Among these valuable secondary metabolites, the most abundant compound accumulated in in vitro cultures was 5-CQA (chlorogenic acid). Highly productive cultures with respect to this phenolic acid were Leonurus sibiricus AtPAP1 transgenic roots, Lonicera macranthoides and Eucomia ulmoides cell suspension cultures which accumulated above 20 mg g-1 DW 5-CQA. It is known that di- and triCQAs are less common in plants than monoCQAs, but it was also possible to obtain them by biotechnological methods.

CONCLUSION

The results indicate that the various in vitro cultures of different plant species can be a profitable approach for the production of CQAs. In particular, an efficient production of these valuable compounds is possible by Lonicera macranthoides and Eucomia ulmoides cell suspension cultures, Leonurus sibiricus transformed roots and AtPAP1 transgenic roots, Echinacea angustifolia adventitious shoots, Rhaponticum carthamoides transformed plants, Lavandula viridis shoots, Sausera involucrata cell suspension and Cichorium intybus transformed roots.

Phenolic fractions from nine Trifolium species modulate the coagulant properties of blood plasma in vitro without cytotoxicity towards blood cells

OBJECTIVE

The study covers an evaluation of the influence of extracts (1-50 μg/ml), isolated from aerial parts of nine Trifolium L. species (i.e. T. alexandrinum, T. fragiferum, T. hybridum, T. incarnatum, T. pallidum, T. pratense, T. resupinatum var. majus, T. resupinatum var. resupinatum and T. scabrum) on haemostatic properties of blood plasma.

METHODS

The clot formation and fibrinolysis assay (CFF), blood clotting times, the extrinsic and intrinsic coagulation pathway-dependent polymerization of plasma fibrin were measured. The effects of plant extracts on amidolytic activity of thrombin were also evaluated and compared with argatroban, an antithrombotic drug. Cytotoxicity was assessed in a model of blood platelets and as the viability of peripheral blood mononuclear cells.

KEY FINDINGS

While no changes in blood clotting times or fibrinolytic properties of blood plasma were found, some fractions impaired the blood plasma coagulation induced by the intrinsic coagulation pathway. Reduction in the maximal velocity of fibrin polymerization was also observed in the clot formation and fibrinolysis assay. No cytotoxicity of Trifolium extracts towards the investigated cells was recorded.

CONCLUSIONS

The most efficient anticoagulant activity in plasma was found for T. fragiferum and T. incarnatum extracts, while the T. alexandrinum fraction was the most effective inhibitor of thrombin amidolytic activity.

Bioactivity Potential of Prunus spinosa L. Flower Extracts: Phytochemical Profiling, Cellular Safety, Pro-inflammatory Enzymes Inhibition and Protective Effects Against Oxidative Stress In Vitro

Flower extracts of Prunus spinosa L. (blackthorn)-a traditional medicinal plant of Central and Eastern Europe indicated for the treatment of urinary tract disorders, inflammation, and adjunctive therapy of cardiovascular diseases-were evaluated in terms of chemical composition, antioxidant activity, potential anti-inflammatory effects, and cellular safety in function of fractionated extraction. The UHPLC-PDA-ESI-MS³ fingerprinting led to full or partial identification of 57 marker constituents (36 new for the flowers), mostly flavonoids, A-type proanthocyanidins, and phenolic acids, and provided the basis for authentication and standardization of the flower extracts. With the contents up to 584.07 mg/g dry weight (dw), 490.63, 109.43, and 66.77 mg/g dw of total phenolics (TPC), flavonoids, proanthocyanidins, and phenolic acids, respectively, the extracts were proven to be rich sources of polyphenols. In chemical in vitro tests of antioxidant (DPPH, FRAP, TBARS) and enzyme (lipoxygenase and hyaluronidase) inhibitory activity, the extracts effects were profound, dose-, phenolic-, and extraction solvent-dependent. Moreover, at in vivo-relevant levels (1-5 μg/mL) the extracts effectively protected the human plasma components against peroxynitrite-induced damage (reduced the levels of oxidative stress biomarkers: 3-nitrotyrosine, lipid hydroperoxides, and thiobarbituric acid-reactive substances) and enhanced the total antioxidant status of plasma. The effects observed in biological models were in general dose- and TPC-dependent; only for protein nitration the relationships were not significant. Furthermore, in cytotoxicity tests, the extracts did not affect the viability of human peripheral blood mononuclear cells (PBMC), and might be regarded as safe. Among extracts, the defatted methanol-water (7:3, v/v) extract and its diethyl ether and ethyl acetate fractions appear to be the most advantageous for biological applications. As compared to the positive controls, activity of the extracts was favorable, which might be attributed to some synergic effects of their constituents. In conclusion, this research proves that the antioxidant and enzyme inhibitory capacity of phenolic fractions should be counted as one of the mechanisms behind the activity of the flowers reported by traditional medicine and demonstrates the potential of the extracts as alternative ingredients for functional products supporting the treatment of oxidative stress-related pathologies cross-linked with inflammatory changes, especially in cardiovascular protection.

Trifolium species - the latest findings on chemical profile, ethnomedicinal use and pharmacological properties

OBJECTIVES

Clovers (Trifolium, Fabaceae) have a long history of use in folk medicine. Furthermore, during last 3 years, a considerable growth in scientific interest in these plants has been observed. This article summarizes and critically reviews an over 3-year progress of knowledge of ethnomedicinal use, phytochemical profile, physiological effects and possible therapeutic action of various clover species. It contains the latest literature (over 80 papers), originated from international databases (MEDLINE/PubMed, Science Direct/Elsevier, Springer Link, Wiley Online Library) and reports from other international and local scientific periodicals.

KEY FINDINGS

Traditional uses of T. pratense and T. repens have been confirmed, while the folk medicine recommendations for administration of other clovers such as T. burchellianum, T. fragiferum, T. hybridum, T. minus and T. purpureum were reported for the first time. Furthermore, several other clover species were also investigated in terms of their antioxidant, antimicrobial and phytoestrogenic effects for the first time. Only T. alexandrinum, T. pratense and T. medium were examined in animal studies.

SUMMARY

Besides T. pratense, other clovers may be a rich source of bioactive phytochemicals. However, in contradiction to red clover, the therapeutic use of other clovers is still limited by the lack of in-vivo evidence.

The anti-adhesive and anti-aggregatory effects of phenolics from Trifolium species in vitro

The present in vitro study includes a comparative evaluation of anti-platelet (anti-thrombotic) properties of plant phenolics, isolated from nine different clover (Trifolium) species. The analysis covered phenolic fractions isolated from T. alexandrinum L., T. fragiferum L., T. hybridum L., T. incarnatum L., T. pallidum Waldst et Kit., T. resupinatum L. var. majus Boiss, T. resupinatum L. var. resupinatum, T. scabrum L., and T. pratense L. (red clover). The inhibitory effects of plant preparations (1–50 µg/ml) on hemostatic functions of blood platelets were assessed by measurements of thrombin- or ADP-induced platelet adhesion to fibrinogen, platelet aggregation in platelet-rich plasma (activated with ADP or collagen), and by the determination of PF-4 secretion from platelet α-granules. The influence of T. phenolics on arachidonic cascade in blood platelets was also determined. T. resupinatum var. majus, T. resupinatum var. resupinatum, and T. scabrum had the strongest anti-platelet effects. These preparations displayed the most evident anti-adhesive and anti-aggregatory effects in response to all of the used agonists: thrombin (0.2 U/ml), ADP (10 µM), and collagen (2 µg/ml), and their inhibitory properties were also confirmed by an analysis of PF-4 secretion. T. scabrum and some of other examined clover species possess significantly higher concentrations of both isoflavones and other bioactive phenolics, when compared to red clover. The obtained results suggest that these clovers contain substances with potent anti-platelet properties.

Free radical scavenging actions of three Trifolium species in the protection of blood plasma antioxidant capacity in vitro

CONTEXT

Three clover [Trifolium L. (Leguminosae)] species were selected on the basis of data from traditional medicine, phytochemical profiles, and agricultural significance.

OBJECTIVE

The in vitro evaluations of free radical scavenging properties, ferric reducing abilities, and antioxidant effects of extracts from T. pratense L. (crude extract and phenolic fraction), T. pallidum L., and T. scabrum L. (phenolic fractions) were performed.

MATERIALS AND METHODS

Activities of the Trifolium extracts were determined at their final concentrations of 1.5-50 µg/ml. Free radical scavenging properties of methanol extract solutions were estimated by the reduction of DPPH(•) and ABTS(•) radicals. Measurements of the total antioxidant capacity (TAC) were carried out to assess the antioxidant activities of the extracts in human blood plasma under conditions of oxidative stress, induced by 200 μM peroxynitrite.

RESULTS

The phenolic fraction of T. pratense displayed the strongest ABTS(•) and DPPH(•) radical scavenging effects (EC50 value of 21.69 and 12.27 µg/ml, respectively). The EC50 value for T. pallidum extract attained 29.77 and 30.06 µg/ml. The two remaining extracts were less potent scavengers (EC50 value higher than 50 µg/ml). Similar differences were obtained during evaluation of the ferric reducing abilities. Analysis of antioxidant properties of the extracts in blood plasma did not provide such evident differences in their actions, however, it indicated that the T. pratense phenolic fraction displayed the strongest effect.

CONCLUSIONS

The examined Trifolium extracts partly protected blood plasma and enhanced its non-enzymatic antioxidant defense against harmful action of peroxynitrite in vitro.

Biological activity of clovers - free radical scavenging ability and antioxidant action of six Trifolium species

CONTEXT

Clovers were chosen on the basis of traditional medicine recommendations, agricultural value, or available information on their promising chemical profiles.

OBJECTIVE

This study evaluates and compares free radical scavenging and antioxidant properties of six clover species: Trifolium alexandrinum L. (Leguminosae), Trifolium fragiferum L., Trifolium hybridum L., Trifolium incarnatum L., Trifolium resupinatum var. majus Boiss., and Trifolium resupinatum var. resupinatum L.

MATERIALS AND METHODS

Free radical scavenging activity of the extracts (1.5-50 µg/ml) was estimated by reduction of 1,1-diphenyl-2-picrylhydrazyl (DPPH(•)) and 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic) acid (ABTS(•)) radicals. The Trifolium extract effects on total antioxidant capacity of blood plasma were determined by the reduction of ABTS(•+) and DPPH(•) radicals, as well as with the use of the ferric reducing ability of plasma (FRAP) assay.

RESULTS

The UPLC analysis of chemical profiles of the examined extracts showed the presence of three or four groups of phenolic substances, including phenolic acids, clovamides, isoflavones, and other flavonoids. The measurements of free radical scavenging and ferric reducing ability of the examined clover extracts revealed the strongest effect for T. alexandrinum. Furthermore, antioxidant activity assays in human plasma have shown protective effects of all extracts against peroxynitrite-induced reduction of total antioxidant capacity.

CONCLUSIONS

Trifolium plants may be a rich source of bioactive substances with antioxidant properties. The examined extracts displayed free radical scavenging action and partly protected blood plasma against peroxynitrite-induced oxidative stress; however, the beneficial effects of T. alexandrinum and T. incarnatum seem to be slightly higher.

Phenolic fractions from Trifolium pallidum and Trifolium scabrum aerial parts in human plasma protect against changes induced by hyperhomocysteinemia in vitro

Elevated concentration of homocysteine (Hcy) in human plasma, defined as hyperhomocysteinemia has been correlated with some diseases, such as cardiovascular, neurodegenerative, and kidney disorders. Homocysteine occurs in human plasma in several forms, including the most reactive form of Hcy - its cyclic thioester - homocysteine thiolactone (HTL), which represents up to 0.29% of plasma total Hcy. It is suggested that Hcy and HTL may also act as oxidants, but various polyphenolic antioxidants are able to inhibit the oxidative damage induced by Hcy or HTL. The aim of our present study was to investigate in vitro oxidative changes in human plasma induced by the model of hyperhomocysteinemia in the presence of the phenolic fractions from selected clovers (Trifolium pallidum and Trifolium scabrum aerial parts). Hyperhomocysteinemia was stimulated by a reduced form of Hcy (final dose 100 μM) or HTL (final dose 1 μM). The aim of our study was also to explain the effect of the phenolic fractions on the coagulation activity of human plasma treated with Hcy and its thiolactone. Tested phenolic fractions significantly inhibited the oxidative stress (measured by the total antioxidant level - TAS) in plasma treated with Hcy or HTL. The phenolic fractions from T. pallidum and T. scabrum also caused a distinct reduction of plasma lipid peroxidation (measured by the level of thiobarbituric acid reactive substance) induced by the model of hyperhomocysteinemia. Moreover, tested fractions modulated the coagulation properties of plasma treated with homocysteine and its thiolactone. It seems that antioxidative activities of the phenolic fractions from T. pallidum and T. scabrum aerial parts may be responsible for their medicinal properties during hyperhomocysteinemia.