Study on the phenolic constituents of the flowers and leaves of Trifolium repens L

Can Simulated Microgravity and Darkness Conditions Influence the Phytochemical Content and Bioactivity of the Sprouts?-A Preliminary Study on Selected Fabaceae Species

Sprouts' consumption has become popular due to their wide availability, easy cultivation process, and proven biological activity. Moreover, stress factors, such as limited access to light or disturbed gravity during growth, may contribute to the increased activity and the synthesis of bioactive compounds. In this study, for the first time, the examination of the impact of darkness and simulated microgravity conditions on the white clover sprouts from the Fabaceae family was conducted. Among several species, used in the preliminary attempts, only white clover was satisfactory sprouting in the disturbed gravity conditions, and thus was chosen for further examination. A random positioning machine setup was used during the cultivation process to simulate microgravity conditions. Additionally, the sprouts were cultivated in total darkness. Simulated microgravity and/or darkness during the first few days of the sprouts' growth caused biomass reduction, the increased synthesis of bioactive compounds (isoflavones and phenolics), and changes in the level of abscisic acid and phenylalanine ammonia-lyase. Moreover, it increased the antioxidant properties of the sprouts, while the enhancement of their cytotoxic impact was observed only for androgen-dependent prostate cancer LNCaP cells. To conclude, the presented results are promising in searching for novel functional food candidates and further studies are necessary, directed at other plant families.

Investigation of Trifolium repens L. from the Indian Himalayan region as a phyto-therapeutic agent

Trifolium repens is a well-known herbaceous, perennial herb and has been extensively used in the traditional medicine system over the years. Various parts of the plant are traditionally used as a curative agent against several health ailments such as skin problems, wound healing, stomach disorders, sedative, fever, antiseptic, analgesic, expectorant, psoriasis and eczema. To maximise the plant's potential for usage in the future, the review also aims to update information about its significant pharmacological properties. The ethnomedicinal benefits of T. repens have been well studied; however, the facets of the plant have not been explored yet. The current review outlines several bioactive compounds quantified from T. repens and a few of them namely quercetin, kaempferol, myricetin, acacetin and linamarin, have been reported to have biological activities such as antibacterial, antifungal, antileishmanial, anti-inflammatory, antiaging and anti-hepatotoxic activities. A significant number of in vitro studies have been done on the plant extract, but little is known about the isolation and efficacy of the potent natural bioactive compounds of T. repens. The bioactive compounds in T. repens can be used for advanced drug development against various health disorders.

Nutritional Evaluation of Quinoa Genetic Resources Growing in the Climatic Conditions of Central Europe

Quinoa displays huge genetic variability and adaptability to distinct climatic conditions. Quinoa seeds are a good source of nutrients; however, the overall nutritional composition and nutrient content is influenced by numerous factors. This study focused on the nutritional and morphologic evaluation of various quinoa genotypes grown in the Czech Republic. Significant differences between years were observed for morphological traits (plant height, inflorescence length, weight of thousand seeds). The weather conditions in the year 2018 were favorable for all the morphological traits. The protein content of quinoa accessions ranged between 13.44 and 20.01% and it was positively correlated to mauritianin. Total phenolic content varied greatly from year to year, while the antioxidant activity remained relatively stable. The most abundant phenolic compounds were the flavonoids miquelianin, rutin, and isoquercetin. Isoquercetin, quercetin, and N-feruoloyl octopamine showed the highest stability under variable weather conditions in the analyzed years. A total of six compounds were detected and quantified in quinoa for the first time. Most varieties performed well under Central European conditions and can be considered a good source of nutrients and bioactive compounds. These data can be used as a source of information for plant breeders aiming to improve the quality traits of quinoa.

Trifolium pratense extract increases testosterone and improves sperm characteristics and antioxidant status in diabetic rats

Male reproductive dysfunction is a common complication of diabetes mellitus. Trifolium pratense exhibits antioxidant and antidiabetic effects. We investigated the effects of an extract of T. pratense on serum antioxidant status, sperm characteristics, testicular tissue changes and testosterone level in diabetic rats. Male Wistar rats were divided into six groups: 1, untreated control; 2, diabetic; 3 and 4, 100 or 200 mg/kg T. pratense extract treated, respectively; 5 and 6, diabetic 100 or 200 mg/kg T. pratense extract treated, respectively. Diabetes was induced by intraperitoneal injection of streptozotocin. After 3 weeks, serum glucose, testosterone and nitric oxide (NO); sperm parameters; testicular histology and total antioxidant capacity (TAC) were evaluated. In diabetic rats treated with T. pratense extract, sperm motility, count and viability, as well as TAC and testosterone were increased significantly compared to untreated diabetic rats, while serum NO and bcl-2 and p53 expression was decreased significantly compared to untreated diabetic rats. T. pratense extract reduced testicular tissue destruction caused by diabetes.

Edible Flowers Extracts as a Source of Bioactive Compounds with Antioxidant Properties—In Vitro Studies

Edible plants began to play an important role in past decade as a part of therapy, a recovery process or a healthy life style. The availability and relatively low price of the raw material, as well as proven bioactive health benefits, are key to consumers’ choice of nutrients. The red clover (Trifolium pratense) is a popular plant with healthy properties such as antiseptic and analgesic effects. The less known white clover (Trifolium repens), a fodder and honey plant, has anti-rheumatic and anti-diabetic properties. Both species may serve as a potential source of bioactive substances with antioxidant properties as a food additive or supplement. The study material consisted of flower extracts of Trifolium repens and Trifolium pratense. The total content of polyphenols and DPPH (2.2-diphenyl-1-picrylhydrazyl) and ferric reducing antioxidant power (FRAP) were measured using spectrophotometry methods. Oxidative stress in THP1 cells was induced via sodium fluoride. Subsequently, flower extracts were added and their influences on proliferation, antioxidant potential and the activity of antioxidant enzymes were evaluated. The extracts have a high total content of polyphenols as well as high antioxidant potential. We also demonstrated positive extracts impact on cells proliferation, high antioxidant potential and increasing activity of antioxidant enzymes on cell cultures under high oxidative stress induced by fluoride. Both red clover and the less known white clover may serve as valuable sources of antioxidants in the everyday diet.

Contribution of Individual Polyphenols to Antioxidant Activity of Cotoneaster bullatus and Cotoneaster zabelii Leaves-Structural Relationships, Synergy Effects and Application for Quality Control

Cotoneaster plants are sources of traditional medicines and dietary products, with health benefits resulting from their phenolic contents and antioxidant activity. In this work, active markers of the leaves of C. bullatus and C. zabelii were characterized and evaluated in an integrated phytochemical and biological activity study. Based on UHPLC-PDA-ESI-MS³ analysis, twelve analytes were preselected from the constituents of the hydromethanolic leaf extracts, and two of them—caffeoylmalic acid and quercetin 3--O-β-d-(2″--O-β-d-xylopyranosyl)galactopyranoside (QPH)—were isolated for full identification (NMR spectroscopy: ¹H, ¹³C, COSY, HMBC, HMQC). All selected phenolics contributed to the antioxidant activity of the extracts, which was demonstrated in chemical in vitro tests (DPPH, FRAP, and TBARS) and in a biological model of human plasma exposed to oxidative/nitrative stress induced by peroxynitrite. This contribution was partly due to the synergy between individual polyphenols, evidenced by an isobolographic analysis of the interactions of (–)-epicatechin, chlorogenic acid, and QPH as representatives of three classes of Cotoneaster polyphenols. All twelve markers, including also neochlorogenic acid, cryptochlorogenic acid, procyanidin B2, procyanidin C1, rutin, hyperoside, isoquercitrin, and quercitrin, were thus applied as calibration standards, and a fast, accurate, reproducible, and fully validated RP-HPLC-PDA method for quality control and standardization of the target extracts was proposed.

Chemical Composition and Antioxidant Activity of Steam-Distilled Essential Oil and Glycosidically Bound Volatiles from Maclura Tricuspidata Fruit

Essential oil obtained from Maclura triscuspidata fruit has been reported to have functional properties. This study aimed at determining chemical compositions and antioxidant activities of steam-distilled essential oil (SDEO) and glycosidically bound aglycone fraction (GBAF) isolated from fully ripe M. triscuspidata fruit. SDEO was isolated by simultaneous steam distillation and extraction (SDE). GBAF was prepared by Amberlite XAD-2 adsorption of methanol extract, followed by methanol elution and enzymatic hydrolysis. Both fractions were analyzed by gas chromatography–mass spectrometry (GC–MS). A total of 76 constituents were identified from both oils. Apart from fatty acids and their esters, the SDEO contained p-cresol in the highest concentration (383.5 ± 17.7), followed by δ-cadinene (147.7 ± 7.7), β-caryophyllene (145.7 ± 10.5), β-ionone (141.0 ± 4.5), n-nonanal (140.3 ± 20.5), theaspirane A (121.3 ± 4.5) and theaspirane B (99.67 ± 9.05 µg/g). Thirteen carotenoid-derived compounds identified in the SDEO are being isolated from M. triscuspidata fruit for the first time. Out of the 22 components identified in GBAF, 14 were present only in the glycosidically bound volatiles. Antioxidant activity of the GBAF was higher than that of SDEO. These results suggest that glycosidically bound volatiles of M. triscuspidata fruit have a good potential as natural antioxidants.

Phenolic Content and Antioxidant Activity in Trifolium Germplasm from Different Environments

Phenolics are important mediators in plant-environment interactions. The presence and concentration of phenolic compounds and their antioxidant activity were evaluated in leaves and flowers of a set of Trifolium species originating from contrasting environments encompassing lowland and mountain sites. The current germplasm proved a great reservoir of phenolic compounds, with different chemical structure and, possibly, diversified biological activity. Germplasm groups with specific phenolic composition were observed. In some cases, different patterns bore a taxonomic meaning. Lowland germplasm showed higher concentration of total phenolics in leaves than mountain accessions (50.30 vs. 34.19 mg/g dry matter (DM)), while the latter had higher concentration in flowers (114.16 vs. 57.44 mg/g DM). Outstanding concentration of isoflavones was observed in leaves of lowland germplasm (24.19 mg/g DM), and of both proanthocyanidins and flavonoids in flowers of mountain germplasm (53.81 and 56.62 mg/g DM, respectively). The pattern of phenolic composition in lowland and mountain germplasm was suggestive of different adaptive strategies. Three assays of antioxidant activity were tested, which were characterised by rather different reactivity towards phenolic composition. The scavenging activity was higher for leaf extracts of lowland germplasm, and for flower extracts of mountain germplasm. Besides identifying germplasm of interest, this study also suggested possible links between environmental factors and concentration and composition of phenolic compounds.

Therapeutic Potential of Temperate Forage Legumes: A Review

The discovery of bioactive molecules from botanical sources is an expanding field, preferentially oriented to plants having a tradition of use in medicine and providing high yields and availability. Temperate forage legumes are Fabaceae species that include worldwide-important crops. These plants possess therapeutic virtues that have not only been used in veterinary and folk medicine, but have also attracted the interest of official medicine. We have examined here Medicago sativa (alfalfa), Trifolium pratense and T. repens (clovers), Melilotus albus and M. officinalis (sweet clovers), Lotus corniculatus (birdsfoot trefoil), Onobrychis viciifolia (sainfoin), Lespedeza capitata (roundhead lespedeza), and Galega officinalis (goat's rue). The phytochemical complexes of these species contain secondary metabolites whose pharmacological potentials deserve investigation. Major classes of compounds include alkaloids and amines, cyanogenic glycosides, flavonoids, coumarins, condensed tannins, and saponins. Some of these phytochemicals have been related to antihypercholesterolemia, antidiabetic, antimenopause, anti-inflammatory, antiedema, anthelmintic, and kidney protective effects. Two widely prescribed drugs have been developed starting from temperate forage legumes, namely, the antithrombotic warfarin, inspired from sweet clover's coumarin, and the antidiabetic metformin, a derivative of sainfoin's guanidine. Available evidence suggests that temperate forage legumes are a potentially important resource for the extraction of active principles to be used as nutraceuticals and pharmaceuticals.

Phenolic Content and DPPH Radical Scavenging Activity of the Flowers and Leaves of Trifolium repens

In order to facilitate the quality control of Trifolium repens flowers and leaves, a RP-HPLC method with UV detection was developed for the simultaneous quantitative determination of flavonols and isoflavones. The total flavonoid and phenolic (TPC) contents were determined spectrophotometrically in a visible part of the light spectrum at 425 and 760 nm, respectively. Additionally, evaluation of the antioxidant properties of the plant materials was performed using the DPPH in vitro test. The results showed that the flowers are the richest source of phenolics ranging from 28.7 to 38.8 mg GAE/g, and flavonoids, calculated for hyperoside, up to 20 mg HP/g, which hydrolyzed mainly to flavonols (the quercetin level greater than 6 mg/g). T. repens is poor in isoflavones; similar quantities of ca. 0.2 mg/g were detected in the flowers and leaves. The flower and leaf extracts showed antioxidant activity towards DPPH with EC50 values ranging from 72.3 to 179.3 μg/mL. Significant linear correlations were found between antioxidant potentials of the studied plant materials and total phenolic and flavonoid contents determined by HPLC and spectrophotometric methods ( R2 in the range of 0.97 - 0.99).