Advances in isoflavone profile characterisation using matrix solid-phase dispersion coupled to HPLC/DAD in Medicago species

Determination of Medicago orbicularis Antioxidant, Antihemolytic, and Anti-Cancerous Activities and Its Augmentation of Cisplatin-Induced Cytotoxicity in A549 Lung Cancer Cells

The anti-lung cancer properties of the plant Medicago orbicularis have not been explored yet. Therefore, we identified its phytochemical composition and investigated the antioxidant, anti-hemolytic, and anti-cancerous properties of extracts of this plant in A549 human lung adenocarcinoma cells. The results show that all parts of M. orbicularis (stems, leaves, and fruits) exhibit remarkable hemolytic activities and modest antioxidant capacity. In addition, all extracts showed a dose-dependent anti-cancerous cytotoxic activity against A549 cells, with fruit extracts being the most potent. This cytotoxic effect could be related, at least partly, to the induction of apoptosis, where M. orbicularis fruit extracts reduced the ratio of anti-apoptotic BCL-2/pro-apoptotic BAX, thereby promoting cellular death. Furthermore, the use of M. orbicularis, in combination with a conventional chemotherapeutic agent, cisplatin, was assessed. Indeed, the combination of cisplatin and M. orbicularis fruit extracts was more cytotoxic and induced more aggregation of A549 cells than either treatment alone. GC-MS analysis and total polyphenol and flavonoid content determination indicated that M. orbicularis is rich in compounds that have anti-cancerous effects. We propose M. orbicularis as a potential source of anti-cancerous agents to manage the progression of lung cancer and its resistance to therapy.

Influence of climate variation on phenolic composition and antioxidant capacity of Medicago minima populations

Medicago minima is a pasture legume that grows almost all over the world. In Tunisia, it occupies various climatic environments and is considered the most abundant annual Medicago plant. However, this species is unconsumed and unused by humans. This study aimed to explore the phytochemical characteristics of Medicago minima selected from different provenances in Tunisia and subsequently investigate the influence of environmental factors on their phenolic composition and antioxidant activity. Therefore, a calorimetric method and DPPH tests provided the total phenolic and total flavonoid contents and antioxidant potential in roots, stems, leaves and seeds. High performance liquid chromatography (HPLC) identified and quantified four phenolic acids and three flavonoids in the studied organs. Roots and leaves showed the greatest phenolic compound content and had high antioxidant activity. Rutin and syringic acid (leaves) represent a characteristic for this species. For each organ, principal component analysis of phenolic profiles showed that the root’s phenolic composition could be an indication of the plant adaptation to even small changes in its environments. Plants originating from a cold climate, higher altitude or semi-arid environment had the highest phenolic compound contents in their organs. Our findings provide useful information for the exploitation of the phenolic compounds in these weeds for the development of environmental sustainability.

Mineral and Phytochemical Profiles and Antioxidant Activity of Herbal Material from Two Temperate Astragalus Species

Only a few species of the large Astragalus genus, widely used for medicinal purposes, have been thoroughly studied for phytochemical composition. The aim of our research was to investigate the rarely studied species A. glycyphyllos L. and A. cicer L. for the distribution of mineral elements and phytochemicals in whole plants at two growth stages and in morphological fractions. We also investigated the capacity of the plant extracts to scavenge 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals and to chelate ferrous ions. Chemical composition and antioxidant properties depended on species, maturity, and plant part. Herbal material of A. glycyphyllos was richer in Fe, total phenolics, and flavonoids, whereas extracts of A. cicer showed a higher antioxidant activity. Young plants had more isoflavones, showed greater quenching of DPPH radicals, and exhibited better mineral profiles than flowering plants. Among plant parts, leaves were the most valuable plant material according to most characteristics investigated. Isoflavone concentration in flowers was lower than in leaves and stems. None of the Astragalus samples contained detectable amounts of the alkaloid swainsonine. The study demonstrates the potential of plant material from two Astragalus species as a valuable source of iron, phenolic substances including isoflavones, free-radical scavengers, and Fe²⁺ chelators for pharmaceutical use.

One-Step Extraction and Hydrolysis of Flavonoid Glycosides in Rape Bee Pollen Based on Soxhlet-Assisted Matrix Solid Phase Dispersion

INTRODUCTION

Flavonoids are frequently found as glycosylated derivatives in plant materials. To determine contents of flavonoid aglycones in these matrices, procedures for the extraction and hydrolysis of flavonoid glycosides are required. The current sample preparation method is both labour and time consuming.

OBJECTIVE

Develop a modified matrix solid phase dispersion (MSPD) procedure as an alternative methodology for the one-step extraction and hydrolysis of flavonoid glycosides.

METHOD

HPLC-DAD was applied for demonstrating the one-step extraction and hydrolysis of flavonoids in rape bee pollen. The obtained contents of flavonoid aglycones (quercetin, kaempferol, isorhamnetin) were used for the optimisation and validation of the method.

RESULTS

The extraction and hydrolysis were accomplished in one step. The procedure completes in 2 h with silica gel as dispersant, a 1:2 ratio of sample to dispersant, and 60% aqueous ethanol with 0.3 M hydrochloric acid as the extraction solution. The relative standard deviations (RSDs) of repeatability were less than 5%, and the recoveries at two fortified levels were between 88.3 and 104.8%.

CONCLUSION

The proposed methodology is simple and highly efficient, with good repeatability and recovery. Compared with currently available methods, the present work has advantages of using less time and labour, higher extraction efficiency, and less consumption of the acid catalyst. This method may have applications for the one-step extraction and hydrolysis of bioactive compounds from plant materials. Copyright © 2017 John Wiley & Sons, Ltd.

Phytochemical profiling of underexploited Fabaceae species: Insights on the ontogenic and phylogenetic effects over isoflavone levels

There is an increasing trend towards finding alternative sources of valued phytochemicals due to their diverse potentialities in food industry and pharmaceutical applications. Phenolic compounds, in particular, have been the focus of several profiling reports, but isoflavones characterization has been studied in fewer cases and in a very limited group of plant species. Despite their acknowledged bioactivity, there's actually a strict number of plants validated for their isoflavones contents. In a previous report, we have identified nine Leguminosae species (from genera Biserrula, Lotus, Ornithopus and Scorpiurus) as potential alternative sources of these phenolic compounds. However, the isoflavone profiles are highly modulated by the ontogenic stage. Therefore, the present study was conducted in the same Leguminosae species, but harvested at three sequential vegetative development stages: vegetative elongation, late bud and late flowering, with the main purpose of assessing the evolution of isoflavones content throughout the plant development. In general, the plant species from Biserrula and Lotus genera showed the highest potential as new natural sources of isoflavones, especially owing their high levels of biochanin A. Independently of the plant species, it was possible to identify the phenologic stages where each of the quantified isoflavones is maximized. These findings are useful to predict isoflavone yields according to harvesting time, validating the potential use of the studied plants in innovative food formulations.

The isoflavone content of two new alfalfa-derived products for instant beverage preparation

The frequent use of plant-based products to promote health leads to the search for scientific information related to efficacy and safety of those products for human consumption. Two alfalfa-derived products (ADP), freeze-dried juice (FDJ) and dehydrated powder (DP), from alfalfa harvested in Mexico, are being developed as new possible nutraceuticals. To the best of our knowledge, any study reports the real composition of such products used to prepare instant beverages in what concerns isoflavone contents. Seven isoflavones (glycitein, formononetin, biochanin A, daidzein, genistein, daidzin and genistin) were assessed by HPLC-DAD analysis as well as its variation in five different batches of these products. Different solvents were tested in order to choose the best one to extract isoflavones. The results showed the presence of daidzein, genistein, genistin and daidzin in most samples while glycitein, formononetin and biochanin A were not detected. Significant differences between isoflavone contents were found with different solvent systems. Water was the best option to extract daidzein (0.40-1.08 mg per unit and 1.30-4.90 mg per unit for DP and FDJ, respectively) whereas the water-methanol-formic acid mixture was efficient to extract genistein (0.19-0.43 mg per unit and 0.15-0.72 mg per unit for DP and FDJ, respectively). In all cases, the total isoflavone content was higher in freeze-dried juices than in dehydrated powders. Genistein and daidzein were the more abundant isoflavones quantified. Further physiological and nutritional studies are needed to complete the validation of effectiveness and safety of these products.