Fagopyrins from Buckwheat Flowers: Structural and Stereochemical Characterization Through Combined NMR/CD Spectroscopy and Theoretical Calculations

Fagopyrins are phenantroperylenequinones present in the flowers of Fagopyrum esculentum (buckwheat) endowed with photodynamic activity. It has been reported that fagopyrin extracts actually contain a complex mixture of closely related compounds, differing only on the nature of the perylenequinone substituents. We report our systematic and detailed study on the chemical composition of fagopyrin extracts by a combination of preparative and analytical techniques. The combined use of 1H-NMR and CD spectroscopy was found to be particularly suited to fully characterize all stereochemical aspects of the extracted fagopyrins. For the first time nine isomers have been structurally characterized and their stereochemistry fully elucidated. The presence of two different heterocyclic ring substituents, two stereogenic centers and the inherent axial chirality of the aromatic system provides a complex stereochemical relationships among isomers, thus giving account of the high level of molecular multiplicity found in the extract.

Anticancer effects of rutin from Fagopyrum tataricum (tartary buckwheat) against osteosarcoma cell line

BACKGROUND

The present study is analysisof the seeds of buckwheat (Fagopyrum sp.),member of the Polygonaceae family for isolation of rutin and its anticancer property againstOsteosarcoma celllines (SAOS2). The selected plant is traditionally used for diabetes and cancer. It has several biological properties such as antibacterial, antioxidant and anti-aging.

PURPOSE

Thirty-five buckwheat cultivars were obtained from Nepal Agriculture Genetic Resources Centre (NAGRC) Khumaltar, Kathmandu, Nepal, and Kumrek Sikkim. These plant varieties are scientifically evaluated their biological properties.

METHODS

Rutin wasfractionated from buckwheat seeds using methanol fraction and analysed for quality by HPLC method. The rutin fraction of the cultivar NGRC03731 a tartary buck wheat and standard rutin was used against Osteosarcoma cell lines (SAOS2) and human gingival fibroblast cells (hGFs) for anticancer activity. The cell viability using rutin fraction and standard rutin treated with SAOS2 cells were assessed by MTT assay. For further research, the best doses (IC-50: 20 g/ml) were applied. By using AO/EtBr dual staining, the effects of Rutin fraction on SAOS2 cell death were analysed. The scratch wound healing assay was used to analyse cell migration. Real-time PCR was used to analyse the pro-/anti-apoptotic gene expression.

RESULTS

The seeds with the highest rutin content, NGRC03731 seeds, had 433 mg/100 g of rutin.The rutin fraction treatment and standard rutin significantly reduced cell viability in the MTT assay, and osteosarcoma cells were observed on sensitive to the IC-50 dose at a concentration of 20 g/ml after 24 h.The SAOS2 cells exposed to rutin fraction at 20 g/ml and standard rutin at 10 g/ml exhibited significant morphological alterations, cell shrinkage and decreased cell density, which indicate apoptotic cells.Rutin-fraction treated cells stained with acridine orange/ethidium bromide (AO/EtBr) dual staining cells turned yellow, orange, and red which indicatesto measure apoptosis.The anti-migration potential of rutin fraction, results prevented the migration of SAOS2 cancer cells.Rutin-fraction significantly increased the expression of pro-apoptotic proteinsBad, using real-time PCR analysis (mRNA for Bcl-2 family proteins) resulted Bcl-2's expression is negatively regulated.

CONCLUSION

Osteosarcoma (SAOS2) cell lines' proliferation, migration, and ability to proliferate were reduced markedly by rutin fraction and it also causes apoptosis of Osteosarcoma cell lines (SAOS2).

Fagopyrum tataricum (L.) Gaertn interacts with Gsk-3β/Nrf-2 signalling to protect neurotoxicity in a zebrafish model

ETHNOPHARMACOLOGICAL RELEVANCE

Fagopyrum tataricum (L.) Gaertn is used as a folk medicine in many Asian countries due to its anti-inflammatory, antioxidant, and several other health-promoting properties. It is also prescribed to improve neurocognitive functions and alleviate inflammatory conditions.

AIM OF THE STUDY

Oxidative stress and neuroinflammation plays a crucial role in neurodegenerative conditions. Hence, based on the ethnomedical claims and available literature, the present study investigated neuroprotective efficacy of a seed extract (ft-ext) of Fagopyrum tataricum against acrylamide (ACR)-induced neurotoxicity.

MATERIALS AND METHODS

The phytochemical characterization of ft-ext was performed by a high-performance liquid chromatography method. Molecular interactions of the identified compounds of ft-ext were studied using an in-silico docking tool. An in-vitro protein denaturation assay was done to check anti-inflammatory activity. The 5 days' post-fertilized zebrafish larvae were exposed to 1 mM and 2.5 mM ACR with or without ft-ext for 72 h to study its neuroprotective efficacy. Real-time polymerase chain reaction and western blotting studies were performed to analyse the oxidative stress-related gene and protein expressions respectively.

RESULTS

The extract showed the presence of chlorogenic acid, rutin, caffeic acid, vitexin, syringic acid, quercetin, p-coumaric acid, kaempferol, and ferulic acid. In-vitro protein denaturation assay of ft-ext showed a potent anti-inflammatory effect. The ft-ext improved ACR-mediated locomotor deficit and reduced overall mortality in the larvae. The brain lipid peroxidation and protein carbonylation results revealed an elevated level of oxidative stress in the ACR-treated group, which was reduced in ft-ext-treated larvae. The extract treatment increased the expression of nrf2, gpx, and hmox1a, while simultaneously downregulated trxr2 levels in the brain of larvae exposed to ACR. The treatment also showed inactivation of Gsk-3β, thus maintaining a normal pool of Nrf2 and β-catenin. Molecular docking of identified compounds of ft-ext showed possible hydrogen and hydrophobic interactions with Gsk-3β.

CONCLUSION

The ft-ext prevents ACR-mediated neurotoxicity by suppressing Gsk-3β mediated oxidative stress.

Changes in Cooking Characteristics, Structural Properties and Bioactive Components of Wheat Flour Noodles Partially Substituted with Whole-Grain Hulled Tartary Buckwheat Flour

The whole-grain, hulled Tartary buckwheat flour (HTBF) with outstanding bioactive functions was prepared, and the effects of partial substitution ratios (0, 30%, 51% and 70%) of wheat flour with HTBF on the characteristics of TB noodles (TBNs) were investigated, mainly including the cooking characteristics, sensory analysis, internal structure, bioactive components, and in vitro starch digestibility. With an increasing replacement level of HTBF, the water absorption index of the noodles decreased, whereas the cooking loss increased. A sensory analysis indicated that there were no off-flavors in all TBN samples. The scanning electron microscope images presented that the wheat noodles, 30% TBNs and 70% TBNs had dense and uniform cross sections. Meanwhile, the deepest color, V-type complexes, and lowest crystallinity (13.26%) could be observed in the 70% TBNs. A HTBF substitution increased the rutin content and the total phenolic and flavonoid contents in the TBNs, and higher values were found in the 70% TBNs. Furthermore, the lowest rapidly digestible starch content (16%) and highest resistant starch content (66%) were obtained in the 70% TBNs. Results demonstrated that HTBF could be successfully applied to make TBNs, and a 70% substitution level was suggested. This study provides consumers with a good option in the realm of special noodle-type products.

Comparative proteomic analyses of Tartary buckwheat (Fagopyrum tataricum) seeds at three stages of development

Tartary buckwheat is among the valuable crops, utilized as both food and Chinese herbal medicine. To uncover the accumulation dynamics of the main nutrients and their regulatory mechanism of Tartary buckwheat seeds, microscopic observations and nutrient analysis were conducted which suggested that starch, proteins as well as flavonoid gradually accumulated among seed development. Comparative proteomic analysis of rice Tartary buckwheat at three different developmental stages was performed. A total of 78 protein spots showed differential expression with 74 of them being successfully identified by MALDI-TOF/TOF MS. Among them, granule bound starch synthase (GBSS1) might be the critical enzyme that determines starch biosynthesis, while 11 S seed storage protein and vicilin seemed to be the main globulin and affect seed storage protein accumulation in Tartary buckwheat seeds. Two enzymes, flavanone 3-hydroxylase (F3H) and anthocyanidin reductase (ANR), involved in the flavonoid biosynthesis pathway were identified. Further analysis on the expression profiles of flavonoid biosynthetic genes revealed that F3H might be the key enzyme that promote flavonoid accumulation. This study provides insights into the mechanism of nutrition accumulation at the protein level in Tartary buckwheat seeds and may facilitate in the breeding and enhancement of Tartary buckwheat germplasm.

Effect of different superfine grinding technologies on the physicochemical and antioxidant properties of tartary buckwheat bran powder

The effect of shear crushing, airflow comminution, and wet grinding on the physical and chemical properties of Tartary buckwheat bran (TBB) powder was compared. Superfine grinding significantly reduces the particle size of bran (1.644 μm), while increasing the protein content (23.60%), water-holding capacity (4.38 g g^-1), solubility (21.077 g 100 g^-1), bulk density (0.34 g mL^-1), and tap density (0.53 g mL^-1) providing good processing characteristics. The antioxidant properties of bran powder prepared by the three methods mentioned above were compared. The results showed that different bran powders subjected to superfine grinding displayed varying levels of antioxidant capacity. The quercetin content (2.18 g 100 g^-1) of the wet-grinding bran powder (WGBP) was twice that of the control group, while no rutin was detected. The total flavonoid content (TFC) and total phenolic content (TPC) were significantly different from those of other groups. The DPPH, ˙OH, and ABTS⁺ removal rates were 60.74%, 86.62%, and 92.98%, respectively, while that of ˙OH was significantly higher than in the other treatment groups. The control group, shear crushed, and airflow comminution bran exhibited no significant differences in TFC, TPC, and oxidation resistance, except for the ability to remove ˙OH. TBB powder obtained via superfine grinding displayed superior taste and functional characteristics, providing a theoretical reference for the processing of this bran.

Bioactive compounds, health benefits, and industrial applications of Tartary buckwheat (Fagopyrum tataricum)

Tartary buckwheat belongs to the family Polygonaceae, which is a traditionally edible and medicinal plant. Due to its various bioactive compounds, the consumption of Tartary buckwheat is correlated to a wide range of health benefits, and increasing attention has been paid to its potential as a functional food. This review summarizes the main bioactive compounds and important bioactivities and health benefits of Tartary buckwheat, emphasizing its protective effects on metabolic diseases and relevant molecular mechanisms. Tartary buckwheat contains a wide range of bioactive compounds, such as flavonoids, phenolic acids, triterpenoids, phenylpropanoid glycosides, bioactive polysaccharides, and bioactive proteins and peptides, as well as D-chiro-inositol and its derivatives. Consumption of Tartary buckwheat and Tartary buckwheat-enriched products is linked to multiple health benefits, e.g., antioxidant, anti-inflammatory, antihyperlipidemic, anticancer, antidiabetic, antiobesity, antihypertensive, and hepatoprotective activities. Especially, clinical studies indicate that Tartary buckwheat exhibits remarkable antidiabetic activities. Various tartary buckwheat -based foods presenting major health benefits as fat and blood glucose-lowering agents have been commercialized. Additionally, to address the safety concerns, i.e., allergic reactions, heavy metal and mycotoxin contaminations, the quality control standards for Tartary buckwheat and its products should be drafted and completed in the future.

Treasure from garden: Bioactive compounds of buckwheat

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An extensive review on diverse bioactive components of buckwheat.

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Versatile beneficial phytochemicals are abundant in buckwheat.

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Buckwheat has a wide range of pharmacological and beneficial health effects.

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Huge research scope on Fagopyrum cymosum to identify the beneficial phytochemicals.

Buckwheat is a gluten-free crop under the family Polygonaceae abundant with beneficial phytochemicals that provide significant health benefits. It is cultivated and adapted in diverse ecological zones all over the world. Recently its popularity is expanding as a nutrient-rich healthy food with low-calories. The bioactive compounds in buckwheat are flavonoids (i.e., rutin, quercetin, orientin, isoorientin, vitexin, and isovitexin), fatty acids, polysaccharides, proteins, and amino acids, iminosugars, dietary fiber, fagopyrins, resistant starch, vitamins, and minerals. Buckwheat possesses high nutritional value due to these bioactive compounds. Additionally, several essential bioactive factors that have long been gaining interest because these compounds are beneficial for healing and preventing several human diseases. The present review demonstrates an overview of the recent researches regarding buckwheat phytochemicals and particularly focusing on the distinct function of bioactive components with their health benefits.