Regulation Mechanism of Phenolic Hydroxyl Number on Self-Assembly and Interaction between Edible Dock Protein and Hydrophobic Flavonoids

In this study, galangin (Gal), kaempferol (Kae), quercetin (Que), and myricetin (Myr) were chosen as the representative flavonoids with different phenolic hydroxyl numbers in the B-ring. The edible dock protein (EDP) was chosen as the new plant protein. Based on this, the regulation mechanism of the phenolic hydroxyl number on the self-assembly behavior and molecular interaction between EDP and flavonoid components were investigated. Results indicated that the loading capacity order of flavonoids within the EDP nanomicelles was Myr (10.92%) > Que (9.56%) > Kae (6.63%) > Gal (5.55%). Moreover, this order was consistent with the order of the hydroxyl number in the flavonoid's B ring: Myr (3) > Que (2) > Kae (1) > Gal (0). The micro morphology exhibited that four flavonoid-EDP nanomicelles had a core-shell structure. In the meantime, the EDP encapsulation remarkably improved the flavonoids' water solubility, storage stability, and sustained release characteristics. During the interaction of EDP and flavonoids, the noncovalent interactions including van der Waals forces, hydrophobic interaction, and hydrogen bonding were the main binding forces. All of the results demonstrated that the hydroxyl number of bioactive compounds is a critical factor for developing a delivery system with high loading ability and stability.

Intestinal Flora Mediates Antiobesity Effect of Rutin in High-Fat-Diet Mice

SCOPE

Intestinal flora plays a critical role in the development of . Rutin is a natural flavonoid with potential prebiotic effects on regulating the intestinal flora composition that is beneficial for host health. Therefore, this study hypothesizes that rutin supplementation has beneficial effects on high-fat-diet (HFD)-induced obesity and metabolic disorder through the modulation of intestinal flora in mice.

METHODS AND RESULTS

The obesity-alleviating property of rutin using 6-week-old C57BL/6J male mice fed on HFD with or without rutin supplementation for 16 weeks is investigated. Rutin supplementation effectively reduces body-weight gain, insulin resistance, and acted favorably on the intestinal barrier, thereby reducing endotoxemia and systemic inflammation. Sequencing of 16S rRNA genes from fecal samples indicate that rutin exerted modulatory effects on HFD-induced intestinal flora disorders (e.g., rutin decreased Firmicutes abundance and increased Bacteroidetes and Verrucomicrobia abundance). Antibiotic treatment and fecal microbiota transplantation further demonstrate that the salutary effects of rutin on obesity control are strongly dependent on the intestinal flora.

CONCLUSION

Rutin can be considered as a prebiotic agent for improving intestinal flora disorders and obesity-associated metabolic perturbations in obese individuals.

[Determination of flavonoids in honey by solid phase extraction coupled with ultra-performance liquid chromatography-tandem mass spectrometry method]

OBJECTIVE

To establish a method for simultaneous determination of 20 flavonoid compounds from honey samples using solid phase extraction coupled with ultra-performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS), which was applied to study the difference of flavonoid compounds in honey samples from different botanical origins.

METHODS

The honey samples were extracted with ultra-water solution by ultrasound, and purified with an Oasis MAX column, and then separated on a Waters ACQUITY UPLC HSS T3(2. 1 mm×100 mm, 1. 8 μm) and eluted with the mobile phase consisted of 0. 1% formic acid in water and acetonitrile in a gradient program, and analyzed by mass spectrometry equipped with an electrospray ionization source, operating in the positive or negative ionization modes, and performed in the multiple reaction monitoring using external standards.

RESULTS

Twenty flavonoid compounds showed good linearity with coefficients higher than 0. 9969; The recoveries of spiked honey samples in the range of 76. 2%-108. 6% at the concentrations of 100, 250 and 500 μg/L; The relative standard deviations were 0. 50%-4. 34% and 2. 51%-6. 71%(n=6)for inter-day and intra-day precisions, respectively. It was found that the variations of flavonoid compounds in 16 types of honey samples from different botanical origins differed largely. Among them, quercetrin content in fennel honey was the highest(165 ng/g). High contents of luteolin in red eucalyptus and manuka honey were 186 ng/g and 304 ng/g, respectively. High contents of kaempferol in buckwheat, fennel and manuka honeys were from 113 to 257 ng/g. High contents of chrysin in snow lotus honey, manuka, sunflower honey and lavender Honey were from 136 to 213 ng/g. The content of pinocembrin(473 ng/g) and pinobanksin(684 ng/g) in manuka honey were much higher than that in other honeys.

CONCLUSION

The proposed method is simple for pretreatment, also sensitive, accurate and producible for quantitative of 20 flavonoid compounds in different honey samples, which provide more scientific data and application basis for quality analysis.

Glucosidase inhibitory activity and antioxidant activity of flavonoid compound and triterpenoid compound from Agrimonia Pilosa Ledeb

BACKGROUND

In Chinese traditional medicine, Agrimonia pilosa Ledeb (APL) exhibits great effect on treatment of type 2 diabetes mellitus (T2DM), however its mechanism is still unknown. Considering that T2DM are correlated with postprandial hyperglycemia and oxidative stress, we investigated the α-glucosidase inhibitory activity and the antioxidant activity of flavonoid compound (FC) and triterpenoid compound (TC) from APL.

METHODS

Entire plants of APL were extracted using 95% ethanol and 50% ethanol successively. The resulting extracts were partitioned and isolated by applying liquid chromatography using silica gel column and Sephadex LH 20 column to give FC and TC. The content of total flavonoids in FC and the content of total triterpenoids in TC were determined by using UV spectrophotometry. HPLC analysis was used to identify and quantify the monomeric compound in FC and TC. The α-glucosidase inhibitory activities were determined using the chromogenic method with p-nitrophenyl-α-D-glucopyranoside as substrate. Antioxidant activities were assessed through three kinds of radical scavenging assays (DPPH radical, ABTS radical and hydroxyl radical) & β-carotene-linoleic acid assay.

RESULTS

The results indicate FC is abundant of quercitrin, and hyperoside, and TC is abundant of 1β, 2β, 3β, 19α-tetrahydroxy-12-en-28-oic acid (265.2 mg/g) and corosolic acid (100.9 mg/g). The FC & the TC have strong α-glucosidase inhibitory activities with IC50 of 8.72 μg/mL and 3.67 μg/mL, respectively. We find that FC show competitive inhibition against α-glucosidase, while the TC exhibits noncompetitive inhibition. Furthermore, The FC exhibits significant radical scavenging activity with the EC50 values of 7.73 μg/mL, 3.64 μg/mL and 5.90 μg/mL on DPPH radical, hydroxyl radical and ABTS radical, respectively. The FC also shows moderate anti-lipid peroxidation activity with the IC50 values of 41.77 μg/mL on inhibiting β-carotene bleaching.

CONCLUSION

These results imply that the FC and the TC could be responsible for the good clinical effects of APL on T2MD through targeting oxidative stress and postprandial hyperglycaemia. So APL may be good sources of natural antioxidants and α-glucosidase inhibitors exhibiting remarkable potential value for the therapy of T2DM.