Effect and Mechanism of Elaeagnus angustifolia Flower and Its Major Flavonoid Tiliroside on Inhibiting Non-enzymatic Glycosylation

Abstract

This study aimed to evaluate the antiglycation ability of Elaeagnus angustifolia flower extract and to elucidate the mechanism with its major compound. The results indicated that E. angustifolia flower extract and its major compound tiliroside (24.2 mg/g of extract) exhibited excellent antiglycation ability with inhibition rates of 92.1 and 78.9% at 37.5 μg/mL, which are much higher than that of aminoguanidine (55.3% at 37.5 μg/mL). The stable tiliroside–ovalbumin (OVA) complexes were formed through a spontaneous exothermic progress in an equimolar manner, and hydrophobic interaction, hydrogen bond, and van der Waals forces were the major driving forces. Tiliroside could significantly ameliorate the conformation changes of OVA induced by the glycation reaction, quench its fluorescence by a static mechanism, and change the microenvironment adjacent to tryptophan and tyrosine. Molecular docking revealed that tiliroside inserted into the OVA hydrophobic pocket resulted in the formation of five hydrogen bonds. Orbitrap tandem mass spectrometry showed that tiliroside significantly suppressed the glycation of OVA, and the number of glycation sites was reduced from 9 to 5 after tiliroside was added. The above results indicated that E. angustifolia flowers and tiliroside have a good antiglycation effect and can be used as food additives to suppress the undesired glycation reaction during food processing.

Influence of Hydroxyl Substitution on the Suppression of Flavonol in Harmful Glycation Product Formation and the Inhibition Mechanism Revealed by Spectroscopy and Mass Spectrometry

“…In total, 12 glycated sites were mapped, and the exact position is shown in Figure ; all glycation sites are located on the outer surface of OVA because these are more liable to contact with fructose. Sites Lys61, Lys92, Lys122, Arg126, Lys181, Lys186, Lys189, Lys206, and Lys226 have previously been mapped in glycated OVA. , Except for Lys16 and Lys122, all glycated sites were located on the β-sheet and random coil structures.…”

“…The formation of initial glycation products and fluorescent AGEs is usually used to reflect the initial and advanced stages of protein glycosylation, respectively, which can be determined through the UV absorbance at 294 nm and fluorescence intensity at Ex 370 nm and Em 440 nm. , As shown in Figure A, Que, Kaem, Irh, and Myri significantly reduced the absorbance of G-OVA at 294 nm and exhibited an obvious dose-dependent relationship. At a concentration of 36.58 μM, Que presented the lowest absorbance with a value of 0.233, followed by Myri (0.255), while Irh gave the highest UV absorbance at 294 nm (0.521).…”

“…Influence of Que, Myri, Kaem, and Irh on the synchronous fluorescence spectra of N-OVA is shown in Figure . Spectra recorded with Δλ at 15 and 60 nm reflect the microenvironment alterations in the vicinity of aromatic amino acids tyrosine (Tyr) and tryptophan (Trp) residues individually, and the maximum excitation wavelength of protein will exhibit a blue or red shift when the polarity in the vicinity of the fluorophore is reduced or increased . The fluorescence intensities of N-OVA were reduced gradually with increasing flavonol concentrations, and the maximum fluorescence intensity was reduced from 1102–1365 to 619–829 for Tyr and from 5762–7608 to 2832–4056 for Trp when 22.8 μM flavonol was added.…”

Volatile Compounds from Flowers of Elaeagnus x submacrophylla Servett.: Extraction, Identification of Flavonoids, and Antioxidant Capacity

“…138, can be potentially proposed as kaempferol-O-p-coumaroylhexose, tiliroside isomers or derivatives, tiliroside having already been identified in the flowers of E. angustifolia. [67] The acylation position and glycosidic linkage could however not be unambigously identified by UPLC-MS/MS although glycosylation and acylation usually occur respectively on the C3 and C7 of the aglycone, and on the C6 of the ose. [68,69] This first attempt in the identification of numerous flavonoids supports the promising antioxidant potential previously observed from the floral EE of E. submacrophylla.…”

A Study on the Volatile Compounds in Elaeagnus angustifolia L. Flowers during Flowering Season by Gas Chromatography-Mass Spectrometry Coupled with Advanced Chemometrics

“…E. angustifolia flowers are widely used as tea beverage in northwest zone of China [14]. It was reported that E. angustifolia flowers have anti-saccharification effect and can be used as a food additive to inhibit the undesirable saccharification reaction in food processing [15]. e essential oils of E. angustifolia flowers and leaves have been extracted and identified as preservatives in the food industry and natural pesticides in agriculture [7].…”