Screening and Evaluation of Novel α-Glucosidase Inhibitory Peptides from Ginkgo biloba Seed Cake Based on Molecular Docking Combined with Molecular Dynamics Simulation.

Food-derived α-glucosidase inhibitory peptides have gained significant interest in treating type 2 diabetes mellitus (T2DM) owing to their favorable safety profiles. Molecular docking combined with molecular dynamics simulation was performed to screen α-glucosidase inhibitory peptides from Ginkgo biloba seed cake (GBSC), and two novel peptides (Met-Pro-Gly-Pro-Pro (MPGPP) and Phe-Ala-Pro-Ser-Trp (FAPSW)) were acquired. The results of molecular docking and molecular dynamics simulation suggested that FAPSW and MPGPP could generate stable complexes with 3wy1, and the electrostatic and van der Waals forces played contributory roles in FAPSW and MPGPP binding to 3wy1. The α-glucosidase inhibition assay corroborated that FAPSW and MPGPP had good α-glucosidase inhibition capacity, with IC50 values of 445.34 ± 49.48 and 1025.68 ± 140.78 µM, respectively. In vitro simulated digestion results demonstrated that FAPSW and MPGPP strongly resisted digestion. These findings lay a theoretical foundation for FAPSW and MPGPP in treating T2DM.

A new insight into synergistic effects between endogenous phenolic compounds additive and α-tocopherol for the stability of olive oil.

Investigation of edible oil stability involves interactions between additive polyphenols and the inherent tocopherols. The work aimed to identify endogenous polyphenols to produce the synergistic effect with α-tocopherol in olive oil and to find the right action ratio. Caffeic acid and quercetin were selected from the 15 main endogenous phenolic compounds in olive oil. Quercetin had the strongest synergistic effect with α-tocopherol at 2:1 in the olive oil model. The rate of 2:1 also was the turning point of the change of synergism. Furthermore, the addition of quercetin and α-tocopherol at 2:1 to olive oil resulted in lower POV, K232, K270, and secondary oxidation products such as (E, E)-2,4-decadienal and 2-pentylfuran than the olive oil model with a single antioxidant in three months of accelerated oxidation. The dynamic changes of antioxidants during oxidation in olive oil indicated that their synergistic effect was the repair and regeneration of α-tocopherol by quercetin.

Inhibitory effect of Ginkgo biloba seeds peptides on methylglyoxal-induced glycations.

The aim of this study was to investigate the antiglycation activity and mechanism of two identified peptides, Valine-Valine-Phenylalanine-Proline-Glycine-Cysteine-Proline-Glutamic acid (VVFPGCPE) and Serine-Valine-Aspartic acid-Aspartic acid-Proline-Arginine-Threonine-Lysine (SVDDPRTL), from Ginkgo biloba seeds protein hydrolysates. Both VVFPGCPE and SVDDPRTL were efficient in bovine serum albumin (BSA)-methylglyoxal (MGO) model to inhibit BSA glycation, while VVFPGCPE showed higher antiglycation activity than SVDDPRTL. In antioxidant assays, VVFPGCPE scavenged more hydroxyl and super anion radicals, and chelated more Fe2+. Moreover, VVFPGCPE was more efficient in alleviating glycoxidation since it retained higher content of tryptophan and reduced dityrosine and kynurenine generation. Compared with SVDDPRTL, VVFPGCPE showed better performance in inhibiting protein aggregation and amyloid-like fibrillation formation. Therefore, VVFPGCPE was selected for further mechanism study. The circular dichroism analysis suggested VVFPGCPE could preserve α-helix structure and stabilize protein structure. The MGO trapping assay indicated VVFPGCPE (5 mg/mL) could capture 66.25% MGO within 24 h, and the mass spectrometry revealed VVFPGCPE could trap MGO by forming VVFPGCPE-mono-MGO adducts. Besides, molecular simulations suggested VVFPGCPE could interact with key glycation residues, arginine and lysine residues, of BSA mainly through van der Waals and hydrogen bonds. This study might supply a theoretical basis for the development of VVFPGCPE as an effective antiglycation agent.

Novel bioactive peptides from ginkgo biloba seed protein and evaluation of their α-glucosidase inhibition activity.

The inhibition of α-glucosidase activity has been recognized as an effective approach for treating type 2 diabetes mellitus (T2DM). In recent years, much emphasis has been placed on identifying peptides with α-glucosidase inhibitory activity and elucidating the mechanisms underlying their inhibitory effect in treating T2DM. This study aims to identify peptides with good α-glucosidase inhibitory activity from the hydrolysate of ginkgo biloba seed cake protein isolate (GCPI) using in silico screening. It was found that the hydrolysate from Alcalase exhibited the strongest inhibitory effect on α-glucosidase (IC50 12.94 ± 0.37 mg/mL). Three novel peptides with α-glucosidase inhibitory activity, i.e., Leu-Ser-Met-Ser-Phe-Pro-Pro-Phe (LSMSFPPF), Val-Pro-Lys-Ile-Pro-Pro-Pro (VPKIPPP) and Met-Pro-Gly-Pro-Pro-Ser-Asp (MPGPPSD), were further identified from the hydrolysate of Alcalase by in silico screening. LSMSFPPF exhibited the strongest inhibitory activity (IC50 454.33 ± 32.45 µM), followed by MPGPPSD (IC50 943.82 ± 73.10 µM) and VPKIPPP (IC50 1446.81 ± 66.98 µM). The pharmacophore model revealed that hydrogen bonds played a critical role in α-glucosidase inhibition.

Effect of geographical location and soil fertility on main phenolic compounds and fatty acids compositions of virgin olive oil from Leccino cultivar in China.

The aim of this study was to evaluate the effects of geographic location (i.e., latitude, longitude, altitude) and soil fertility (i.e., nitrogen, phosphorus) on main phenolic compounds and fatty acids in VOO nearby the Bailong River in Longnan city, a representative planting-region in China. The geographical distribution analysis showed that the sampling-points from the middle reaches of Bailong River had higher secondary metabolites, such as oleacein and oleocanthal. Correlation analysis revealed that the contents of ligustroside, vanillic acid and rutin were negatively correlated with altitude while the contents of heptadecenoic acid, oleic acid and eicosenoic were positively related to the altitude. Moreover, the excessive available nitrogen had an adverse effect on the content of phenolic compounds and fatty acids in virgin olive oil. It was helpful for the accumulation of phenolic compounds and fatty acids in virgin olive oil when the level of available nitrogen ranged from 51 to 100 mg/kg. These findings are helpful for the geographic-location selection and fertilization management of olive orchard.

Research advances in chemical modifications of starch for hydrophobicity and its applications: A review.

Starch has received research focus due to its low cost, excellent film-forming ability, bio-compatibility, extensive sources, renewability and biodegradability. However, native starch with relatively strong hydrophilicity greatly limits its application in industries. Therefore, in this paper, the recent research advances in chemical modifications of starch for hydrophobicity, e.g., esterification, etherification, crosslinking, grafting and condensing reaction etc., were discussed. The changes of hydrophobicity and other properties due to chemical modifications were described, as well. Different applications of modified starch with better hydrophobicity, i.e., packaging industries, Pickering emulsion and pharmaceutical, are presented, too. Finally, the future research and prospects on chemical modifications of starch for hydrophobicity and their applications are proposed.

Novel polysaccharide from Chaenomeles speciosa seeds: Structural characterization, α-amylase and α-glucosidase inhibitory activity evaluation.

Purification and structural characterization of a novel polysaccharide fraction from Chaenomeles speciosa seeds were investigated. After hot water extraction and ethanol precipitation, the crude polysaccharide was sequentially purified with Cellulose DEAE-52 and gel-filtration chromatography, and a highly purified polysaccharide fraction (F3) was obtained. The structure of F3 was characterized by high-performance gel permeation chromatography (HPGPC), high performance liquid chromatography (HPLC), ultraviolet-visible (UV), Fourier transform infrared (FT-IR) and nuclear magnetic resonance (NMR) spectrum, together with methylation, scanning electron microscopy (SEM), atomic force microscope (AFM), and Congo-red test analysis. The results indicated that F3 was a homogeneous polysaccharide fraction with a molecular weight of 8.65 × 106 Da, and it was composed of Rha, GlcA, Gal, and Ara in a molar ratio of 6.34:5.73:47.14:40.13. The backbone of F3 was consisted of →3,6)-Galp-(1→, and the side chains of F3 were composed of Araf-(1→, →4)-GlcpA-(1→, →4)-Galp-(1→ and →3)-Rhap-(1→. The hypoglycemic assays demonstrated F3 had good α-amylase and α-glucosidase inhibition activities, and their IC50 values were 6.24 mg/mL and 4.59 mg/mL respectively. Thus, the polysaccharide from Chaenomeles speciose could be applied as a potential natural source in retarding postprandial hyperglycemia effects.

Chinese quince seed proteins: sequential extraction processing and fraction characterization.

Chinese quince seed proteins were sequentially extracted based on the modified Osborne method. Investigations showed that albumin and glutelin were the major fractions. The physicochemical and functional properties of these two fractions were determined. The results showed that both albumin and glutelin posed appropriate essential amino acid composition and met the minimum recommendation (World Health Organization/Food and Agriculture Organization) for adult diet, except for methionine. The hydrophobicity of albumin and glutelin were 1063.56 and 1170.21, respectively. According to differential scanning calorimeter analysis, the denaturation temperature of albumin and glutelin was 101.44 °C and 108.36 °C respectively, and the glutelin fraction had a better thermal stability. The solubility and apparent viscosity of albumin and glutelin were presented to be greatly influenced by pH values. The water holding capacity and oil adsorption capacity of glutelin were 5.44 g/g and 8.15 g/g, higher than those of albumin which were 3.76 g/g and 3.71 g/g, respectively. Circular dichroism determination revealed albumin and glutelin were mainly composed by α-helix and random coil structures. Albumin and glutelin presented the potential as favorable nutrition and functional additive in food industries.

Physicochemical and functional properties of Chinese quince seed protein isolate.

Chinese quince seed protein isolate (CPI) was extracted using aqueous extraction and the isoelectric precipitation method, and its physicochemical and functional properties were investigated. Results showed that CPI contained all essential amino acids with exception of methionine which met the minimum recommendations for adults (World Health Organization/Food and Agriculture Organization). The electrophoresis analysis of sodium dodecyl sulphate polyacrylamide gel indicated that the molecular weights of protein fractions were approximately 15-60 kDa. Differential scanning calorimetry analysis was conducted, and the denaturation temperature of CPI was 103.4 °C. The surface hydrophobicity of CPI was found to be 932.80. The experiments showed that CPI had high emulsifying capacity, foaming stability, water holding capacity and oil adsorption capacity. Moreover, CPI also had outstanding gel formation capacity since its least gelation concentration of CPI was only 8%. All these results implied that CPI could be a nutritional protein resource and functional ingredient in the food industry.

Enhanced extraction of hydroxytyrosol, maslinic acid and oleanolic acid from olive pomace: Process parameters, kinetics and thermodynamics, and greenness assessment.

Three techniques of ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE) and solvent extraction (SE) were used for enhancing the hydroxytyrosol (HT), maslinic acid (MA) and oleanolic acid (OA) extraction from olive pomace, being evaluated and compared through process parameters, kinetics and thermodynamics, plus greenness assessment analysis. Results showed that UAE yielded the maximum compounds due to a strong cavitation effect and the strongest mass and heat transfer efficiency involving the kinetic constants (h, Ce and K) and thermodynamic parameters (△H, △S and △G). Additionally, the optimal extraction conditions were acquired: ethanol concentration of 90%, extraction temperature of 50 °C, extraction time of 5 min, liquid to solid ratio of 30 mL/g, ultrasound intensity of 135.6 W/cm2, and ultrasound frequency of 60 kHz. UAE was confirmed as an effective and greener technique with the lowest E factor, energy consumption and carbon emission during the extraction process of bioactive compounds from olive pomace.