Fraction F1 Research Articles

Anti-Inflammatory, Fibrinolytic and Anti-Oxidant Activities of the N-Hexane Extract of Ficus sur Forssk (Moraceae) Leaves

This study investigates the anti-inflammatory, fibrinolytic and anti-oxidant activities of the n-hexane extract and fractions of Ficus sur Forssk leaves. The extract was separated on column chromatography using a gradient elution of hexane, dichloromethane and ethanol. Pooled column fractions were assayed for membrane stabilizing for anti-inflammatory, Streptokinase inhibition for fibrinolytic and 2, 2-diphenyl-1-picrylhydrazyl (DPPH) reduction for anti-oxidant activity. Column fractions were pooled into five fractions (F1 – F5). The n-hexane crude extract and the fraction F3 consistently exhibited anti-inflammatory and fibrinolytic ability. The leaf extract of F. sur showed negligible anti-oxidant activity. Except for F1 all the fractions and the crude extract showed very high dose-dependent anti-inflammatory property even significantly higher (p <0.05) than the reference drug – diclofenac. Crude extract, F2 and F3 exhibited fibrinolytic ability. F1 showed the lowest assayed biological activity consistently. The study shows that the column fractions of n-hexane extract of F. sur leaves have fibrinolytic and anti-inflammatory activity and can be used in the management of thrombosis and inflammation.

Comparative study on the characteristics and environmental risk of potentially toxic elements in biochar obtained via pyrolysis of swine manure at lab and pilot scales

Pyrolysis is considered as a promising method to immobilize potentially toxic elements (PTEs) in animal manures. However, comparative study on characteristics and environmental risk of PTEs in biochar obtained by pyrolysis of animal manure at different reactors are lacking. In this study, swine manure was pyrolyzed at 300–600 °C in a lab-scale or pilot-scale reactor with the aim to investigate their effects on characteristics and environmental risk of As, Cd, Cu, Ni, Pb, and Zn in swine manure biochar. Results showed that biochars produced from pilot scale had lower pH and carbon (C) content but higher oxygen (O) content than those from lab scale. Biochars from pilot scale had higher total PTEs (except Cd) concentrations and releasable PTEs (except Pb) but lower CaCl2-extractable PTEs and phytotoxicity germination index (GI) to radish seedings than those from lab scale. Chemical speciation analysis indicated that PTEs in biochar produced from pilot-scale fast pyrolysis at 400 °C had higher percentage of more stable fraction (F5 fraction) and lower potential ecological risk index (RI) than those from lab-scale slow pyrolysis. These findings demonstrated that bioavailability and potential ecological risk of PTE in swine manure biochar were greatly decrease in the pilot-scale pyrolysis reactor and the optimum temperature was 400 °C considering the lowest potential ecological risk index.

Does Soil Drying in a Lab Affect Arsenic Speciation in Strongly Contaminated Soils?

This study examined the changes in extractability and fractionation of arsenic (As) that can be caused by the drying of strongly polluted anoxic soil samples. Two untreated and manure-amended soils were incubated for 7 and 21 days in flooded conditions. Thereafter, As water- and 1 M NH4NO3-extractability and As fractionation in a 5-step sequential extraction according to Wenzel were examined in fresh, oven-dried and air-dried samples. Soil treatment with manure considerably affected the results of the sequential extraction. Air-drying caused a significant decrease in As extractability with 1 M NH4NO3 and in As concentrations in the F1 fraction. The highest reduction of extractability (30–41%) was found in manure-treated soils. Oven-drying resulted in a smaller reduction (5–34%) of As extractability. These effects were explained by opposing processes of As mobilization and immobilization. Sequential extraction did not allow for balancing As redistribution due to drying, as As loss from the F1 fraction was smaller than the confidence intervals in the other fractions. The results showed that for the precise determination of As extractability in anoxic soils, fresh samples should be analyzed. However, oven-dried samples may be used for a rough assessment of environmental risk, As the order of magnitude of easily soluble As did not change due to drying.

Process development of cholesterol removed Pacific white shrimp lipid enriched with astaxanthin using silica column

This study used silica column to eliminate cholesterol and to fractionate astaxanthin for production of cholesterol free shrimp lipid rich in astaxanthin. Polar fraction was loaded onto silica gel column and eluted using hexane/ acetone mixture with different ratios consecutively. The first fraction (F1) was obtained after elution with hexane. For fraction 2 and 3 (F2, F3), hexane/ acetone mixture (98: 2) and (96: 4) were used, respectively. Both fractions were rich in cholesterol, while F4 eluted with hexane/ acetone mixture (94: 6) consisted of pigments and fatty acid conjugates. Astaxanthin was found in F5, where hexane/ acetone mixture (98:2) was used for elution and it constituted 30% of total components. Cholesterol containing fractions (F2 and F3) accounting for 26% were removed and other fractions were combined with non-polar lipid. Fraction F5 was further injected into HPLC to separate astaxanthin peak from other compounds. The collected astaxanthin containing peak had 87% purity. LCMS result showed the presence of wax esters along with cholesterol in F2 and F3 and fatty acid conjugates along with astaxanthin were found in F5. Lowered cholesterol fraction had negligible wax esters. Overall, the developed method could be used for production of cholesterol removed shrimp oil.

Liquid Chromatography-Mass Spectrometry Characterized Hydrolysate Fractions Possess Anticancer Activity In Vitro

To find new plant-derived antitumor drugs, hydrolysate and fractions of poplar were analyzed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay for their inhibitory effect against liver cancer HepG-2 cells. Strong cytotoxicity of hydrolysate was revealed at processing temperature of 180 °C or above. The hydrolysate formed at 180 °C was sequentially extracted using organic solvent to obtain five fractions, and only the diethyl ether-soluble fraction (FDe) showed specific cytotoxicity. The eluted fraction of acetone/n-hexane (F1) was further isolated by column chromatography separation from the FDe fraction at a yield of 70%, and could severely decrease cell viability. LC-MS chromatography indicated that 5-hydroxymethyl furfural, ρ-hydroxybenzoic acid and syringaldehyde were the main compounds in the F1 fraction. Furthermore, the results of flow cytometry, Western blotting, and polymerase chain reaction indicated that syringaldehyde could tightly control the growth and metabolism of HepG-2 cells. The findings could move forward the value-added applications of lignocellulosic hydrolysate on traditional medicines.

Evaluation of in vivo Lethality and in vitro Cytotoxic Effect of Odontobuthus bidentatus Scorpion Venom.

The results of numerous studies have revealed that some deadly scorpion venoms are composed of various bioactive molecules that have significant cytotoxic effects on cancer cells. In this study, the in vivo lethality and cytotoxic effect of Odontobuthus bidentatus venom were evaluated in different cancer cell lines. Through MTT assay, the cytotoxic effects of O. bidentatus scorpion venom were analyzed on the MCF-7, A549, AGS, HepG2, and Ht-29 cancer cell lines and Hu02 normal cells. To this end, six venom fractions were obtained through a Sephadex G-50 column, and the cytotoxic effects of isolated fractions were evaluated on A549 lung cancer cells. The median lethal dose of O. bidentatus scorpion venom was determined at 0.73 mg/kg by intravenous administration of different venom doses in male BALB/c mice according to the Spearman-Karber method. The O. bidentatus scorpion whole venom had a significant cytotoxic effect on MCF-7, A549, and AGS cells. The treatment of A549 cells with various concentrations of fraction F1 showed that this fraction significantly induced growth inhibitory effect on the cells in a dose-dependent manner, compared to untreated cells.

In-vitro anti-gonorrheal activity of a sesquiterpene lactone, xerantholide, isolated from the leaves of Pechuel-loeschea leubnitziae

Gonorrhea is the second most prevalent bacterial sexually transmitted infection in the world. The global increase in the spread of gonorrhea is due to the fact that Neisseria gonorrhoeae has developed resistance to antimicrobials used as first-line treatments. In the search for new anti-gonorrheal agents, this study seeks to validate the use of a medicinal plant, namely, Pechuel-loeschea leubnitziae, for which both the root and the leaf extracts are commonly used as a remedy for gonorrhea. Bioassay guided fractionation of dichloromethane and methanol crude extracts (MIC50 = 0.730 - 3.07 mg/mL) was carried out. From the most active fraction F6, nearly colorless crystals were isolated and single crystal X-ray diffraction analysis identified the compound as a known sesquiterpene lactone, xerantholide. The compound showed activity against N. gonorrhoeae (MIC50 = 0.095 mg/mL) comparable with tetracycline, a positive control. This study shows that P. leubnitziae extracts have in-vitro anti-gonococcal activity and that xerantholide is the active anti-gonorrheal ingredient. The finding supports the traditional use of this plant to treat gonorrhea. This is the first report on the activity of xerantholide isolated from P. leubnitziae crude leaf extract against N. gonorrhoeae.

An exploration of angiotensin-converting enzyme (ACE) inhibitory peptides derived from gastrointestinal protease hydrolysate of milk using a modified bioassay-guided fractionation approach coupled with in silico analysis

An improved bioassay-guided fractionation was performed to effectively screen angiotensin-I converting enzyme inhibitory (ACEI) peptides from milk protein hydrolysate. The aqueous normal phase liquid chromatography, namely hydrophilic interaction liquid chromatography (HILIC), was used as a format of solid-phase extraction (SPE) short column for the first fractionation, then the HILIC-SPE fraction with the best ACEI activity (IC50 = 61.75 ± 5.74 µg/mL; IC50 = half-maximal inhibitory concentration) was obtained when eluted by 95% acetonitrile + 0.1% formic acid (fraction F1). The best HILIC-SPE fraction was further fractionated using reversed-phase (RP)-SPE short column. The best RP-SPE fraction was obtained when eluted by 20% acetonitrile + 0.1% formic acid (fraction P3) with an ACEI activity of IC50 36.22 ± 1.18 µg/mL. After the 2-step fractionation, the IC50 value of fraction P3 significantly decreased by 8.92-fold when compared with the crude hydrolysate. Several peptides were identified from fraction P3 using liquid chromatography-tandem mass spectrometry. The in silico analysis of these identified sequences based on the BIOPEP database predicted that HLPLPLL (HL-7) was the most active peptide against angiotensin-converting enzyme (ACE). The HL-7 derived from β-casein showed a potent ACEI activity (IC50 value is 16.87 ± 0.3 µM). The contents of HL-7 in the gastrointestinal protease hydrolysate and RP-SPE fraction originated from 1 mg of milk proteins were quantified using a multiple reaction monitoring mode upon liquid chromatography-tandem mass spectrometry analysis to give 19.86 ± 1.14 pg and 14,545.8 ± 572.9 pg, respectively. Besides, the kinetic study indicated that HL-7 was a competitive inhibitor and the result was rationalized using the docking simulation. The study demonstrated an efficient screening of ACEI peptides from commercially available milk powders using a simple SPE process instead of a sophisticated instrument such as HPLC. Moreover, the potent ACEI peptide HL-7 uncovered by this method could be a natural ACE inhibitor.

Cytotoxicity extract and fraction of knobweed (Hyptis capitata) and its effect on migration and apoptosis of T47D cells

Abstract. To’bungan N, Pratiwi R, Widyarini S, Nugroho LH. 2021. Cytotoxicity extract and fraction of knobweed (Hyptis capitata) and its effect on migration and apoptosis of T47D cells. Biodiversitas 23: 572-580. Hyptis capitata Jacq. has an ethnobotanical history. The leaves and stems of H. capitata have been reported to have potential anticancer properties. This study was conducted to determine the anticancer potential of the roots, stems, leaves, and flowers of H. capitata. Organs of H. capitata were extracted in stages using chloroform and continued with methanol to obtain eight extracts. Crude extracts were tested for cytotoxicity on T47D and WiDr cells with the MTT method. Potential inhibition of cell migration by potential fraction was tested with scratch wound healing assay and the content of secondary metabolites was analyzed with gas chromatography-mass spectrometry (GC-MS). An Annexin V-Pl apoptosis test was performed to determine the number of living cells, necrosis, and apoptosis. The results showed that the root chloroform extract showed the highest cytotoxic activity against T47D cells (34.90 ± 4.78µg/mL) and WiDr (44.65 ± 12.07 µg/mL), and it was referred to as a potential extract. Fractionation of the root chloroform extract resulted in four fractions (F1, F2, F3, and F4). Fraction F2 had the highest cytotoxic activity (13.8 ± 0.65 µg/mL) and was selective against T47D cells (selectivity index 3.71). Fraction F2 showed its antimetastatic and apoptotic potential against T47D cells. Gas chromatography-mass spectrometry analyses combined with library showed that the root chloroform extract and fraction F2 contain ferruginol, campesterol, and stigmasterol.

Anxiolytic Potentiality of Tamarindus indica Flowers

Tamarindus indica (Fabaceae) have been using in traditional medicine to cure various diseases, including mental stress and anxiousness. The current study was aimed to evaluate phytochemical analysis and anxiolytic activity of Tamarindus indica flower extracts (n-Hexane, Ethyl acetate, Chloroform and methanol) using different animal models such as elevated plus-maze, mirror chamber, light/dark, hole board tests. The extracts had showed presence of different phytochemical constituents. The mice were given two different doses of these extracts to see whether they had any anti-anxiety effects in an elevated maze-plus experiment. The methanol extract showed prominent activity compared to other extracts. The methanol extract was used for further analysis using column chromatography and four fractions (F1-F4) were separated and their activity was tested and further to investigate the anti-anxiety properties. The fraction F3 had showed better anxiolytic activity and using preparative thin layer chromatography three fractions were isolated. The fraction (F3.2) was identified as flavonoid through phytochemical tests and Fourier transform infrared, Nuclear Magnetic Resonance, data as showed 3570 (-OH Str, Ar-OH) and 1753(C=O Str). The fraction F3.2 has anti-anxiety properties (4.8±0.31 and 7.2±0.30 secs) elevated by elevated plus maze test. Fraction F3.2 at 80 mg/kg dose administered orally showed a considerable anti-anxiety effect on different anxiolytic activity tests. From the results of current study, there is a need to do a thorough investigation in finding out the mechanism of action whether it is either through the serotonergic or GABAergic pathway of fraction F3.2. The current study was may be first report about the flavonoids had showing anti-anxiety properties of Tamarindus indica flower extracts.

Hypotensive Effects and Phytochemical Profile of Aqueous Extract and Fractions of <i>Desmodium velutinun</i> Leaves (Willd) D. C. (Fabaceae) in the Rat

Desmodium velutinum (D. velutinum) is a plant of the family Fabaceae used in traditional Congolese medicine for the treatment of high blood pressure (HBP) or hypertension (HT). The present work evaluated the hypotensive activity and determined the phytochemical profile of the aqueous extract and fractions of Desmodium velutinun (Willd) D. C. (Fabaceae) in the rat. The hypotensive effect of the aqueous extract and different fractions (F1, F2, F3 and F4) was evaluated at the dose of 2.5 mg/kg in normotensive rats anesthetized with 15% urethane at 1.5 g/kg, i.p. (intraperitoneally). Our results showed that the F3 fraction after administration caused a significant decrease in blood pressure and heart rate which remained higher than that of the aqueous extract and fractions (F1, F2 and F4). The richness in polyphenolic and flavonoid compounds as well as the separating capacity of the eluent used within the F3 fraction clearly justifies the beneficial effects of the latter on blood pressure and heart rate compared with the extract and fractions (F1, F2 and F4). In a second part we carried out the qualitative (thin-layer chromatography) and quantitative (total polyphenols and flavonoids determination) analysis. The chemical compounds remained dominated by the polyphenolic and flavonoid groups, the content of total polyphenols and total flavonoids meets the following increasing order: (extract, F1, F2, F3 and F4). The results obtained could certify the use of Desmodium velutinun in traditional Congolese medicine.

Peptides Derived from In Vitro and In Vivo Digestion of Human Milk Are Immunomodulatory in THP-1 Human Macrophages

BackgroundMilk proteins contain many encrypted bioactive peptides. Whether these bioactive peptides are released in the infant intestine and exert immunomodulatory activity remains unknown. ObjectiveThis study examined in vitro immunomodulatory activities of peptides from in vitro– and in vivo–digested human milk. MethodsPeptides were extracted from in vitro–digested human milk and pooled intestinal samples from 8 infants fed human milk. Peptides extracted from in vitro–digested samples were fractionated. The in vitro effects of these peptides and fractions on the secretion of TNF-α and IL-8 in LPS-treated human immune THP-1 macrophages were evaluated. The significance of differences between in vitro peptide fraction treatment and control on cytokine production was analyzed by t test. LC-MS/MS–based peptidomics was conducted to identify the peptides. The peptides were screened for potential bioactivity using a sequence homology search using the Milk Bioactive Peptide Database (MBPDB). ResultsSix fractions of the peptide mixture extracted from the in vitro–digested human milk significantly inhibited TNF-α production by LPS-challenged THP-1 macrophages. Fractions F4, F8, F11, F14, and F17 attenuated IL-8 secretion, and F6/7 and F18 increased IL-8 secretion. Peptides extracted from the pooled in vivo intestinal samples attenuated both TNF-α and IL-8 secretion. There were 266 and 418 peptides identified in the in vitro and in vivo samples, respectively. Among the peptides, 34 and 50 in the in vitro and in vivo samples, respectively, had >80% sequence similarity to bioactive peptides in the MBPDB. ConclusionsPeptides released by in vitro and in vivo infant digestion of human milk were immunomodulatory in human immune cells; fractions F4, F8, and F11 were anti-inflammatory; and F6/7 and F18 were proinflammatory. Thirteen peptides were present in all fractions with anti-inflammatory activity, and 38 peptides were present in all fractions with proinflammatory activity. These peptides potentially contributed to the observed immunomodulatory activity of the peptide mixtures.

Alangium chinense (Lour.) Harms Leaves with Anti-inflammatory, Antioxidant Property: in vitro and in silico Study

The present investigation aimed to find the in vitro antioxidant and anti-inflammatory potential of fractions of methanol extract of Alangium chinense (Lour.) Harms leaves followed by isolation and identification bioactive molecule and evaluate its possible mechanism through in silico study. A methanol extract of Alangium chinense (Lour.) Harms leaves subjected for chromatographic fractionation and pure isolates (F1-F8) were evaluated for their in vitro anti-inflammatory activity using albumin denaturation inhibition assay and in vitro antioxidant activity. Fraction F4 showed highest in vitro anti-inflammatory activity (IC50 = 70.02 μg/mL), whereas fractions F3, F4, F7 showed better in vitro antioxidant activity compare to other fractions. F4 fraction was screened for its tentative structure using FTIR, 1H and 13C NMR. The spectral analysis showed that the fraction F4 has a tentative structure of olean 19-ene-1yl-acetate. The molecular docking studies showed that test ligand significantly interact with different key active sites of amino acids and thus confirm possible COX-2 inhibitory activity of fraction F4. In vitro and in silico study confirmed the isolation of possible anti-inflammatory from Alangium chinense (Lour.) Harms leaves, which may further used as lead to a development of a new therapeutic agent.

Analysis of chemical components from “white turmeric” (Curcuma sp.) fraction with antioxidant activity by ultrahigh-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF/MS)

Curcuma (Zingiberaceae) is a large rhizomatous herb genus found in tropical and subtropical areas. The biological activities of Curcuma species have been extensively studied. This research concentrated on rapidly determining the phytochemicals with antioxidant activity from Curcuma sp. with the aid of high-resolution mass spectrometry (HRMS). In this study, the antioxidant activity of Curcuma sp. extract and fractions were determined by DPPH assay. Overall, fraction F3 had the highest antioxidant property (IC50 = 20.91 µg/mL), which was then analyzed by UHPLC-Q-TOF/MS in negative electrospray ionization (ESI) mode. LC analysis was performed on an ExionLCTM UHPLC system, and mass spectrometric analysis was conducted on an X500R QTOF mass spectrometer (AB SCIEX, USA). The data were analyzed using SCIEX OS software version 1.2.0.4122 (AB SCIEX, USA). The characterization of three types of curcuminoids from Curcuma sp. was discussed and distinguished by ESI-MS/MS analyses. As a result, 13 curcuminoid compounds from the best bioactive Curcuma sp. fraction were successfully identified. This study laid a foundation for isolating specific antioxidant phytochemicals from Curcuma sp.

Identification of novel antioxidant peptides from sea squirt (Halocynthia roretzi) and its neuroprotective effect in 6-OHDA-induced neurotoxicity.

Ocean life contains a wealth of bioactive peptides that could be utilized in nutraceuticals and pharmaceuticals. This study aimed to obtain neuroprotective antioxidant peptides in sea squirt (Halocynthia roretzi) through protamex enzymolysis. Fraction F4 (ultrafiltration generated four fractions) had a lower molecular weight (<500 Dalton (Da)) with greater 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS) radical scavenging activities (94.24 ± 2.50% and 91.80 ± 1.19%). After gel filtration, six peptides, including Phe-Gly-Phe (FGF), Leu-Gly-Phe (LGF), Leu-Phe-VAL (LFV), Val-Phe-Leu (VFL), Trp-Leu-Pro (WLP), and Ile-Ser-Trp (ISW), were identified and sequenced by liquid chromatography-mass spectrometry (LC-MS/MS). Peptides WLP and ISW showed higher oxygen radical absorbance capacity (ORAC) values (2.72 ± 0.47 and 1.93 ± 0.01 μmol L-1 of Trolox equivalent (TE) per μmol L-1 of peptide) than glutathione (GSH). Additionally, WLP effectively increased cell viability, dramatically attenuated 6-Hydroxydopamine (6-OHDA)-induced cell apoptosis and decreased reactive oxygen species (ROS) levels to nearly two-fold, and significantly boosted glutathione peroxidase (GSH-Px) activity in PC12 cells. Transcriptome sequencing revealed differential expression of genes associated with various oxidative stress pathways after WLP treatment, such as glutathione metabolism. These results suggest that the Halocynthia roretzi-derived tripeptide WLP could alleviate neurodegenerative diseases associated with oxidative stress.

Leaf Extract and Active Fractions of Dillenia pentagyna Roxb. Reduce In Vitro Human Cancer Cell Migration Via NF-κB Pathway.

Different parts of Dillenia pentagyna have long been used in traditional medicines to cure several diseases including cancer. However, the mechanism(s) of anti-cancer effects are still unknown. We aimed to elucidate the anti-metastatic potential of ethanolic extracts of leaves of D. pentagyna (EELDP) and active fractions of it in highly metastatic human cancer cells. We screened different HPLC fractions of EELDP based on their anti-metastatic effect. We used TLC and ESI-MS for determining the presence of various phytochemicals in EELDP and fractions. We monitored in vitro anti-metastasis effect of EELDP (0-0.6 mg/ml) and active fractions (0-0.050 mg/ml) on various human cancer cells like A549, HeLa, and U2OS. EELDP significantly reduced cell viability and cell migration in A549, HeLa, and U2OS cells. However, higher sensitivity was observed in A549 cells. We screened 2 active HPLC fractions F6 and F8 having anti-MMPs activity. EELDP and active fractions reduced metastasis via the NF-κB pathway, decreased the expression of Vimentin, N-cadherin, and increased the expression of Claudin-1. Significant reduction of metastasis by EELDP at a dose of 0.1 mg/ml or by active fractions at 0.050 mg/ml implicates that the active compound(s) present in crude or fractions are extremely potent to control highly metastatic cancer.

The quantity and stability of soil organic carbon following vegetation degradation in a salt-affected region of Northeastern China

Understanding the influence of vegetation conversion induced by land degradation on soil organic carbon (SOC) dynamics provides a basis for the sustainable use of grasslands. While labile carbon fractions often vary with the type of vegetation, little is known about whether and how vegetation degradation affects the recalcitrant carbon fraction that is highly resistant to oxidation. Here, we studied the influence of vegetation degradation on changes in SOC and four oxidizable fractions with different stabilities in Northeastern China. The soil was collected from a vegetation degradation sequence, including Leymus chinensis (LEY, native grassland), Puccinellia tenuiflora(PUC, light degradation), Chloris virgata (CHL, moderate degradation), and Suaeda heteroptera (SUA, severe degradation). Contents of total SOC and four oxidizable SOC fractions extracted under a gradient of oxidation (F1, very labile; F2, labile; F3, less labile; F4, oxidizable resistant) were measured using a modified Walkley-Black method. Results showed that the contents of total SOC and oxidizable SOC fractions were significantly different under different vegetation types and soil depths. Under PUC, CHL, and SUA, contents of total SOC (29.0%, 34.3%, and 55.4%, respectively), F1 (22.5%, 20.8%, and 40.8%, respectively), F2 (28.2%, 53.8%, and 72.1%, respectively), F3 (52.0%, 40.6%, and 66.2%, respectively), and F4 (15.0%, 21.9%, and 42.8%, respectively) were lower than those under LEY. Vegetation degradation had a significant effect on the F4 fraction as well as the F1, F2, and F3 fractions. Regression coefficients of the relationship between oxidizable SOC fractions as a function of total SOC showed that these fractions, as a proportion of total SOC, were 22% for F1 and F2, 26% for F3, and 31% for F4. There were no significant differences in the percentages of active carbon fractions (F1 + F2) in total SOC and the lability of total SOC among the four vegetation types. These findings suggest that the recalcitrant carbon fraction can be affected by land degradation as well as the labile carbon fraction, and that shifts in land use affect the contents of total SOC and its fractions, but have no effect on the stability of SOC in semi-arid areas.

Functional Properties of Yellowfin Tuna (Thunnus albacares) Skin Collagen Hydrolysate Fraction obtained by Ultrafiltration Purification

Hydrolyzed collagen with different fractions is broadly applied in various industries due to its functional properties. The study aimed to purify and fractionate the hydrolyzed collagen from yellowfin tuna skin by ultrafiltration and evaluate the functional properties of its fractions. The effect of temperature, pH, and pressure on membrane flux, nitrogen recovery efficiency, and degree of separation was investigated. Afterward, several functional properties of hydrolyzed collagen fractions including solubility, emulsification, foaming, and antioxidant properties were evaluated. The optimum ultrafiltration conditions for hydrolyzed collagen were temperature 25 °C, pH 6.5 and pressure 12 psi provided optimum membrane flux (3.4 L/m2.h) and nitrogen recovery efficiency (80.81%), and the smallest degree of separation (27.45%). The products after ultrafiltration were separated into two fractions, F1 (&lt; 3 kDa), and F2 (3-5 kDa), with the volume of 10% and 90%, respectively. Both hydrolyzed collagen fractions were more than 96% soluble at pH below 8.0, where the F2 fraction dissolved better than F1. As pH was higher than 8.0, both fractions were almost completely dissolved. In addition, the emulsifying and foaming abilities of the F1 fraction were better than the F2. However, the F2 fraction was more resistant to oxidation with higher antioxidant activity. In conclusion, this research indicates that different fractions from hydrolyzed collagen from yellowfin tuna skin have various functional properties that could be applied in food, cosmetic and pharmaceutical industries.

In vitro-in silico screening strategy and mechanism of angiotensin I-converting enzyme inhibitory peptides from α-lactalbumin

This work proposed an in vitro-in silico strategy for the discovery of angiotensin I-converting enzyme (ACE) inhibitory peptides. Alpha-lactalbumin was hydrolyzed by pepsin and pancreatin. The hydrolysate under 3 kDa was separated into five fractions, among which the fractions F3, F4 and F5 exhibited potent ACE inhibition, by ultrafiltration and dextran gel chromatography. Thirty-eight peptides were identified by Nano-HPLC-MS/MS from fractions F3, F4 and F5 to form a peptide library. Five novel ACE inhibitory peptides (SLPEW, VSLPEW, GVSLPEW, VGINYW and LDQWL) were predicted according to the binding energy calculated by molecular docking. The IC50 values of such peptides ranged from 6.94 to 17.5 μmol/L. Lineweaver-Burk plots revealed LDQWL as competitive inhibitor, and SLPEW and VSLPEW as mixed-type, while other peptides as non-competitive ones. Molecular docking showed that the competitive inhibitors interacted with the residues of active pocket, and the non-competitive peptides connected to the residues outside the active site and the mixed-type inhibitors anchored in both entrance channel and active pocket of ACE. Circular dichroism indicated that these peptides significantly changed the secondary structure of ACE. VGINYW binding caused the most reduction of α-helix and the most increase of random coils.

Identification and characterization of dipeptidyl peptidase IV inhibitory peptides from wheat gluten proteins

The objective of this study was to investigate the dipeptidyl peptidase IV (DPP-IV) inhibitory properties of wheat gluten-derived peptides. Wheat gluten protein was hydrolyzed by flavourzyme, papain, neutral protease, and alkaline protease with or without subsequent hydrolysis by trypsin. Results showed that the wheat gluten hydrolysate by flavourzyme displayed the highest DPP-IV inhibitory activity with IC50 of 1.25 ± 0.09 mg/mL. After purified by Sephadex G-15 gel column, the fraction F1 from the hydrolysate by flavourzyme had a superior DPP-IV inhibitory activity with IC50 of 0.15 ± 0.04 mg/mL. The peptide sequences from F1 were identified by UPLC-MS/MS and found that six wheat gluten-derived peptides of LPF, MPF, MAMG, VAVPV, MAMGL, and LAGAP showed DPP-IV inhibitory activity. MPF and VAVPV exerted the highest DPP-IV inhibitory activity of 57.33% ± 4.11% and 56.08% ± 1.40% at the concentration of 500 μM, respectively. In addition, molecular docking revealed that MPF and VAVPV were predicted to form multiple hydrogen bonds, attractive charge, and hydrophobic interactions with the residues located in the active site of DPP-IV, which might contribute to the DPP-IV inhibitory activity. It indicates that wheat gluten is a good source for DPP-IV inhibitory peptides, and wheat gluten-derived DPP-IV inhibitory peptides have potential as ingredients in functional foods or candidates of drugs for the management of prediabetes and Type 2 diabetes mellitus.