Highest Metal Chelating Activity Research Articles

Secondary metabolic profiling, antioxidant potential, enzyme inhibitory activities and in silico and ADME studies: a multifunctional approach to reveal medicinal and industrial potential of Tanacetum falconeri

Tanacetum falconeri is a significant flowering plant that possesses cytotoxic, insecticidal, antibacterial, and phytotoxic properties. Its chemodiversity and bioactivities, however, have not been thoroughly investigated. In this work, several extracts from various parts of T. falconeri were assessed for their chemical profile, antioxidant activity, and potential for enzyme inhibition. The total phenolic contents of T. falconeri varied from 40.28 ± 0.47 mg GAE/g to 11.92 ± 0.22 mg GAE/g in various extracts, while flavonoid contents were found highest in TFFM (36.79 ± 0.36 mg QE/g extract) and lowest (11.08 ± 0.22 mg QE/g extract) in TFSC (chloroform extract of stem) in similar pattern as found in total phenolic contents. Highest DPPH inhibition was observed for TFFC (49.58 ± 0.11 mg TE/g extract) and TFSM (46.33 ± 0.10 mg TE/g extract), whereas, TFSM was also potentially active against (98.95 ± 0.57 mg TE/g) ABTS radical. In addition, TFSM was also most active in metal reducing assays: CUPRAC (151.76 ± 1.59 mg TE/g extract) and FRAP (101.30 ± 0.32 mg TE/g extract). In phosphomolybdenum assay, the highest activity was found for TFFE (1.71 ± 0.03 mg TE/g extract), TFSM (1.64 ± 0.035 mg TE/g extract), TFSH (1.60 ± 0.033 mg TE/g extract) and TFFH (1.58 ± 0.08 mg TE/g extract), while highest metal chelating activity was recorded for TFSH (25.93 ± 0.79 mg EDTAE/g extract), TFSE (22.90 ± 1.12 mg EDTAE/g extract) and TFSC (19.31 ± 0.50 mg EDTAE/g extract). In biological screening, all extracts had stronger inhibitory capacity against AChE while in case of BChE the chloroform extract of flower (TFFC) and stem (TFSC) showed the highest activities with inhibitory values of 2.57 ± 0.24 and 2.10 ± 0.18 respectively. Similarly, TFFC and TFSC had stronger inhibitory capacity (1.09 ± 0.015 and 1.08 ± 0.002 mmol ACAE/g extract) against α-Amylase and (0.50 ± 0.02 and 0.55 ± 0.02 mmol ACAE/g extract) α-Glucosidase. UHPLC-MS study of methanolic extract revealed the presence of 133 components including sterols, triterpenes, flavonoids, alkaloids, and coumarins. The total phenolic contents were substantially linked with all antioxidant assays in multivariate analysis. These findings were validated by docking investigations, which revealed that the selected compounds exhibited high binding free energy with the enzymes tested. Finally, it was found that T. falconeri is a viable industrial crop with potential use in the production of functional goods and nutraceuticals.

Structure and Properties of Exopolysaccharide Produced by Gluconobacter frateurii and Its Potential Applications.

An exopolysaccharide (EPS)-producing bacterium was isolated from apricot fermentation broth and identified as Gluconobacter frateurii HDC-08 (accession number: OK036475.1). HDC-08 EPS is a linear homopolysaccharide mainly composed of glucose linked by α-(1,6) glucoside bonds. It contains C, H, N and S elements, with a molecular weight of 4.774 × 106 Da. Microscopically, it has a smooth, glossy and compact sheet structure. It is an amorphous noncrystalline substance with irregular coils. Moreover, the EPS showed surface hydrophobicity and high thermal stability with a degradation temperature of 250.76 °C. In addition, it had strong antioxidant properties against DPPH radicals, ABPS radicals, hydroxyl radicals and H2O2. The EPS exhibited high metal-chelating activity and strong emulsifying ability for soybean oil, petroleum ether and diesel oil. The milk solidification test indicated that the EPS had good potential in fermented dairy products. In general, all the results demonstrate that HDC-08 EPS has promise for commercial applications as a food additive and antioxidant.

DNA protection, molecular docking, antioxidant, antibacterial, enzyme inhibition, and enzyme kinetic studies for parietin, isolated from Xanthoria parietina (L.) Th. Fr.

Parietin was isolated from Xanthoria parietina (L.) Th. Fr.’ (methanol:chloroform) extract, using a silica column. 13 C NMR and 1H NMR were used to confirm the structure of the isolated parietin. For the first time, parietin was investigated for its antioxidant, antibacterial and DNA protective activities. Molecular docking was carried out to determine the binding affinity and interactions between the enzymes and our molecule. Inhibition and kinetic mechanism studies for the action of the enzymes were performed too. Parietin exhibited high metal chelating activity. The MIC values of parietin were sufficient to inhibit different bacterial strains; E. coli, P. aeruginosa, K. pneumoniae and S. aureus. Molecular docking applications exhibited that acetylcholinesterase (AChE), butyrylcholinesterase (BChE), lipase, and tyrosinase have high potential for binding with the parietin. Especially, the parietin’s highest binding affinity was recorded with AChE and tyrosinase. These results were confirmed by the inhibition and kinetics results, where, parietin observed a potent inhibition with an IC50 values between 0.013-0.003 µM. Moreover, parietin acts’ as a non-competitive inhibitor against AChE, BChE, and lipase, and as a competitive inhibitor against tyrosinase with a high rate of inhibition stability. The promising biological properties of parietin revealed its effectiveness in terms of suitability in the food and pharmaceutical industries. Communicated by Ramaswamy H. Sarma

Physicochemical Properties and Antioxidant Activity of Portuguese Craft Beers and Raw Materials.

There is an increase in the popularity of craft beer, which is produced by small, independent, and traditional breweries. Since craft beer popularity is rising in Portugal this research focused on assessing physicochemical parameters, total phenolic content (TPC) and the antioxidant capacity of Portuguese craft beers and raw materials used in beer production. In this experimental study, 19 beer samples were analyzed. Parameters such as pH, Total Acidity, Reducing Sugar Content and TPC were evaluated. For the determination of antioxidant activity, DPPH scavenging activity and metal chelating activity (MCA) were analyzed in all samples. Craft beers demonstrated a high phenolic content (ranging from 343.78 mg GAE/L to 2172.49 mg GAE/L), significantly different from industrial beers. Craft beers demonstrated a higher inhibition of DPPH radicals and higher MCA than the raw materials. DPPH inhibition ranged from 36.5% to 96.0% for malt and 64.7% to 79.6% in hops samples. MCA also varied between the different samples, with results of 12.0% to 24.8% in malt samples and 3.8% to 23.5% in hops. Raw materials can potentially influence the antioxidant activity of the resulting beer. Positive correlations between TPC and physicochemical properties can be useful to help consumers choose beers with added value for health.

Antioxidant Activities of Optimized Enzymatic Protein Hydrolysates from Hybrid Sturgeon (Huso dauricus × Acipenser schrenckii) Prepared Using Two Proteases

ABSTRACT The objective of this work was to optimize the hydrolysis conditions of hybrid sturgeon (Huso dauricus × Acipenser schrenckii) protein using flavourzyme and compound proteinase, and to evaluate the antioxidant activity of hydrolysates. The lyophilized flavourzyme hydrolysate (FH) and compound proteinase hydrolysate (CPH) with degree of hydrolysis of 18.16% and 19.35% under optimal conditions had 85.36% and 87.24% protein content, 89.19 and 96.97 g/100 g protein total amino acid content, 92.86% and 95.12% protein solubility, and 902.47 nm and 1025.76 nm particle size, respectively. The CPH had the highest DPPH and ABTS radical scavenging activities, which were 71.04 and 66.84% with IC50 at 2.85 and 3.37 mg/mL, respectively; while the FH had higher metal-chelating activity, which was 58.37% with IC50 at 24.81 mg/mL. The obtained hydrolysates have excellent antioxidant properties and could be used as food additives and natural substitutes for synthetic antioxidants compounds, particularly in food and pharmaceuticals.

Optimization of Selective Hydrolysis of Cruciferins for Production of Potent Mineral Chelating Peptides and Napins Purification to Valorize Total Rapeseed Meal Proteins.

Preventing oxidation and microbial spoilage are both major concerns in food industries. In this context, this study aimed to valorize the total rapeseed meal proteins with controlled enzymatic proteolysis to generate potent mineral-chelating peptides from cruciferins while keeping intact the antimicrobial napins. Implementation of proteolysis of total rapeseed protein isolate with the Prolyve® enzyme highlighted an interesting selective hydrolysis of the cruciferins. Hence, the mechanism of this particular hydrolysis was investigated through a Design of Experiments method to obtain a model for the prediction of kinetics (cruciferin degradation and napin purity) according to the operating conditions applied. Then, multicriteria optimization was implemented to maximize the napin purity and yield while minimizing both enzymatic cost and reaction time. Antioxidant assays of the peptide fraction obtained under the optimal conditions proved the high metal-chelating activity preservation (EC50 = 247 ± 27 µg) for more than three times faster production. This fraction might counteract lipid oxidation or serve as preventing agents for micronutrient deficiencies, and the resulting purified napins may have applications in food safety against microbial contamination. These results can greatly help the development of rapeseed meal applications in food industries.

Investigation of Enzyme Inhibitory Activities, Antioxidant Activities, and Chemical Properties of Pistacia vera Leaves Using LC-QTOF-MS and RP-HPLC.

Since the leaves of some Pistacia species are used in traditional folk medicine for diabetes, this study investigated the in vitro antidiabetic effect (α-glucosidase and α-amylase) of Pistacia vera leaves. Additionally, the current study investigated the antihypercholesterolemic (cholesterol esterase), antiobesity (pancreatic lipase), and antioxidant activities (i.e., total antioxidant capacity, DPPH (2,2-Diphenyl-1-picrylhydrazyl) radical scavenging activity, metal chelating activity, and ferric-reducing antioxidant power) of P. vera leaves. The aqueous-alcoholic leaf extract inhibited α-amylase, α-glucosidase, and pancreatic lipase with the half-maximal inhibitory concentration values of 7.74 ± 0.72, 11.08 ± 3.96, and 168.43 ± 26.10 µg/mL, respectively. It was determined that the crude extract had high DPPH radical scavenging activity, ferric-reducing power, and moderate metal chelating activity. The ethyl acetate (EtOAc) subextract obtained by the liquid-liquid fractionation of the crude extract showed potent α-amylase and α-glucosidase inhibitory activities. The EtOAc subextract (5.794 ± 0.027 g/100 g subextract) was standardized by reversed-phase high-performance liquid chromatography based on β-pentagalloyl glucose, which showed inhibitory effects on both amylase and glucosidase enzymes. Fifteen compounds, seven of which are organic acid derivatives and eight of which are flavonoids, were identified by liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) analysis in the crude extract of P. vera leaves. Seven of the fifteen phenolic compounds detected in the crude extract by LC-QTOF-MS have both glucosidase and amylase inhibitory effects. As a result, P. vera leaves can be a potential source for compounds with high antioxidant effects that show inhibitory effects on enzymes involved in carbohydrate digestion in the prevention and treatment of diabetes or can be evaluated as a standardized extract.

In vitro antioxidant, anticholinesterase inhibitory, and antimicrobial activity studies of Terminalia chebula (Retz) and Terminalia arjuna (Roxb)

Ethanol extracts of Terminalia chebula and Terminalia arjuna were studied for the determination of phytochemical constituents, in vitro antioxidant, anticholinesterase, inhibitory, and antimicrobial activities. Results of phytochemical analysis showed that T. arjuna has significant phenolic and flavonoid contents (108.2 mg PEs/mg extract and 74.2 mg QEs/mg extract) respectively. T. chebula also showed good phenolic contents 113.4 mg PEs/mg extract and low value of flavonoids contents 8.91 QEs/mg extract correspondingly. The antioxidant activity was performed using three complementary assays, including lipid peroxidation inhibitory, metal chelating, and reducing power assays. The acetylcholinesterase assay was performed according to Ellman's method spectrophotometrically. The antibacterial and antifungal activity, however, was determined by the disc and well diffusion methods. Terminalia arjuna exhibited higher lipid peroxidation inhibitory activity (IC50: 57.7 ± 3.7 μg/mL), higher reducing power (A0.5: 0.63 ± 0.4 mg/mL), and higher metal chelating activity (IC50: 115 ± 5.01 μg/mL) that Terminalia arjuna. Both Terminalia species indicated high acetylcholinesterase inhibitory activity (IC50: 29.6 ± 3.9 and 29.7 ± 0.5 μg/mL, respectively). Promising antibacterial activity was recorded for Terminalia chebula (72.44 % and 60.0 %) against Bacillus sp. and Staphylococcus species with MIC values of 5.0 mg/mL and 2.5 mg/mL, respectively. Similarly, Terminalia arjuna (72.41 % and 63.33 %) revealed activity against Bacillus sp. and Staphylococcus species with MIC values of 2.5 mg/mL and 5.0 mg/mL. However, all the tested fungal strains were resistible to both species. In conclusion, Terminalia arjuna and Terminalia chebula may be significant sources of potential new acetylcholinesterase inhibitors, which could be utilized to treat Alzheimer's disease. The plants are also recommended for further studies to isolate antimicrobial agents and lipid peroxidation inhibitors.

Innovative Biochemometric Approach to the Metabolite and Biological Profiling of the Balkan Thistle (Cirsium appendiculatum Griseb.), Asteraceae.

The widespread genus Cirsium Mill. (Asteraceae) is renowned in traditional medicine. In the present study, an innovative biochemometric-assisted metabolite profiling of the flower heads, aerial parts and roots of Cirsium appendiculatum Griseb. (Balkan thistle) in relation to their antioxidant and enzyme inhibitory potential was developed. The workflow combines ultra-high-performance liquid chromatography–high-resolution mass spectrometry (UHPLC–HRMS) with partial least-square analysis to discriminate the herbal extracts and identify the most prominent biological activities. The annotation and dereplication of 61 secondary metabolites were evidenced, including 15 carboxylic (including hydroxybenzoic and hydroxycinnamic) acids and their glycosides, 11 acylquinic acids, 26 flavonoids and 9 fatty acids. All compounds were reported for the first time in the studied species. The root extract revealed the highest cupric and ferric reducing power (618.36 ± 5.17 mg TE/g and 269.89 ± 8.50 mg TE/g, respectively) and antioxidant potential in phosphomolybdenum (3.36 ± 0.15 mmol TE/g) as well as the most prominent enzyme inhibitory potential on α-glucosidase (0.72 ± 0.07 mmol ACAE/g), acetylcholinesterase (4.93 ± 0.25 mg GALAE/g) and butyrylcholinesterase (3.80 ± 0.26 mg GALAE/g). Nevertheless, the flower heads were differentiated by their higher metal chelating activity (32.53 ± 3.51 mg EDTAE/g) and total flavonoid content (46.59 ± 0.89 mgRE/g). The partial least-square discriminant and heat-map analysis highlighted the root extract as the most active and a promising source of bioactive compounds for the therapeutic industry.

Variations in the L-DOPA Content, Phytochemical Constituents and Antioxidant Activity of Different Germlines of Mucuna pruriens (L.) DC.

In this study a ‘wonder plant’ Mucuna pruriens (L.) DC., which is commercially important medicinal plant of the Fabaceae family known for its treatment in Central Nervous System disorders like Dementia, Parkinson’s, Alzheimer’s, etc. have been selected. Different germplasms have been collected to analyze the phytochemical variations between them and quantify the L-DOPA in root, stem, leaves and seeds of all the five germlines using HPLC. Along with the biochemical assays, antioxidant activity by DPPH, phosphomolybdneum method, the metal chelating and reductive potential activity of all the germplasms were studied. All parts of the plant have shown the presence of L-DOPA but, seeds have the highest quantity followed by the roots, stem and leaves. Arka Shubra seeds showed high L-DOPA content (51.9 mg/g) while the other germplasms showed L-DOPA ranging from 43-45 mg/g. Highest content of carbohydrates (258.8 mg/g) and phenolics (157.0 mg/g) was seen in the seeds of Arka Aswini. While the seeds and leaves of Arka Charaka showed high protein (332.2 mg/g) and flavonoid (10.2 mg/g) content, respectively. High proline (1.74 mg/g) was observed in the seeds of Arka Shubra. Antioxidant studies revealed that Arka Charaka and Arka Daksha to be having high reductive power and free radical scavenging activity by phosphomolybdate method while high metal chelating activity was observed in Arka Aswini (88.7%) and high antioxidant activity by DPPH method was seen in Arka Shubra (86.5%).

LC-ESI-MS/MS-MRM Profiling of Polyphenols and Antioxidant Activity Evaluation of Junipers of Different Origin

This study was aimed at identifying new efficient antioxidant juniper species and their metabolites, which are responsible for this activity. About 30 juniper representatives were assayed for antioxidant activity (DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,2′-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) radical scavenging) and total polyphenol content (TPC). The most active species were identified, and their most abundant polyphenols were quantified by the LC-electrospray ionization (ESI)-MS/MS-multiple reaction monitoring (MRM) method. In the group of studied species, J. ashei (mountain cedar) leaf extract was outlined as the best antioxidant with the highest TPC. Catechin was revealed as the most abundant polyphenol in the J. ashei extract, contributing to its superior antioxidant properties. An in-depth analysis of antioxidant capacity was also performed. The higher metal-chelating activity was observed in the case of J. sibirica (0.83 mg DE/mL), whereas the lowest was observed for J. communis (3.2 mg dry extract (DE)/mL) extracts. All efficient antioxidant extracts were also able to inhibit lipoxygenase. EC50 values ranged from 1.77 to 2.44 mg DE/mL. The most effective inhibitors were J. ashei and J. formozana extracts, which acted as uncompetitive lipoxygenase (LOX) inhibitors. The presented results have potential application in the pharmacy and cosmetics for the generation of antioxidant compositions based on naturally derived lead compounds for the prevention of oxidative-stress associated organ-degenerative diseases, cancer, or other free radical-induced disorders.

Effect of Pepsin–Trypsin In Vitro Gastro-Intestinal Digestion on the Antioxidant Capacities of Ultra-Filtrated Rice Bran Protein Hydrolysates (Molecular Weight > 10 kDa; 3–10 kDa, and < 3 kDa)

The antioxidant capacities of rice bran protein hydrolysates (RBPH) obtained by in vitro gastro-intestinal (GI) digestion by pepsin–trypsin (P–T) system were investigated. The hydrolysates were separated by ultrafiltration into three fractions (FI: molecular weight (MW) > 10 kDa, FII: MW 3–10 kDa, and FIII: MW < 3 kDa). Furthermore, the protein content and free amino acids of hydrolysates were studied. The results showed that fraction FII with MW 3–10 kDa had the highest antioxidant activity: DPPH of 28.34 ± 0.16%, ABTS of 30.66 ± 0.29%, and metal chelating activity of 61.04 ± 0.38%, and was further purified by RP-HPLC. Four sub-peptide fractions (F1, F2, F3, and F4) were collected and their antioxidant activities were assessed. The results displayed that F2 sub-peptide fraction owned a higher metal chelating activity (72.09 ± 0.32%) than other sub-peptide fractions. The amino acids composition of the purified peptide (F2) was evaluated, which could play an essential role in its antioxidant activity. The results indicated that rice bran proteins are rich in antioxidant peptides which can be employed as a potential source of natural bioactive compounds. The peptides produced can resist physiological digestion in the GI tract.

Isolation of crude fucoidan from Sargassum wightii using conventional and ultra-sonication extraction methods

Fucoidan, a fucose rich sulphated polysaccharide, generally found in cell wall matrix of brown seaweeds possess diverse physiological properties. Crude fucoidan was extracted from Sargassum wightii, a brown seaweed common along the Indian coastline. A comparison was made between hot water extraction (HWE) and ultra-sonication extraction (UAE) methods. The UAE method gave higher yield (14.61 g/100 g) than HWE method (10.59 g/100 g). The UAE fucoidan had lighter colour than HWE, as indicated by Hunter colour values. The water activity values for fucoidans obtained were 0.14 for HWE and 0.19 for UAE. The sulphate content was similar in both fucoidans (̴17%). However, HWE fucoidan had higher content of fucose. The Fourier transform infrared spectroscopy spectra confirmed the presence of sulphate groups in both the fucoidans. The absorption bands at 1245.37 cm−1 and 1294.99 cm−1 in the HWE and UAE fucoidan respectively, indicated the S–O stretching due to sulphate groups in the fucose monomer. The thermal transition temperature as obtained by differential scanning calorimetry for HWE (127.3 °C) was lower than UAE fucoidan (131.8 °C). HWE fucoidan had higher DPPH radical scavenging and reducing power than UAE fucoidan. On the other hand, UAE fucoidan had higher metal chelating activity. The present study demonstrated that ultra-sonication can be an effective alternative for the extraction of sulphated polysaccharide from seaweed, in term of higher yield. The health benefits of Sargassum wightii and fucoidan obtained from it, could be explored by incorporation in different food systems.

Macro micronutrients and Antioxidant Potentials of Plants and Fungal based Food from Tawang Area Arunachal Pradesh India

Certain variety of plants such as vegetables, spices and seaweed are abundantly being grown in high altitude cold desert region of Tawang in Arunachal Pradesh, India. Therefore, five different vegetables, spices and seaweed were taken from that particular cold region viz., finger millet, nori seaweed, pepper corn, bean and mushroom have been selected based on the higher consumption of people of Northeast (NE) India for the proximate analysis, mineral, antioxidant and vitamin contents. So far, there is no nutritional composition studies have been carried out with available vegetables, spices and seaweeds growing in NE. For this reason, this study was undertaken to determine the macro and micro nutrients and antioxidant potential of these plant foods. Different analyzed varieties were significantly different for proximate composition and mineral content, and each variety showed significant differences. Common bean showed higher percentage of protein with 35.09% and fat percentage of the finger millet is higher (9.2%) as compared to other varieties from other regions (1-1.5%). Higher crude fibre was assessed in mushroom with 47.77% followed with pepper corn (38.42%), bean with 30.987%, and finger millet (5.14%).Calcium was higher in finger millet with 225 mg per 100g whereas iron content was higher in mushroom with 652 mg followed with beans (543 mg), pepper corn (408 mg per 100g). Higher amount of polyphenols observed in finger millet with 8.716 µg (GAE)/mg and highest total flavonoids in pepper corn with 48.196 µg (RU)/ml. Likewise, highest FRAP in finger millet noticed with 72.0 µg of FeSO4 equivalent /mg and reducing power (ascorbic acid equivalent /mg) in mushroom (244.0) and pepper corn (242.0). All samples had higher metal chelating activity between 86.657- 83.383 IC50 µg. Similarly, higher amount of vit B6 was noted in pepper corn with 197.0 mg while lowest in seaweed with 1.76 mg/100gm.&#x0D;

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The effect of the addition of rennet from different origin (animal, plant and microbial) on the release of potential antioxidant peptides was evaluated in hard cow milk cheese. After cheese making, chemical parameters, colour, TBARs and riboflavin content were determined in the final product. Antioxidant activity of the water soluble extracts from cheese was evaluated by the DPPH radical scavenging and metal chelating activity assays. Separation of peptide fractions (<3 kDa) was performed by RP-HPLC and fractions with potential antioxidant activity were analyzed by LC-MS/MS for further identification of peptides. Results suggested that colour and riboflavin content were affected by the type of rennet used (P < .05). On the other hand, extracts of cheese with microbial rennet showed the highest antioxidant activity (P < .05). Only nine fractions isolated from the extracts showed either DPPH radical scavenging or metal chelating activities. Peptides EIVPN and DKIHPF, previously reported in other studies by showing ACE-inhibitory activity, were identified in these fractions and revealed high metal chelating activity. Moreover, a new peptide, with also high metal chelating activity, has been identified (VAPFPQ). In conclusion, it would be worthwhile to synthesis these peptides and confirm their antioxidant and metal chelating activities.

Polysaccharides obtained from bamboo shoots (Chimonobambusa quadrangularis) processing by-products: New insight into ethanol precipitation and characterization

Chimonobambusa quadrangularis polysaccharides (CPS) were extracted by ultrasonic-assisted extraction from bamboo shoots (C. quadrangularis) processing by-products. Three polysaccharide fractions, CPS70, CPS75 and CPS80, were obtained by precipitation at final ethanol concentrations of 70%, 75% and 80%, respectively. The physicochemical characterization and chemical antioxidant activities of the three polysaccharide fractions were compared on the basis of HPLC, FT-IR, XRD, TGA, and antioxidant measurements in vitro. The results suggested that ethanol concentrations used for precipitation of CPS can affect its physicochemical and associated functional properties, and antioxidant activities. Compared with CPS70 and CPS80, CPS75 had lower glucose content, higher total sugar content, and higher protein and uronic acid contents. The CPS70 and CPS80 were composed of Man, Rha, GlcA, Glc, Gal, Xyl and Ara, but none of them were found to contain GalA. In contrast, CPS75 consisted of Man, Rha, GlcA, GalA, Glc, Gal, Xyl and Ara. CPS75 had the lowest medium-high-molecular-weight value (116.53–118.18kDa) and the highest medium-low-molecular-weight value (21.30–22.68kDa). Meanwhile, CPS75 exhibited better functional properties including the repose angle, swelling capacity (SC), water retention capacity (WRC), and oil retention capacity (ORC). Moreover, CPS75 possessed higher scavenging capacities on DPPH, hydroxyl and ABTS radicals, higher oxygen radical absorbance capacity (OARC), higher metal chelating activity, and more significant reducing power. According to the results above, a final ethanol concentration of 75% could be chose to precipitate polysaccharides from bamboo shoots (C. quadrangularis) processing by-products. In summary, it is strongly recommended that the ethanol concentration employed in precipitation of natural polysaccharides could be optimized in advance.

Antioxidant Activities of Okra Protein Concentrate and Isolate after Enzymatic Hydrolysis

Three different proteolytic enzymes (pepsin, trypsin and papain) were used to prepare okra seed protein concentrate and okra seed protein isolate hydrolysates. The hydrolysates were assayed for antioxidant properties using radical scavenging, reducing power and metal chelating assays. The highest degree of hydrolysis (after 360 min) for okra protein isolates was 35.20%, 35.21% and 10.53% for pepsin, papain and trypsin respectively. The highest degree of hydrolysis (after 360 min) for okra protein concentrates was 26.8%, 28.59% and 6.47% for pepsin, papain and trypsin respectively. Pepsin hydrolysates showed higher metal chelating activity and radical scavenging activity than trypsin and papain hydrolysates. Trypsin hydrolysates showed the lowest antioxidant activities, which may be due to the low degree of hydrolysis. In general, for antioxidant activity, there was an increase in activity with an increase in the degree of hydrolysis. Similar antioxidant activity was found in both the okra protein isolate and concentrate hydrolysates except for metal chelating activity which was higher in okra protein isolate hydrolysates. This may be due to the higher ash concentration in the concentrates (9.4% in concentrates vs. 2.6% in isolates). In this study, pepsin hydrolysates with a final DH of 35.2% showed higher reducing power and metal chelating activity than trypsin and papain hydrolysates. Okra protein hydrolysates were found to have varying levels of antioxidant activity, which was dependent on the specificity of the protease and proportional to the degree of hydrolysis achieved.

Profiling of phenolic compounds and antioxidant activity of Melia azedarach L. leaves and fruits at two stages of maturity

The present work aims to investigate the maturation-related changes in phenolic profile of Melia azedarach (L.) leaves (young and old) and fruits (pulp and kernel) at two developmental stages. A total of 26 phenolic compounds were identified by high-performance liquid chromatography-diode-array detector-hyphenated with tandem mass spectrometry (HPLC-DAD-ESI–MS/MS). They include phenolic acids, flavonols and flavanols which were found mostly in glycosylated forms. The main phenolic compounds were found to be rutin (5.86–21.33%, of total integrated peak area at 280nm), quercetin-3-O-neohesperidoside (3.95–8.76%), kaempferol-3-O-rutinoside (2.73–11.23%), feruloylglucaric acid (0.85–11.84%) and feruloylquinic acid derivative (1.94–11.07%). The pattern distribution of phenolic compounds was organ-specific, and somewhat variable depending on the stage of maturation. Additionally, the total phenol content was determined as well as the antioxidant capacity using different in vitro assays. The extracts of young leaves demonstrated the highest total phenol content (85.4mg GAE/g extract), and exhibited the strongest scavenging activity against 2,2-diphenyl-1-picrylhydrazyl DPPH and the highest oxygen radical absorbance capacity ORAC (235 and 328mg Trolox equivalents/g extract, respectively) compared to old leaves and immature/mature fruit parts. In contrast, the highest metal chelating activity (MCA) was observed in immature pulp extracts (22.85mg EDTA equivalents/g extract). Pearson’s correlation and principal component analysis (PCA) showed that quercetin-3-O-neohesperidoside, rutin and kaempferol-3-O-rutinoside were the main contributors on the antioxidant capacity. On the basis of these results, M. azedarach could serve as an excellent source of natural antioxidants which could be used for pharmaceutical and cosmeceutical applications.

Soluble and bound phenolics of two different millet genera and their milled fractions: Comparative evaluation of antioxidant properties and inhibitory effects on starch hydrolysing enzyme activities

Soluble and bound phenolic extracts of foxtail and little millet whole grains and their milled fractions (dehulled, hull, bran and pearled) were comparatively evaluated for their phenolic contents, antioxidant properties and inhibition of α-amylase and α-glucosidase activities. Although whole grain foxtail millet had higher total phenolic content than little millet, both the millets possess similar total flavonoid contents. Phenolic contents decreased from outer layers to the inner layers in the order hull>bran>pearled grains in millets. Thus, hull and bran fractions possess higher phenolic content compared to other fractions. Hydroxycinnamic acid derivatives accounted for more than 83% to the total phenolic content in soluble and bound extracts of milled fractions. Caffeic, ferulic and sinapic acids were the major phenolic acids in soluble fractions of whole grain millets, while ferulic and p-coumaric acids were present in higher levels in bound fractions. Quercetin was the most abundant flavonoid detected in all the fractions. However, a remarkably high amount of daidzein was found in bran and pearled grain fractions. Milled fractions of millets exhibited various antioxidant activities. Bound extracts of pearled grain fractions with lower phenolic content presented very high metal chelating activity than other fractions. Furthermore, soluble and bound extracts of both the millets inhibited α-amylase and α-glucosidase activities in a dose-dependent manner. These results suggest the potential utility of millets and their milled fractions as ingredients in functional foods for the management of diabetes by controlling oxidative stress and inhibiting α-glucosidase and α-amylase activities.

Physicochemical, antioxidant, and antimicrobial properties of chitooligosaccharides produced using three different enzyme treatments

Abstract The objectives of this study were to investigate the efficiency of three non-substrate specific enzymes on chitooligosaccharides (COS) production and to examine the antioxidant and antimicrobial properties of different average molecular weight (MW) COS. Two chitosans with 80 and 90 degrees of deacetylation (DD) were hydrolyzed using lysozyme, papain, or cellulase (0.003% w/w) for 0–16 h. Papain showed the highest MW reduction of chitosan DD90. After 16 h of DD90 hydrolysis with papain, the average MW was 4.3 kDa which meets the requirement to be a COS (≤10 kDa). Materials produced from chitosan DD90 and papain with different MW of 5.1 (COS5), 14.3 (COS14), and 41.1 (COS41) kDa were used to determine antioxidant and antimicrobial activities. COS5 had the highest antioxidant activities of all of the assays used, i.e., the lowest 50% effective concentration (EC50) for DPPH radical scavenging activity, the highest reducing power, and the highest metal chelating activity. Escherichia coli, Salmonella typhimurium, and Salmonella enteritidis were most susceptible to COS5. All three COS were more effective against Escherichia coli than against the other pathogens. However, native chitosan inhibited Staphylococcus aureus, more efficiently.