Functional properties of fenugreek (Trigonella foenum graecum) protein concentrate

Proximate composition and physicochemical properties of a protein concentrate prepared from fenugreek seed were determined. The effects of pH and/or NaCl concentration on these properties were investigated. The protein content of fenugreek was found to be 28.4%. The crude fibre content was 9.3% and crude fat was 7.1%. The minimum protein solubility was observed at pH 4.5, which was 18.5%, while maximum protein solubility was observed at pH 11, which was 91.3%.     

Proteolytic activity,amino acid composition and protein quality of germinating fenugreek seeds (Trigonella foenum graecum L.)

This study determined the changes in proteolytic activity and trypsin inhibitor, due to germination for 120 h, and their relationships to amino acid content and protein quality. The activities of cas-ase, Hb-ase, and BAPA-ase, as well as the trypsin inhibitor of the fenugreek, increased as germination proceeded. Glutamic and aspartic acids were the richest amino acids in fenugreek seeds, followed by leucine, arginine, lysine and proline. After germination, the contents of aspartic acid, phenylalanine, tyrosine, threonine, tryptophan and valine increased, while those of glutamic acid, proline and four of the essential amino acids decreased. All the free amino acids increased after germination, while glycine decreased. Cystine, tryptophan and proline originated in a free form after germination. The chemical score, based on the essential amino acid pattern of whole egg protein, for fenugreek seeds, showed a marked decrease (21%) after germination. The in vitro pepsin, followed by pancreatin digestion, showed a slight increase for the germinated seeds. Germination of seeds lowered the C-PER, a result which indicates that the protein quality decreased.     

Isolation and purification of a novel antioxidant protein from the water extract of Sundakai (Solanum torvum) seeds

Reactive oxygen species (ROS) at physiological concentrations may be required for normal cell function. Excessive production of ROS can be detrimental to cells, because ROS can cause oxidative damage to lipids, proteins, and DNA. Herein, we describe the isolation and purification of a novel antioxidant protein the water extract of dried, powdered Sundakai (Solanum torvum [Solanaceae]) seeds. Sundakai belongs to the Solanaceae family, a small shrub, which is distributed widely in India, Malaya, China, Phillipines and tropical America. Fifty percent of ammonium sulphate-precipitated crude water extract was fractionated on a Sephadex G100 column, which yielded two peaks, PI and PII. Peaks PI and PII inhibited lipid peroxidation up to 40% and 89%, respectively in linolenic acid micelles. Rechromatographing of peak PII on Sephadex G100 yielded a single peak, indicating the homogeneity of the purified protein. SDS–PAGE analysis indicated the molecular weight of the purified protein to be ∼28 kDa. The purified protein, at 0.8 μM, inhibited deoxyribose degradation induced by generation of hydroxyl radicals by 90% and scavenged DPPH (1,1-diphenyl-2-picrylhydrazyl) radicals by 76%. The reducing power and chelating power of the purified protein, at 0.8 μM, were found to be 72% and 85%, respectively. The protein, at 0.8 μM, also offered significant protection to calf thymus DNA damage induced by H₂O₂ (1 mM). Therefore, the present study demonstrates, for the first time, a novel protein from the water extract of Sundakai seeds as an excellent antioxidant.     

Assay of the antioxidant capacity of foods using an iron(II)-catalysed lipid peroxidation model for greater nutritional relevance

The formation of free radicals by the iron-catalysed Fenton reaction is a major cause of oxidative damage in the body. Here a common assay of antioxidant capacity, inhibition of the β-carotene-linoleic acid model of lipid peroxidation, has been modified by the addition of ferrous iron (final concentration 36 μmol/l), which makes the rate of oxidation of the lipids occur 25 times faster. Such an assay can simulate the oxidative damage to membrane lipids and low density lipoproteins occurring in the body in the presence of free iron. It thus may be nutritionally more relevant than traditional chemical assays of antioxidant capacity, as it measures pre-emptive antioxidant activity, i.e. activity which prevents free radicals being formed in the first place. Pre-empting their formation is likely to be more protective than scavenging of free radicals. The relative antioxidant activity of some food products found using this new assay was very different from that found using a radical-scavenging assay. Vitamin C, at 280 mg/l, was found to be 60 times better than blackcurrant puree in scavenging free radicals, but only one eighth as good as the blackcurrant puree in preventing iron-catalysed lipid peroxidation.     

Antioxidant properties and quantitative UPLC-MS analysis of phenolic compounds from extracts of fenugreek (Trigonella foenum-graecum) seeds and bitter melon (Momordica charantia) fruit

Freeze-dried fenugreek (Trigonella foenum-graecum) seeds and bitter melon (Momordica charantia) fruit were extracted sequentially using non-polar to polar solvents, with further separation carried out on polar extracts by molecular weight cut off dialysis. The fenugreek ethyl acetate crude extract (FGE3) demonstrated the highest antioxidant activity, in terms of Trolox Equivalents (TE), for both the DPPH (35.338 ± 0.908 mg TE/g) and FRAP (77.352 ± 0.627 mg TE/g) assays. This extract also contained the highest phenolic content, in terms of Gallic Acid Equivalents (GAE) (106.316 ± 0.377 mg GAE/g). Despite having considerably lower antioxidant activity than fenugreek, the highest antioxidant activities for bitter fruit were observed in the hexane (BME1) and methanol hydrophilic < 3.5 kDa dialysed (BME4 < 3.5 kDa) extracts, while the highest phenolic content was found in the methanol hydrophilic > 3.5 kDa (BME4 > 3.5 kDa) dialysed extract. UPLC-MS was used to quantify 18 phenolic compounds from fenugreek and 13 from bitter melon in active crude extracts. The flavonoids apigenin-7-O-glycoside (1955.55 ng/mg) and luteolin-7-O-glycoside (725.50 ng/mg) were the most abundant compounds in FGE3, while bitter melon extracts contained only small amounts of mainly phenolic acids. A further 5 fenugreek and 1 bitter melon compounds were identified in trace amounts from the same extracts, respectively.     

Evaluation of antioxidant potential in selected green leafy vegetables

Green leafy vegetables represent a class of underexploited plants that are stipulated to be rich sources of natural antioxidants. A fundamental study of free radical-scavenging activity in four plant species, namely Trigonella foenum-graecum, Centella asiatica, Sauropus androgynus and Pisonia alba, was carried out by measuring the ability of methanol extracts of these plants to scavenge radicals generated by in vitro systems and by their ability to inhibit lipid peroxidation. The levels of non-enzymatic antioxidants were also determined by standard spectrophotometric methods. Correlation and regression analysis established a positive correlation between some of these antioxidants and the in vitro free radical-scavenging activity of the plant extracts. The conclusions drawn from the study indicate that in vivo studies, isolation and analysis of individual bioactive components will reveal the crucial role that these plants may play in several therapeutic formulations.     

Starch–fenugreek (Trigonella foenum-graecum L.) polysaccharide interactions in pure and soup systems

The effect of replacement of varying levels of a fenugreek polysaccharide (FP) product (0.1–0.9%) on 5% wt/wt corn starch cream soups and pure starch systems was investigated. Pasting, textural and viscoelastic characteristics along with granule size and sensory properties were determined. Significant changes were revealed with increasing FP replacement, with the effects being more pronounced on the soup formulations compared to the effects on pure starch/fenugreek systems.     

Effect of germination on the nitrogenous constituents,protein fractions, in vitro digestibility and antinutritional factors of fenugreek seeds (trigonella foenum graecum L.)

This study was designed to determine the effect of germination on nitrogenous constituents, protein fractions, in vitro digestibility and antinutritional factors (namely trypsin inhibitor and haemagglutinin) of the Egyptian fenugreek seeds Geiza 2 variety. After 96 h of germination, there was 18% decrease in the dry weight of seeds, a slight increase of total nitrogen (TN), a decrease of protein nitrogen (PN) and a marked increase of both non-protein nitrogen (NPN) and free amino acid nitrogen (FAAN). Non-protein nitrogen other than FAAN, amido nitrogen and ammonia nitrogen also increased. The protein fractions (namely albumin, globulin, prolamin and glutelin) were separated according to their solubilities in different solvents. The ratio between the four protein fractions in ungerminated seeds was 4:3.5:2.8:1 and became 2:6.5:7.7:1 after germination as calculated on the basis of their PN.Trypsin inhibitor activity per gramme of fenugreek was found to be higher by 66% in germinated fenugreek than ungerminated seeds. Both ungerminated and germinated fenugreek was found devoid of the haemagglutinin activity.Germination resulted in a slight increase in pancreatic digestibility, 33.7% decrease in digestibility by pepsin followed by pancreatin, while a small decrease was found in peptic digestibility.     

Chemical composition and in vitro antioxidant evaluation of a water-soluble Moldavian balm (Dracocephalum moldavica L.) extract

The chemical composition and antioxidant properties of a water-soluble extract of Moldavian balm (Dracocephalum moldavica L., syn. Moldavian dragonhead) prepared by hydrodistillation are presented in this study. The total phenol content was estimated as gallic acid equivalents by the Folin-Ciocalteu reagent method, while the qualitative-quantitative composition of the extract was determined by high performance liquid chromatography coupled with photodiode array detection. The antioxidant properties assessed included iron(III) reduction and iron(II) chelation and 1,1-diphenyl-2-picrylhydrazyl, 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonate) and superoxide anion free radical scavenging. In addition, the ability of the extract to protect 2-deoxy-d-ribose and bovine brain-derived phospholipids against hydroxyl radical-mediated degradation was assessed. The extract principally contained polar compounds including hydroxycinnamic acids and flavonoids, with caffeic and ferulic acids, luteolin-7-O-glucoside, rosmarinic acid, luteolin and apigenin being identified from their chromatographic behavior and spectral characteristics. The Moldavian balm extract demonstrated activity in all the antioxidant assays; however, it was not as potent as the positive control except in the phospholipid-based assay where its hydroxyl radical scavenging activity was statistically indistinguishable from that demonstrated by Pycnogenol.     

Hypocholesterolaemic and antioxidant effects of Glycyrrhiza glabra (Linn) in rats

The hypocholesterolaemic and antioxidant effects of Glycyrrhiza glabra (GG) root powder were examined in hypercholesterolaemic male albino rats. A 4-week administration of GG root powder (5 and 10 gm% in diet) to hypercholesterolaemic rats resulted in significant reduction in plasma, hepatic total lipids, cholesterol, triglycerides and plasma low-density lipoprotein and VLDL-cholesterol accompanied by significant increases in HDL-cholesterol levels. Furthermore, significant increases in fecal cholesterol, neutral sterols and bile acid excretion along with an increase in hepatic HMG-CoA reductase activity and bile acid production were observed in these animals. The root powder administration to hypercholesterolaemic rats also decreased hepatic lipid peroxidation with a concomitant increase in superoxide dismutase (SOD) and catalase activities and total ascorbic acid content. Thus, the hypocholesterolaemic and antioxidant effects of GG root appeared to be mediated via (i) accelerated cholesterol, neutral sterol and bile acid elimination through fecal matter with an increased hepatic bile acid production and (ii) improving the activities of hepatic SOD, catalase and increasing the ascorbic acid content. The normo-cholesterolaemic animals when fed with GG root powder at 10 gm% level, registered a significant decline in plasma lipid profiles and an increase in HDL-cholesterol content. The antioxidant status of these animals also was improved upon treatment.     

Chemical constituents with antioxidant activities from litchi (Litchi chinensis Sonn.) seeds

Litchi (Litchi chinensis Sonn.) is widely accepted as a delicious fruit in China and its seeds have been commonly used in traditional Chinese medicine to relieve neuralgic pain. In the present study, chemical investigation of the 95% ethanol extract of Litchi chinensis seeds led to the isolation of four new compounds, 2α,3α-epoxy-5,7,3′,4′-tetrahydroxyflavan-(4β-8-catechin) (5), 2β,3β-epoxy-5,7,3′,4′-tetrahydroxyflavan-(4α-8-epicatechin) (7), litchiol A (9) and litchiol B (12), together with 11 known ones, 2,5-dihydroxy-hexanoic acid (1), soscopoletin (2), coumaric acid (3), protocatechuic acid (4), 2α,3α-epoxy-5,7,3′,4′-tetrahydroxyflavan-(4β−8)-epicatechin (6), pterodontriol d-6-O-β-d-glucopyranoside (8), Narirutin (10), naringin (11), dihydrocharcone-4′-O-β-d-glucopyranoside (13), pinocembrin-7-rutinoside (14), pinocembrin-7-neohesperidoside (15). Their structures were mainly elucidated on the basis of NMR, MS, IR, CD and UV spectral evidences. Antioxidant activities of 14 compounds were determined by DPPH radical-scavenging assay and Trolox equivalent antioxidant capacity assay, and the results showed that four compounds, protocatechuic acid (4), 2α,3α-epoxy-5,7,3′,4′-tetrahydroxyflavan-(4β-8-catechin (5), 2α,3α-epoxy-5,7,3′,4′-tetrahydroxyflavan-(4β−8)-epicatechin (6), 2β,3β-epoxy-5,7,3′,4′-tetrahydroxyflavan-(4α-8)-epicatechin (7), exhibited moderate antioxidant activities.     

Studies on antioxidant potential of methanol extract/fractions of Acacia auriculiformis A. Cunn

Antioxidant activities of the methanol extract/fractions of Acacia auriculiformis A. Cunn were evaluated by three in vitro experiments, namely, DPPH, relative reducing power and hydroxyl radical (site specific and non site specific) assays. The differential activities of methanol extract/fractions could be correlated with their respective total phenolic contents and compared with standards (BHT and l-ascorbic acid.). The bark powder of the plant was extracted with different solvents of increasing and decreasing polarity by a maceration extraction method and then the methanol extract was further partitioned with ethyl acetate and water. The scavenging activity of extract was found to be enhanced on fractionating the extract. Moreover, among the two fractions (ethyl acetate and water fraction) and the crude extract, the water fraction exhibited good scavenging responses of 72.0%, (57.2%), 1.76 (1.52), 88.0% (82.6%) and 93.6% (83.47) in DPPH, reducing power, site specific and non-site specific hydroxyl radical scavenging assay in increasing and (decreasing) order of solvent polarity at maximum concentration, respectively. Studies are in progress to evaluate the effect of extracts/fractions in other antioxidant assays and to identify the factors responsible for the activity.     

In vitro antioxidant activity and in vivo anti-fatigue effect of loach (Misgurnus anguillicaudatus) peptides prepared by papain digestion

The in vitro antioxidant activity and in vivo anti-fatigue activity of loach peptide (LP) were determined. Results showed that LP contained the amino acids, which were expected to contribute to its antioxidant and anti-fatigue activities. LP could scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) (IC₅₀ 17.0 ± 0.54 mg/ml) and hydroxyl radicals (IC₅₀ 2.64 ± 0.29 mg/ml). It could chelate cupric ion and inhibit the lipid peroxidation in a linoleic acid emulsion system. It also prolonged the swimming time to exhaustion of mice by 20–28% compared to the control. It increased the levels of blood glucose (28–42% increase) and liver glycogen (2.3–3.0-fold increase). It decreased the levels of lactic acid and blood urea nitrogen by 10.9–27.5% and 8.6–17.5%, respectively. It also improved the endogenous cellular antioxidant enzymes in mice by increasing the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px). Therefore, LP can increase an endurance capacity and facilitate recovery from fatigue.     

Antioxidant Properties of Carotenoids In Vitro and In Vivo

Carotenoids are a class of natural pigments familiar to all through the orange-red to yellow colors of many fruits, vegetables, and flowers, as well as for the provitamin A activity that some of them possess. A body of scientific evidence suggests that carotenoids may scavenge and deactivate free radicals, acting thereby as antioxidants both in food systems (in vitro) and in the human organism (in vivo). Overall, epidemiological evidence links higher carotenoid intakes and tissue concentrations with reduced cancer and cardiovascular disease risk. However, research has also shown that the antioxidant activity of carotenoids may shift to a prooxidant character depending mainly on the biological environment in which they act. A summary of the antioxidant potential of natural carotenoids both in oil model systems and in vivo is presented in this article.     

六种中药水提物体外抗氧化活性研究

从羟自由基清除率、还原力、抑制脂质过氧化能力和清除DPPH自由基等四个方面研究了旱莲草、积雪草、莱菔子、马齿苋、女贞子、枇杷核等六味中药水提物的体外抗氧化作用。结果显示,在羟自由基清除率方面,从强到弱清除能力依次是马齿苋、积雪草、旱莲草、枇杷核、女贞子和莱菔子。在还原力方面,六味中药从强至弱顺序依次是积雪草、马齿苋、旱莲草、枇杷核、女贞子和莱菔子。在抑制脂质过氧化方面,抗氧化能力从强到弱依次是马齿苋、女贞子、莱菔子、枇杷核、积雪草和旱莲草。在DPPH自由基方面,其清除能力从大到小依次是积雪草、马齿苋、枇杷核、旱莲草、女贞子和莱菔子。结论表明,六味中药的水提物均具有一定的体外抗氧化活性。     

The in vitro antioxidant activity of lotus germ oil from supercritical fluid carbon dioxide extraction

The in vitro antioxidant activity of lotus germ oil extracted by supercritical fluid extraction (SFE) has been investigated. The distinctly high total phenolic compounds content and tocopherol content in lotus germ oil composition were found to be 9.06 ± 0.11% and 485.1 ± 50 mg/100 g, respectively. The lotus germ oil exhibited a dose-dependent inhibitory effect on the hydroxyl free radical and superoxide anion free radical. However, the scavenging effects on the superoxide anion free radical were deceased when the extract concentration was greater than 70 mg/mL. Lotus germ oil showed substantial antioxidant activity in the mice liver and kidney tissues homogenates in a dose-dependent manner. The auto-haemolysis of mice red blood cells was also blocked by lotus germ oil in a dose-dependent manner. Lotus germ oil showed a higher antioxidant activity in the lard system. The high content of phenolic compounds and tocopherol in the lotus germ oil could partially account for the antioxidant activity. These results suggest the lotus germ oil can be used as healthcare oil to develop.     

Identification of phenolic compounds and appraisal of antioxidant and antityrosinase activities from litchi (Litchi sinensis Sonn.) seeds

Antioxidant and antitryrosinase compounds from Litchi sinensis Sonn. seeds were extracted with five different types of polar solvents. The five extracts, namely ethanol extract (EE), 50% ethanol extract (50% EE), methanol extract (ME), 50% methanol extract (50% ME), and water extract (WE), were used for the evaluations of total phenolic content, antioxidant capabilities and antityrosinase activity. The 50% EE showed the highest total antioxidant capacity, scavenging the 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical and inhibitory activity against lipid peroxidation, and it was comparable to the activity of the synthetic antioxidant, butylated hydroxyl toluene. Fifty percent EE showed a better antityrosinase activity compared to the other extracts. After application of reverse phase high performance liquid chromatography, coupled to a diode array detector and electrospray ionisation mass spectra, five phenolic compounds, namely, gallic acid, procyanidin B2, (−)-gallocatechin, (−)-epicatechin and (−)-epicatechin-3-gallate were identified from 50% EE. This study suggests that litchi seed can potentially be used as a readily accessible source of natural antioxidants.     

Studies on antioxidant activities of mucuna seed (Mucuna pruriens var utilis) extract and various non‐protein amino/imino acids through in vitro models

The antioxidant activities of a methanolic extract of mucuna beans (Mucuna pruriens var utilis) and several non‐protein amino/imino acids, namely L ‐3,4‐dihydroxyphenylalanine (L ‐dopa), L ‐3‐carboxy‐6,7‐dihydroxy‐1,2,3,4‐tetrahydroisoquinoline (compound I), (?)‐1‐methyl‐3‐carboxy‐6,7‐dihydroxy‐1,2,3,4‐tetrahydroisoquinoline (compound II) and 5‐hydroxytryptophan (5‐HTP), were evaluated. By virtue of their hydrogen‐donating ability, all the tested compounds and the mucuna seed extract showed excellent reducing power, with the highest values being recorded for L ‐dopa in a dose‐dependent manner. Similarly, as compared with synthetic antioxidants (BHT and BHA) and quercetin, all the tested compounds and the seed extract were found to be more potent in free radical‐scavenging activity (P < 0.05) against α,α‐diphenyl‐β‐picrylhydrazyl (DPPH^?) radicals. Hydroxyl radicals (OH^?) and superoxide anion radicals (O₂^??) were effectively scavenged by the tested compounds, with the exception that no scavenging activity of 5‐HTP was observed on (O₂^??) up to a concentration of 2 mg ml^?1, as was also the case for BHA. Among the tested non‐protein amino/imino acids and seed extract the highest peroxidation‐inhibiting activity (95%) was recorded for 5‐HTP. On the other hand, in the linoleic acid/β‐carotene‐bleaching system, L ‐dopa, compound I and compound II acted as pro‐oxidants, whereas the seed extract showed only weak antioxidant activity as in the linoleic acid emulsion system. Copyright © 2003 Society of Chemical Industry