Effect of γ-irradiation on the antioxidant activity of turmeric (Curcuma longa L.) extracts

Effect of γ-irradiation (10KGy) on the antioxidant property of turmeric extracts was investigated. γ-irradiated as well as non-irradiated turmeric samples were subjected to successive solvent extraction using hexane, benzene, and 80% aq. methanol. Benzene extract, containing mainly curcuminoids were subjected to column fractionation in order to isolate the individual curcuminoids. The curcuminoid analogues as well as the above fractions were then tested for their antioxidant activity by measuring thiobarbituric acid value (TBAV) and peroxide value (PV) based on the air oxidation of linoleic acid. γ-irradiation at a dose of 10KGy did not affect the antioxidant activity of turmeric extracts studied.     

Assessment of Indigo (Polygonum tinctorium Ait.) water extracts’ bioactive compounds,and their antioxidant and antiproliferative activities

There are a few investigations on Indigo (Polygonum tinctorium Ait.), as a medicinal plant. Therefore, the aim of this study was to assess the contents of bioactive compounds, antioxidant and antiproliferative activities and to compare with another medicinal plant Prolipid. It was found that the bioactive compounds from different parts of Indigo water extracts varied (P < 0.05): polyphenols and flavonoids were significantly higher in Prolipid, flavanols in Indigo seeds, and vitamin C similar in Indigo leaves and Prolipid. The antioxidant activity by ABTS, FRAP, CUPRAC and DPPH assays was significantly different (P < 0.05): the highest in Prolipid, following by Indigo mature leaves. DPPH kinetic measurements compared, distinguished and discriminated the antiradical activity among Indigo and Prolipid water extracts by multivariate analysis. The interaction between polyphenol extracts of Indigo mature leaves and BSA showed that Indigo has a strong ability, as other medicinal plants, to quench the intrinsic fluorescence of BSA by forming complexes. In conclusion, for the first time Indigo mature leaves were analyzed and compared with widely consumed Prolipid. The relatively high content of bioactive compounds, positive antioxidant, fluorescence and antiproliferative properties of Indigo justify the use of this plant as a new source of valuable antioxidants.     

Effect of γ-irradiation on antioxidant activity of black pepper (Piper nigrum L.)

Antioxidant activity and EPR investigations of irradiated ground black pepper (Piper nigrum L.) were evaluated. The black pepper was exposed to γ-irradiation at doses from 5 to 30 kGy. The effect of irradiation on antioxidant properties of black pepper extracts was investigated by radical-scavenging effect on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, by determination of reducing power and content of thiobarbituric acid-reactive substances. Some significant changes were observed in creation of thiobarbituric acid-reactive substances (TBARS). Difference between non-irradiated and irradiated samples at the legal European limit dose of 10 kGy reached, on average, 23% and, at the Food and Drug Administration (FDA) 30 kGy limit, 33%. Irradiation affected significantly the DPPH radical-scavenging activity and reducing power of ground black pepper extracts. The γ-radiation treatment of ground black pepper samples observed by EPR, resulted in the production of three paramagnetic species (GI–GIII) characterized by different origin, thermal behaviour and stability. The axially symmetric EPR resonances, GI and GII, were assigned to the carbohydrate radical structures. The spin Hamiltonian parameters of GIII possessed the characteristic features of “cellulosic” radical species. The EPR measurements, performed 20 weeks after the radiation process, confirmed that temperature increase from 298 to 353 K, caused significant decrease of integral EPR signal intensity for γ-irradiated samples (∼40%), compared to the reference (non-irradiated) ground black pepper, where only 13% drop was found. Significant correlation between EPR and thiobarbituric acid methods was assessed by study of antioxidant activity changes in relation to irradiation doses and also in the case of spice storage, between EPR and reducing power methods.     

Effect of enzyme treatment with β-glucosidase on antioxidant capacity of mulberry (Morus alba L.) leaf extract

This study was carried out to investigate the effect of enzyme treatment with β-glucosidase on antioxidant capacity of the mulberry leaf extract (MLE) using oxygen radical absorbance capacity (ORAC) and cellular antioxidant capacity (CAC) assay. The MLE was prepared by autoclaving at 121°C for 15 min and treated with β-glucosidase for 9 hr. High pressure liquid chromatography (HPLC) analysis showed that only qercetin-3-β-d-glucose (QT-G) among quercetin (QT) glycosides of MLE, including QT-G, quercetin-3-O-glucose-6″-acetate (QT-GA), and rutin (RT), was converted into QT by 3 hr treatment with β-glucosidase. The in vitro peroxyl radical- and hydroxyl radical scavenging capacity significantly increased after the enzyme treatment using β-glucosidase for 6 and 9 hr, respectively. The metal chelating activity increased after the enzyme treatment using β-glucosidase for 3 hr. The intracellular antioxidant capacity of MLE to protect AAPH- and Cu²⁺-induced oxidative stress in HepG2 cells significantly increased after the enzyme treatment using β-glucosidase for 3 and 6 hr, respectively, indicating that QT may be released from QT-G by β-glucosidase and penetrate into cell membrane so that it can contribute to the intracellular antioxidant capacity of MLE.     

Anthocyanin stability and antioxidant activity of spray-dried açai (Euterpe oleracea Mart.) juice produced with different carrier agents

Anthocyanin stability and antioxidant activity of powdered açai juice was evaluated throughout 120 days. Powders were produced by spray drying using four types of carrier agents: maltodextrin 10DE, maltodextrin 20DE, gum Arabic and tapioca starch. Samples were stored at different temperatures (25 and 35 °C) and water activities (0.328 and 0.529), in order to verify the effect of these conditions on anthocyanin degradation and antioxidant activity reduction. Anthocyanin degradation exhibited two first-order kinetics: the first one, with higher reaction rate constant, up to 45–60 days of storage, and the second one, after this period, with lower degradation rate. Both temperature and water activity negatively affected anthocyanin stability. Antioxidant activity also decreased with increasing water activity, but was higher for the powders stored at 35 °C. Maltodextrin 10DE was the carrier agent that showed the best pigment protection and the highest antioxidant activity, for all the conditions studied.     

Effects of γ-irradiation on the biological activity of burdock (Arctium lappa L.) extracts

Burdock (Arctium lappa L.) extracts were prepared with different extraction methods, ethanol (70%, RT) and hot water (85°C for 3 hr, HT), and their biological activities were investigated after γ-irradiation (10 and 20 kGy). Color of the burdock extracts became brighter after application of irradiation regardless of the extraction system. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity of the burdock extracts with RT and HT were 54.56 and 59.21% at 500 ppm, respectively, and the lipid oxidation of oil emulsion was delayed by addition of the extracts. The HT29 cancer cell viability was inhibited by burdock extracts with RT up to 52.45 at a 250 ppm level. The anti-mutagenicitiy against 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole and 2-nitrofluorene were also found. Results indicate that burdock extract possesses biological activities and RT showed an increasing trend in antixodiative activity and inhibition of cancer cell viability. Brighter color of the burdock extract after irradiation may improve industrial applicability.     

Effects of heating method and temperature in combination with hypoxic treatment on γ-aminobutyric acid,phenolics content and antioxidant activity of germinated rice

Heat and hypoxic treatments were combined with soaking to enhance γ-aminobutyric acid (GABA) production in germinated paddy (GP). Effects of heating temperature, heating techniques, that is, impinging stream drying (ISD) and tray drying (TD), and germination time on the GABA content, phenolics content and antioxidant activity were also investigated. Heating temperature had a significant effect on the GABA content; both ISD and TD helped increase the GABA content when the post-treatment grain temperature was 38–40.5 °C. Within this grain temperature range, soaking in combination with heat and hypoxic treatments (S-ISD-H and S-TD-H) yielded GP with higher GABA content than soaking (S) and soaking in combination with hypoxic treatment (S-H). However, ISD was noted to be more suitable than TD. Phenolics content and antioxidant activity of GP prepared by S-ISD-H at different heating temperatures and S-H were not significantly different but were higher than those of the GP prepared by S.     

Fast LC–MS analysis of gallotannins from mango (Mangifera indica L.) kernels and effects of methanolysis on their antibacterial activity and iron binding capacity

Mango (Mangifera indica L.) kernels were successively extracted with hexane and methanol and the effects of extraction on the profile of gallotannins as well as on their antimicrobial activity and iron-binding capacity were determined. A new method based on fast liquid chromatography with diode array and mass spectrometric detection was developed which allowed the separation of gallotannins in less than 7 min. Gallotannins remained stable during Soxhlet extraction with hexane. Methanolysis led to the degradation of highly galloylated tannins to yield penta-O-galloylglucose and methyl gallate. The antimicrobial activity of the extracts was not affected by the compositional change, whereas the iron binding capacity increased with increasing amounts of methyl gallate. The less complex profile of antimicrobial compounds obtained after methanolysis compared to the crude extract will facilitate the standardization of extracts and their application in target products.     

Effectiveness of edible coatings combined with mild heat shocks on microbial spoilage and sensory quality of fresh cut broccoli (Brassica oleracea L.)

The use of edible coatings and mild heat shocks is proposed as postharvest treatments to prevent microbial deterioration of refrigerated broccoli. Minimally processed broccoli was coated with either chitosan or carboxymethyl-cellulose (CMC) combined or not with a previous application of a mild heat shock. The evolution of microbial populations (mesophilic, psycrotrophic, Enterobacteriaceae, molds and yeast, and lactic acid bacteria) was studied during 20 d of storage and fitted to Gompertz and logistic models. Results revealed that, at the end of the storage, chitosan coating significantly reduced all microbiological population counts, except lactic acid bacteria; while higher reduction was observed with chitosan coating combined with a heat shock treatment. A significant delay at the beginning of the exponential phase was observed for all the bacterial populations analyzed. On the other hand, CMC coating, with and without a previous thermal treatment, did not exert any antibacterial effect. Excellent agreement was found between experimental microbial counts and predicted values obtained from Gompertz and logistic models. Kinetic modeling was found to be valuable for prediction of microbiological shelf life of broccoli during storage. Results showed that the application of chitosan coating effectively maintained microbiological quality and extended shelf life of minimally processed broccoli. According to these results, the use of the edible chitosan coating alone or in combination with a heat mild shock appear to be a viable alternative for controlling microbiological growth and sensory attributes in minimally processed broccoli. PRACTICAL APPLICATION: The continuous consumer interest in high quality and food safety, combined with environmental concern has induced to the development and study of edible coatings that avoid the use of synthetic materials. The edible coatings, formed from generally recognized as safe materials, have the potential to reduce weight loss, respiration rate, and improve food appearance and integrity. It is one of the most effective methods to maintain food quality. On the other hand, heat treatments have been demonstrated to be effective as a nonchemical means of improving postharvest quality for a variety of horticultural products. The applications of mild heat shocks combined with edible coatings constitute an alternative for the natural preservation of crops for which the use of synthetic chemicals is objectionable.     

Effect of γ-irradiation on bioactivity, fatty acid compositions and volatile compounds of clary sage seed (Salvia sclarea L.)

Clary sage seeds (Salvia sclarea L.) were obtained from plants cultivated, and 2.5, 4.0, 5.5, and 7.0 kGy doses of γ-irradiation were applied to the clary sage seeds. They were then analyzed for their protein, ash, oil and dry matter contents, and fatty acid composition. Additionally, the total phenolic contents, antiradical, antioxidant activities, and volatile compounds of the clary sage seed extract were determined. There was no significant difference in protein content. However, the moisture, oil, and ash contents of the samples were affected by irradiation. While the 7 kGy dose had a positive effect on the total phenolic content and antiradical activity of the sage seed extract, all doses have negative effects on the antioxidant activity of the sage seed. The main fatty acid of the sage seed was remarkably found as α-linolenic acid. The four irradiation levels caused significant differences in fatty acid composition by affecting all fatty acids except palmitic, palmitoleic, and eicosenoic acids. The dominant volatile compounds of control sage seed were found as β-pinene (18.81%) and limonene (15.60%). Higher doses of the irradiation decreased volatile components of sage seed. Clary sage seed including high omega-3 can be irradiated with low doses (≤ 2.5 kGy) of γ-irradiation. PRACTICAL APPLICATION: Clary sage is one of the most popular Salvia species in Turkey and many countries. Clary sage seed has approximately 29% oil content and this oil contains >50% of α-linolenic acid. γ-Irradiation is widely applied in the preservation of spice quality. The present study shows that the antioxidant activity of the clary sage seed is decreased by γ-irradiation. Additionally, higher doses of irradiation also decreased the volatile components of sage seed. Therefore, we suggest that clary sage seed which includes high levels of omega-3 should be irradiated with low doses (≤ 2.5 kGy) of γ-irradiation.     

Inhibition of DNA polymerase λ by glucosyl compounds from soybean (Glycine max L.) and their associated inflammatory activity

During the screening of selective DNA polymerase (pol) inhibitors, we isolated two glucosyl compounds, a cerebroside (glucosyl ceramide, AS-1-4, compound 1) and a steroidal glycoside (eleutheroside A, compound 2) from soybean (Glycine max L.). Compounds 1 and 2 selectively inhibited the activity of eukaryotic pol λ in vitro, with IC₅₀ values of 12.2 and 9.1 μM, respectively. These compounds did not influence the activities of other eukaryotic pols including those from the A-family (pol γ), B-family (pols α, δ and ε), and Y-family (pols η, ι and κ), and also showed no effect on the activity of pol β which is of the same family (X) as pol λ. The tendency for in vitro pol λ inhibition by these compounds showed a positive correlation with the in vivo suppression of TPA (12-O-tetradecanoylphorbol-13-acetate)-induced inflammation in mouse ear. These results suggest that these glucosyl compounds from soybean may be useful for their anti-inflammatory properties.     

Isolation and identification of phenolic compounds from the seeds of Perilla frutescens (L.) and their inhibitory activities against α-glucosidase and aldose reductase

Five phenolic compounds were isolated from the seeds of Perilla (Perilla frutescens L.) using gradient solvent fractionation, silica gel column chromatography, and preparative high-performance liquid chromatography (HPLC). Their chemical structures were identified as caffeic acid-3-O-glucoside (1), rosmarinic acid-3-O-glucoside (2), rosmarinic acid (3), luteolin (4), and apigenin (5) using NMR spectroscopy and HPLC-ESI/MS analysis. Among them, luteolin (4) inhibited α-glucosidase (EC 3.2.1.20) with IC(50) value of 45.4μM. The inhibition kinetic analysed by Dixon plot indicate that luteolin is a noncompetitive inhibitor, and the inhibition constant K(I) was calculated at 45.0μM. Moreover, rosmarinic acid (3) and luteolin (4) inhibited recombinant human aldose reductase (EC 1.1.1.21) with IC(50) values of 11.2 and 0.6μM, respectively. Notably, the inhibition kinetic of luteolin (4) follows a hyperbolic dependence on aldose reductase inhibition by Dixon plot. Thus, inhibition kinetic indicates that luteolin (4) is a mixed-type inhibitor.