Active recombinant thioredoxin h protein with antioxidant activities from sweet potato (Ipomoea batatas [L.] Lam Tainong 57) storage roots

An insight investigation to the antiurolithic activity of Trachyspermum ammi using the in vitro and in vivo experiments

The crude extract of Trachyspermum ammi seeds (Ta.Cr) was studied for its antiurolithic activity using the in vivo and in vitro experiments. In the in vivo experiments, Ta.Cr treatment showed a diuretic activity at the dose of 30 and 100 mg/kg and exhibited curative effect in male hyperoxaluric Wistar rats, which received 0.75% ethylene glycol (EG) in drinking water given for 3 weeks, with 1% ammonium chloride (AC) for initial three days. In the in vitro experiments, Ta.Cr delayed the slopes of nucleation and inhibited the calcium oxalate (CaOx) crystal aggregation in a concentration-dependent manner like that of potassium citrate. Ta.Cr also inhibited DPPH free radicals like standard antioxidant drug butylated hydroxytoluene (BHT), and significantly reduced cell toxicity and LDH release in Madin-Darby canine kidney (MDCK) cells, exposed to oxalate (0.5 mM) and COM (66 µg/cm²) crystals. In isolated rabbit urinary bladder strips, Ta.Cr relaxed high K⁺ (80 mM) and CCh (1 µM)-induced contractions, showing antispasmodic activity. The findings of this study suggest that the antiurolithic activity of crude extract of Trachyspermum ammi seeds may be mediated by a number of mechanisms, including a diuretic, an inhibitor of CaOx crystal aggregation, an antioxidant, renal epithelial cell protection, and an antispasmodic, thus, showing the therapeutic potential in urolithiasis, for which there is no viable non-invasive option in modern medicine.

Progress in our understanding of plant responses to the stress of heavy metal cadmium

Heavy metal pollution is a major environmental stress affecting plant growth and development. The heavy metal cadmium inhibits various physiological processes in plants, including seed germination and seedling growth, photosynthesis, and antioxidation. Extensive research has been conducted on the toxic effects of Cd²⁺ on plants and the mechanisms of Cd²⁺ tolerance. Here, we review recent advancements in our understanding of the absorption, transport, and accumulation of Cd²⁺ in plants and the mechanisms of Cd²⁺ tolerance.

Comparative Assessment of Phenolic Profiles, Cellular Antioxidant and Antiproliferative Activities in Ten Varieties of Sweet Potato (Ipomoea Batatas) Storage Roots

Sweet potato is the sixth most important crop widely cultivated around the world with abundant varieties. Different varieties gain different phenolic profiles which has drawn researchers' attention for its unique health benefits. Our study evaluated the phenolic profiles, total and cellular antioxidant activities, antiproliferative activities, and cytotoxicity in 10 cultivated varieties of sweet potato in different colours. Among fourteen metabolites detected in our study, hyperoside, ferulic acid and caffeic acid were considered as prominent in SPSRs. According to the principle component analysis, phytochemical composition of HX22, YS15 and YS7 was quite similar. The results also evidenced that purple-fleshed varieties, such as YS43, YZ7 and YY153, have higher total phenolics content and corresponding stronger total antioxidant capacities as well as cellular antiproliferative activities against human liver cancer HepG2 cells than other varieties. The extremely significant correlation between phenolics and total antioxidant activity was also revealed by Pearson correlation analysis (p < 0.05). However, no significant relevance was found between intracellular antioxidant activity and total phenolic content or flesh colour of sweet potatoes.

Phytochemical Characterization, Antioxidant and In Vitro Cytotoxic Activity Evaluation of Juniperus oxycedrus Subsp. oxycedrus Needles and Berries

In order to evaluate the antioxidant properties of aqueous and methanol extracts of needles and berries of Juniperus oxycedrus subsp. oxycedrus (Joo) species, various antioxidant capacity assessment tests (free radical scavenging assays (DPPH• and ABTS•+ tests), ferrous ions (Fe2+) chelating activity and reducing power assay (FRAP) were conducted. In all of the tests, the extracts exhibited strong antioxidant activity. Furthermore, in-vitro cytotoxic activity assays of the methanolic extracts showed potent cytotoxic effects against two breast cancer cell lines (MDA-MB-468 and MCF-7), with no cytotoxicity towards normal cells (PBMCs). Reactive oxygen species generation was presumed to be a potential reason for the observed cytotoxic effects. According to all the above, and considering its appropriate composition of mineral elements and phenolic compounds, Joo could offer a beneficial and natural source of bioactive compounds that can be either used on the preventive side as it could potentially be used in the clinic without toxicity.

Fluorescent Carbon Dots Derived from Maillard Reaction Products: Their Properties, Biodistribution, Cytotoxicity, and Antioxidant Activity

Food-borne nanoparticles have received great attention because of their unique physicochemical properties and potential health risk. In this study, carbon dots (CDs) formed during one of the most important chemical reactions in the food processing field, the Maillard reaction from the model system including glucose and lysine, were investigated. The CDs purified from Maillard reaction products emitted a strong blue fluorescence under ultraviolet light with a fluorescent quantum yield of 16.30%. In addition, they were roughly spherical, with sizes of around 4.3 nm, and mainly composed of carbon, oxygen, hydrogen, and nitrogen. Their surface groups such as hydroxyl, amino, and carboxyl groups were found to possibly enable CDs to scavenge DPPH and hydroxyl radicals. Furthermore, the cytotoxicity assessment of CDs showed that they could readily enter HepG2 cells while causing negligible cell death at low concentration. However, high CDs concentrations were highly cytotoxic and led to cell death via interference of the glycolytic pathway.

Essential Oil from Sweet Potato Vines, a Potential New Natural Preservative, and an Antioxidant on Sweet Potato Tubers: Assessment of the Activity and the Constitution

Pathogenic fungi and oxidation are the major factors that cause the deterioration of sweet potatoes and also cause the loss of quality that makes consumption unsafe. In the present study, the in vitro results demonstrate that the essential oil from sweet potato vines exhibits significantly enhanced activity compared to that of the control. Furthermore, the essential oil can actively inhibit the growth of some common microorganisms inducing pathogenic bacteria and fungi (inhibition rates above 50% at low concentrations). A total of 31 constituents were identified using GC-MS and confirmed that linalool and p-hydroxybenzoic acid are the major active ingredients. The experiment involving actual tubers showed that the essential oil could retains its quality and effectiveness again the fungus disease. This suggests that it could be used in the food industry to increase the shelf life of stored produce (tubers) to ensure food safety without the use of additives or preservatives.

Sweet potato cysteine proteases SPAE and SPCP2 participate in sporamin degradation during storage root sprouting

Sweet potato sporamins are trypsin inhibitors and exhibit strong resistance to digestion by pepsin, trypsin and chymotrypsin. In addition, they constitute the major storage proteins in the sweet potato and, after degradation, provide nitrogen as a nutrient for seedling regrowth in sprouting storage roots. In this report, four cysteine proteases-one asparaginyl endopeptidase (SPAE), two papain-like cysteine proteases (SPCP1 and SPCP2), and one granulin-containing cysteine protease (SPCP3)-were studied to determine their association with sporamin degradation in sprouting storage roots. Sporamin degradation became significant in the flesh of storage roots starting from week 4 after sprouting and this correlated with expression levels of SPAE and SPCP2, but not of SPCP1 and SPCP3. In the outer flesh near the skin, sporamin degradation was more evident and occurred earlier than in the inner flesh of storage roots. Degradation of sporamins in the outer flesh was inversely correlated with the distance of the storage root from the sprout. Exogenous application of SPAE and SPCP2, but not SPCP3, fusion proteins to crude extracts of the outer flesh (i.e., extracted from a depth of 0.3cm and within 2cm of one-week-old sprouts) promoted in vitro sporamin degradation in a dose-dependent manner. Pre-treatment of SPAE and SPCP2 fusion proteins at 95°C for 5min prior to their application to the crude extracts reduced sporamin degradation. These data show that sweet potato asparaginyl endopeptidase SPAE and papain-like cysteine protease SPCP2 participate in sporamin degradation during storage root sprouting.

Antioxidant activities of two metallothionein-like proteins from sweet potato (Ipomoea batatas [L.] Lam. `Tainong 57') storage roots and their synthesized peptides

BACKGROUND

Metallothionein (MT) characterized by their low molecular weight and high cysteine content.

RESULTS

Two recombinant proteins of MT-I and MT-II overproduced in E. coli (M15) was purified by Ni2+-chelated affinity chromatography. The molecular mass of MT-I and MT-II are ca. 6,600 and 8,000 Da as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Total antioxidant status, DPPH radical scavenging activity, reducing power method, Fe2+-chelating ability, ferric thiocyanate (FTC) method, and protecting calf thymus DNA against hydroxyl radical-induced damage were studied. The MT-I and MT-II proteins with a concentration of 100 μg/mL exhibited the highest activity (expressed respectively as 61.72 ± 0.13 and 74.28 ± 1.15 μM Trolox equivalent antioxidative capacity, TEAC) in total antioxidant status test. Like total antioxidant status, DPPH radical scavenging activity, reducing power, Fe2+-chelating ability, FTC activity, and protecting calf thymus DNA against hydroxyl radical-induced damage all showed that MT-1 and MT-II proteins have antioxidant activities. In this study, we also found that antioxidant activities of MT-I and MT-II increased from 17% and 16% (0 h) to about 26% and 28% (24 h) after 24 h hydrolysis by trypsin. Smaller peptides increased the antioxidant activities. Four and three peptides, respectively, from MT-I and MT-II protein sequences for testing antioxidative activity were synthesized according to tryptic hydrolysis simulation. The obtained MSSGCK, CGSDCK, LTLEGSSEK, ATEGGHACK, CGNGCGGCK, and CDPCNCK showed IC50 values of 309.87, 1423.37, 3925.54, 561.32, 300.76, and 610.12 μM, respectively, when scavenging activity of DPPH radicals (%) was measured.

CONCLUSIONS

These findings mean that a cysteine residue is most important in antiradical activities. It was suggested that MT-I and MT-II might contribute their antioxidant activities against hydroxyl and peroxyl radicals.

Microwave heating enhances antioxidant and emulsifying activities of ovalbumin glycated with glucose in solid-state

The aim of this study was to characterize the properties of ovalbumin (OVA) after glycated with glucose under microwave heating. For this purpose, microwave at 480 and 640 W power levels were used for heating the OVA-glucose system in solid-state for 0, 5, 10, 15, 20 and 25 min, respectively. The results indicated that the protein molecular weight was increased after glycated with glucose under microwave treatment, the pH of the system was decreased with the increase of microwave treatment power and time, while the UV absorbance, browning intensity, antioxidant activities as well as the emulsifying activity and emulsion stability of the Maillard reaction products (MRPs) were increased in according with the raise of microwave treatment power and time. The reaction time of microwave treatment is much shorter than those using traditional methods, suggesting that microwave irradiation is a novel and efficient approach to promote Maillard reaction (MR) in dry state and improve protein antioxidant and functional properties.

A dithiol glutaredoxin cDNA from sweet potato (Ipomoea batatas [L.] Lam): enzyme properties and kinetic studies

Glutaredoxins (Grx) play an important role in reduction of protein glutathione mixed disulphides. An IbGrx cDNA (561 bp, EF362614) encoding a putative dithiol Grx was cloned from sweet potato (Ipomoea batatas [L.] Lam). The deduced amino acid sequence is conserved among the reported dithiol Grx, having a CGYC dithiol motif at the active site. A 3-D structural model was created based on the known crystal structure of a poplar Grx (GrxC1). To characterise the IbGrx protein, the coding region was subcloned into an expression vector and transformed into Escherichia coli. The recombinant His(6) -tagged IbGrx was expressed and purified by metal affinity chromatography. The purified enzyme showed a monomeric band, as demonstrated with 15% SDS-PAGE. The Michaelis constant (K(M) ) for ß-hydroxyethyl disulphide (HED) was 0.50 ± 0.08 Mm. The enzyme retained 60% activity at 80 °C for 16 min. The enzyme was active over a broad pH range from 6.0 to 11.0, and in the presence of imidazole up to 0.4 M. The enzyme was susceptible to protease.

Mitochondrial thioredoxin-2 from Manila clam (Ruditapes philippinarum) is a potent antioxidant enzyme involved in antibacterial response

Thioredoxin (TRx) is a ubiquitous protein involved in the regulation of multiple biological processes. The TRx-2 isoform is exclusively expressed in mitochondria, where it contributes to mitochondrial redox state maintenance. In the present study, a novel thioredoxin-2 gene was identified in the Manila clam, Ruditapes philippinarum. The full-length sequence of RpTRx-2 (1561 bp) consists of a 498 bp coding region encoding a 166 amino acid protein. The N-terminal region of RpTRx-2 harbors a mitochondrial localization signal (56 amino acids), while the C-terminal portion contains the characteristic (89)WCGPC(93) catalytic active site. Phylogenetic analysis revealed that RpTRx-2 is closest to its ortholog from abalone. The broad distribution pattern of RpTRx-2 mRNA in healthy animal tissues implicates a generally significant function in normal clam physiology. The transcription level of RpTRx-2, however, is highest in hemocytes. Lipopolysaccharide and Vibrio tapetis bacterium caused up-regulation of the RpTrx-2 transcript levels in gill and hemocytes. Interestingly, clam manganese superoxide dismutase (MnSOD) mRNA levels in hemocytes elicited a corresponding response to these immune challenges. RpTRx-2 was recombinantly expressed in Escherichia coli BL21 (DE3) and used in insulin disulfide reduction assay as well as metal-catalyzed oxidation assay to elucidate its antioxidant property by reducing substrate and protecting super-coiled DNA from oxidative damage through free radical scavenging, respectively. Collectively, our data indicated that RpTRx-2, a mitochondrial TRx-2 family member, is an antioxidant enzyme that may be involved in antibacterial defense of clams.

Antiurolithic activity of Origanum vulgare is mediated through multiple pathways

Background

Origanum vulgare Linn has traditionally been used in the treatment of urolithiasis. Therefore, we investigated the crude extract of Origanum vulgare for possible antiurolithic effect, to rationalize its medicinal use.

Methods

The crude aqueous-methanolic extract of Origanum vulgare (Ov.Cr) was studied using the in vitro and in vivo methods. In the in vitro experiments, supersaturated solution of calcium and oxalate, kidney epithelial cell lines (MDCK) and urinary bladder of rabbits were used, whereas, in the in vivo studies, rat model of urolithiasis was used for the study of preventive and curative effect.

Results

In the in vitro experiments, Ov.Cr exhibited a concentration-dependent (0.25-4 mg/ml) inhibitory effect on the slope of nucleation and aggregation and also decreased the number of calcium oxalate monohydrate crystals (COM) produced in calcium oxalate metastable solutions. It also showed concentration-dependent antioxidant effect against DPPH free radical and lipid peroxidation induced in rat kidney tissue homogenate. Ov.Cr reduced the cell toxicity using MTT assay and LDH release in renal epithelial cells (MDCK) exposed to oxalate (0.5 mM) and COM (66 μg/cm²) crystals. Ov.Cr relaxed high K⁺ (80 mM) induced contraction in rabbit urinary bladder strips, and shifted the calcium concentration-response curves (CRCs) towards right with suppression of the maximum response similar to that of verapamil, a standard calcium channel blocker. In male Wistar rats receiving lithogenic treatment comprising of 0.75% ethylene glycol in drinking water given for 3 weeks along with ammonium chloride (NH₄Cl) for the first 5 days, Ov.Cr treatment (10-30 mg/kg) prevented as well as reversed toxic changes including loss of body weight, polyurea, crystalluria, oxaluria, raised serum urea and creatinine levels and crystal deposition in kidneys compared to their respective controls.

Conclusion

These data indicating the antiurolithic activity in Ov.Cr, possibly mediated through inhibition of CaOx crystallization, antioxidant, renal epithelial cell protective and antispasmodic activities, rationalizes its medicinal use in urolithiasis.

Antioxidative activity of water extract of sweet potato leaves in Taiwan

This study reports the preparation of four varieties of water extract from sweet potato leaves from Taiwan, including TNG10, TNG57, TNG66 and YSP, and evaluates their antioxidative activity. The EC50 values (scavenging DPPH radicals) of TNG10, TNG57, TNG66 and YSP were 0.27±0.01, 0.19±0.01, 0.41±0.02, and 0.31±0.02mg/ml, respectively, on a freeze-dry weight basis. The total phenolic contents of these water extracts were in the order: TNG57>TNG10>TNG66>YSP. The TNG10 and TNG57 extracts exhibited better reducing power and scavenging effects of superoxide radicals than did TNG66 and YSP. At a concentration of 1mg/ml, TNG10 and TNG57 significantly protected HaCaT cells from H2O2-induced cytotoxicity. The water extracts of YSP had more flavonoids than had those of TNG66 which may have contributed to their higher activity in many antioxidative assays. These results suggest that the water extracts of all four varieties of sweet potato leaves, and especially TNG10 and TNG57, display potent antioxidative effects.

Cloning, expression, and purification of a functional glutathione reductase from sweet potato (Ipomoea batatas [L.] Lam): kinetic studies and characterization

A cDNA encoding a putative glutathione reductase (GR) was cloned from sweet potato (Ib). The deduced protein showed high level of sequence homology with GRs from other plants (79-38%). A three-dimensional (3-D) homology structure was created. The active site Cys residues are conserved in all reported GR. Functional IbGR was overexpressed and purified. The purified enzyme showed an active monomeric form on a 10% native polyacrylamide gel electrophoresis (PAGE). The monomeric nature of the enzyme was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and molecular mass determination of the native enzyme. The Michaelis constant (K(m)) values for GSSG (glutathione disulfide) and NADPH (β-nicotinamide adenine dinucleotide phosphate, reduced form) were 0.114 and 0.056 mM, respectively. The enzyme activity was inhibited by Cu(2+) and Zn(2+), but not by Ca(2+). The protein's half-life of deactivation at 70 °C was 3.3 min, and its thermal inactivation rate constant K(d) was 3.48 × 10(-1) min(-1). The enzyme was active in a broad pH range from 6.0 to 11.0 and in the presence of imidazole up to 0.8 M. The native enzyme appeared to be resistant to digestion by trypsin or chymotrypsin.

Dehydroascorbate reductase cDNA from sweet potato (Ipomoea batatas [L.] Lam): expression, enzyme properties, and kinetic studies

A cDNA encoding a putative dehydroascorbate reductase (DHAR) was cloned from sweet potato. The deduced protein showed a high level of sequence homology with DHARs from other plants (67 to approximately 81%). Functional sweet potato DHAR was overexpressed and purified. The purified enzyme showed an active monomeric form on a 12% native PAGE. The protein's half-life of deactivation at 50 degrees C was 10.1 min, and its thermal inactivation rate constant K(d) was 6.4 x 10(-2) min(-1). The enzyme was stable in a broad pH range from 6.0-11.0 and in the presence of 0.8 M imidazole. The K(m) values for DHA and GSH were 0.19 and 2.38 mM, respectively.

Redox regulation: a broadening horizon

Initially discovered in the context of photosynthesis, regulation by change in the redox state of thiol groups (S-S <--> 2SH) is now known to occur throughout biology. Several systems, each linking a hydrogen donor to an intermediary disulfide protein, act to effect changes that alter the activity of target proteins: the ferredoxin/thioredoxin system, comprised of reduced ferredoxin, a thioredoxin, and the enzyme, ferredoxin-thioredoxin reductase; the NADP/thioredoxin system, including NADPH, a thioredoxin, and NADP-thioredoxin reductase; and the glutathione/glutaredoxin system, composed of reduced glutathione and a glutaredoxin. A related disulfide protein, protein disulfide isomerase (PDI) acts in protein assembly. Regulation linked to plastoquinone and signaling induced by reactive oxygen species (ROS) and other agents are also being actively investigated. Progress made on these systems has linked redox to the regulation of an increasing number of processes not only in plants, but in other types of organisms as well. Research in areas currently under exploration promises to provide a fuller understanding of the role redox plays in cellular processes, and to further the application of this knowledge to technology and medicine.