An antioxidant protein in Curcuma comosa Roxb. Rhizomes

Curcuma comosa Roxb. is an indigenous Thai herb which is usually used as a food ingredient but it is also used in traditional folk medicine for the treatment of uterine inflammation. The crude protein extract from the rhizomes of this plant was found to possess free radical scavenging capacity, as detected by the DPPH assay. This antioxidant activity was purified by DEAE anion exchange chromatography to a fraction (called IE-1) that was comprised of a single main protein band of ∼18 kDa (UB-DEAE), as determined by SDS–PAGE resolution with Coomassie blue staining, and had a specific activity of 193.8 U/mg. In-gel trypsin digestion of the SDS–PAGE resolved UB-DEAE band followed by liquid chromatography–tandem mass spectrometry produced three reliably sequenced peptides, which all were found to very likely be fragments of a superoxide dismutase homologue (SOD, EC 1.15.1.1), an antioxidant enzyme that has been found in several plants. In support of this notion, the IE-1 fraction was found to yield positive results with the riboflavin–nitroblue tetrazolium (NBT) assay, a standard test for SOD-like activity. Together, these data then support the existence of an SOD homologue antioxidant protein in the rhizomes of C. comosa as a contributing agent to the total observed antioxidant activity.     

Anti-osteoclastogenic,estrogenic, and antioxidant activities of cell suspension cultures and tuber root extracts from Pueraria mirifica

The flavonoid contents of intact tubers and cell culture media were determined and physiological activities of Pueraria mirifica extracts were investigated. The total flavonoid contents from cell culture media (PMC) were higher than from tubers (PMT). Results from in vivo estrogenic activity assays indicated that PMT had a strong estrogenic activity in ovariectomized rats. The same amount of PMC exhibited a weak activity. In vitro osteoclast suppression investigations indicated that both PMT and PMC extracts exhibited anti-osteoclastogenic activities with low toxicities in a standard test cell line. Determination of the antioxidant potential using the DPPH assay revealed that the IC₅₀ value for PMT was lower than for PMC. P. mirifica cell cultures produce more flavonoids and exhibit a mild estrogenic and more antioxidant activities than tubers.     

Effects of protein hydrolysate from chicken feather meal on tyrosinase activity and melanin formation in B16F10 murine melanoma cells

Tyrosinase is a copper-containing enzyme that controls mammalian melanogenesis. Tyrosinase inhibitors are important for their potential application in cosmetic products. Chicken feather meal is a rich source of amino acids, which have been linked with tyrosinase inhibition activity. This study investigated the tyrosinase inhibitory properties of protein hydrolysates prepared from chicken feather meal. Protein hydrolysates prepared by pepsin-pancreatin with MW <3 kDa exhibited strong tyrosinase inhibition activity for both monophenolase (IC₅₀ 5.780 ± 0.188 µg/mL) and diphenolase activities (IC₅₀ 0.040 ± 0.024 µg/mL) in a cell-free mushroom tyrosinase system. These samples were uncompetitive inhibitors with Ki values of 18.149 and 27.189 µg/mL in monophenolase and diphenolase activities, respectively. A cell culture model showed that this hydrolysate had the strongest inhibition on the viability of B16F10 cells (IC₅₀ 1.124 ± 0.288 µg/mL) and 0.210 µg/mL of the sample exhibited inhibition of tyrosinase activity by 50.493% and melanin synthesis by 14.680% compared to the control.     

The effects of duty cycles on pulsed current electrodeposition of ZnNiAl2O3 composite on steel substrate: Microstructures,hardness and corrosion resistance

In this study, we examine the effect of duty cycles (33%, 50% and 67%) under square-wave galvanostatic pulses on the electrodeposition of zinc-nickel-alumina (ZnNiAl₂O₃) composites from a sulfate bath. XRD results showed that the dominant phases of the ZnNiAl₂O₃ electrodeposits were mixtures of Zn₂₁Ni₅ and Zn₂₂Ni₃ phases together with as Al₂O₃. The Ni content measured in the electrodeposits using EDS varied from 9.73 to 13.47 wt%. SEM results showed that finer and smoother surface electrodeposits were obtained by pulsed current electrodeposition at a low (33%) duty cycle. In addition, the corrosion properties of the electrodeposits were characterized by Tafel plots and electrochemical impedance spectroscopy (EIS), while the microhardness of the electrodeposits was measured by a Vickers hardness tester. In summary, this study revealed that pulsed current electrodeposition at a 33% duty cycle led to a finer and smoother surface morphology, an enhanced strength, a greater corrosion resistance, and a higher Ni content in the ZnNiAl₂O₃ composite coatings compared to plating at higher duty cycles or plating through DC electrodeposition.     

Antifungal and antibacterial activities of lectin from the seeds of Archidendron jiringa Nielsen

A Archidendron jiringa Nielsen lectin was purified by aqueous extraction, 90% ammonium sulphate precipitation and concanavalinA-Sepharose 4B affinity chromatography. Its specific activity was of 88.3 × 10² hemagglutination unit/mg protein for a yield of 51.6% total protein. The molecular weight is of 35.7 kDa. It has hemagglutinating activity against human blood group, rabbit, mouse, rat, guinea pig, geese and sheep erythrocytes. The hemagglutination activity of lectin was relatively insensitive to acidic pH above 2, had an optimal activity at pH 8, and stable below 45 °C for 30 min. The activity was stimulated by Ca²⁺, Mg²⁺ and Mn²⁺. The internal sequence indicated similarity with legume lectin family. Moreover, even at low concentrations antifungal activity was observed against Exserohilum turcicum, Fusarium oxysporum and Colletotrichum cassiicola. The minimal inhibitory concentrations were 0.227, 0.0567 and 0.0567 mg/ml for Bacillus subtilis, Staphylococcus aureus, and Candida albicans, respectively.     

A lectin from the rhizomes of turmeric (Curcuma longa L.) and its antifungal, antibacterial, and α-glucosidase inhibitory activities

A Curcuma longa L. lectin was purified by aqueous extraction, 80% ammonium sulfate precipitation and ConA Sepharose affinity chromatography. Its specific activity was of 64,566 HU/mg protein for a yield of 41.2% total protein. The molecular weight is of 17.3 kDa. It has hemagglutinating activity against human blood group B, rabbit, mouse, rat, guinea pig, geese, and sheep erythrocytes. The optimum pH is between 6–7, and stable up to 40°C. Activity was stimulated by Ca²⁺ and Mn²⁺. The internal sequence indicated similarity with legume lectin family. Moreover, at concentration of 47 and 94 mg/0.3 cm² disc showed antifungal activity against Exserohilum turicicum, Fusarium oxysporum, and Colectrotrichum cassiicola. The minimal inhibitory concentration were 0.002, 0.005, 0.011, 0.09, and 0.046 mg/mL Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis, Escheriehia coli, and Candida albicans, respectively. Additionally, it contains a high α-glucosidase inhibitory activity with an IC₅₀ of 8 mg/mL.     

A thermostable lectin from the rhizomes of Kaempferia parviflora

BACKGROUND: Kaempferia parviflora, or black galingale (Kra‐Chai‐Dam), belongs to the Zingiberaceae family and is used as both a food ingredient and a medicinal plant. There are diverse reports on the biological activities of compounds extracted from the plant, such as antimalarial, antifungal and an effective sexual‐enhancing role, but not on the lectins. RESULTS: A lectin was isolated from the rhizomes of Kaempferia parviflora using affinity chromatography on Concanavalin A followed by gel filtration chromatography on Sephacryl S‐100. The molecular weight of the purified lectin was about 41.7 kDa. This lectin showed haemagglutinating activity against erythrocytes from several sources, with the highest level being against those from rabbits. Moreover, the lectin was thermostable, with significant haemagglutinating activity detectable up to 75 °C. The results of trypsin digestion and liquid chromatography/tandem mass spectrometry analysis suggested that this protein could be a member of the lectin/endochitnase1 family. CONCLUSION: A lectin that showed thermotolerant haemagglutinating activity against erythrocytes from several sources was successfully purified from K. paviflora rhizomes. Peptide sequence analysis indicated that this lectin is similar to lectin/endochitinase 1 (Urtica dioica) or Hevein‐like protein (Hevea brasiliensis). Copyright © 2010 Society of Chemical Industry