Quantification of endospores in ancient permafrost using time-resolved terbium luminescence.

We describe herein a simple procedure for quantifying endospore abundances in ancient and organic-rich permafrost. We repeatedly (10x) extracted and fractionated permafrost using a tandem filter assembly composed of 3 and 0.2 µm filters. Then, the 0.2 µm filter was washed (7x), autoclaved, and the contents eluted, including dipicolinic acid (DPA). Time-resolved luminescence using Tb(EDTA) yielded a LOD of 1.46 nM DPA (6.55 × 103 endospores/mL). In review, DPA/endospore abundances were ~2.2-fold greater in older 33 ky permafrost (258 ± 36 pmol DPA gdw-1; 1.15 × 106 ± 0.16 × 106 spores gdw-1) versus younger 19 ky permafrost (p = 0.007297). This suggests that dormancy increases with permafrost age.

Cytotoxic, Cellular Antioxidant, and Antiglucuronidase Properties of the Ethanol Leaf Extract from Bulbine asphodeloides.

Bulbine asphodeloides (L.) Spreng (Xanthorrhoeaceae family), popularly known in South Africa as "ibhucu" or "Balsamkopieva," is a perennial plant traditionally used to treat skin diseases, including sunburns, rough skin, dressing burns, itches, and aging. The present study reports the cytotoxic, cellular antioxidant, and antiglucuronidase properties of the ethanol leaf extract from B. asphodeloides. The cytotoxic effect of the plant extract on human dermal fibroblast (MRHF) cells was evaluated by the bis-Benzamide H 33342 trihydrochloride/propidium iodide (Hoechst 33342/PI) dual-staining method. A validated biological cell-based assay was used to determine the cellular antioxidant activity of the extract. The antiglucuronidase and metal chelating activities were evaluated using standard in vitro methods. Lipopolysaccharide- (LPS-) induced RAW 264.7 cell model was used to determine the anti-inflammatory effect of the plant extract, and the immune-modulatory activity was performed using RAW 264.7 cells. The extract demonstrated no cytotoxic effect towards the MRHF cells at all the tested concentrations. Furthermore, the extract also possessed significant cellular antioxidant and antiglucuronidase activities, but a weak effect of metal chelating activity in a dose-dependent manner. However, the extract showed no significant anti-inflammatory and immune-stimulatory activities. Overall, the results showed that B. asphodeloides may be a useful therapeutic agent for the treatment of skin diseases, therefore supporting its ethnomedicinal usage.

Chromatographic separation simulation of metal-chelating peptides from surface plasmon resonance binding parameters.

Some metal-chelating peptides have antioxidant properties, with potential nutrition, health, and cosmetics applications. This study aimed to simulate their separation on immobilized metal ion affinity chromatography from their affinity constant for immobilized metal ion determined in surface plasmon resonance, both technics are based on peptide-metal ion interactions. In our approach, first, the affinity constant of synthetic peptides was determined by surface plasmon resonance and used as input data to numerically simulate the chromatographic separation with a transport-dispersive model based on Langmuir adsorption isotherm. Then, chromatographic separation was applied on the same peptides to determine their retention time and compare this experimental tR with the simulated tR obtained from simulation from surface plasmon resonance data. For the investigated peptides, the relative values of tR were comparable. Hence, our study demonstrated the pertinence of such numerical simulation correlating immobilized metal ion affinity chromatography and surface plasmon resonance.

Milk thistle (Silybum Marianum) as an antidote or a protective agent against natural or chemical toxicities: a review.

Biological and chemical agents cause dangerous effects on human health via different exposing ways. Recently, herbal medicine is considered as a biological and safe treatment for toxicities. Silybum marianum (milk thistle), belongs to the Asteraceae family, possesses different effects such as hepatoprotective, cardioprotective, neuroprotective, anti-inflammatory and anti-carcinogenic activities. Several studies have demonstrated that this plant has protective properties against toxic agents. Herein, the protective effects of S. marianum and its main component, silymarin, which is the mixture of flavonolignans including silibinin, silydianin and silychristin acts against different biological (mycotoxins, snake venoms, and bacterial toxins) and chemical (metals, fluoride, pesticides, cardiotoxic, neurotoxic, hepatotoxic, and nephrotoxic agents) poisons have been summarized. This review reveals that main protective effects of milk thistle and its components are attributed to radical scavenging, anti-oxidative, chelating, anti-apoptotic properties, and regulating the inflammatory responses.

Chemistry and Biology of Siderophores from Marine Microbes.

Microbial siderophores are multidentate Fe(III) chelators used by microbes during siderophore-mediated assimilation. They possess high affinity and selectivity for Fe(III). Among them, marine siderophore-mediated microbial iron uptake allows marine microbes to proliferate and survive in the iron-deficient marine environments. Due to their unique iron(III)-chelating properties, delivery system, structural diversity, and therapeutic potential, marine microbial siderophores have great potential for further development of various drug conjugates for antibiotic-resistant bacteria therapy or as a target for inhibiting siderophore virulence factors to develop novel broad-spectrum antibiotics. This review covers siderophores derived from marine microbes.

Catenulobactins A and B, Heterocyclic Peptides from Culturing Catenuloplanes sp. with a Mycolic Acid-Containing Bacterium.

The production of two new heterocyclic peptide isomers, catenulobactins A (1) and B (2), in cultures of Catenuloplanes sp. RD067331 was significantly increased when it was cocultured with a mycolic acid-containing bacterium. The planar structures and absolute configurations of the catenulobactins were determined based on NMR/MS and chiral-phase GC-MS analyses. Catenulobactin B (2) displayed Fe(III)-chelating activity and moderate cytotoxicity against P388 murine leukemia cells.

DNA-fragmentation is a source of bactericidal activity against Pseudomonas aeruginosa.

Pseudomonas aeruginosa airway infection is common in cystic fibrosis (CF), a disease also characterized by abundant extracellular DNA (eDNA) in the airways. The eDNA is mainly derived from neutrophils accumulating in the airways and contributes to a high sputum viscosity. The altered environment in the lower airways also paves the way for chronic P. aeruginosa infection. Here, we show that mice with P. aeruginosa airway infection have increased survival and decreased bacterial load after topical treatment with DNase. Furthermore, DNA from the sputum of CF patients showed increased bactericidal activity after treatment with DNase ex vivo. Both degraded DNA of neutrophil extracellular traps (NETs) and genomic DNA degraded by serum, acquired bactericidal activity against P. aeruginosa In vitro, small synthetic DNA-fragments (<100 base pairs) but not large fragments nor genomic DNA, were bactericidal against Gram-negative but not Gram-positive bacteria. The addition of divalent cations reduced bacterial killing, suggesting that chelation of divalent cations by DNA results in destabilization of the lipopolysaccharide (LPS) envelope. This is a novel antibacterial strategy where fragmentation of eDNA and DNA-fragments can be used to treat P. aeruginosa airway infection.

Phytochelatin 2 accumulates in roots of the seagrass Enhalus acoroides collected from sediment highly contaminated with lead.

Phytochelatins (PCs), the heavy metal-binding peptides of plants, play a main function in heavy metal detoxification. In this study, Enhalus acoroides samples collected at six distinct seagrass beds from the coast of Khanh Hoa province, Viet Nam, were evaluated for their PCs. The contents of different PCs in each organ including leaf, rhizome, and root were determined by using HPLC analysis. Significant differences of PC2 contents among specific organs and their relation were tested by ANOVA, Tukey test, and Pearson's correlation. The results showed that higher PC2, appearance of PC3 and a strong correlation between PC2 and Pb concentration were found in the root organ collected from a Pb contaminated area. We conclude that high Pb in the sediment induce high PC2 and PC3 production in the root. This first report on in situ detection of PCs of seagrass encourages future investigation on the ability to use seagrass for phytoremediation and as a bioindicator of heavy metals based on PC contents.

Antioxidant, anticholinesterase and antibacterial activities of Stachys guyoniana and Mentha aquatica.

CONTEXT: Stachys guyoniana Noë ex. Batt. and Mentha aquatica L. are two Algerian Lamiaceae used in folk medicine. OBJECTIVE: To investigate their antioxidant, anticholinesterase and antibacterial activities. MATERIAL AND METHODS: n-Butanol (BESG), ethyl acetate (EESG) and chloroform (CESG) extracts of S. guyoniana and methanol (MEMA) and chloroform (CEMA) aerial part extracts of M. aquatica and methanol (MERMA) and acetone (AERMA) roots extracts of M. aquatica were evaluated for their antioxidant activity by the ß-carotene-linoleic acid, DPPH• and ABTS•+ scavenging, CUPRAC and metal chelating assays. The anticholinesterase activity was tested against AChE and BChE. The antibacterial activity was assessed by MICs determination against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella heidelberg, Klebsiella pneumoniae, Enterobacter aerogenes and Morganella morganii strains. RESULTS: In the ß-carotene test, the CESG (IC50: 2.3 ± 1.27 µg/mL) exhibited the highest activity. The BESG was the best scavenger of DPPH• (IC50: 2.91 ± 0.14 µg/mL). In the ABTS test, AERMA was the most active (IC50: 4.21 ± 0.28 µg/mL). However, with the CUPRAC, the BESG exhibited the best activity (A0.50: 0.15 ± 0.05 µg/mL) and was active in metal chelating assay with 48% inhibition at 100 µg/mL. The BESG was the best AChE inhibitor (IC50: 5.78 ± 0.01 µg/mL) however, the AERMA showed the highest BChE inhibitory activity (IC50: 19.23 ± 1.42 µg/mL). The tested extracts exhibited a good antibacterial activity. CONCLUSION: This study demonstrated good antioxidant, anticholinesterase and antibacterial potential of S. guyoniana and M. aquatica, which fits in well with their use in folk medicine.

Effect of the chelation of metal cation on the antioxidant activity of chondroitin sulfates.

The antioxidant potencies of chondroitin sulfates (CSs) from shark cartilage, salmon cartilage, bovine trachea, and porcine intestinal mucosa were compared by three representative methods for the measurement of the antioxidant activity; DPPH radical scavenging activity, superoxide radical scavenging activity, and hydroxyl radical scavenging activity. CSs from salmon cartilage and bovine trachea showed higher potency in comparison with CSs from shark cartilage and porcine intestinal mucosa. Next, CS from salmon cartilage chelating with Ca(2+), Mg(2+), Mn(2+), or Zn(2+) were prepared, and their antioxidant potencies were compared. CS chelating with Ca(2+) or Mg(2+) ions showed rather decreased DPPH radical scavenging activity in comparison with CS of H(+) form. In contrast, CS chelating with Ca(2+) or Mg(2+) ion showed remarkably enhanced superoxide radical scavenging activity than CS of H(+) or Na(+) form. Moreover, CS chelating with divalent metal ions, Ca(2+), Mg(2+), Mn(2+), or Zn(2+), showed noticeably higher hydroxyl radical scavenging activity than CS of H(+) or Na(+) form. The present results revealed that the scavenging activities of, at least, superoxide radical and hydroxyl radical were enhanced by the chelation with divalent metal ions.

Phytochemicals from Dodonaea viscosa and their antioxidant and anticholinesterase activities with structure-activity relationships.

Context Dodonaea viscosa (L.) Jacq (Sapindaceae) has been used in traditional medicine as antimalarial, antidiabetic and antibacterial agent, but further investigations are needed. Objective This study determines the antioxidant and anticholinesterase activities of six compounds (1-6) and two crystals (1A and 3A) isolated from D. viscosa, and discusses their structure-activity relationships. Materials and methods Antioxidant activity was evaluated using six complementary tests, i.e., ß-carotene-linoleic acid; DPPH(•), ABTS(•+), superoxide scavenging, CUPRAC and metal chelating assays. Anticholinesterase activity was performed using the Elman method. Results Clerodane diterpenoids (1 and 2) and phenolics (3-6) - together with three crystals (1A, 3A and 7A) - were isolated from the aerial parts of D. viscosa. Compound 3A exhibited good antioxidant activity in DPPH (IC50: 27.44 ± 1.06 µM), superoxide (28.18 ± 1.35% inhibition at 100 µM) and CUPRAC (A0.5: 35.89 ± 0.09 µM) assays. Compound 5 (IC50: 11.02 ± 0.02 µM) indicated best activity in ABTS assay, and 6 (IC50: 14.30 ± 0.18 µM) in ß-carotene-linoleic acid assay. Compounds 1 and 3 were also obtained in the crystal (1A and 3A) form. Both crystals showed antioxidant activity. Furthermore, crystal 3A was more active than 3 in all activity tests. Phenol 6 possessed moderate anticholinesterase activity against acetylcholinesterase and butyrylcholinesterase enzymes (IC50 values: 158.14 ± 1.65 and 111.60 ± 1.28 µM, respectively). Discussion and conclusion This is the first report on antioxidant and anticholinesterase activities of compounds 1, 2, 5, 6, 1A and 3A, and characterisation of 7A using XRD. Furthermore, the structure-activity relationships are also discussed in detail for the first time.

Antioxidant, anticholinesterase and tyrosinase inhibition activities, and fatty acids of Crocus mathewii - A forgotten endemic angiosperm of Turkey.

Context We report the first ever chemical/biochemical study on Crocus mathewii Kerndorff (Iridaceae) - a Turkish endemic angiosperm. This plant has never been explored for its phytochemistry and bioactivities. Objective This study explores C. mathewii corm and aerial parts for the chemical and biological properties of hexane, ethyl acetate, methanol and water fractions of the extracts. Material and methods Plant material (20 g) was extracted by methanol (250 mL × 5, 3 days each) and fractioned into hexane, ethyl acetate, methanol and water. All fractions were subjected to ß-carotene-linoleic acid, DPPH(·), ABTS(·)(+), CUPRAC, metal chelating and tyrosinase inhibition activities. Hexane fractions were submitted to GC-MS analysis. Results Ethyl acetate fractions showed excellent IC50 values in DPPH(·) (aerial 36.21 ± 0.76 and corm 33.87 ± 0.02 mg/L) and ABTS(·)(+) (aerial 33.01 ± 0.79 and bulb 27.87 ± 0.33 mg/L); higher than the IC50 of the standard α-tocopherol (DPPH 116.25 ± 1.97; ABTS 52.64 ± 0.37 mg/L), higher than BHA in DPPH (57.31 ± 0.25 mg/L), but slightly lower in ABTS (19.86 ± 2.73 mg/L). Methanol extract of aerial parts also showed higher activity than α-tocopherol in DPPH (85.56 ± 11.51 mg/L) but slightly less (72.90 ± 3.66 mg/L) than both the standards in ABTS. Linoleic (aerial 53.9%, corm 43.9%) and palmitic (aerial 22.2%, corm 18%) were found as the major fatty acids. Discussion and conclusion Some fractions of C. mathewii showed higher antioxidant activities than the standards. There is a need to explore more about this plant.

Chelating Properties of Peptides from Red Seaweed Pyropia columbina and Its Effect on Iron Bio-Accessibility.

The aim of this work was to evaluate copper-chelating, iron-chelating and anticariogenic activity of peptides obtained by enzymatic hydrolysis of P. columbina protein concentrate and to study the effects of chelating peptides on iron bio-accessibility. Two hydrolyzates were obtained from P. columbina protein concentrate (PC) using two hydrolysis systems: alkaline protease (A) and alkaline protease + Flavourzyme (AF). FPLC gel filtration profile of PC shows a peak having molecular weight (MW) higher than 7000 Da (proteins). A and AF hydrolyzates had peptides with medium and low MW (1013 and 270 Da), respectively. Additionally, AF presented free amino acids with MW around 82 Da and higher content of His and Ser. Peptides from AF showed the highest chelating properties measured as copper-chelating activity (the lowest ß-carotene oxidation rate: Ro; 0.7 min(-1)), iron-chelating activity (33%), and phosphorous and Ca(2+) release inhibition (87 and 81%, respectively). These properties could indicate antioxidant properties, promotion of iron absorption and anticariogenic activity, respectively. In fact, hydrolyzates promoted iron dialyzability (≈ 16%), values being higher than that found for P. columbina seaweed. Chelating peptides from both hydrolyzates can maintain the iron in a soluble and bio-accessible form after gastrointestinal digestion.

Fusaric acid induces a notochord malformation in zebrafish via copper chelation.

Over a thousand extracts were tested for phenotypic effects in developing zebrafish embryos to identify bioactive molecules produced by endophytic fungi. One extract isolated from Fusarium sp., a widely distributed fungal genus found in soil and often associated with plants, induced an undulated notochord in developing zebrafish embryos. The active compound was isolated and identified as fusaric acid. Previous literature has shown this phenotype to be associated with copper chelation from the active site of lysyl oxidase, but the ability of fusaric acid to bind copper ions has not been well described. Isothermal titration calorimetry revealed that fusaric acid is a modest copper chelator with a binding constant of 4.4 × 10(5) M(-1). These results shed light on the toxicity of fusaric acid and the potential teratogenic effects of consuming plants infected with Fusarium sp.

Biological Activities and Chemical Composition of Methanolic Extracts of Selected Autochthonous Microalgae Strains from the Red Sea.

Four lipid-rich microalgal species from the Red Sea belonging to three different genera (Nannochloris, Picochlorum and Desmochloris), previously isolated as novel biodiesel feedstocks, were bioprospected for high-value, bioactive molecules. Methanol extracts were thus prepared from freeze-dried biomass and screened for different biological activities. Nannochloris sp. SBL1 and Desmochloris sp. SBL3 had the highest radical scavenging activity against 1,1-diphenyl-2-picrylhydrazyl, and the best copper and iron chelating activities. All species had potent butyrylcholinesterase inhibitory activity (>50%) and mildly inhibited tyrosinase. Picochlorum sp. SBL2 and Nannochloris sp. SBL4 extracts significantly reduced the viability of tumoral (HepG2 and HeLa) cells with lower toxicity against the non-tumoral murine stromal (S17) cells. Nannochloris sp. SBL1 significantly reduced the viability of Leishmania infantum down to 62% (250 µg/mL). Picochlorum sp. SBL2 had the highest total phenolic content, the major phenolic compounds identified being salicylic, coumaric and gallic acids. Neoxanthin, violaxanthin, zeaxanthin, lutein and ß-carotene were identified in the extracts of all strains, while canthaxanthin was only identified in Picochlorum sp. SBL2. Taken together, these results strongly suggest that the microalgae included in this work could be used as sources of added-value products that could be used to upgrade the final biomass value.

Anti-proliferative and matrix metalloproteinase-2 inhibition of Longkong (Lansium domesticum) extracts on human mouth epidermal carcinoma.

CONTEXT: Longkong [Lansium domesticum Corr. (Meliaceae)] is a popular tropical plant producing economic edible fruits found mainly in Southeast Asia. However, limited information is available concerning anticancer activity of Longkong. OBJECTIVE: To investigate anticancer activities in human mouth epidermal carcinoma (KB) of Longkong extracts. MATERIALS AND METHODS: Various parts of Longkong which was collected from Northern and Eastern of Thailand were extracted by the hot and cold processes using water, chloroform, and methanol. The extracts were tested for anti-oxidative activities and anti-proliferation as well as matrix metalloproteinase inhibition on KB cells. RESULTS: The hot water extract of seeds from Northern region (NSEWH), the cold water extract of old leaves from Northern region (NOLWC), and the hot chloroform extract of young leaves from Eastern region (EYLCH) showed the highest free radical scavenging, metal ion chelating, and lipid peroxidation inhibition with SC50, MC50 and IPC50 values of 0.34 ± 0.03, 0.47 ± 1.60 and 0.86 ± 0.31 mg/ml, respectively. The hot and cold chloroform extract of young fruits from Northern region (NYFCH and NYFCC) exhibited anti-proliferation effect against KB cells with IC50 values of 603.45 ± 55.35 and 765.06 ± 46.19 mg/ml, respectively. NYFCC exhibited the highest pro- and active MMP-2 inhibition at 53.03 ± 2.65 and 31.30 ± 0.43%, more than all tested standard anticancer drugs except cisplatin. DISCUSSION AND CONCLUSION: The cold chloroform extract of young fruits from Northern region appeared to contain anticancer active compounds against KB cells because of its high anti-proliferation and MMP-2 inhibition activities.

Reverse-phase HPLC separation of hemp seed (Cannabis sativa L.) protein hydrolysate produced peptide fractions with enhanced antioxidant capacity.

Hemp seed protein hydrolysate (HPH) was produced through simulated gastrointestinal tract (GIT) digestion of hemp seed protein isolate followed by partial purification and separation into eight peptide fractions by reverse-phase (RP)-HPLC. The peptide fractions exhibited higher oxygen radical absorbance capacity as well as scavenging of 2,2-diphenyl-1-picrylhydrazyl, superoxide and hydroxyl radicals when compared to HPH. Radical scavenging activities of the fractionated peptides increased as content of hydrophobic amino acids or elution time was increased, with the exception of hydroxyl radical scavenging that showed decreased trend. Glutathione (GSH), HPH and the RP-HPLC peptide fractions possessed low ferric ion reducing ability but all had strong (>60 %) metal chelating activities. Inhibition of linoleic acid oxidation by some of the HPH peptide fractions was higher at 1 mg/ml when compared to that observed at 0.1 mg/ml peptide concentration. Peptide separation resulted in higher concentration of some hydrophobic amino acids (especially proline, leucine and isoleucine) in the fractions (mainly F5 and F8) when compared to HPH. The elution time-dependent increased concentrations of the hydrophobic amino acids coupled with decreased levels of positively charged amino acids may have been responsible for the significantly higher (p < 0.05) antioxidant properties observed for some of the peptide fractions when compared to the unfractionated HPH. In conclusion, the antioxidant activity of HPH after simulated GIT digestion is mainly influenced by the amino acid composition of some of its peptides.

Variation of chemical composition of essential oils in wild populations of Thymus algeriensis Boiss. et Reut., a North African endemic species.

UNLABELLED: ABSBACKGROUND: Thymus algeriensis is an endemic aromatic plant to Tunisia largely used in folk medicine and as a culinary herb. The bulks aromatic plants come from wild populations whose essential oils compositions as well as their biological properties are severely affected by the geographical location and the phase of the plant development. Therefore, the aim of the present work is to provide more information on the variation of essential oil composition of T. algeriensis collected during the vegetative and the flowering phases and from eight different geographical regions. Besides, influence of population location and phenological stage on yield and metal chelating activity of essential oils is also assessed. METHODS: The essential oil composition of Thymus algeriensis was determined mainly by GC/FID and GC/MS. The chemical differentiation among populations performed on all compounds was assessed by linear discriminate analysis and cluster analysis based on Euclidean distance. RESULTS: A total of 71 compounds, representing 88.99 to 99.76% of the total oil, were identified. A significant effect of the population location on the chemical composition variability of T. algeriensis oil was observed. Only 18 out of 71 compounds showed a statistically significant variation among population locations and phenological stages. Chemical differentiation among populations was high. Minor compounds play an important role to distinguish between chemical groups. Five chemotypes according to the major compounds have been distinguished. Chemotypes distribution is linked to the population location and not to bioclimate, indicating that local selective environmental factors acted on the chemotype diversity. CONCLUSIONS: The major compounds at the species level were α-pinene (7.41-13.94%), 1,8-cineole (7.55-22.07%), cis-sabinene hydrate (0.10-12.95%), camphor (6.8-19.93%), 4-terpineol (1.55-11.86%), terpenyl acetate (0-14.92%) and viridiflorol (0-11.49%). Based on major compounds, the populations were represented by (α-pinene/1,8-cineole/cis-sabinene hydrate/camphor/viridiflorol), (1,8-cineole/camphor/terpenyl acetate), (α-pinene/1,8-cineole/camphor), (1,8-cineole/camphor/4-terpineol) and (α-pinene/1,8-cineole/cis-sabinene hydrate/camphor/4-terpineol) chemotypes. Variation of phenological stage did not have a statistically significant effect on the yield and metal chelating activity of the essential oil. These results can be used to investigate the geographical location and the harvesting time of this plant for relevant industries.

Phenolic content and antioxidant activity of Hibiscus cannabinus L. seed extracts after sequential solvent extraction.

A sequential solvent extraction scheme was employed for the extraction of antioxidant compounds from kenaf (Hibiscus cannabinus L.) seeds. Yield of extracts varied widely among the solvents and was the highest for hexane extract (16.6% based on dry weight basis), while water extract exhibited the highest total phenolic content (18.78 mg GAE/g extract), total flavonoid content (2.49 mg RE/g extract), and antioxidant activities (p < 0.05). DPPH and hydroxyl radical scavenging, β-carotene bleaching, metal chelating activity, ferric thiocyanate and thiobarbituric acid reactive substances assays were employed to comprehensively assess the antioxidant potential of different solvent extracts prepared sequentially. Besides water, methanolic extract also exhibited high retardation towards the formation of hydroperoxides and thiobarbituric acid reactive substances in the total antioxidant activity tests (p < 0.05). As conclusion, water and methanol extracts of kenaf seed may potentially serve as new sources of antioxidants for food and nutraceutical applications.

Amino acid composition and antioxidant activities of hydrolysates and peptide fractions from porcine collagen.

The amino acid composition and antioxidant activities of different hydrolysates from porcine collagen were analyzed. The gelatin was hydrolyzed for antioxidative peptides with various proteases, namely papain, protease from bovine pancreas, protease from Streptomyces, and cocktail mixture of protease from bovine pancreas and protease from Streptomyces. The hydrolysates were assessed using methods of DPPH radical-scavenging ability, metal-chelating ability and lipid peroxidation inhibition activity. It was found that the collagen hydrolysates by different protease treatments had different amino acid compositions and antioxidant properties. However, the contents of Hyp and Pro were improved and the content of Gly was decreased in each collagen hydrolysate compared with collagen. The hydrolysate prepared with the cocktail mixture of proteases, which exhibited the highest antioxidant activity, was separated into 6 fractions by gel filtration chromatography. Fraction 2 was further separated by ion exchange chromatography. Fraction 2b with abundant basic amino acids and Fraction 2d which was slightly acidic fractions had higher radical-scavenging and metal-chelating activities, and both Fraction 2b and 2d contained more hydrophobic amino acids. The results confirmed that the antioxidative peptides were rich in Hyp, Pro and Gly, which accounted for half of amino acid composition. This article added further support to the preparation of natural antioxidative peptides from porcine skin collagen.