Bioactive peptides generated in an enzyme membrane reactor using Bacillus lentus alkaline peptidase

Bacillus lentus alkaline peptidase (BLAP) was used for casein (CN) hydrolysis in an enzyme membrane reactor (EMR) because it was found that BLAP was competitively inhibited by its products. The employed membranes had different molecular weight cut-offs (MWCO 1, 5 and 10 kDa). It was shown that the productivity of the EMR could be significantly improved (28 %) in comparison with batch hydrolysis under the same conditions after 20 h. All resulting EMR peptide mixtures showed a homogenous peptide pattern in HPLC–UV analysis. The obtained peptide mixtures exhibited Angiotensin-I-converting enzyme (ACE) inhibitory and antioxidative activity. The ACE inhibition of the peptide mixtures was dependent on the MWCO of the membranes. The resulting apparent IC₅₀ values were 115, 131 and 420 μg ml^?1 for the 1, 5 and 10 kDa MWCO membranes, respectively. In kinetic studies, a mixed-type inhibition was observed for the three peptide mixtures. The radical scavenging activity was determined with the ABTS assay, and IC₅₀ values between 20 and 25 μg ml^?1 were obtained for the generated peptide mixtures. In addition, the identified VYPFPGPIPN peptide exhibited ACE inhibition and antioxidant activity with IC₅₀ values of 325 and 6.2 μM, respectively. The peptide YQEPVLGPVRGPFPIIV exhibited radical scavenging activity with an IC₅₀ value of 5.2 μM.     

Antioxidant and melanogenesis‐inhibitory activities of collagen peptide from jellyfish (Rhopilema esculentum)

BACKGROUND: Jellyfish collagen was hydrolysed with trypsin and properase E, and jellyfish collagen peptide (JCP) was purified from the enzymatic hydrolysate using ion exchange chromatography and gel filtration. The antioxidant activity of JCP in a linoleic acid emulsion system, its superoxide anion‐ and hydroxyl radical‐scavenging activities and its copper‐chelating ability were evaluated in vitro. Initial investigations of JCP's ability to inhibit melanogenesis were carried out using cultured B16 melanoma cells. RESULTS: The molecular weight distribution of JCP was from 400 to 1200 Da. Amino acid analysis showed that JCP was rich in Gly, Pro, Ser, Ala, Glu and Asp and had a total hydrophobic amino acid content of 384.2 g kg^?1. JCP showed high antioxidant activity (IC₅₀147.8 µg mL^?1), superoxide anion‐scavenging activity (IC₅₀21.9 µg mL^?1), hydroxyl radical‐scavenging activity (IC₅₀16.7 µg mL^?1) and copper‐chelating ability (IC₅₀88.7 µg mL^?1) in vitro. It also significantly inhibited intracellular tyrosinase activity, decreased melanin content and enhanced glutathione synthesis (P < 0.05). Furthermore, JCP decreased intracellular cAMP levels and suppressed tyrosinase mRNA expression. CONCLUSION: Based on the results of this study, JCP exerts anti‐melanogenic actions via its antioxidant properties and copper‐chelating ability. JCP could be used as a natural skin‐lightening agent in the medicine and food industries. Copyright © 2009 Society of Chemical Industry     

Antioxidant peptides isolated from sea cucumber Stichopus Japonicus

The sea cucumber Stichopus japonicus protein was hydrolyzed by pepsin, trypsin, papain, acid protease and neutral protease, respectively, to get five kinds of peptide fractions: pepsin peptides (PP), trypsin peptides (TP), acid protease peptides (AP), neutral protease peptides (NP) and papain peptide (PAP). Antioxidative activities of all peptide fractions were evaluated by hydroxyl radical– (·OH) and Superoxide anion (O₂ ^{· −} )–scavenging activity. Trypsin peptide (TP) exhibited the highest antioxidative activity compared to other peptide fractions. In considering scavenging effects on hydroxyl radicals (·OH) and Superoxide anions (O₂ ^{· −} ), TP was employed for isolation, purification and identification of antioxidant peptide. To purify and characterize antioxidative peptide, two steps gel filtration, one-step ion-exchange column chromatography and reversed-phase high-performance liquid chromatography (RP-HPLC) were used. The purified antioxidative peptide TP2b-1 was a novel peptide and was sequenced as GPEPTGPTGAPQWLR, in which the low molecular weight and some amino acid constituents played important role in the radical-scavenging effects according reports. The IC₅₀ values of TP2b-1 were 138.9 μM on ·OH and 353.9 μM on O₂ ^{· −} .     

Antioxidant activity and DNA protection against oxidative damage of bambara groundnut seeds (Vigna subterranea (L.) Verdc.) as affected by processing methods

This research investigated the effects of processing by dry heating, boiling, and steaming on the antioxidant activity and DNA protection against oxidative damage of bambara groundnut seeds (Vigna subterranea (L.) Verdc.). Comparing raw and processed samples of bambara groundnut seeds, dry heating caused a significant (P < 0.05) reduction of ferric-reducing antioxidant power (FRAP), metal chelating activity, DPPH^? and ABTS^?+ radical scavenging activity. The boiling process did not cause a significant difference in FRAP and metal chelating activity and caused smaller losses in DPPH^? and ABTS^?+ radical scavenging activity than the dry heating and steaming processes. The steaming process caused a significant (P < 0.05) reduction of FRAP, DPPH^? and ABTS^?+ radical scavenging activity. For DNA protection against oxidative damage, boiled and steamed bambara groundnut seed samples were more effective with a lower minimum concentration (50 µg/mL) than raw and dry heated samples. These results indicated that the boiling process caused smaller losses antioxidant activity than dry heating and steaming. Therefore, boiling was recommended as processing method for bambara groundnut seeds to preserve antioxidant components and antioxidant activity.     

Antioxidant activity of predigested protein obtained from a range of farmed edible insects

This study investigated the antioxidant activities of peptides obtained by in vitro gastrointestinal digestion of edible insects. The antioxidant potential of edible insects' hydrolysates was determined as the free radical‐scavenging activity, ion chelating activity and reducing power. The highest antiradical activity against DPPH^˙, whose IC₅₀ value is the lowest, was noted for Amphiacusta annulipes (19.1 μg/mL) and that against ABTS^˙+ was the highest for Zophobas morio (4.6 μg/mL). The peptides obtained from A. annulipes also showed the highest Fe²⁺ chelation ability (58.82%) and reducing power (0.652). The highest ability to chelate Cu²⁺ was noted for Locusta migratoria (86.05%). The locust was characterised by the highest concentration of peptides before digestion and after digestion (3.13 and 5.88 mg/mL, respectively), and the DH was 36.29%.     

Isolation and identification of an antioxidant flavonoid compound from citrus-processing by-product

BACKGROUND: Large amounts of citrus by‐products are released from juice‐processing plants every year. Most bioactive compounds are found in the peel and inner white pulp. Flavonoids are a widely distributed group of bioactive compounds. The methanolic extract of citrus peel powder has been shown to possess strong antioxidant activity. Therefore the aim of this study was to isolate the major antioxidant flavonoid compound from Citrus unshiu (satsuma) peel as citrus by‐product and evaluate its antioxidant activity. RESULTS: The major flavonoid isolated from C. unshiu peel was identified as quercetagetin. The structure of the compound was determined by tandem mass spectrometry and ultraviolet spectroscopy. Its antioxidant activity was assessed by assays of 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) radical, hydroxyl radical and intracellular reactive oxygen species (ROS) scavenging and DNA damage inhibition. Quercetagetin showed strong DPPH radical‐scavenging activity (IC₅₀7.89 µmol L^?1) but much lower hydroxyl radical‐scavenging activity (IC₅₀203.82 µmol L^?1). Furthermore, it significantly reduced ROS in Vero cells and showed a strong protective effect against hydrogen peroxide‐induced DNA damage. CONCLUSION: The results of this study suggest that quercetagetin could be used in the functional food, cosmetic and pharmaceutical industries. Copyright © 2011 Society of Chemical Industry     

Purification and characterisation of antioxidative peptides from enzymatic hydrolysates of venison protein

To prepare antioxidative peptides from venison protein hydrolysates (APVPH), six proteases were employed for enzymatic hydrolysis, and the antioxidative activities of the hydrolysates were investigated using a free radical scavenging assay. Among the hydrolysates, papain hydrolysates which had the highest free radical scavenging activity were further separated into four groups and purified using consecutive chromatographic methods. Finally, two antioxidative peptides were obtained, and their sequences identified as Met-Gln-Ile-Phe-Val-Lys-Thr-Leu-Thr-Gly (APVPH I) and Asp-Leu-Ser-Asp-Gly-Glu-Gln-Gly-Val-Leu (APVPH II). The free radical scavenging activity of APVPH I was higher than that of APVPH II, and the IC₅₀ values of the hydroxyl, DPPH, superoxide, and peroxyl radical scavenging activities were 44, 77, 217, and 85 μg/ml, respectively. These results indicate that enzymatic hydrolysates of venison protein possess potent antioxidative activity.     

Antibacterial and antioxidant activities of the essential oil and methanol extracts of Bidens frondosa Linn

Antibacterial and antioxidant potential of essential oil, extract and its fractions of Bidens frondosa Linn were evaluated. Sixty‐one components representing 95.41% of the total oil were identified. The essential oil (7.5 μL disc^?1), methanol extract and its different organic subfractions (0.5 μg disc^?1) of B. frondosa displayed a great potential of antibacterial activity against Staphylococcus aureus (ATCC 6538 and KCTC 1916), Listeria monocytogenes ATCC 19116, Bacillus subtilis ATCC 6633, Pseudomonas aeruginosa KCTC 2004, Salmonella enteritidis KCTC 12021 and Enterobacter aerogenes KCTC 2190. Antioxidant activity was evaluated by using 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) assay. The free radical scavenging activity of ethyl acetate (EtOAc) fraction was superior to all other fractions (IC₅₀ = 11.96 μg mL^?1), which was higher than synthetic antioxidant butylated hydroxyanisole, (IC₅₀ = 18.27 μg mL^?1). Furthermore, the amount of total phenolic compounds was determined and its content in EtOAc fraction was the highest as compared to methanol extract or other fractions. The results indicate that the oil and extracts of B. frondosa could serve as an important bio‐resource of antimicrobial agents and antioxidants for using in the food industries.     

In vitro evaluation of the antioxidant activities in the differentially processed seeds from underutilized legume, Bauhinia vahlii Wight & Arn

Antioxidant potential and total phenolics content of 70% acetone extracts of the raw and processed seeds of Bauhinia vahlii were evaluated. The extract of raw seeds contained higher levels of total phenolics (30.8 g/100 g) and tannins (19.6 g/100 g) compared to dry heated and soaking followed by autoclaving seed extracts. Extracts were screened for antioxidant and free radical scavenging activities using various chemical and in vitro model systems. In all the models, except DPPH radical scavenging activity, the extract from raw seeds manifested the strongest antioxidant activity than that from processed seeds. In β-carotene/linoleic acid emulsion system and superoxide scavenging activity, the raw seed extract registered more activity when compared to the standards (butylated hydroxyanisole and α-tocopherol). Whereas, the extract from dry heated seed exhibited higher DPPH^· scavenging activity (IC₅₀ 70.77 μg/mL) than the raw seeds (IC₅₀ 74.4 μg/mL). This study has to some extent validated the antioxidant potential of the seeds of B. vahlii.     

Characterization and density functional theory study of the antioxidant activity of quercetin and its sugar-containing analogues

Inhibition of free radicals using quercetin, hyperin and rutin is examined to determine their antioxidant effects and the structure–activity relationships of flavonoids. Two species of the free radicals are used, including hydroxyl radical (·OH) and superoxide anion radical (O₂ ^?·). Density functional theory calculations under the level of B3LYP/6-311G (d) have been utilized to explore the structure, molecular properties and antioxidant abilities of the three flavonoids. Bond dissociation enthalpy (BDE) and frontier molecular orbital energy gap are investigated. They are compared with the experiment results assayed by the spectrophotometric. All of the flavonoids show a high activity on inhibiting ·OH and O₂ ^?· radicals. Scavenging activity determined by half maximal inhibitory concentration (IC₅₀) values of the three flavonoids decreases in the order: quercetin > hyperin > rutin. The calculations show that quercetin owns the lowest BDE values, which agree well with the experimental results of antioxidant activity determined by IC₅₀ values.     

The Impact of Ozone Treatment on Changes in Biologically Active Substances of Cardamom Seeds

The overall objective of this study was to develop a decontamination method against microorganisms in cardamom (Elettaria cardamomum (L.) Maton) seeds using ozone as a decontaminating agent. Ozone treatment was conducted 3 times, at 24‐h intervals, and the parameters of the process were determined assuring the least possible losses of biologically active substances (essential oils and polyphenols): ozone concentration 160 to 165.0 g/m³; flow rate 0.1 L/min; pressure 0.5 atm; time 30 min. After each step of decontamination, the microbiological profile of the cardamom seeds was studied, and the contaminating microflora was identified. Next to the microbiological profile, the total polyphenol content (TPC), composition of essential oils, free radical‐scavenging capacity, total antioxidant capacity, ferric‐reducing antioxidant power (FRAP), and LC–MS polyphenol analysis were determined. This study shows that extract from cardamom seeds after ozone treatment is characterized by a better radical scavenging activity (IC₅₀ = 24.18 ± 0.04 mg/mL) than the control sample (IC₅₀ = 31.94 ± 0.05 mg/mL). The extract from cardamom seeds after ozone treatment showed an improved FRAP activity as well (613.64 ± 49.79 mmol TE/g compared to 480.29 ± 30.91 mmol TE/g of control sample). The TPC and the total antioxidant capacity were negatively affected, respectively, 41.2% and 16.2%, compared to the control sample.     

Sweet potato protein hydrolysates: antioxidant activity and protective effects on oxidative DNA damage

In this study, sweet potato protein (SPP) hydrolysates were prepared by six enzymes (alcalase, proleather FG‐F, AS1.398, neutrase, papain and pepsin). The antioxidant activities and protective effect against oxidative DNA damage of SPP hydrolysates were investigated. Alcalase hydrolysates exhibited the highest hydroxyl radical‐scavenging activity (IC₅₀ 1.74 mg mL^?1) and Fe²⁺‐chelating ability (IC₅₀ 1.54 mg mL^?1) (P < 0.05). Compared with other five hydrolysates, the hydrolysates obtained by alcalase had the most abundant <3‐kDa fractions. In addition, below 3‐kDa fractions of alcalase hydrolysates showed the highest antioxidant activities and protective effects against DNA damage through both scavenging hydroxyl radicals and chelating Fe²⁺, which was probably because of the increase in several antioxidant amino acids, such as His, Met, Cys, Tyr and Phe, as well as the hydrophobic amino acids. The results suggested that enzymatic hydrolysis could be used as an effective technique to produce high value‐added peptides products from SPP.     

Identification of radical scavenging peptides (<3 kDa) from Burgos-type cheese

The aim of the present study was to identify low molecular weight peptides with radical scavenging activity from cheese made using different types of rennet: batch 1, animal rennet (95% chymosin and 5% bovine pepsin), batch 2, rennet of plant origin (Cynara cardunculus) and batch 3, microbial rennet (Mucor miehei). After preparation of the peptide extracts (<3 kDa), antioxidant activity was assayed by their DPPH radical scavenging and metal chelating a6ctivity. All of the batches showed antioxidant activity, which could be dependent on the peptides which are present in extracts: Batch 2 and 3 showed the highest values for DPPH inhibition and chelating effect. Fourteen fractions out of the total peptide fractions collected after RP-HPLC analysis showed radical scavenging activity using the DPPH inhibition method. Free amino acids and peptides were identified from these fractions. One of the peptides, derived from α_s1-casein, was a potential new antioxidant peptide. These antioxidant peptides were present in a lower content in extracts obtained from animal rennet cheese in comparison with the other extracts.     

Identification of phenolics in the fruit of emblica (Phyllanthus emblica L.) and their antioxidant activities

An activity-directed fractionation and purification process was used to identify the antioxidative components of emblica fruit. Dried fruit of emblica was extracted with methanol and then partitioned by ethyl ether, ethyl acetate, butanol and water. The ethyl acetate fraction showed the strongest 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity among four fractions. The ethyl acetate fraction was then subjected to separation and purification using Sephadex LH-20 chromatography and reverse-phase high-performance liquid chromatography (HPLC). Six compounds were identified to be geraniin (1), quercetin 3-β-d-glucopyranoside (2), kaempferol 3-β-d-glucopyranoside (3), isocorilagin (4), quercetin (5), and kaempferol (6), respectively, by spectral methods, ¹H and ¹³C nuclear magnetic resonance (NMR) spectroscopy, ultraviolet–visible (UV–Vis) spectrophotometry and mass spectroscopy (MS), and comparison with literatures. Compounds 2–4 and 6 were identified from emblica fruit for the first time. Furthermore, the antioxidant activities of purified compounds were screened for their antioxidative potential using lipid peroxidation and DPPH systems. All the purified compounds showed strong antioxidant and radical scavenging activities. Amongst, geraniin showed the highest antioxidant activity (4.7 and 65.7 μM of IC₅₀ values for DPPH and lipid peroxidation assay, respectively) than other purified compounds.     

Metabolite profiling and inhibitory properties of leaf extracts of Ficus benjamina towards α-glucosidase and α-amylase

The use of antioxidant-rich medicinal plants having the potential to reduce oxidative stress and postprandial hyperglycemic pressure is one of the most promising option for the management of diabetes. This study presents information on metabolite profiling and in vitro anti-diabetic effects of leaf extracts of Ficus benjamina. The DPPH (2, 2-diphenyl-1-picrylhydrazyl radicals) assay was performed to determine the in vitro antioxidant potential of the plant extracts. The anti-diabetic effects were investigated by evaluating inhibitory properties of F. benjamina leaf extracts towards carbohydrate hydrolyzing enzymes, i.e., α-glucosidase and α-amylase, whereas ¹H NMR and UHPLC-QTOF-MS/MS analytical methods were employed for metabolite profiling of F. benjamina leaf extracts. Among 40, 60, 80, and 100% ethanolic leaf extracts of F. benjamina, 80% ethanolic extract exhibited the highest antioxidant activity based upon its DPPH radical scavenging ability (IC₅₀ value: 63.71 ± 2.66 µg/mL). The 80% ethanolic leaf extract of F. benjamina also proved to be the most efficient α-glucosidase and α-amylase inhibitor with IC₅₀ values of 9.65 ± 1.04 µg/mL and 13.08 ± 1.06 µg/mL, respectively; these values were even better than acarbose with α-glucosidase inhibition activity (IC₅₀ = 116.01 ± 3.83 µg/mL) and α-amylase inhibition activity (IC₅₀ = 152.66 ± 7.32 µg/mL). Moreover, a total of 31 metabolites were identified in F. benjamina leaf extract, which may have the potential to contribute to its antioxidant and inhibitory properties against carbohydrate hydrolyzing enzymes. The findings of this study depict F. benjamina leaf extracts as a promising α-glucosidase and α-amylase inhibitor, and therefore, can be utilized for the development of anti-diabetic functional diets/nutra-pharmaceuticals.     

Antioxidant Potential of Different Dill (Anethum Graveolens L.) Leaf Extracts

Dill (Anethum graveolens L.) have been extensively used in salads, soups, and pickles for its aromatic odor and flavor. Recently, interest in plant-derived food additives has grown. In this study, the possible antioxidant properties of water, ethanol, and acetone extracts of dill leaves were investigated. In order to evaluate antioxidant activities of all extracts, different antioxidant tests were used, such as total antioxidant activity by ferric thiocyanate method, reducing power, DPPH (1,1-diphenyl-2-picryl-hydrazyl) free radical scavenging, hydrogen peroxide scavenging, and ferrous ions chelating activities. The content of phenolic compounds was also determined to be the gallic acid equivalent. Among the three extracts, the water extract of dill leaf showed the most potent antioxidative capacity in each assay, showing 79.66% (at 1 mg/mL) in the DPPH^? radical scavenging activity, 63% (at 800 μg/mL) in the metal chelating effect, 60% (at 400 μg/mL) in the H₂O₂ scavenging activity, and 0.61 absorbance (at 1 mg/mL) in the reducing power.     

Characteristics of the leaf parts of some traditional Korean salad plants used for food

BACKGROUND: Total phenolics content, antioxidant activity and cytotoxicity of the methanol extracts from leaf parts of 13 Korean traditional salad plants were investigated in order to determine their properties. RESULTS: The highest phenolics content (mg ferulic acid equivalents kg^?1 dry weight (d.w.), omit one) was found in methanol extracts from Polygonum aviculare, at 293.7 ± 6.0, followed by Euonymus alatus, at 250.7 ± 3.3, Saxifraga stolonifera, at 125.0 ± 8.1 and Ligularia fischeri, at 122.5 ± 5.9. The methanol plant extracts dose‐dependently increased free radical scavenging activity. Methanol extracts of Polygonum aviculare, Euonymus alatus and Saxifraga stolonifera, at 31 mg kg^?1, exhibited the highest 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical scavenging activity (%) by 90.8 ± 4.2, 85.7 ± 3.9 and 64.1 ± 3.2, respectively. According to 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assay, the methanol extracts from Portulaca oleracea (IC₅₀ < 25.0 µg mL^?1) showed the highest cytotoxicity against Calu‐6, followed by Plantago asiatica (49.2 µg mL^?1) and Osmunda japonica (89.6 µg mL^?1). CONCLUSION: Total phenolics content of the tested plant extracts was correlated with the DPPH radical scavenging activity, suggesting the phenolics compounds are contributing to the antioxidant properties of Korean salad plants. The leaf parts of the 13 Korean traditional salad plants described here that are currently used as foods may also provide some benefit to human health, and research into their potential benefits as preventative and/or therapeutic agents is warranted. Copyright © 2008 Society of Chemical Industry     

Effects of cationic property on the in vitro antioxidant activities of pea protein hydrolysate fractions

Yellow pea seed protein-derived peptides were produced through enzymatic hydrolysis of pea protein isolate, which was followed by ultrafiltration to isolate peptides with < 3 kDa sizes (PPH). The PPH was separated by cation-exchange chromatography into five peptide fractions (F1-F5) based on their affinity for the stationary phase. F1 contained peptides with the least amount (7.5%) of cationic amino acids while F5 contained peptides with more than 50% content of cationic amino acids. F1-F5 peptide fractions were evaluated for in vitro antioxidant activities in comparison to glutathione (GSH), an endogenous antioxidant peptide. Results showed that the peptide fraction with the least cationic property (F1) had significantly strongest (p < 0.05) scavenging activity against 1,1-diphenyl-2-picrylhydrazyl radical and hydrogen peroxide (H₂O₂) when compared to F2-F5. Generally, the scavenging of O₂?B⁻ and H₂O₂ was negatively related with the cationic property of the peptide fractions. Fractionation according to cationic property resulted in significantly increased (p < 0.05) O₂?B⁻ scavenging power of the peptide fractions (F1-F5) when compared to the unfractionated PPH. The peptide fractions showed weak or nil ferric reducing power and, regardless of cationic property, were significantly (p < 0.05) more effective at inhibiting lipid oxidation than GSH over a 7-day period. In contrast, with the exception of H₂O₂ scavenging, GSH was a more effective antioxidant than PPH and the peptide fractions. We concluded that the PPH and some of its fractions have the potential to be used as therapeutic agents against chronic diseases that develop from oxidative damage, and that the cationic property of amino acids contributed negatively to the antioxidant activity of the peptide fractions.     

Antioxidant and tyrosinase inhibitory activities of different parts of guava (<Emphasis Type="Italic">Psidium guajava</Emphasis> L.)

The antioxidant and the tyrosinase inhibitory activities of 4 different solvents (acetone, ethanol, methanol, and water) for preparation of extracts from guava (branch, fruit, leaf, and seed) were evaluated by measuring total phenolic contents (TPC), DPPH radical scavenging activity, ABTS radical scavenging activity, reducing power (RP), and tyrosinase inhibitory activity. The extracts of branch and leaf showed relatively higher antioxidant properties than those of fruit and seed. The highest TPC (141.28 mg/g gallic acid equivalents), DPPH radical scavenging activity (IC₅₀=34.01 μg/mL), ABTS radical scavenging activity (IC₅₀=3.23 μg/mL), and RP (IC₅₀= 75.63 μg/mL) were found in acetone extract of leaf, while water extract of seed had the lowest antioxidant activity. The tyrosinase inhibitory activity of ethanol extract from guava leaf was 69.56%, which was the highest activity among the extracts. These results indicate that useful bioactive substances exist in the guava branch as well as leaf extracts.     

不同极性柳叶蜡梅叶萃取物总酚含量及其抗氧化、抑菌能力研究

采用甲醇回流提取、梯度萃取得到正己烷萃取物、二氯甲烷萃取物、乙酸乙酯萃取物、正丁醇萃取物和水萃取物5个不同极性部分,以多酚含量、还原能力、对1,1-二苯基-2-三硝基苯肼(DPPH)自由基的清除能力及抑制微生物生长为评价指标,研究其体外抗氧化和抑菌活性能力。结果表明:柳叶腊梅叶多酚量较为丰富,乙酸乙酯萃取物含量最多,为(309.5±4.81)mg/g。柳叶腊梅叶萃取物具有较强的抗氧化活性,其还原能力和对DPPH自由基清除能力随其浓度的增加而增强。甲醇、正己烷、二氯甲烷、乙酸乙酯、正丁醇和水萃取物对DPPH自由基清除能力的半数抑制浓度(IC50)值分别为1.24,1.11,0.61,0.48,0.98,1.36 mg/mL。柳叶腊梅叶萃取物对大肠杆菌、金黄葡萄球菌、枯草芽孢杆菌和绿脓杆菌均有抑制作用,二氯甲烷萃取物的抑菌活性最显著,其对4种受试菌的最低抑制浓度为2 mg/mL。故柳叶腊梅叶萃取物具有较好的抗氧化和抑菌特性,为进一步分离提取活性化合物提供依据。