HPLC–PDA–ESI–MS/MS profiling and chemopreventive potential of Eucalyptus gomphocephala DC

An HPLC–PDA–ESI/MS/MS method was developed to identify the phytoconstituents of the EtOAc fraction of Eucalyptus gomphocephala DC. The antioxidant effect of the EtOAc fraction together with its sub-fractions was determined in vitro. The cytotoxicity was evaluated on different cell lines. The EtOAc fraction exhibited strong antioxidant activity, reduced the viability of all cell lines and was more active on MCF-7 and HepG-2 cell lines. Subsequently, the cytotoxicity of the sub-fractions and the isolated compounds were tested on MCF-7, HepG-2. The EtOAc fraction possessed potential antitumour promoting properties. It inhibited the stimulated NO (20%), 5-LOX (48.0%) and COX-2 (49.7%) respectively (at concentration of 20 μg/ml). This study suggests that this fraction is a source of different antioxidant and cytotoxic compounds with potential chemopreventive properties that might prevent different stages of the carcinogenesis process.     

Star-anise (Illicium verum) and black caraway (Carum nigrum) as natural antioxidants

The various solvent fractions of star-anise (Illicium verum) and black caraway (Carum nigrum), along with their spice powders and volatile oils, were prepared and evaluated for antioxygenic activity, using different methods. Star-anise powder and its ethanol/water (80:20)-soluble fraction showed strong antioxygenic activity in refined sunflower oil while the petroleum ether fraction exhibited marginal antioxygenic activity and the water-soluble fraction was practically devoid of any activity in sunflower oil. The black caraway powder showed marginal antioxygenic activity while its ethanol/water fraction (80:20) showed strong antioxygenic activity and all other fractions showed slight pro-oxygenic activity in refined sunflower oil. Both the spice powders and their extracts were also evaluated for antioxidant activity by linoleic acid peroxidaton, β-carotene-linoleate and 1, 1-diphenyl-2-picryl hydrazyl (DPPH) methods. Both the star-anise and black caraway powders, as well as their ethanol/water extracts, exhibited strong antioxygenic activity. Volatile oils from both the spices exhibited antioxygenic activity and the activity did not seem to be concentration-dependent. Volatile oils from star-anise showed relatively higher antioxygenic activity than did those from black caraway. Gas chromatography–mass spectroscopy (GC–MS) studies on star-anise and black caraway volatile oils resulted in the identification of 25 and 22 compounds, respectively, representing 94–97% of the total content.     

Identification of the major flavonoids from pericarp tissues of lychee fruit in relation to their antioxidant activities

Large amount of polyphenolic compounds with strong antioxidant activity was present in the pericarp of harvested lychee fruits. Flavonoids were extracted with 85% ethanol:15% HCl from lychee fruit pericarp tissues. Most of the lychee flavonoids were partitioned into the ethyl acetate fraction. Three major components of the ethyl acetate fraction were obtained by reverse phase high-performance liquid chromatography and determined to be flavanol by their ultraviolet/visible spectra. Furthermore, these three components were identified as proanthocyanidin B4, proanthocyanidin B2 and epicatechin by nuclear magnetic resonance and mass spectrometry. The ethyl acetate fraction, proanthocyanidin B4, proanthocyanidin B2 and epicatechin exhibited a good antioxidant capability. The hydroxyl radical and superoxide anion scavenging activities of proanthocyanidin B2 was greater than those of proanthocyanidin B4 and epicatechin, while the epicatechin had the highest DPPH scavenging activity     

Antioxidant phenolic compounds from Smilax sebeana Miq.

Methanol extract and sub-fractions of Smilax sebeana rhizomes and roots were analyzed to evaluate the compounds involved in antioxidant activity. In all separated fractions of the different polarity solvents, ethyl acetate fraction showed the highest antioxidant activity and total phenolic content. This fraction was subjected to the sephadex LH-20 column and preparative HPLC for purification. Six phenolic compounds, chlorogenic acid (1), 4-formylphenol (2), epicatechin (3), cinchonain IIa (4), Ia (5) and Ib (6) were isolated and identified by spectroscopic analyses and further evaluated their potential antioxidant activities by DPPH and superoxide radical scavenging assays. Compared with synthetic antioxidant Trolox, except 4-formylphenol, the other isolated five compounds exhibited excellent antioxidant activities. This is the first report on the chemical constituents of S. sebeana which potentially involved in antioxidant activity. The results suggest that the ethyl acetate extract of S. sebeana might be used as a readily accessible source of natural antioxidant.     

Antioxidant activity and phenolic composition of sumac (Rhus coriaria L.) extracts

Antioxidant activity and phenolic compounds of sumac extracts were investigated. Sumac was extracted in methanol and subjected to solvent–solvent partitioning to yield two fractions as ethyl acetate and aqueous. Methanol extract was further fractioned over Sephadex LH-20 column. Antioxidant activity of extracts and fractions were screened using ferric thiocyanate and DPPH radical scavenging methods. Phenolic composition of active fraction(s) was determined by HPLC–MS systems. Those fractions which exhibited strong antioxidant activity were rich in anthocyanins and hydrolysable tannins. While gallic acid was the main phenolic acid in the extracts, anthocyanin fraction contained cyanidin, peonidin, pelargonidin, petunidin, and delphinidin glucosides and coumarates. Pentagalloyl glucose was abundant in the hydrolysable tannin fraction. Effective scavenging concentration (EC₅₀) on DPPH radical was 0.70 μg/mL both in ethyl acetate and tannin fractions, and 5.33 μg/mL in anthocyanin rich fraction. Same extracts and fractions showed moderate lipid peroxidation inhibition effect compared with the synthetic antioxidants. The findings demonstrate that sumac can be used as a natural antioxidant.     

Antioxidant and antibacterial activities of Nephelium lappaceum L. extracts

Ether, methanolic and aqueous extracts of lyophilized rambutan (Nephelium lappaceum L.) peels and seeds were evaluated for phenolic contents, antioxidant and antibacterial activities. High amounts of phenolic compounds were found in the peel extracts and the highest content was in the methanolic fraction (542.2 mg/g dry extract). Several potential antioxidant activities, including reducing power, β-carotene bleaching, linoleic peroxidation and free radical scavenging activity, were evaluated. The peel extracts exhibited higher antioxidant activity than the seed extracts in all methods determined (P < 0.05). The methanolic fraction was found to be the most active antioxidant as shown by their 50% DPPH inhibition concentration, 4.94 μg/mL. The results indicated this fraction exhibited greater DPPH radical scavenging activity than BHT and ascorbic acid (0.32 g dry extract/g BHT or ascorbic acid). Antibacterial activity against eight bacterial strains was assessed by disc diffusion and broth macrodilution methods. All peel extracts exhibited antibacterial activity against five pathogenic bacteria. The most sensitive strain, Staphylococcus epidermidis, was inhibited by the methanolic extract (MIC 2.0 mg/mL).     

Biological activity and composition of extract from aerial root of Ficus microcarpa L. fil.

Total phenolic content, antioxidant and antibacterial activities of Ficus microcarpa aerial roots were determined on methanol extract and its sub-fractions (hexane, ethyl acetate, n -butanol and water). The ethyl acetate fraction possessed the highest amount of phenolic compounds evaluated by Folin-Ciocalteu reagent method. It also showed the highest antioxidant activity when tested the following methods: DPPH, ABTS⁺ radical-scavenging, superoxide radical scavenging, reducing power and β -carotene linoleic acid bleaching. On the other hand, high phenolics content extracts (ethyl acetate, methanol and n -butanol) showed significantly higher inhibitory activity than low phenolics content extracts (water and hexane) against five tested Gram positive and Gram negative bacteria. Protocatechuic acid, catechol, p -vinylguaiacol, syringol, p -propylphenol, vanillin, p -propylguaiacol, isovanillic acid, 4- n -Propylresorcinol, syringaldehyde and oleanolic acid contained in ethyl acetate fraction were identified by GC-MS and HPLC based on their cochromatography with standard compounds. Protocatechuic acid, catechol and syringol exhibited nearly same antioxidant activity as did by positive control Trolox using the mentioned assays. Results here showed that the ethyl acetate fraction has strong antioxidant and antibacterial activities, which are correlated with its high level of phenolic compounds.     

老蒜提取物萃取部位的抑菌活性及成分分析

本实验将大蒜切片后于室温下浸泡于10%乙醇水溶液或者蒸馏水一段时间,得到老蒜提取物样品一和样品二;依次用石油醚、乙酸乙酯、正丁醇对样品一和样品二进行萃取,得到不同极性的萃取部位,以多种细菌、霉菌、放线菌为供试菌进行抑菌圈实验,研究各个萃取部位的抑菌活性。实验结果表明石油醚层和乙酸乙酯层表现出了较强的抑菌活性,正丁醇层抑菌活性较弱,水层没有抑菌活性。选取抑菌活性较强的石油醚层和乙酸乙酯层进行了气质联用分析,样品一石油醚层中含有的多种具有二硫键的化合物可能使其具有较强的抑菌活性,而且样品一和样品二的石油醚层和乙酸乙酯层均鉴定出多种酚类物质和有机酸,对其抑菌活性可能有一定的贡献。老蒜提取物样品一、样品二的功能成分存在的差异导致了其抑菌活性的不同。     

Ethyl acetate leaf fraction of Cnidoscolus aconitifolius (Mill.) I. M. Johnst: antioxidant potential,inhibitory activities of key enzymes on carbohydrate metabolism,cholinergic, monoaminergic,purinergic, and chemical fingerprinting

In this study, the antioxidant, carbohydrate metabolism, cholinergic, monoaminergic, and purinergic enzyme activities of ethyl acetate leaf fraction of Cnidoscolus aconitifolius were evaluated with the high-performance liquid chromatography (HPLC) analysis. The ethyl acetate fraction of the plant leaf was tested for antioxidant properties, key carbohydrate metabolism, cholinergic, monoaminergic, and purinergic enzyme activities using standard procedures, while the chemical composition of the fraction was evaluated using HPLC. The results revealed that the fraction has higher phenolic compounds than flavonoid and exhibited the ability to scavenge iron chelation and ABTS. The fraction also inhibited the activities of α-amylase and α-glucosidase, acetylcholinesterase, butyrylcholinesterase, monoamine oxidase, tyrosinase, arginase, Ecto-5’-nucleotidase, phosphodieterase-5, angiotensin-I-converting enzyme and encouraged the activity of Na⁺/K⁺-ATPase. The HPLC analysis revealed that the ethyl acetate fraction contained coumaric acid, amentoflavone, hesperidin, protocatechuic acid, kaempferol, dihydromyricetin, quercetin,and rutin. The obtained results in this study suggest that the ethyl acetate fraction obtained from aqueous extracts of Cnidoscolus aconitifolius leaf possessed outstanding antioxidative potentials. Thus, excellent enzyme inhibitory activities probably due to bioactive compounds are also observed in the leaf.     

Antioxidant Activity and Chemical Composition of the Fractions from Burdock Leaves

Abstract: The antioxidant activities of each burdock leaves fraction were first investigated alone and in combination with tertiary butylhydroquinone (TBHQ). The burdock leaves extract was fractioned with petroleum ether, ethyl acetate, n-butanol, and water, named as PF, EF, BF, and WF, respectively. The EF exhibited the highest antioxidant activity. Although TBHQ exhibited higher lipid peroxidation inhibitory activity than EF, the reducing power, superoxide anion scavenging capability, DPPH radical and hydroxyl radicals scavenging ability of EF were higher than those of synthetic antioxidant (TBHQ). Moreover, a synergistic antioxidant effect between EF and TBHQ was first demonstrated by isobolographic analysis, indicating that EF dramatically enhances the antioxidant efficiency of TBHQ. For all the fractions, the antioxidant capacity had a significant correlation with total phenolic content. The phenolic compounds of the fractions were then identified, namely chlorogenic acid, o-hydrobenzoic acid, caffeic acid, p-coumaric acid, and rutin. The results indicate that the EF could be used as sources of nature antioxidant in food industry, and allows a decrease of about 4 folds in the amounts of the synthetic compounds used.     

Antiglycative and antioxidative properties of coffee fractions

In this work the inhibitory activity of coffee low molecular weight compound (LMWC) and high molecular weight compound (HMWC) fractions against in vitro advanced glycation end-products (AGEs) formation was investigated. The HMWC fraction was characterised for its content in total phenolic groups, proteins and carbohydrates. The chlorogenic acids of LMWC fraction were identified by liquid chromatography coupled with tandem mass spectrometry. HMWC inhibited bovine serum albumin glycation by acting as radical scavenger and Fe-chelator in the post-Amadori phase of the reaction and by inhibiting dicarbonyl reactive compounds production during glucose autoxidation. LMWC fraction was able to inhibit protein glycation and dicarbonyl reactive compounds formation more than HMWC fraction. Chlorogenic acids are the main compounds responsible for the antiglycative activity of LMWC fraction.     

Methyl jasmonate treatment of strawberry fruits enhances antioxidant activity and the inhibition of nitrite production in LPS-stimulated Raw 264.7 cells

The effect of methyl jasmonate postharvest application on the antioxidant and anti-inflammatory activity of strawberry fruits was evaluated. Results showed that the methyl jasmonate treated strawberry extract had higher antioxidant activity and suppresses the nitrite production in LPS-stimulated RAW 264.7 murine macrophages. The HPLC profiles of both treated and untreated strawberry extracts were compared. To evaluate which compounds are responsible of these higher activities it was also investigated the antioxidant and anti-inflammatory capacities of the hexane, chloroform, EtOAc, and n-butanol fractions obtained from the methyl jasmonate treated strawberry. The EtOAc and n-butanol fractions exhibited the most potent antioxidant activity compared to the hexane and chloroform fractions. In addition the n-butanol fraction was able to decrease nitrite production. The EtOAc and n-butanol fractions were analyzed by LC–MS. These results showed that methyl jasmonate promotes antioxidant and anti-inflammatory capacity of strawberry fruits by the stimulation of phenolic compounds and anthocyanins production.     

Evaluation and Improvement of Antioxidant Activity of Water-soluble Lignin Products from Steam Explosion Processing of Corn Stalk

In this study, corn stalk was pretreated by steam explosion under various processing conditions, and the antioxidant activity of hydrolysates in the post-process washing liquor was analyzed using the 1,1''-diphenyl-2-picrylhydrazyl (DPPH?) scavenging method. The yield and composition of the hydrolysates obtained under different treatment conditions were also determined; the results indicated that the steam explosion extent had a significant effect on both properties. Under optimized conditions (1.5 MPa, 20 min), the obtained hydrolysate had the highest phenolic compound yield (18.6 mg/g untreated corn stalk) and the highest radical scavenging capacity (IC₅₀=0.24 mg/mL). To confirm the positive effect of phenolic compounds on the antioxidant activity of the hydrolysate, one-step ethanol fractionation was carried out. Due to the enrichment of phenolic compounds, the ethanol-soluble fraction (ESF) exhibited significantly enhanced antioxidant activity with an IC₅₀ value of 0.06 mg/mL, which was close to that of butylated hydroxytoluene (BHT, IC₅₀ = 0.056 mg/mL). Consequently, this work indicated that phenolic compounds have a significant effect on the antioxidant activity of hydrolysate from steam-exploded corn stalk and that simple one-step ethanol fractionation is an effective way to enrich the phenolic compounds in the hydrolysate and improve the antioxidant activity.     

Anti-Inflammatory Effects of Lychee (Litchi chinensis Sonn.) Seed Peptide Hydrolysate on RAW 264.7 Macrophage Cells

Lychee (Litchi chinensis) seeds, a by-product from the canned lychee processing, were hydrolyzed using various concentrations of proteases (Alcalase, Flavourzyme, and Neutrase). The protein hydrolysate produced with Neutrase at a concentration of 50 mg/mL exhibited the highest free radical scavenging activity. After ultrafiltration, the fraction containing peptides of less than 650 Da was purified by using gel filtration chromatography into G1–G3. The G1 fraction exhibited the highest activity and was further purified by reversed phase high performance liquid chromatography (RP-HPLC). Four fractions (H1–H4) were isolated and exhibited efficient nitric oxide (NO) scavenging activity. The G1 fraction inhibited NO production in lipopolysaccharide (LPS) stimulated RAW 264.7 cells with down-regulation of inducible nitric oxide synthase (iNOS) and interleukin-6 (IL-6). The results showed that lychee seed peptide hydrolysates exhibited potent anti-inflammatory activities, suggesting the peptides may be useful as additives to health products such as functional foods and/or pharmaceuticals.     

Antibacterial activity of proteins extracted from the pulp of wild edible fruit of Bromelia pinguin L.

Bromelia pinguin L. is a natural source of bioactive compounds. The main purpose of this research was to isolate and characterize bioactive proteins from its fruit. B. pinguin proteins were fractionated by gel filtration chromatography, and analyzed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The antibacterial activity of the proteins was analyzed against Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 25923, and the enzymatic activity was evaluated by protease activity and trypsin inhibitions assays. Protein fraction obtained by gel filtration chromatography exhibited antibacterial activity against E. coli (minimum inhibitory concentration [MIC] 0.3492 mg/mL) and S. aureus (MIC 0.6845 mg/mL). The proteolytic activity of the fraction was 0.985 U_cas/mL. The substrate-sodium dodecyl sulfate-polyacrylamide gel electrophoresis assay detected protease inhibitors with molecular weights of 43 and 74 kDa. Antibacterial studies of E.coli and S. aureus were determined by comparing the protein fraction with different antibiotics. The antibacterial activity of proteins extracted from the pulp of the fruit of Bromelia pinguin L. could be related to the presence of enzymes, protease inhibitors and peptides.     

Antioxidant and anti‐inflammatory activities of water distillate and its dichloromethane extract from licorice root (Glycyrrhiza uralensis) and chemical composition of dichloromethane extract

BACKGROUND: Licorice root is one of the most widely used medicinal herbs and its medicinal properties, such as antibacterial, anti‐ulcer, anti‐tumorigenic and anti‐atherosclerotic activities, have been widely reported. However, there are only a few reports on basic chemical and biological studies of the water distilled components of licorice root. RESULTS: Chinese licorice root was water distilled and the distillate was subsequently extracted with dichloromethane. Residual aqueous solution from the extraction was fractionated using column chromatography. A total of 127 chemicals were identified in the dichloromethane extract, which inhibited hexanal oxidation by over 90% for 45 days at the level of 50 µg mL^?1. A fraction eluted from the residual aqueous solution with acetone exhibited potent antioxidant activities both in a thiobarbituric acid assay and in a malonaldehyde/gas chromatography assay. The acetone fraction also exhibited strong anti‐inflammatory activity (77.9% inhibition at the level of 62 µg mL^?1) in a lipoxygenenase inhibitor screening anti‐inflammatory assay. CONCLUSION: This study demonstrated the antioxidant and anti‐inflammatory activities of the water distillate obtained from Chinese licorice root. Some volatile chemicals among the many components identified in the water distillate exhibited antioxidant activity, suggesting that many medicinal compounds escape with water vapor into the ambient air during the preparation of herbal medicine. Copyright © 2008 Society of Chemical Industry     

Phenolic compounds from the edible seeds extract of Chinese Mei (Prunus mume Sieb. et Zucc) and their antimicrobial activity

Prunus mume seeds have been used as a healthy food and traditional drug in China. The present study investigated the phenolic compounds and antimicrobial activity of ethanolic extract from seeds of P. mume. Total phenolic content was determined as gallic acid equivalents by the Folin-Ciocalteu method. The antibacterial activity was measured by a filter paper disc method. Three chlorogenic acid isomers, namely, 3-O-caffeoylquinic acid, 5-O-caffeoylquinic acid and 4-O-caffeoylquinic acid, were identified from P. mume seeds for the first time. The contents of these isolated compounds were quantified by HPLC. Results showed that 3-O-caffeoylquinic acid was of the highest level in these three isomers. The ethanolic extract exhibited inhibition activity against bacteria and fungi obviously. The isolated phenolic compounds also exhibited inhibition activity against bacteria significantly, but showed weak or no inhibition activity against yeasts and mold. The results exhibited that the antimicrobial activity of P. mume seeds may be partly due to the phenolic compounds.     

槐米抗食用油脂氧化活性及其成分研究

用1:2的氯仿:甲醇超声提取槐米成分,并用石油醚、乙酸乙酯和正丁醇依次进行萃取,利用Schaal烘箱法进行抗氧化实验,同时与合成抗氧化剂BHT进行对照。结果显示正丁醇提取物(BF)具有最高的抗氧化活性,其活性大于人工合成抗氧化剂BHT。利用硅胶、RP-18和SephadexLH-20对其进行活性追踪分离,得到两种纯的抗氧化成分。利用现代波谱技术对其化学结构进行了鉴定,结果显示为槲皮素和芦丁。抗氧化活性大小顺序为槲皮素>芦丁>BF>BHT。含酚羟基化合物的抗氧化活性与其结构密切相关。活性大小主要取决于酚羟基的数目。     

Chemical composition and biological activity of Citrus jambhiri Lush

The fresh peel of Citrus jambhiri was extracted with aqueous methanol and the residue was fractionated using light petroleum, chloroform and ethyl acetate. The constituents of the extracts were separated by column chromatography employing solvents of different polarity. The chemical structure of the isolated compounds was then identified by MS and NMR. Column chromatography of the petroleum fraction resulted in the isolation of nobiletin, 5-O-demethylnobiletin, tangeretin, 5-hydroxy-3,6,7,8,3′,4′-hexamethoxyflavone, 3,5,6,7,8,3′,4′-heptamethoxyflavone, and a mixture of β-sitosterol and stigmasterol. The chloroform fraction afforded 6-demethoxynobiletin, 5,4′-dihydroxy-6,7,8,3′-tetramethoxyflavone, limonin and nomilin. The flavonoid glycosides naringin, hesperidin and neohesperidin were isolated from the ethyl acetate fraction. The chemical structure of the isolated compounds was established by MS and NMR (APT, COSY, HSQC, HMBC, and NOESY). LC–ESI-MS analysis of the ethyl acetate fraction afforded eight flavonoid glycosides, while the dichloromethane fraction of the defatted seeds contained seven limonoid aglycones. The chloroform fraction exerted the strongest DPPH^∗ free radical scavenging activity in comparison to other fractions. The petroleum fraction showed a significant inhibition of lipoxygenase indicating an anti-inflammatory action (IC₅₀ 29 ± 1 μg/mL). Some of the isolated polymethoxyflavones exhibited strong cytotoxicity against COS7, HeLa and Caco-2 cell lines.     

Isolation of specific cranberry flavonoids for biological activity assessment

Characterisation of cranberry compound biological activity is constrained by limitations in isolation methodology. A single rapid procedure for polyphenolic isolation was developed using semi-preparative-HPLC. Non-flavonoid compounds were removed by pre-purification procedures prior to semi-preparative-HPLC. Fractions were analysed to ascertain purity (99%) with HPLC and ESI mass spectrometric detection in negative ion mode and on-line diode array ultraviolet–visible spectroscopy. Isolated cranberry flavonols included quercetin-3-galactoside, quercetin-3-glucoside, quercetin-3-rhamnoside, myricetin-3-galactoside, myricetin-3-arabinofuranoside, and quercetin-3-O-(6″-p-benzoyl)-β-galactoside. Proanthocyanidin isolates contained monomers, dimers, trimers, and larger polymers. Anthocyanins consisted largely of galactoside and arabinoside conjugates of cyanidin and peonidin. Identities were confirmed using 1D-NMR- and 2D-NMR-spectrometry as well as reference standards. Flavonol fractions exhibited the highest antioxidant activity in a dosedependent manner, while the anthocyanin fraction exhibited the least activity. Biological activity studies of cranberry phenolics will benefit from the improved isolation procedures described in this study and the confirmation of antioxidant activities of various cranberry constituents.