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.     

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.     

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.     

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.     

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).     

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.