Antioxidant activity of Egyptian Eucalyptus camaldulensis var. brevirostris leaf extracts

Leaves from Eucalvptus camaldulensis var. brevirostris trees, planted in the Nile delta in Egypt, were examined for the antioxidant activity of their nonvolatile compounds. The extracts obtained by ethanol digestion and by supercritical fluid extraction (SFE; CO2 with 15% ethanol) showed the most promising antioxidative activities. In order to identify the most active compounds, both extracts were subjected to a semipreparative reversed-phase HPLC separation, the main fractions were collected, tested for antioxidative activity and analysed by different chromatographical and spectroscopical methods for identification of the most relevant compounds. Gallic and ellagic acid were found to be the prevailing antioxidants in the ethanolic extract. The main two compounds of the SFE extract with antioxidative activity revealed to be flavones. To a high degree of probability they were identified as 5-hydroxy-7,4'-dimethoxy flavone and 5-hydroxy-7,4'-dimethoxy-8-methyl flavone, respectively. The extracts obtained by ethanoldigestion were dried and administered to rats for toxicity evaluation (up to 3 g/kg body weight). No mortality was observed which indicates a very low lethality of the tested extract.     

Effect of extraction techniques on the chemical composition and antioxidant activity of Eucalyptus camaldulensis var. brevirostris leaf oils

 The volatile oil compositions of Eucalyptus camaldulensis var. brevirostris leaves obtained by hydrodistillation (HD) and supercritical fluid extraction methods (SFE) were analysed qualitatively and quantitatively by GLC-MS. Ninety different components were separated and most of them identified. In both extracts the main constituents were found to be β-phellandrene (8.94 and 4.09%), p–cymene (24.01 and 10.61%), cryptone (12.71 and 9.82%) and spathulenol (14.43 and 13.14%). The yield of the monoterpene hydrocarbons in HD oil (0.288 g/100 g fresh leaves) was slightly higher compared with that in the SFE extract (0.242 g/100 g fresh leaves). The SFE extract possessed higher concentrations of the sesquiterpenes, light oxygenated compounds and heavy oxygenated compounds than the HD oil. The relationship between the antioxidant activity and chemical composition of the extracted oils was investigated. The significant amounts of p–cymen-7-ol and thymol are responsible for the antioxidative activity of both extracts. The concentration of both compounds, but especially that of p–cymen-7-ol (2.25%), is higher in the SFE extract. This corresponds with the higher antioxidative activity of the SFE compared with the HD extract. p–Cymen-7-ol, a compound newly identified in leaves of Eucalyptus species, exhibited superior antioxidant activity in comparison with that of butylated hydroxyanisole. Received: 30 April 1998     

Effect of extraction techniques on the chemical composition and antioxidant activity of Eucalyptus camaldulensis var. brevirostris leaf oils

 The volatile oil compositions of Eucalyptus camaldulensis var. brevirostris leaves obtained by hydrodistillation (HD) and supercritical fluid extraction methods (SFE) were analysed qualitatively and quantitatively by GLC-MS. Ninety different components were separated and most of them identified. In both extracts the main constituents were found to be β-phellandrene (8.94 and 4.09%), p–cymene (24.01 and 10.61%), cryptone (12.71 and 9.82%) and spathulenol (14.43 and 13.14%). The yield of the monoterpene hydrocarbons in HD oil (0.288 g/100 g fresh leaves) was slightly higher compared with that in the SFE extract (0.242 g/100 g fresh leaves). The SFE extract possessed higher concentrations of the sesquiterpenes, light oxygenated compounds and heavy oxygenated compounds than the HD oil. The relationship between the antioxidant activity and chemical composition of the extracted oils was investigated. The significant amounts of p–cymen-7-ol and thymol are responsible for the antioxidative activity of both extracts. The concentration of both compounds, but especially that of p–cymen-7-ol (2.25%), is higher in the SFE extract. This corresponds with the higher antioxidative activity of the SFE compared with the HD extract. p–Cymen-7-ol, a compound newly identified in leaves of Eucalyptus species, exhibited superior antioxidant activity in comparison with that of butylated hydroxyanisole.     

ANTIMICROBIAL AND ANTIOXIDANT ACTIVITY OF EMBLICA EXTRACTS OBTAINED BY SUPERCRITICAL CARBON DIOXIDE EXTRACTION AND METHANOL EXTRACTION

ABSTRACT

This study is aimed to evaluate the antimicrobial and antioxidant activities of two extracts of emblica (Phyllanthus emblica L.) obtained by supercritical fluid extraction (SFE) and methanol extraction. The SFE extract showed strong antimicrobial activity against all microorganisms tested, whereas the methanolic extract showed low activity against Staphylococcus aureus and fungi. In contrast, the methanolic extract exhibited significantly higher antioxidant activity than the SFE extract. The SFE extract was analyzed by gas chromatography with mass spectrometric detector. Thirty compounds were tentatively identified, representing 99.67% of the volatile components. β‐Bourbonene, teracosane, palmitic acid, thymol, β‐caryophyllene and undecane were the major compounds. The methanolic extract was subjected to separation and purification using reverse‐phase high‐performance liquid chromatography. Kaempferol 3‐β‐D‐glucopyranoside (1), kaempferol (2), quercetin (3), isocorilagin (4) and geraniin (5) respectively, were identified by spectral methods, ¹H and ¹³C nuclear magnetic resonance spectroscopy, ultraviolet‐visible spectrophotometry and mass spectroscopy, and comparison with literatures.

PRACTICAL APPLICATIONS

The study can be considered as the first report on the in vitro antimicrobial and antioxidant properties of supercritical fluid extraction (SFE) and methanolic extracts prepared from Phyllanthus emblica. The results introduce a unique natural source that possesses strong antimicrobial and antioxidant substances. The SFE extract had a strong and broad spectrum of antimicrobial activity, and in some cases, even found to have similar activity to the antibiotics ampicillin and nystatin. On the other hand, the methanolic extract exhibited quite strong antioxidant activities, which were found to be similar, and in some cases even higher than the reference compound butylated hydroxytoluene (BHT). Hence, the extracts of P. emblica could be used as a natural preservative ingredient in food and/or pharmaceutical industry.     

Application of Green Technology for the Acquisition of Extracts of Araçá (Psidium grandifolium Mart. ex DC.) Using Supercritical CO2 and Pressurized Ethanol: Characterization and Analysis of Activity

Brazil is home to a wide variety of flora, including several lesser known species, such as araçá that were processed in this study using two green technologies consecutively: supercritical fluid extraction (SFE) for nonpolar fraction and pressurized liquid extraction. For polar fraction, the experiments followed a central composite design involving ethanol as solvent, with temperature and static time in each bath as independent variables. Both extracts were analyzed for antioxidant and antimicrobial activities. Total phenolics content (TPC) was determined for all ethanol extracts. In the araçá essential oil (AEO) obtained by SFE, the extraction yield was 2.33%. The three major compounds of AEO were α‐pinene (20.75%), p‐cymene (20.50%), and o‐cymene (20.05%). In ethanol extracts, the high yield (14.49%) was obtained at 74 °C/6 min and the major TPC (136.95 mg GAE/100 g) at 60 °C/9 min. Ethanol extracts presented good antioxidant activity (EC₅₀ = 6.37 mg/mL) at 74 °C/6 min. AEO was unable to reduce DPPH? concentration by 50%. Both extract types presented an inhibitory effect against Staphylococcus aureus, Pseudomonas aeruginosa, and Bacillus cereus, while only the ethanol extracts presented effect against Listeria monocytogenes. This work had the aim to present the innovation of the use of a whole typical Brazilian fruit that gives rise to extracts with excellent properties for employment in both the pharmaceutical and food industries.     

Rapid screening of antioxidant activity of sage (Salvia officinalis L.) extracts obtained by supercritical carbon dioxide at different extraction conditions

Sage herb (Salvia officinalis L.) was extracted at supercritical fluid extraction (SFE) conditions with carbon dioxide at different parameters and the extracts tested on their antioxidant activity (AA). SFE of sage herb at 35 MPa pressure was found to be an effective method to obtain pure extracts. The yields of the extracts were substantially increased by using 1% of entrainer solvent ethanol. The fractionation of sage extract was a complex procedure in terms of extract distribution between separators operating at various pressure and temperature conditions. It was also proved by testing the AA of the extracts in rapeseed oil. The effect of the extracts on the rapeseed oil weight gain varied in a wide range (from ‘very low’ to ‘high’) depending on the fractionation conditions. Preliminary results showed that to obtain more effective antioxidant fractions separation steps should be started at 10 MPa lower pressure than that used for the extraction.     

Extractability of antioxidants from legume seed flour after cooking and in vitro gastrointestinal digestion in comparison with methanolic extraction of the unprocessed flour

Antioxidant activities were studied in methanolic and water extracts of nonprocessed, cooked and in vitro enzymatically digested seed flour, as well as in total protein hydrolysates and small peptide fractions (<3 and <10 kDa) of three pea and five grass pea cultivars. The antioxidative properties were determined by three spectrophotometric methods: 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) radical scavenging assay, Folin‐Ciocalteu (FC) reducing capacity assay and H₂O₂ scavenging. We also applied one luminometric assay for hydroxyl radical scavenging. The study showed that cooking and enzymatic digestion strongly enhanced the release of phenolic compounds in methanolic extracts of four analysed cultivars. Scavenging activity against DPPH radical, hydroxyl radical and hydrogen peroxide was increased in majority of analysed flour specimens subjected to processing. Our findings indicate that, besides the phenolic compounds, the small peptide fraction, especially the MW <3 kDa, in methanolic and aqueous extracts of cooked and digested seed flour significantly contribute to free radical and hydrogen peroxide scavenging activity in all investigated cultivars. Our data strongly suggest that simple cooking treatment and in vitro digestion of seed flour applied prior to extraction with methanol could improve antioxidative activity of obtained extracts.     

Antioxidant and antimicrobial activities of Polygonum cognatum Meissn extracts

The antioxidant activities, reducing powers, 2,2‐diphenyl‐l‐picrylhydrazyl (DPPH) radical‐scavenging activities, total phenolic compound contents and antimicrobial activities of ether, ethanol and hot water extracts of Polygonum cognatum Meissn were studied in vitro. The highest antioxidant activity was found in the water extract. However, there were no statistically significant differences among 15 µg ml^?1 extract‐containing samples in linoleic acid emulsion (0.02 M , pH 7.0) during 120 h of incubation (P > 0.05). The reducing power of the water extract was the highest, but its reducing power was markedly lower than that of ascorbic acid. The highest DPPH radical‐scavenging activity was found in the water extract, with 50% DPPH radical scavenging at a concentration of 100 µg ml^?1 dried water extract, while at the same concentration of dried ethanol extract the value was 12%. Surprisingly, no DPPH radical‐scavenging activity was observed in the ether extract. The concentrations of phenolic compounds found were 0.48, 0.50 and 0.01 µg ml^?1 gallic acid equivalent in 10 µg ml^?1 water, ethanol and ether extracts respectively. The ether and ethanol extracts showed antimicrobial activity against Staphylococcus aureus and Bacillus subtilis. The water extract did not show antimicrobial activity against the studied micro‐organisms. © 2002 Society of Chemical Industry     

Free‐radical scavenging activity of wormwood (Artemisia absinthium L) extracts

In an effort to discover new antioxidant natural compounds, wormwood (Artemisia absinthium L) an aromatic‐bitter herb, was screened. The sequential extraction was realized with five solvents of different polarities (70% methanol, petroleum ether, chloroform, ethyl acetate, n‐butanol). The antioxidative activity was tested by measuring their ability to scavenge stable 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) free radical and reactive hydroxyl radical during the Fenton reaction trapped by 5,5‐dimethyl‐1‐pyrroline‐N‐oxide (DMPO), using electron spin resonance (ESR) spectroscopy. Results demonstrated that the antiradical and antioxidative activity depend on the type and concentration of applied extracts and increased in the order ethyl acetate > methanol > n‐butanol > chloroform > petroleum ether > remaining water extracts. The investigation showed that the antiradical activity increased with increasing concentration of all extracts. The high contents of total phenolic compounds (25.6 mg g^?1) and total flavonoids (13.06 mg g^?1) indicated that these compounds contribute to the antiradical and antioxidative activity. In a model system, the formation of o‐semiquinone radicals from quercetin and chlorogenic acid was obtained to prove the mechanism (hydrogen donating and/or one‐electron reduction) of free‐radical scavenging activity. Copyright © 2004 Society of Chemical Industry     

Proanthocyanidin Oligomers Isolated from Salacia reticulata leaves potently Inhibit Pancreatic Lipase Activity

Abstract: The pancreatic lipase inhibitory (PLI) activity of leaf extracts (aqueous, 60 and 99.8 (v/v)% EtOH) of Salacia reticulata Wight, referred to “Kothala himbutu” (KT) in Singhalese, was compared with that of KT stem extracts. Evaporated residue contents and PLI activity of each leaf extract were higher than those of each stem extract, respectively. Among the extracts, the 60% EtOH leaf extract showed the most potent PLI activity. The 60% EtOH leaf extract was separated by a Diaion HP20/water‐acetone system and furthermore the most potent fraction by a Sephadex LH20/water‐ethanol‐acetone system. The 60% acetone fraction from the LH20/water‐ethanol‐acetone system had the most potent PLI activity (IC₅₀ value; 15 ppm). The active compounds in the active fraction of KT leaves were most likely a polyphenol, as assessed by the Folin–Ciocalteu method. Based on these spectroscopic and chemical examinations, the active fraction was shown to be proanthocyanidin oligomers composed of epigallocatechin, epicathechin, and epiafzelechin as main constituents. The degree of polymerization was estimated to be about 5 from the ratio of the peak area of the thio ethers/flavan‐3‐ols at 230 nm. This was consistent with the results of matrix‐assisted laser desorption ionization time‐of‐flight (MALDI‐TOF) MS, which showed the [M+Na]⁺ peaks corresponding to trimers—octamers. From the average molecular weight and IC₅₀ value of the active compounds estimated on these results, the active compounds from the KT leaf extract were one of the stronger effective lipid‐lowering therapeutic agent, of which PLI activity (μM/L) was almost the same as epigallocatechin gallate. Practical Application: Proanthocyanidin oligomers isolated from Salacia reticulata, referred to “Kothala himbutu” (KT) in Singhalese, leaves was proved to potently inhibit pancreatic lipase activity. After confirming in vivo examination, healthy foods, teas, and liquors containing the extracts of KT leaves are expected to be on market.     

EVALUATION OF GLOBAL YIELD, COMPOSITION, ANTIOXIDANT ACTIVITY AND COST OF MANUFACTURING OF EXTRACTS FROM LEMON VERBENA (ALOYSIA TRIPHYLLA[L'HÉRIT.] BRITTON) AND MANGO (MANGIFERA INDICA L.) LEAVES

In this work, the global yields, composition and antioxidant activity (AA) of extracts from lemon verbena (Aloysia triphylla) and mango (Mangifera indica) leaves obtained by different separation processes were determined. Lemon verbena extracts were obtained by supercritical fluid extraction (SFE), while mango leaf extracts were obtained by SFE, low‐pressure solvent extraction (LPSE) and hydrodistillation. The extract's constituents were analyzed by thin‐layer chromatography, gas chromatography/mass spectrometry and gas chromatography/flame ionization detector. The AA of the extracts was evaluated by the coupled reaction of β‐carotene/linolenic acid. The cost of manufacturing (COM) was estimated for the SFE extracts. Higher global yields were obtained using SFE at 350 bar/45C (1.49%) for lemon verbena and LPSE (3.04%) for mango. The AAs of the extracts were larger than that of the β‐carotene for both plants. The minimum values of COM were U.S.$26.96 and 52.45/kg of extract for lemon verbena and mango, respectively.     

Chemical composition and antioxidant and radical‐scavenging activities of Periploca laevigata root bark extracts

BACKGROUND: The root powder of Periploca laevigata is used for preparing soft drinks and as an aromatic in Tunisia. The infusion or decoction of its root bark has widespread use in folk medicine. The plant is used to treat digestive disorders and hypertensive effects as well as other health problems. RESULTS: The antioxidant activities of extracts of P. laevigata root bark obtained with solvents of different polarity were investigated using assays of 1,1‐diphenyl‐2‐picrylhydrazyl radical‐scavenging activity, ferric‐reducing capacity, β‐carotene‐bleaching ability, hydroxyl radical‐scavenging activity and lipid peroxidation inhibition. The methanol extract, with the highest amount of total phenolics and flavonoids, showed the highest antioxidant activities in all assays, followed by the water extract. Gas chromatography/mass spectrometry was used to determine the composition of the water and methanol extracts. Thirty‐four compounds were identified in the methanol extract, with proflavine (516.2 g kg^?1 dry matter (DM)) and 4‐methoxysalicylaldehyde (198.3 g kg^?1 DM) being the most abundant. Sixteen compounds were identified in the water extract, of which 4‐hydroxy‐3‐methoxyphenethylene glycol (351.2 g kg^?1 DM) was the main component. CONCLUSION: As far as is known, this is the first report on the chemical composition and biological activities of phenolic extracts from P. laevigata. The results of the study indicate that the root bark of this plant might be a good candidate for further investigation in developing new antioxidants. Copyright © 2009 Society of Chemical Industry     

Phenolic and antioxidant potential of olive oil mill wastes

Olive oil mill waste was subjected to conventional liquid solvent extraction and supercritical fluid extraction using different solvents and carbon dioxide, respectively. The optimum solvent extraction conditions of phenols were 180 min using ethanol, at a solvent to sample ratio 5:1 v/w, and at pH 2. Solvent and SFE extracts were tested for their antioxidant activity by the DPPH radical scavenging method and by determination of peroxide value on virgin olive oil and sunflower oil. The ethanol extract exhibited the highest antiradical activity, and no correlation was found between antiradical activity and phenol content. The SFE extract exerted good antioxidant capacity although its phenolic yield was not quite high. Moreover, the ethanol extract appeared to be a stronger antioxidant than BHT, ascorbyl palmitate and vitamin E by the Rancimat method on sunflower oil. HPLC analysis of the extracts showed that the predominant phenolic compound was hydroxytyrosol. Various phenolic acids and flavonoids were also identified.     

Effect of loquat (Eriobotrya japonica) extracts on LDL oxidation

The antioxidative activity of the extracts of loquat fruits, Eriobotrya japonica Lindley was examined. Loquat fruit was separated into three parts (peel, flesh and seed), and each part was extracted with either water or ethanol. The extracts were then assessed for their free radical scavenging ability and effects on the oxidation of human low density lipoprotein (LDL) in vitro. Results in this study show that the ethanol extracts of all three loquat parts and the water extract of the peels exhibited a strong ability to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical. Among extracts of different loquat parts, the ethanol extract of loquat seeds was the most potent one. The ethanol extract of the seed was also effective in suppressing the oxidation of linoleic acid which was demonstrated by a slow discoloration of β-carotene/linoleic acid conjugation system. The ethanol extract of loquat seeds as compared to other extracts could also suppress significantly the 2,2′-azobis(4-methoxy-2,4-dimethylvaleronitrile) (MeO-AMVN)-induced LDL oxidation. When the content of total polyphenolic compounds in different loquat parts (peel, flesh and seed) was examined, a significantly higher level of total polyphenols was found in the seed than the peels and flesh. Using reverse-phase HPLC-ESI EM analysis, significant levels of polyphenolic compounds such as chlorogenic acid, cyanidine glucoside, epicatechin, epigalocatechin gallate and procyanidin B₂ in the ethanol extract of different loquat parts were identified and quantified. The latter two compounds were found mainly in the ethanol extract of loquat seeds, but not in peels and flesh. Therefore, it is suggested that the high ability to scavenge free radicals and suppress the LDL oxidation exerted by the ethanol extract of loquat seeds was at least in part due to the high content of polyphenolic compounds in the seeds.     

Antioxidative activity of extracts from Mengkudu (Morinda citrifolia L.) root,fruit and leaf

This study was conducted to evaluate the antioxidative activity of extracts from different parts of Mengkudu (Morinda citrifolia L.), including leaf, fruit and root. Methanol and ethyl acetate were used as solvents and antioxidative effects measured by a ferric thiocyanate method (FTC) and thiobarbituric acid test (TBA). The methanol extract of Mengkudu root exhibited high antioxidative activity that was not significantly (P<0.05) different from α-tocopherol or butylated hydroxyl toluene (BHT), while the methanol extracts of fruit and leaf showed negligible activities. On the other hand, the ethyl acetate extract of all parts of Mengkudu exhibited significant antioxidative activity, which is comparable to that of both α-tocopherol and BHT. Similar trends of antioxidant activity were observed using either the FTC or TBA methods. Roots showed the highest activity of the parts tested. The results suggest that several compounds contribute to antioxidative activity of different parts of Mengkudu. Activity in the roots may be due to both polar and non-polar compounds but, in the leaf and fruit, only to non-polar compounds.     

Effect of irradiation on the antioxidative and antigenotoxic activities of a green tea leaf and stem extract

Green tea (Camellia sinensis) leaf and stem extract, a major byproduct of the green tea industry, was investigated for its antioxidative and antigenotoxic activities after 20 kGy of irradiation. In vitro antioxidative activities, including 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical scavenging, hydrogen peroxide inhibition, tyrosinase inhibition activities, and the reducing power were tested. Green tea leaf extract (GTLE) had higher antioxidative activities than the green tea stem extract (GTSE). Irradiation of 20 kGy to GTLE showed a decreasing tendency in DPPH radical, hydrogen peroxide‐scavenging activities, and reducing power, while that to GTSE showed an increasing tendency of the antioxidative activities. Tyrosinase inhibition activity showed no difference on irradiation, in GTLE and GTSE. Overall, irradiation had positive influences on the antioxidative activity in the GTSE more than in the GTLE. Antigenotoxic effect of the green tea extracts on an oxidative DNA damage in human leucocytes by a DNA comet assay also indicated a protective effect of GTLE. The irradiated GTLE began to decrease the DNA damage significantly at 10 μg mL^?1, which showed a higher inhibition activity than the non‐irradiated GTLE. The non‐irradiated and irradiated GTSE showed similar inhibition trends and they were comparable with that of the GTLE. Results suggest that the extract of GTSE, a major byproduct of the green tea industry, can be considered as a cost‐effective functional ingredient for industrial applications. Furthermore, irradiation of the GTSE may have beneficial effects on its functional activity.     

Antibacterial Constituents of Hainan Morinda citrifolia (Noni) Leaves

Noni (Morinda citrifolia L.) is an edible and medicinal plant distributed in Hainan, China. The antibacterial activities of the extracts of water (WE), petroleum ether (PEE), ethyl acetate (EAE), chloroform (CE), and n‐butanol (BE) were assayed by the disk diffusion method. The results showed that the extracts from Noni leaves possessed antibacterial effects against Bacillus subtilis, Escherichia coli, Proteus vulgaris, and Staphylococcus aureus. Among 5 different extracts, the BE produced the best antibacterial activity. The samples were first extracted by ethanol, and the primary compounds in the BE fraction of ethanol extract was further isolated and identified. Six phenolic compounds, including 5, 15‐dimethylmorindol, ferulic acid, p‐hydroxycinamic acid, methyl 4‐hydroxybenzoate, methyl ferulate, and methyl 4‐hydroxycinnamate, were identifiedby NMR. The results indicated that the phenolic compounds might significantly contribute to antibacterial activities of Noni leaves.     

Rye and Wheat Bran Extracts Isolated with Pressurized Solvents Increase Oxidative Stability and Antioxidant Potential of Beef Meat Hamburgers

Rye and wheat bran extracts containing phenolic compounds and demonstrating high DPPH? (2,2‐diphenyl‐1‐picrylhydrazyl), ABTS^?+ (2,2′‐azino‐bis(3‐ethylbenzthiazoline‐6‐sulphonic acid) scavenging and oxygen radical absorbance capacities (ORAC) were tested in beef hamburgers as possible functional ingredients. Bran extracts significantly increased the indicators of antioxidant potential of meat products and their global antioxidant response (GAR) during physiological in vitro digestion. The extracts also inhibited the formation of oxidation products, hexanal and malondialdehyde, of hamburgers during their storage; however, they did not have significant effect on the growth of microorganisms. Hamburgers with 0.8% wheat bran extract demonstrated the highest antioxidant potential. Some effects of bran extracts on other quality characteristics such as pH, color, formation of metmyoglobin were also observed, however, these effects did not have negative influence on the overall sensory evaluation score of hamburgers. Consequently, the use of bran extracts in meat products may be considered as promising means of increasing oxidative product stability and enriching with functional ingredients which might possess health benefits.     

Effect of solvent type on the extractability of bioactive compounds,antioxidant capacity and colour properties of natural annatto extracts

This study was conducted to obtain annatto extracts with both high antioxidant capacity and colour potential using solvents of different polarities (water, ethanol/water, ethanol, ethanol/ethyl acetate and ethyl acetate). The highest levels of total phenolic compounds were found in the water, ethanol/water and ethanol extracts (0.5 mg GAE mL^?1), and the highest level of bixin was found in the ethanol/ethyl acetate extract (5.2 mg mL^?1), which was characterised as the reddest and the most vivid one (a* = 40.5, h° = 46.1, C* = 58.4). The ethanol/ethyl acetate extract also showed the highest antioxidant activity (4.7 μm TEAC mL^?1) and the highest percentage of tryptophan protection against singlet oxygen (63.6%). On the other hand, ethyl acetate and ethanol/water were the least effective solvents for the extraction of phenolic compounds and bixin, respectively. According to the multivariate statistical analysis, ethanol/ethyl acetate and ethyl acetate were the most promising solvents to obtain annatto extracts with both antioxidant and colour properties.     

生姜、红辣椒提取物的抗氧性

采用乙醇、丙酮、乙酸乙酯、正已烷、石油醚从姜、红辣椒中制得各种提取物并用烘箱法和Rancimat法测定他们在猪油、菜油中的抗氧性,还与BHA、BHT的抗氧性进行了比较。添加提取物的香肠的TBA值也较空白样品低。实验证明这些提取物都有抗氧性,其中红辣椒皮的乙醇提取物具有与BHT类似的抗氧性。另外,红辣椒的各种提取物的抗氧活性次序与其辛辣指数、色泽单位次序相关。