Phenolic compounds in frozen avocados

The ethyl acetate-soluble phenolic compounds present in frozen ripe Fuerte avocados were extracted with methanol and ethyl acetate. The compounds were separated by two-dimensional paper chromatography with n-butanol-acetic acid-water (4:1:5, v/v) and 2% acetic acid solvents. Fifteen spots were found when the chromogenic reagent was FeCl ₃-K₃Fe(CN)₆. The individual compounds were identified by their R_f values, colour reactions, fluorescent behaviour and absorption spectra. Chlorogenic and _p-coumarylquinic acid isomers, catechins, leucoanthocyanidins, isoflavone and caffeic and _p-coumaric acids were present in the extracts of frozen avocados. Ascorbic acid-treated frozen avocado chunks did not darken when kept under vacuum at —26°C, but turned dark if left exposed to air. Darkening of frozen chunks was associated with disappearance of most phenolic substances, except the simple cinnamic acid derivatives. Formation of new phenolic substances, especially leucoanthocyanidins and catechins, was observed during storage of the frozen chunks under vacuum.     

Evolution of the antioxidant capacity and phenolic contents of persimmon during fermentation

The changes in antioxidant capacity and phenolics of persimmon during alcoholic fermentation, acetification, and short aging were investigated. An increase in the antioxidant activity was observed when persimmon was transformed from puree to vinegar. The total content of phenolics remained stable, in contrast to the concentration of condensed tannin, which significantly (p < 0.05) increased during alcoholic and acetic fermentations, although followed by a decrease after aging. The phenolic compounds were characterized and quantitated. Gallic acid was the main phenolic compound, and its content increased by 14.4% during alcoholic fermentation and reduced by 53.5% during acetic fermentation. Additionally, the flavan-3-ol compounds increased during alcoholic fermentation and acetification. Vanillyl alcohol, (?)-epigallocatechin, and p-coumaric acid were not observed in persimmon puree but detected in persimmon wine and vinegar. These results indicate that alcoholic and acetic fermentation can improve the antioxidant capacity of persimmon fruit.     

Gravimetric determination of soluble phenolics including tannins from leaves by precipitation with trivalent ytterbium

A method for the gravimetric determination of soluble phenolics based on precipitation with trivalent ytterbium is described. Solutions of ytterbium-precipitated phenolics can be prepared in order to study u.v. absorbance, colorimetric assays for phenolics, protein precipitation and cellulase inhibition. The method was applied to mature leaves of 10 East African browse species in the diets of goats and camels. There was a large range in ytterbium-precipitated phenolics (Yb-ppt), from 50% dry matter (DM) in Acacia nilotica to less than 15% in Acacia brevispica and Cadaba farinosa. Results from u.v. absorbance and the Folin-Ciocalteu assay on solutions of ytterbium-precipitated phenolics indicated that ytterbium precipitates many types of phenolics including proanthocyanidins. The vanillin-HCl and n-butanol-HCl assays for proanthocyanidins separated the samples into two groups with high or low levels. The group with high levels of proanthocyanidins had greater protein precipitation capacity and cellulase inhibition at similar amounts of Yb-ppt. The results indicate that the method may be useful in nutritional studies involving browse and other forages. Gravimetric analysis avoids problems associated with colorimetric assays because it does not rely on the use of standards. The preparation of solutions of Yb-precipitated phenolics allows direct comparison between amount and nutritional effects such as protein precipitation and enzyme inhibition.     

Organochlorine pesticides and polychlorinated biphenyls in cod from the southern Baltic, 1983

Summary Hexachlorobenzene (HCB), -, -, - and -benzenehexachloride (BHC; HCH),p,p-DDE,o,p-DDD,o,p-DDT,p,p-DDD and p,p-DDT (DDT) and polychlorinated biphenyls (PCB) levels have been determined in muscle tissue of 207 cod (Gadus morhua) netted during 1983 in different regions in the southern part of the Baltic Sea. The mean levels found for cod muscle tissue (g/kg) related to wet weight were: 0.65 HCB, 1.2 -BHC, 9.0 -BHC, 2.8 -BHC, -BHC remained undetected, 13 BHC, 4.4p,p-DDE,o,p-DDD ando,p-DDT remained undetected, 4.0p,p-DDD, 1.8p,p-DDT, 10 DDT and 55 PCBs. The results are compared with levels found in cod caught in different regions of the Baltic Sea during 1967–1983, and reported previously by other authors.

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Organochlorpesticide und polychlorierte Biphenyle in Kabeljau aus der südlichen Ostsee,1983

Zusammenfassung Die Werte für Hexachlorbenzol (HCB), -, , -, und -Benzolhexachlorid (BHC; HCH),p,p-DDE,o,p-DDD,o,p-DDT,p,p-DDD undp,pDDT (DDT) und polychlorierte Biphenyle (PCB) wurden im Muskelgewebe von 207 Kabeljaus (Gadus morhua), mit Netz in verschiedenen Regionen der südlichen Ostsee 1983 gefangen, bestimmt. Die mittleren Werte, bezogen auf das Frischgewicht, waren: 0,65 g/kg HCB, 1,2 g/kg -BHC, 9,0 g/kg -BHC, 2,8 g/kg -BCH, -BHC blieben unbestimmt, 13 g/kg BHC, 4,4 g/kgp,p-DDE,o,p-DDD undo,p-DDT blieben unbestimmt, 4,0p,p-DDD, 1,8p,p-DDT, 10 g/kg DDT und 55 g/kg PCB. Die Ergebnisse wurden mit den Werten früherer Jahre von 1967–1983 und mit denen anderer Autoren verglichen.

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Partially with financial support under grant PR-4 (Sea Fisheries Institute)     

Effects of roasting on phenolics composition and antioxidant activity of peanut (<Emphasis Type="Italic">Arachis hypogaea</Emphasis> L.) kernel flour

The effects of roasting on the phenolics composition and antioxidant activity of peanut (Arachis hypogaea L.) kernel flour were appraised. Peanut kernel flour, with and without skin, were roasted at 160 °C for 10, 20, 30, 40 and 50 min. The resultant changes in the antioxidant activity of roasted peanut kernel flour were assessed by the determinations of total phenolics, 1,1-diphenyl-2-picrylhydrazyl free radical-scavenging capacity, percent inhibition of linoleic acid oxidation and thiobarbituric acid test and compared with those of unroasted kernel flour. It was observed that roasting significantly (p < 0.05) increased the antioxidant activity of the peanut kernel flour. HPLC analysis revealed the detection of three phenolic acids (p-hydroxybenzoic, chlorogenic, p-coumaric), two flavonols (quercetin, kaempferol), and a stilbene (resveratrol) both in the roasted and unroasted samples. In peanut kernel flour without skin, the contents of the phenolics increased in the initial roasting phase, however, decreased gradually in the later phase (>20 min of roasting time). In contrast, over the course of heating, the amounts of phenolics were noted to be slightly increased in the peanut kernel flour with skin; the most significant (p < 0.05) increase occurred in the concentration of p-coumaric acid and quercetin at 30, 40, and 50 min of roasting. The results of this study reveal that optimum roasting time should be sought to enhancing the antioxidant capacity and phenolics concentration in peanut kernel flour.     

Preparative separation and purification of phenolic compounds from Canarium album L. by macroporous resins

BACKGROUND: Canarium album L. (also called Chinese olive) is a traditional medicine material in China, and phenolic compounds from C. album possess great pharmacological activities. To obtain high‐purity phenolics from C. album, a crude extract of C. album phenolics was prepared by ethanol extraction. The use of macroporous resins for further separation and purification of phenolics in the extract was studied. RESULTS: Through static adsorption and desorption tests, AB‐8 resin was chosen for the separation of phenolics because of its higher adsorption capacity and desorption ratio than other resins. Then, dynamic adsorption and desorption experiments were carried out on an AB‐8 resin packed column to obtain optimal separation parameters. The highest adsorption capacity of AB‐8 was achieved when variables including initial concentration (C₀), feed flow rate and feed volume were 10 mg mL^?1, 2 mL min^?1 and 9 bed volumes (BV), respectively, and saturated resin was first washed with 5 BV of water to remove impurities, then a purified product containing more than 85% of C. album phenolics was obtained by desorbing the resin with 2.5 BV of 70% (v/v) aqueous ethanol at flow rate of 1 mL min^?1, and the recovery of phenolics was up to 75%. In addition, five phenolic compounds in the product were identified as gallic acid, ellagic acid, corilagin, hyperin and kaempferol‐3‐glucopyranoside by UV and LC–ESI–MS analysis. CONCLUSION: The results in this study could provide scientific references for the large‐scale production of phenolics from C. album. Copyright © 2007 Society of Chemical Industry     

Wine phenolics: contribution to dietary intake and bioavailability

Current research suggests that wine contains substances that may reduce the mortality rate from coronary heart diseases. The oxidation of low-density liporoteins (LDL) is thought to be a key step in the development of atherosclerosis. In previous research, catechin oligomers, procyanidin dimers and trimers were extracted, isolated and purified from grapes seeds and tested for their inhibition on LDL oxidation, along and with other monomeric wine phenolics.We quantify the level of phenolics, major catechins [(+)-catechin, (−)-epicatechin, procyanidin dimers B1, B2, B3, B4], phenolics acids, caftaric acid and malvidine-3-glucoside by HPLC with UV detection for 60 French varietal commercial wines taken from the South of France in order to appreciate the daily dietary intake of these compounds for French population. Based on a still significant French red wine consumption of 180 ml/day, the current daily intake of phenolics can be estimated at 400.2 mg/day/resident and catechins (monomers, dimers B₁, B₂, B₃, B₄) at 83.2 mg/day/resident, including 40% of monomers for the French population. Red wine, and particularly Egiodola, and Cabernet-Sauvignon varieties, contributes to a very significant proportion of phenolics dietary intake and, in particular catechins. These results provide a basis for epidemiological evaluation of phenolics and catechins intake by wine consumption in the French population. Few data exist on absorption and metabolism of phenolics from wine. Further studies are necessary to determine the behaviour of this class of compounds in vivo after wine absorption.     

Stereoisomere Aromastoffe XXVII. Optisch reine Carbons?urealkan-3-ylester - Darstellung und Eigenschaften

Summary Diastereomeric (S)-O-acetyllactic acid alkan-3-yl esters were separated by liquid chromatography to yield optically pure alkan-3-ols by reductive cleavage. The absolute configuration of alkan-3-ol enantiomers was concluded from the¹H-NMR data of their diastereomeric esters with optically pure (R)-2-phenylpropionic acid and (R)--methoxy--(trifluoromethyl)phenylacetic acid. The¹H-NMR spectroscopic behaviour of diastereomeric (S)-O-acetyllactic acid alkan-3-yl ester was found to be very similar to those of the corresponding (R) 2-methoxy-2-(trifloromethyl)phenyl acetic acid esters; the direct elucidation of the absolute configuration of (S)-O-acetyl-lactic acid alkan-3-yl esters was demonstrated. The esterification of alkan-3-ols (C₆–Cn8) with acetic acid, butyric acid, hexanoic acid and octanoic acid respectively yields 12 pairs of optically pure mirror images. Their sensory properties are discussed.Zusammenfassung Die aromarelevanten chiralen Alkohole Hexan-, Heptan- und Octan-3-ol werden durch flüssigchromatographische Trennung diastereomerer (S)-O-Acetylmilchsäureester und anschließende reduktive Esterspaltung in optisch reiner Form erhalten. Die Zuordnung der absoluten Konfiguration wird durch¹H-NMR Spektroskopie diastereomerenreiner (R)-2-Phenylpropionsäurealkan-3-ylester bestimmt. Es wird gezeigt, daß die Konfigurationszuordnung auch aus dem¹H-NMR spektroskopischen Verhalten diastereomerer (S)-O-Acetylmilchsäureal-kan-3-ylester abgeleitet werden kann. Die enantiomeren Alkan-3-ole werden mit den Säurechloriden der Essigsäure, Buttersäure, Hexan- and Octansäure zu chiralen Carbonsdurealkan-3-ylestern umgesetzt. Zwölf Enantiomerenpaare werden optisch rein dargestellt und sensorisch beurteilt.     

Effects of added phenolics on the storage stability of avocado and coconut oils

This study investigated the effects of added phenolics on the storage stability of avocado and coconut oils. Avocado and coconut oils in the absence (control oil) and presence (treated oil) of caffeic acid (CA) or p‐coumaric acid (pCA) were stored at 20 and 60 °C for 50 days. The total phenolic content, peroxide value, p‐anisidine value (p‐AV), free fatty acids (FFAs) and FA composition of the obtained oils were examined on days 0, 7, 15, 23, 35 and 50. Results showed that storage at 60 °C accelerated oil oxidation, and the CA or pCA helped preserve avocado and coconut oils to different extents. CA and pCA protected some desirable unsaturated fatty acids at 60 °C, but facilitated the hydrolysis of triglycerides. Substantially extractable phenolics were still detected in the treated oils after either storage. Incorporation of phenolics into oil products is feasible and beneficial for increasing oil stability and nutritional value.     

Selective elution of tea catechins and caffeine from polyvinylpolypyrrolidone

Desorption of catechins and caffeine from polyvinylpolypyrrolidone (PVPP) was comprehensively investigated. The result showed that caffeine could easily be desorbed from PVPP by the tested solvents except n‐hexane, while catechins could only be thoroughly done by dimethyl sulphoxide (DMSO) and N, N‐dimethylformamide (DMF). Excellent desorption efficiency of DMSO and DMF might be attributed to their high dipole moments and H‐bond potentials. Addition of ethanol was recommended considering the elution efficiency and fluidity, but ethanol volume should be <40% (v/v) for DMSO or 20% (v/v) for DMF. Desorption would get to equilibrium within 1 h and followed the pseudo‐second‐order model. Caffeine and catechins could be separately desorbed through two‐stage elution procedure, that is, water or 20% aqueous ethanol for desorbing caffeine and part of nongalloylated catechins and DMSO/ethanol (8/2, v/v) for eluting the remaining catechins. Highly purified catechins (~95%) with high level (~70%) galloylated catechins would be achieved when the desorption procedure was applied in column chromatograph.     

HPLC method for screening of flavonoids and phenolic acids in berries

An HPLC method is described for the simultaneous detection of selected flavonoids (kaempferol, quercetin, myricetin) and phenolic acids (p-coumaric, caffeic, ferulic, p-hydroxybenzoic, gallic and ellagic acids) in berries. Three extraction and hydrolysis methods and three HPLC column and solvent systems were tested for strawberry and blackcurrant. The optimal extraction and hydrolysis of these phenolics was obtained by incubating freeze-dried berry samples for 16 h at 35°C in 50% methanol and 1·2 M HCl. The best separation of the hydrolysed phenolics was achieved in ODS-Hypersil column using a ternary solvent system (dihydrogen ammonium phosphate, orthophosphoric acid and acetonitrile) with increasing hydrophobicity and changing pH. The method was used for the determination of the phenolic profiles of strawberry and blackcurrant. The relative content of flavonoids was low in strawberry but over 50% in blackcurrant. Ellagic acid was the main phenolic in strawberry while its relative content was very low in blackcurrant. Although the precision of the method was not equally good for all the phenolics, a reasonable amount of information was obtained within a single analysis. This simple, semiquantitative method is suitable for routine screening of the major phenolics in berries. © 1998 SCI.     

The influence of pectolytic enzyme addition and prefermentative mash heating during the winemaking process on the phenolic composition of Okuzgozu red wine

The effects of pectolytic enzyme addition and mash heating prior to fermentation on the phenolic component of Okuzgozu red wine during the winemaking and ageing processes were investigated. In general, the highest concentration of total phenolics was found in the mash-heated wines, whereas the total flavan-3-ol and total anthocyanin contents in all of the wines, decreased notably during the winemaking and ageing processes. As determined by HPLC, hydroxycinnamic acids were the major phenolic acids in the red wines. After 6 months in the bottle, the enzyme-treated wines had lower phenolic acid concentrations than had the control and mash-heated wines, but no significant (p < 0.05) differences were found in the concentration of total phenolic acids between the control and mash-heated wines. All of the phenolic acid levels decreased with the winemaking and ageing processes whereas only gallic acid increased. The wines treated by the pectolytic enzyme addition had a lower monomeric flavan-3-ol content than had the other wines, and the amount of monomeric anthocyanins extracted did not increase with the addition of enzymes.     

Genomic Study of the Absorption Mechanism of p‐Coumaric Acid and Caffeic Acid of Extract of Ananas Comosus L. Leaves

Cardiac disease has emerged as the leading cause of death worldwide, and food rich in phenolic acids has drawn much attention as sources of active substances of hypolipidemic drug. Ananas comosus L. (pineapple) is one of the most popular tropical and subtropical fruits. Isolated from pineapple leaves, EAL(Extract of Ananas Comosus L. Leaves) is rich in phenolic acids, such as p‐coumaric acid, caffeic acid, and other phenolics, highly relevant to the putative cardiovascular‐protective effects, which suggests its potential to be a new plant medicine for treatment of cardiac disease, but little is known about absorption, distribution, metabolism, and excretion of EAL in animals or human beings. In this study, we employed cDNA microarray, Caco‐2 cell lines, and rat intestinal model to explore the absorption behavior of p‐coumaric acid and caffeic acid in EAL. The permeation of 2 substances was concentration and time dependent. Results also indicated that monocarboxylic acid transporter was involved in the transepithelial transport of p‐coumaric acid and caffeic acid.     

Does u.v. light affect the total phenolic compound,anthocyanin, antioxidant capacity,and sensory profiles in wines?

In the study, by applying ultraviolet (u.v.) lights (254 nm) for 45 min to red wines from fermented Cabernet Franc, Cabernet Sauvignon, Merlot, and Petit Verdot (Vitis vinifera L.) grapes, we examined the total phenolic compound, total anthocyanin, and antioxidant capacity by four different methods, trans-resveratrol, (+)-catechin, gallic acid content, and the change in tasting profiles of the wines after application. According to the results of the research, the u.v.-C application has caused an increase in all parameters examined. If we talk about averages without distinguishing between varieties, after the application the total phenolic compound content of 3206 increased to 3356 mg gallic acid equivalent (GAE) per L and after u.v.-C application, the total anthocyanin content increased from 411 to 780 mg L⁻¹, the ABTS [2,2′-azinobis(3-ethyl-benzothiazoline-6-sulphonic acid)] value increased from 30 to 33 μmol trolox mL⁻¹, the DPPH ((2,2-diphenyl-1-picrylhydrazyl) level increased from 13 to 16 μmol trolox mL⁻¹, the FRAP (ferric reducing antioxidant power) level increased from 15 to 16 μmol trolox mL⁻¹, and the CUPRAC (cupric reducing antioxidant capacity) level increased from 40 to 45 μmol trolox mL⁻¹. The u.v. application affected trans-resveratrol the most among the phenolic compounds and an average increase of 12.99% was obtained. The rate of increase after u.v. application was 3.33% in (+)-catechin and 5.57% in gallic acid. The highest correlation between antioxidant activity measurement methods was measured to be 0.998 between FRAP and DPPH. In addition, u.v.-C application has had a positive effect on taste-based sensory profiles. In recent years, the search for a diet with a high antioxidant content has become even more important.     

Phenolic compounds and antioxidant activity of Brazil nut (Bertholletia excelsa)

Brazil nuts were shelled and separated as kernel and brown skin; whole nuts were also used. Soluble phenolics from each portion as well as the whole nut were extracted using 70% acetone under reflux conditions. Insoluble-bound phenolics were subsequently extracted into diethyl ether–ethyl acetate mixture (1:1, v/v) after alkaline hydrolysis. Both soluble and insoluble-bound phenolic extracts were separately examined for their total phenolics content; antioxidant activities were evaluated by trolox equivalent antioxidant capacity (TEAC), 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and hydroxyl radical scavenging activities using electron paramagnetic resonance (EPR), reducing power, and oxygen radical scavenging capacity (ORAC). Soluble phenolics in brown skin was 1236.07 as compared to 406.83 in kernel and 519.11 mg/100 g in whole nut. Bound phenolics content of brown skin was also 86- and 19-folds higher than kernel and whole nut, respectively. Similarly extracts from the brown skin exhibited the highest antioxidant activity. Free- and bound phenolics were identified and quantified; these included nine phenolic acids and flavonoids and their derivatives (gallic acid, gallocatechin. protocatechuic acid, catechin, vanillic acid, taxifolin, myricetin, ellagic acid, and quercetin). However, some phenolics were present only in the bound form. Furthermore, the phenolics were dominant in the brown skin.     

Phenolic acid concentrations in organically and conventionally cultivated spring and winter wheat

BACKGROUND: Organic crops are often thought to contain more phenolic secondary metabolites than conventional ones. This study evaluated the influence of organic and conventional farming on concentrations of phenolic acids in spring and winter wheat cultivars. RESULTS: Five phenolic acids were identified: ferulic, sinapic, p‐coumaric, vanillic and p‐hydroxybenzoic acid. Ferulic acid was the main phenolic acid in the grain of all tested wheat varieties. Significant differences among the examined cultivars in concentration of particular compounds were observed. Concentrations of phenolic acids varied significantly in organic and conventional wheat. Levels of ferulic and p‐coumaric acids, as well as the total phenolic acid content were higher in organic crops. Concentrations of sinapic acid in spring wheat, as well as vanillic and p‐hydroxybenzoic acid levels in both types of wheat were significantly higher in conventional grains. The 1000 kernel weight (TKW) of spring and winter wheat was significantly lower in organic crops. CONCLUSION: Organically produced spring and winter wheat had significantly higher concentrations of ferulic and p‐coumaric acid as well as the total phenolic acid content than conventional wheat, though the differences in the levels of phenolics were not large. However, these differences are probably caused mainly by smaller size of organic wheat kernels (lower TKW). Copyright © 2011 Society of Chemical Industry     

Antioxidant activity and contents of essential oil and phenolic compounds in flowers and seeds of Alpinia zerumbet (Pers.) B.L. Burtt. & R.M. Sm

Alpinia zerumbet leaves and rhizomes have been extensively studied for their chemical compositions and biological activities. However, less attention has been given to its flowers and seeds. In our study, essential oil, total phenolics and antioxidant capacities assayed by 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging and β-carotene bleaching methods were evaluated in flowers and seeds of A. zerumbet. In addition, their phenolic composition was determined by GC–MS and HPLC. 1,8-Cineol, camphor, methyl cinnamate and borneol were the major constituents in flower oils, whereas the main components in seeds oil were α-cadinol, T-muurolol, α-terpineol, δ-cadinene and terpinene-4-ol. The results showed that the hexane extract of flowers contained a significantly higher quantity of dihydro-5,6-dehydrokawain (DDK) than that of seeds. Total phenolic contents of flower and seed extracts were measured as 56.7 and 13.7 mg gallic acid equivalent per gram extract, respectively. The ethyl acetate extract of flowers and seeds possessed a high antiradical activity and prevented the bleaching of β-carotene. The HPLC analysis indicated that p-hydroxybenzoic acid, ferulic acid and syringic acid were the predominant phenolics in the ethyl acetate extract of flowers, whilst p-hydroxybenzoic acid, syringic acid and vanillin were the major phenolics in seeds.     

Evaluation of the extraction efficiency for polyphenol extracts from by‐products of green kiwifruit juicing

The health benefits of fruits are attributable in part to their bioactive components such as phenolics and pectic polysaccharides. By‐products derived from kiwifruit processing can be a good source of such bioactive compounds. Extracts were produced using different concentrations of ethanol in water (0%, 30%, 50%, 74% and 96% v/v) from by‐products (skin, residue and pulp) of the green‐fleshed kiwifruit (Actinidia deliciosa‘Hayward’) juicing process. The amounts of phenolic compounds and uronic acid (UA) as well as the phenolic composition in each extract were determined. Results show that different by‐products contained different concentrations of phenolics and pectic polysaccharides. Based on total phenolic contents, 96% v/v ethanol appeared to be the best extraction medium. The 30% or 74% ethanolic dilution was the second best medium for phenolic extraction from skin and pulp/residue, respectively. Water was a good medium for extracting satisfactory quantities of phenolics as well as the highest concentration of pectic polysaccharides. Phenolic profiling by high‐performance liquid chromatography (HPLC) was used to detect individual phenolic compounds in an extract. Results using HPLC showed that alkali pre‐treatment has improved the extraction efficiency of phenolics as a function of alkali concentration, fruit tissue type, extraction media, by‐product preparation method, and class of polyphenols. As a result more efficient methods for both extraction and characterisation of polyphenols could be evaluated.     

Essential oils of Origanum vulgare L. subsp. glandulosum (Desf.) Ietswaart from Tunisia: chemical composition and antioxidant activity

BACKGROUND: Characterisation of the essential oils from O. glandulosum collected in three locations of Tunisia, chemical composition and the evaluation of their antioxidant activities were carried out. RESULTS: The essential oils from Origanum vulgare L. subsp. glandulosum (Desf.) Ietswaart collected from three localities of north Tunisia—Krib, Bargou and Nefza—were obtained in yields of 2.5, 3.0 and 4.6% (v/w), respectively. The essential oils were analysed by GC and GC/MS and assayed for their total phenolics content, by the Folin–Ciocalteu method, and antioxidant effectiveness, using the 2,2‐diphenyl‐1‐picrylhydrazil (DPPH) radical scavenging assay. The main components of these essential oils, from Nefza, Bargou and Krib, were p‐cymene (36%, 40% and 46%), thymol (32%, 39% and 18%), γ‐terpinene (24%, 12% and 16%) and carvacrol (2%, 2% and 15%), respectively). The ability to scavenge the DPPH radicals, expressed by IC₅₀, ranged from 59 to 80 mg L^?1. The total phenolic content, expressed in gallic acid equivalent (GAE) g kg^?1 dry weight, varied from 9.37 to 17.70 g kg^?1 dw. CONCLUSIONS: A correlation was identified between the total phenolic content of the essential oils and DPPH radical scavenger capacity. The occurrence of a p‐cymene chemotype of O. glandulosum in the northern region of Tunisia is demonstrated. Copyright © 2010 Society of Chemical Industry     

Antioxidant activity and chemical constituents of essential oil and extracts of Rhizoma Homalomenae

Antioxidant activity and composition of essential oil and extracts of Rhizoma Homalomenae were determined. The extracts, especially the ethyl acetate extract (QJ4 fraction) of the aqueous residue after oil distillation, had considerable antioxidant potency which was significantly associated with their total phenolic and flavonoid contents, but the essential oil showed only weak or moderate activity. GC–MS analysis of the essential oil (yield: 0.82%, v/w) resulted in the identification of 77 compounds, accounting for 96.5% of the content of the oil. The major components, epi-α-cadinol (14.8%), α-cadinol (14.8%), α-terpineol (13.8%), linalool (11.1%), terpinen-4-ol (4.92%), and δ-cadinene (4.91%) constituted 64.3% of it. LC–MS/MS and HPLC analyses showed seven phenolic compounds (protocatechuic acid, vanillic acid, syringic acid, caffeic acid, p-coumaric acid, ferulic acid and apigenin) with a great amount in the ethyl acetate extract (QJ4 fraction). The strong antioxidant properties of the plant extracts may be attributed to the presence of these phenolics.