Volatile composition analysis by solid-phase microextraction applied to oak wood used in cooperage (Quercus pyrenaica and Quercus petraea): effect of botanical species and toasting process

The purpose of this study was to investigate the sorption of selected volatile substances from oak wood-chip samples (Quercus pyrenaica Willd. and Quercus petraea L.) subjected to different toasting levels, namely, without toasting, with medium toasting, and with strong toasting, through the use of solid-phase microextraction (SPME). The main volatile compounds identified as a function of the toasting level and botanical species were furfural, hexanal, α-pinene, d-limonene, decanal, vitispirane, ethyl hexanoate, cis-3-methyl-γ-octalactone (“oak lactone” or “whisky lactone”), α-terpineol, p-xylene, and nonanal. Considering the data obtained from the toasted woods (medium and strong intensity) in comparison with those of nontoasted woods, it can be pointed out that the average peak area and the number of compounds identified in the gas chromatogram decreased during the toasting process. In general, regarding the compounds analyzed, quantitative differences were found between the two oak wood species under study. High values of volatile compounds were found in Quercus pyrenaica oak wood chips. In addition, for the number of compounds identified in oak wood extracts and directly extracted from solid oak wood chips by SPME, it is concluded that the best extraction process for volatile compounds from oak wood is the use of oak wood-chip liquid extracts.     

Antioxidative activity and anti-inflammatory effects of diarylheptanoids isolated from <Emphasis Type="Italic">Alnus hirsuta</Emphasis>

Two diarylheptanoids, 1,7-bis-(3,4-dihydroxyphenyl)-heptane-3-one-5-O-β-d-xylopyranoside (I) and 1,7-bis-(3,4-dihydroxyphenyl)-heptane-5-O-β-d-xylopyranoside (II), were isolated from the bark of Alnus hirsuta. Compounds I and II exhibited strong antioxidative activity against 1,1-diphenyl-2-picrylhydrazyl radicals, with IC₅₀ values of 8.36 ± 0.54 and 8.67 ± 1.46 μM, respectively. In addition, we demonstrated that compounds I and II inhibited the production of nitric oxide and reactive oxygen species and the expression of proinflammatory molecules such as inducible nitric oxide synthase and cyclooxygenase-2 in lipopolysaccharide-induced macrophages. According to our results, the two diarylheptanoids isolated from the bark of A. hirsuta exhibited significant antioxidative activity and anti-inflammatory effects and may be useful in the pharmaceutical industry for alleviating oxidative stress.     

Antioxidative compounds from leaves of Tahongai (<Emphasis Type="Italic">Klienhovia hospita</Emphasis>)

In our effort to find antioxidant agent, we focused on Tahongai (Kleinhovia hospita) which have been used traditionally in Indonesia as medicinal herbal to cure liver disease. Based on the biologically guided fractionation using DPPH radical scavenging assay, eleutherol and kaempferol 3-O-β-d-glucoside was isolated from the leaves of K. hospita. Kaempferol 3-O-β-d-glucoside (1) and eleutherol (2) scavenged the radical with IC₅₀ of 71.4 and 491.8 μM, respectively. In addition, both of the compounds did not exhibit cytotoxicity on HepG2 cells.     

Chemical constituents from Gmelina arborea bark and their antioxidant activity

Gmelina arborea Roxb. is a fast-growing species and is known to have been used in traditional Indian medicine. Chemical constituents from the bark have not been reported, although some chemical constituents from part of this plant (heartwood, leaf, and root) are known. In this study, the bark meal was successively extracted with acetone and methanol. Fractionation of the acetone extract with n-hexane, diethyl ether, and ethyl acetate and subsequent chromatographic separation of the fractions led to the isolation of four compounds. The diethyl ether-soluble fraction yielded tyrosol [2-(4-hydroxyphenyl)ethanol] (1); (+)-balanophonin (2), an 8-5′ neolignan, with opposite optical rotation to known (−)-balanophonin; and gmelinol (3), a known lignan. The ethyl acetate-soluble fraction afforded a new phenylethanoid glycoside to the best of our knowledge, which was identified as (−)-p-hydroxyphenylethyl[5′″-O-(3,4-dimethoxycinnamoyl)-β-d-apiofuranosyl(1′" → 6′)]-β-d-glucopyranoside (4). From the methanol extract, two known compounds, 2,6-dimethoxy-p-benzoquinone (5) and 3,4,5-trimethoxyphenol (6), were isolated and identified. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging assay of the identifi ed compounds indicated that 3,4,5-trimethoxyphenol (6) exhibited moderate activity. Part of this report was presented at the 57th and 58th Annual Meetings of the Japan Wood Research Society, Hiroshima and Tsukuba, August 2007 and March 2008, respectively     

Rapid changes of induced volatile organic compounds in Pinus massoniana

Using the thermal-desorption cold trap gas chromatography/mass spectrometer (TCT-GC-MS) technique, the composition and relative contents of volatile compounds were analyzed in undamaged (control), insect-damaged (ID) and artificially-damaged (AD) leaves of Pinus massoniana in field at different times and levels of damage. Results showed that although volatile substances were highly released earlier in AD leaves plants, they were significantly less abundant in AD than in ID leaves treatments. Also, the damage level considerably influenced the changes of induced volatile products from leaves. Compared with the control, the emission rate of camphene, β-pinene, phellandrene, caryophyllene and (E)-farnesene was high after 1 h in 25%–40% ID-affected leaves, whereas that of tricyclene, myrcene, camphene, β-Pinene, phellandrene and caryophyllene reached its maximum after 24 h in 60%–75% ID-affected leaves. In the same manner, some volatile compounds in the AD leaves treatment displayed their peaks just after 1 h, but others after 24 h. The AD and ID leaves at the damage level of 25%–40% did not exhibit an obvious regularity with time; however, in 60%–75% AD leaves, peaks of volatile substances were attained after 1 or 2 h. Our results also showed that the relative content of β-pinene increased and was higher in damaged than control plants. β-pinene plays an important role in inducing the insect resistance of P. massoniana trees. __________ Translated from Scientia Silvae Sinicae, 2006, 42(4): 65–70 [译自: 林业科学]     

Stereochemistry and biosynthesis of (+)-lyoniresinol,a syringyl tetrahydronaphthalene lignan in <Emphasis Type="Italic">Lyonia ovalifolia</Emphasis> var. <Emphasis Type="Italic">elliptica</Emphasis> II: feeding experiments with <Superscript>14</Superscript>C labeled precursors

To clarify the biosynthetic pathway for syringyl lignans, especially syringyl tetrahydronaphthalene lignans and formation of the C2–C7′ linkage, production of (+)-lyoniresinol (LYR) and its predicted intermediates [syringaresinol (SYR), 5,5′-dimethoxylariciresinol (DMLR), and 5,5′-dimethoxysecoisolariciresinol (DMSLR)] in Lyonia ovalifolia var. elliptica was investigated by means of feeding experiments with radiolabeled precursors. Following individual administration of l-[U-¹⁴C]phenylalanine (Phe), [8-¹⁴C]sinapyl alcohol (SA), and [8,8′-¹⁴C]SYR to excised young shoots of L. ovalifolia and their subsequent metabolism, free [¹⁴C]lignans and [¹⁴C]lignan glycosides were extracted with methanol from stems and leaves and were divided into ethyl acetate-soluble fractions (lignans) and aqueous fractions (lignan glycosides), respectively. Using a combination of xylanase, cellulase, and β-glucosidase, the glycosides were hydrolyzed to liberate [¹⁴C]lignans as aglycones. l-[U-¹⁴C]Phe was incorporated into (+)-[¹⁴C]SYR [stem 0.38%, 8% enantiomeric excess (e.e.)], (−)-[¹⁴C]SYR (leaves 2.75%, 72% e.e.), (+)-[¹⁴C]DMLR (stem 0.07%, 18% e.e. and leaves 0.009%, 58% e.e.), (−)-[¹⁴C]DMSLR (stem 0.03%, 46% e.e. and leaves 0.05%, 20% e.e.), (+)-[¹⁴C]LYR (leaves 0.013%, 22% e.e.) and glycosides of (+)-[¹⁴C]LYR (stem 0.036%, 50% e.e.) in 24h. Based on the percent incorporation and enantiomeric composition of the lignans, the biosynthetic pathway of (8R,8′R)-(+)-LYR was proposed as follows: a nonselective dehydrogenative dimerization of sinapyl alcohol yields (±)-SYR, which is reduced with low specificity to give (8R,8′R)-(+)-DMLR. This is cyclized to directly give (+)-LYR as well as reduced again to (8R,8′R)-(−)-DMSLR. Although further transformation of (−)-DMSLR also leads to the formation of (+)-LYR, cyclization could be a main pathway for (+)-LYR biosynthesis. This report was presented at the IAWPS 2005 International Symposium on Wood Science and Technology, Yokohama, November 2005     

Structural unit of xylans from sugi (<Emphasis Type="Italic">Cryptomeria japonica</Emphasis>) and hinoki (<Emphasis Type="Italic">Chamaecyparis obtusa</Emphasis>)

Arabinoglucuronoxylans (AGXs) isolated from the holocellulose of sugi (Cryptomeria japonica) and hinoki (Chamaecyparis obtusa) contained one 4-O-methyl-d-glucopyranosyluronic acid (4-O-Me-d-GlcAp) residue per 6.2 d-xylopyranose (d-Xylp) residues and one 4-O-Me-d-GlcAp residue per 3.8 d-Xylp residues. These AGXs were subjected to partial acid hydrolysis. Analyses by size exclusion chromatography and electrospray-ionization mass spectroscopy of the neutral sugar fractions in the hydrolysates showed the presence of xylooligosaccharides having a degree of polymerization of 2-8 in addition to d-Xyl, suggesting that the AGXs from sugi and hinoki contained unsubstituted chains consisting of at least eight d-Xyl residues. The acidic sugars in the hydrolysates were separated into two series of aldouronic acids composed of 4-O-Me-d-GlcAp and d-Xylp by ion-exchange chromatography. The first series included aldouronic acids from aldobiouronic acid (4-O-Me-d-GlcAp-Xyl) to aldopentaouronic acids (4-O-Me-d-GlcAp-Xyl₄). The second series were aldouronic acids composed of two 4-O-Me-d-GlcAp residues and 2-4 d-Xyl residues. In these acidic sugars, the uronic acid side chains were located on two contiguous d-Xyl residues. These facts indicated that AGXs from sugi and hinoki had a structural unit containing two 4-O-Me-d-GlcAp residues on two contiguous d-Xyl residues as well as AGXs from spruce and larch.     

Feeding responses of the western dry-wood termite <Emphasis Type="Italic">Incisitermes minor</Emphasis> (Hagen) (Isoptera: Kalotermitidae) against ten commercial timbers

Five Japanese timbers, four timbers from the USA, and one Malaysian timber were evaluated for their resistance to the invasive dry-wood termite Incisitermes minor (Hagen) using laboratory choice and no-choice feeding tests with holed specimens. The highest survival rates of I. minor in both the heartwood and sapwood no-choice feeding tests were more than 70% after 3 months. When offered sapwood and heartwood choice feeding tests and the combined choice feeding tests, the highest survival rates of I. minor were more than 75% after 3 months. With regards to the percentage of wood mass losses in the no-choice and choice feeding tests, karamatsu (Larix leptolepsis), buna (Fagus crenata), and Douglas fir (Pseudotsuga menziesii) were classified as “resistant” species among the ten sapwood specimens. In the heartwood no-choice and choice feeding tests, the resistant species were buna, karamatsu, Douglas fir, sugi (Cryptomeria japonica), akamatsu (Pinus densiflora), and western red cedar (Thuja plicata). The ranking of the resistance of the ten commercial timbers against I. minor was buna > karamatsu > sugi > western red cedar > Douglas fir > rubber > western hemlock > hinoki > spruce.     

Investigation on hydrogen abstraction from methyl glucoside by active oxygen species under oxygen delignification conditions III: effects of the origin of active oxygen species

Carbohydrate model compounds methyl β-d-glucopyranoside (MGPβ), methyl α-d-glucopyranoside (MGPα), and methyl β-d-mannopyranoside (MMPβ) and the deuterium compounds of MGPβ labeled at the anomeric or C-2 positions (MGPβ-1D, MGPβ-2D) were reacted with active oxygen species (AOS) generated in situ by reactions between O₂ and a co-treated phenolic lignin model compound, 4-hydroxy-3-methoxybenzyl alcohol (VAlc), under conditions simulating oxygen delignification (0.5 mol/l NaOH, 0.36 mmol/l Fe³⁺, 1.1 MPa O₂, 95°C). MGPβ was degraded more than MGPα but less than MMPβ when the pairs MGPβ/MGPα and MGPβ/MMPβ, respectively, were treated, which indicates that the configurational differences at the anomeric and C-2 positions influence the reactivity of AOS toward these compounds. When the pairs MGPβ/MGPβ-1D and MGPβ/MGPβ-2D were treated, no clear kinetic isotope effects were observed in either case. These results contrasted with those obtained when another phenolic compound, 2,4,6-trimethylphenol (TMPh), was used as the AOS generator instead of VAlc under exactly the same conditions. Clear kinetic isotope effects were observed when using TMPh. Because it is not easily accepted that the anomeric and C-2 hydrogen abstractions are minor reaction modes only for AOS generated in the VAlc system, it is suspected that the AOS do not show any clear kinetic isotope effect even though the AOS abstract an objective hydrogen.     

Physicochemical properties and chemical compositions of <Emphasis Type="Italic">Melaleuca leucadendron</Emphasis> leaf oils taken from the plantations in Java,Indonesia

Melaleuca leucadendron Linn. leaf oils from Gunung Kidul, Gundih and Sukun, Java, Indonesia, at tree ages of 5, 10, and 15 years were analyzed to elucidate their qualities and chemical compositions. These oils gave yields from 0.61% to 1.59%. The samples from Gundih produced the highest yields (1.42–1.59%) compared to those from Gunung Kidul and Sukun. These oils were colorless with an odor typical of Melaleuca oils. The specific gravity of essential oils in this study ranged from 0.870 to 0.912. The samples from Gunung Kidul were the highest in specific gravity (0.905–0.912). The refractive index values of oil samples ranged from 1.468 to 1.470, optical rotation ranged from (−)2.47° to (−)0.98°, and ratio miscibility of oils in 70% ethanol ranged from 1:1 to 1:9.67. The organoleptic profiles and physicochemical properties of M. leucadendron Linn. leaf oils in this study were evaluated based on the Indonesian National Standard (SNI) 06-3954-2006 for standard quality of Melaleuca essential oils; only a few specific gravity values were below the standard. GC-MS spectrometry analysis indicated the presence of 26 compounds. Among them, 1,8-cineole (44.76–60.19%), α-terpineol (5.93–12.45%), d(+)-limonene (4.45–8.85%), and β-caryophyllene (3.78–7.64%) were the major components. Samples from each site tended to decrease in 1,8-cineole content and increase in β-caryophyllene content as plant age increased. α-Terpineol was highest at plant age 10 years, and d(+)-limonene varied according to plant site and age.     

Four glucosides ofp-hydroxyphenyl derivatives from birch leaves

The extractive of shirakamba (Betula platyphylla Sukatchev var.japonica Hara) leaves was investigated. Four glucosides ofp-hydroxyphenyl derivatives were isolated, and their structures were indentified as betuloside (I), 3,4-dihydroxy-propiophenone-3--d-glucopyranoside (II), salidroside (III), and arbutin (IV). Arbutin was newly found in the leaves of shirakamba.     

Antihyperglycemic effects of Japanese maple Acer amoenum leaf extract and its constituent corilagin

The antihyperglycemic effects of the leaves of Acer amoenum and purification and identification of an active compound were investigated. In screening experiments for α-glucosidase inhibitory activity, methanolic extracts of A. amoenum leaves showed potent inhibitory action. This extract showed antihyperglycemic effects in sucrose-loaded mice. Fractionation of the crude extract gave the active compound corilagin [β-1-O-galloyl-3,6-(R)-hexahydroxydiphenoyl-d-glucose] by spectroscopic analysis. This is the first report about the possibility of novel utilization of the Japanese maple tree as a source of compounds for prevention or treatment of diabetes mellitus.     

Effects of stilbenes from bark of <Emphasis Type="Italic">Picea glehnii</Emphasis> (Sieb. et Zucc) and their related compounds against feeding behaviour of <Emphasis Type="Italic">Reticulitermes speratus</Emphasis> (Kolbe)

The effects of stilbene glucosides and related compounds on termite feeding behavior were investigated using paper disc methods against the subterranean termite Reticulitermes speratus. The stilbene-rich fraction and isorhapontin (3-methoxy-3,4, 5-trihydroxystilbene-3--d-glucoside) from bark extracts of Picea glehnii showed avoidance by termites in choice tests. In the no-choice tests using compounds purified from the stilbene-rich fraction, the largest feeding deterrent effect was observed for piceid (3,4,5-trihydroxystilbene-3--d-glucoside), followed by isorhapontin, and astringin (3,3,4,5-tetrahydroxystilbene-3--d-glucoside), at the concentrations from 0.63 to 2.5µmol/disc. No change in activity was observed at retentions of more than 5.0µmol/disc. When the activities of isorhapontin and its aglycone derivative (isorhapontigenin: 3-methoxy-3,4,5-trihydroxystilbene) were compared with that of taxifolin (3,3,4,5,7-pentahydroxyflavanone) in the no-choice test, the stilbenes exhibited a larger antifeedant potential. Methylation of isorhapontigenin increased its termiticidal activity.Part of this study was presented at the 32nd Annual Meeting of the International Research Group on Wood Preservation, 2001     

A glucosylceramide with antimicrobial activity from the edible mushroom <Emphasis Type="Italic">Pleurotus citrinopileatus</Emphasis>

The golden oyster mushroom Pleurotus citrinopileatus is a popular edible mushroom with multifunctional biological activities, but there are a limited number of previous studies on its chemical composition. This is the first report of the isolation of glucosylceramide with antimicrobial activity from the fruiting body of this mushroom. This compound was identified as 1-O-β-d-glucopyranosyl-(2S,3R,4E,8E)-2-[(2R)-2-hydroxyhexadecanoylamino]-9-methyl-4,8-octadecadiene-1,3-diol. The IC₅₀ value of this compound for the growth of Escherichia coli and Staphylococcus aureus was 275.1 μM (200 μg/ml) and 323.2 μM (235 μg/ml), respectively.     

Essential oil from the leaves of Cryptomeria japonica acts as a silverfish (Lepisma saccharina) repellent and insecticide

This is the first article to report the evaluation of a natural product used as an antisilverfish agent. Silverfish (Lepisma saccharina), primitive wingless insects, feed on a variety of materials, including paper, cotton, starch, and cereals. They can be a problem in libraries and other places where books, documents, and papers are stored. In this pilot study, the essential oil from leaves of Cryptomeria japonica was investigated to test its properties as a silverfish repellent and insecticide. The results from a repellency bioassay show that the essential oil significantly repelled silverfish. The repellent activity was 80% at a dosage of 0.01 mg/cm³. When silverfish were exposed to a concentration of 0.16 mg/cm³ of essential oil, they were killed within 10h. The chemical composition of essential oil, the emissions from a test chamber, and the residue left on filter papers previously soaked with the essential oil in a chamber were analyzed by gas chromatography-mass spectrometry. The components of the essential oil were found to be: elemol (18.22%), 16-kaurene (11.63%), 3-carene (9.66%), sabinene (9.37%), 4-terpineol (9.06%), β-eudesmol (5.70%), α-pinene (5.62%), and limonene (5.26%). Only some constituents of the essential oil compounds collected by solid-phase microextraction were found to be emitted in the test chamber. The main constituents were: 3-carene (21.03%), p-cymene (10.95%), limonene (9.49%), β-myrcene (9.39%), γ-terpinene (9.10%), α-terpinene (8.57%), and 4-terpineol (7.97%).     

Inhibitory effects of <Emphasis Type="SmallCaps">l</Emphasis>-pipecolic acid from the edible mushroom, <Emphasis Type="Italic">Sarcodon aspratus</Emphasis>, on angiotensin I-converting enzyme

The aqueous extract of the edible mushroom Sarcodon aspratus showed inhibitory effects against angiotensin I-converting enzyme (ACE). l-Pipecolic acid (l-piperidine-2-carboxylic acid) was isolated from a hot-water extract in a 0.02% yield as an active principle. The mode of inhibition of l-pipecolic acid was found to be competitive, whereas its d-isomer showed no significant inhibitory effects against ACE, suggesting that the configuration of the carboxyl group in the molecule plays an important role in the enzyme inhibition.     

The monomer composition controls the Σ<Emphasis Type="Italic">β-O</Emphasis>-4/Σ<Emphasis Type="Italic">O</Emphasis>-4 end monomer ratio of the linear lignin fraction

Lignins are cell wall phenolic heteropolymers that result from the oxidative coupling of three monolignols bearing p-coumaryl (H), coniferyl (G), and sinapyl (S) units, in a reaction mediated by peroxidases. Here, we report the existence of a relationship between the Σβ-O-4/ΣO-4 end monomer ratio of the linear lignin fraction, released through the specific cleavage of the alkyl ether linkages by thioacidolysis, and the G/S ratio of lignins, when this was estimated in differentially evolved vascular land plants. Most importantly, in the case of angiosperms, Gnetales, and lycopods, the Σβ-O-4/ΣO-4 end monomer ratio was apparently predictable from the proportions at which the G and S units were mixed. In the case of G lignins (present in basal gymnosperms and ferns), the Σβ-O-4/ΣO-4 end monomer ratio decayed exponentially to increase the O-4-linked dihydroconiferyl alcohol (DHCA) content. The results obtained suggest that the Σβ-O-4/ΣO-4 end monomer ratio of the linear lignin fraction depends intimately on the lignin monomer composition, and, therefore, on the chemical nature of the radicals derived from three monolignols (coniferyl, dihydroconiferyl, and sinapyl alcohols), whose gain have been finely tuned during land plant evolution.     

Dormancy release in male flowers of <Emphasis Type="Italic">Cryptomeria japonica</Emphasis>

To clarify key characteristics of the process whereby dormancy is released in male flowers of Cryptomeria japonica, twigs with male flowers were collected every three days between December 1992 and February 1993. Half of the twigs collected on each date were chilled at 0°C for three days and the cumulative temperatures required by the chilled and non-chilled flowers for florescence were compared. There was no difference in the cumulative temperature required for florescence between chilled and non-chilled male flowers collected before 19 December. However, for samples collected between 21 December and 21 January, the cumulative temperature needed for the florescence of chilled male flowers was 8–68°C lower than that required for non-chilled male flowers. However, there was little difference again in the cumulative temperature required to induce the florescence of chilled and non-chilled male flowers for collection dates later than 24 January. These results suggest that the dormancy of male C. japonica flowers was gradually released by exposure to low temperature and the process was completed by 24 January. The cumulative temperature required for florescence and the sum of the mean daily temperatures between the date of collection and the date of natural pollen dispersal were almost equal after the dormancy of the male flowers was released. The exact day on which pollen will be released can be predicted using the dormancy characteristics of male flowers.     

Antimicrobial activity against <Emphasis Type="Italic">Streptococcus sobrinus</Emphasis> and glucosyltransferase inhibitory activity of taxifolin and some flavanonol rhamnosides from kempas (<Emphasis Type="Italic">Koompassia malaccensis</Emphasis>) extracts

Twenty plant materials collected from the islands of Java and Kalimantan in Indonesia were extracted with 50% aqueous ethanol (crude extract). The crude extracts were assayed for antimicrobial activities against Streptococcus sobrinus and for glucosyltransferase (GTase) inhibition. Fourteen extracts inhibited the growth of S. sobrinus by more than 50% and six extracts inhibited GTase activity by more than 50% at a concentration of 100 μg/ml. Koompassia malaccensis (kempas) extracts showed 90% depression of S. sobrinus growth and 80% inhibition of GTase activity at a concentration of 100 μg/ml. Kempas crude extracts were subjected to column chromatography using Sephadex LH-20 and then preparative high-performance liquid chromatography to isolate four compounds A, B, C, and D. These compounds were identified as taxifolin and the flavanonol rhamnoside isomers neoastilbin, astilbin, and isoastilbin, respectively, from ¹H and ¹³C nuclear magnetic resonance (NMR) spectra and other two-dimensional NMR techniques (COSY, HMBC, and HMQC). Each compound depressed the growth of S. sobrinus over a concentration range of 9.3242.7 μg/ml and showed GTase inhibitory activity with IC₅₀ values in the range 27.4–57.3 μg/ml. Taxifolin and flavanonol rhamnoside isomers isolated for the first time from kempas could be potent compounds for preventing dental caries. Part of this report was presented at the 57th Annual Meeting of the Japan Wood Research Society Conference, Hiroshima, 2007     

Heartwood extractives from the Amazonian trees <Emphasis Type="Italic">Dipteryx odorata,Hymenaea courbaril</Emphasis>, and <Emphasis Type="Italic">Astronium lecointei</Emphasis> and their antioxidant activities

Heartwood extracts from Amazonian trees cumaru-ferro (Dipteryx odorata), jatoba (Hymenaea courbaril), and guarita (Astronium lecointei) exhibit antioxidant activities comparable with that of α-tocopherol, a well-known antioxidant. This article reports the characterization of the antioxidant compounds in the extracts of the three heartwoods. Silica gel column chromatography of the cumaru-ferro EtOAc extract yielded (−)-(3R)-7,2′,3′-trihydroxy-4′-methoxyisoflavan and (+)-(3R)-8,2′,3′-trihydroxy-7,4′-dimethoxyisoflavan. Silica gel column chromatography followed by preparative high-performance liquid chromatography of the jatoba EtOAc extract yielded (−)-fisetinidol and (+)-trans-taxifolin. Chemical structures were assigned using electron-ionization mass spectrometry, ¹H and ¹³C nuclear magnetic resonance (NMR) spectroscopy including nuclear Overhauser effect spectroscopy (NOESY), as well as optical rotation and circular dichroism. Gas chromatography-mass spectrometry demonstrated that the isolated compounds were predominant in the EtOAc extracts. In the guarita EtOAc extract, catechin and gallic acid were identified by comparing their retention times and mass fragmentation patterns with those of authentic samples. Antioxidant activity determined by the 1,1-diphenyl-2-picrylhydrazyl assay demonstrated that all these compounds had activities comparable with that of α-tocopherol. Part of this report was presented at the 57th Annual Meeting of the Japan Wood Research Society, Hiroshima, August 2007