Fumio Kawamura

Antifungal activity of constituents from the heartwood of Gmelina arborea : part 1. Sensitive antifungal assay against Basidiomycetes

Abstract Antifungal activity of constituents from the heartwood of the Malaysian Gmelina arborea against Trametes versicolor and Fomitopsis palustris was investigated. A sensitive bioassay system for antifungal activity against basidiomycetes was developed which uses a medium in which homogenized hyphae were dispersed. Ethyl acetate- solubles from the heartwood showed the highest activity against both fungi, although the activity against F. palustris was quite weak. Spots exhibiting antifungal activity against T. versicolor were specified by autobiography of ethyl acetate-solubles, and five constituents were isolated and identified as (+)-7′-O-ethyl arboreol, (+)-paulownin, (+)-gmelinol, (+)-epieudesmin and (−)-β-sitosterol. The four lignans showed antifungal activity, whereas β-sitosterol did not. From the comparison of antifungal activity, it was concluded that the piperonyl nucleus contributed to the activity of lignans. Of the four lignans isolated, gmelinol appeared to be an important antifungal constituent, since it was rich in the heartwood of G. arborea. Furthermore, the synergism by coexistence of these five compounds was confirmed.

Photodiscoloration of western hemlock (Tsuga heterophylla) sapwood III Early stage of photodiscoloration reaction with lignans

The reaction during the early stage of photodiscoloration of constituents in western hemlock [Tsuga heterophylla (Raf. Sarg., Pinaceae] sapwood was investigated with chemical methods. The main photodiscoloring constituents, hydroxymatairesinol, allohydroxymatairesinol, α-conidendrin, and oxomatairesinol, were used as substrates for light-irradiation experiments in vitro. The structures of photodiscoloration reaction products were elucidated by isolation and instrumental analyses and/or co-high-performance liquid chromatography analyses with authentic specimens. The experiment was undertaken to distinguish each series of liquid phases using chloroform, water (both including a trace of methanol), and methanol, and the solid phase. The reaction products allohydroxymatairesi (2), oxomatairesinol (3), α-conidendrin (4), allo-7′-methoxymatairesinol (5), 7′-methoxymatairesinol (6), and vanillin (7) were isolated or detected in the reaction mixture of a hydroxymatairesinol system. The reaction products hydroxymatairesinol (1), 3, 4, 5, 6, and 7 were confirmed in the reaction system of allohydroxymatairesinol, which was an epimer of hydroxymatairesinol. Product 3 was confirmed from the α-conidendrin system, and reaction product 7 was confirmed from oxomatairesinol. The photodiscoloration reaction of western hemlock sapwood could be initiated by the formation of phenoxy radicals from the respective constituents. The reaction was then presumed to progress via formation of a quinonemethide intermediate in many of them. It was suggested that the reactive species, such as phenoxy radical or quinonemethide intermediate, formed by lightirradiation might be converted to quinone derivatives and colored oligomers. Products 1, 2, 3, 4, and 7, formed from substrates such as hydroxymatairesinol, allohydroxymatairesinol, α-conidendrin, and oxomatairesinol, were the same as the original metabolic constituents of western hemlock. Therefore it was concluded that the photodiscoloration of western hemlock depends not on the quantitative level of a few respective metabolites but, rather, on the coexistence of many metabolites.

Antifungal activity of iridoid glycosides from the heartwood of Gmelina arborea

Gmelina arborea Linn. (Verbenaceae) is a deciduous broad-leaved tree widely distributed from Southeast Asia to South Asia (Greaves 1981) and all parts of this plant are used in medicine to cure various ailments (Rao et al. 1967; Tiwari 1995; Rechnagel and Glende 1973; Chanh et al. 1987). Trees of the Verbenaceae family contain iridoid glycosides (Jacke and Rimpler 1983; Rathore et al. 1989; Otsuka et al. 1991, 1992; Stuppner et al. 1993; Calis et ̧ al. 1994; Dellar et al. 1996; Hosny and Rosazza 1998; Hannedouche et al. 1999; Helfrich and Rimpler 1999; Ghisalberti 2000; Chowdhury et al. 2003). A total of 15 and 8 derivatives of 6-O-a-L-rhamnopyranosylcatalpols have been reported from the leaves of G. arborea (Hosny and Rosazza 1998) and the aerial parts of Holmskioldia sanguinea (Helfrich and Rimpler 1999), respectively. The aerial parts of Gmelina philippensis, which is the same genus of G. arborea, contains catalpol (Helfrich and Rimpler 2000). Iridoid glycosides have been found to possess a range of biological activities, i.e., antiinflammatory (Schapoval et al. 1998), antitumoral (Kapadia et al. 1996; Konoshima et al. 2000) and antioxidative (Chander et al. 1992). Cinnamate esters of catalpol from Westringia fruticosa and W. viminalis exhibited antifungal activity against the plant pathogenic fungus Cladosporium cucumerinum (Dellar et al. 1996). In the first part of this series, it was shown that four lignans contained in the heartwood of G. arborea showed antifungal activity against Trametes versicolor (Kawamura et al. 2004). In the present paper, we report on the isolation and identification of four iridoid glycosides from the same source and the determination of their antifungal activity.

Evaluation of biological activities of extracts from 22 African tropical wood species

Heartwoods of 22 African tropical wood species were extracted with methanol and the contents of total phenolic compounds in these extracts were measured. Three bioassays were conducted to evaluate the antioxidant activity, tyrosinase inhibitory activity, and antifungal activity of the methanol extracts. The results indicated that the extracts from 13 species exhibited high antioxidant potential, and their inhibitory concentrations that caused 50% scavenging of the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical (IC50) were less than 10 μg/ml. The crude extract from Cylicodiscus gabunensis showed the highest antioxidant activity, and was even higher than that of (+)-catechin, which is known as a potent antioxidant. There was a good correlation between the antioxidant activity and the content of total phenolic compounds, indicating that phenolic compounds played a predominant role in the antioxidant property of the wood extracts. Among all 22 species, only 1 species, Milicia excelsa, contained extractives that showed very high tyrosinase inhibitory activity. The extracts from 9 species showed high antifungal activity. No consistent relationship was observed between the tyrosinase inhibitory activity or antifungal activity and the content of total phenolics in the extracts.

Sesquilignans and lignans from Tsuga heterophylla

Abstract Two epimeric sesquilignans and two lignans were isolated from the sapwood of Tsuga heterophylla (western hemlock, Pinaceae). By spectroscopic analyses their structures were deduced to be (8 R ,8′ R ,7′ R ,8″ S ,7″ R )-7′-hydroxylappaol E and (8 R ,8′ R ,7′ R ,8″ S ,7″ S )- epi -7′-hydroxylappaol E, and (8′ R ,7′ S )-8-hydroxy-α-conidendrin and (8′ R ,7′ S )-8-hydroxy-α-conidendric acid methyl ester. Their presence in several samples of western hemlock sapwood was confirmed by quantitative analyses.

Evaluations of some properties of exterior particleboard made from oil palm biomass

This study investigated some physical and mechanical properties of experimental particleboard panels manufactured from different parts of oil palm including bark, leaves, fronds, and trunk consisting of mid-part and core-part using phenol formaldehyde adhesive. Two types of panels with target densities of 0.80 and 1.0 g/cm 3 were manufactured using pressure levels of 5 and 12 MPa, respectively. Both types of panels were pressed at a temperature of 180°C for 20 min. The findings indicated density and pressure level had an influence on the overall properties of the panels. Samples from the core-part had the highest modulus of rupture (MOR) values followed by those panels made from fronds and bark particles. Such samples satisfied MOR characteristics for particleboard type 13 listed in the Japanese Standard. Similarly, panels made from mid-part and leaves also showed satisfactory MOR values for particleboard type 8 based on the same standard. All panels met the IB strength requirement for type 8 except panels made from leaves made at a target density of 1.0 g/cm 3 pressed at 12 MPa. None of the samples satisfied the thickness swelling requirements. The scanning electron microscopy and Fourier transform infrared spectroscopy study indicated positive effect of the resin on interfacial bonding between the particles. Different parts of oil palm may have potential to manufacture exterior particleboard panels with acceptable strength properties. Dimensional properties of the samples need to be enhanced by using different chemicals such as wax or application of various treatments including heat treatment.

Phenolic constituents of Taxus cuspidata I: lignans from the roots

The phenolic constituents of the roots ofTaxus cuspidata (Japanese yew) were investigated. Four lignans, [(+)-taxiresinol (1), (+)-lariciresinol (2), (−)-secoisolariciresinol (3), and (+)-pinoresinol (4)] were isolated and identified. The assignment of proton and carbon atoms for the lignans were finally solved by one- and twodimensional-nuclear magnetic resonance spectra. The enantiomeric excess of these lignans were determined by chiral high-performance liquid Chromatographic analyses. (+)-Lariciresinol and (−)-secoisolariciresinol were optically pure; (+)-taxiresinol was also suggested to be optically pure, although (+)-pinoresinol was not (77% enantiomeric excess).

Constituents from the roots of Taxus cuspidata

The known propelargonidin, afzelechin-(4α→8)-afzelechin (1), the known lignans 7′-hydroxynortrachelogenin (2), epinortrachelogenin (3), nortrachelogenin (4), hydroxymatairesinol (5), allohydroxymatairesinol (6), matairesinol (7), oxomatairesinol (8), and isotaxiresinol (9), and the known taxoids taxinine M (10), taxayuntin (11), and 10-deacetyltaxol (12), and 10-deacetylbaccatin III (13) were isolated from the roots of Taxus cuspidata (Japanese yew, Taxaceae). The propelargonidin was isolated from Taxus spp. for the first time, and was detected in the roots, bark, and twigs.

Some properties of particleboard panels treated with extractives of Cerbera odollam tree

This study investigated certain aspects of physical and mechanical properties and resistance against biological deterioration of particleboard panels treated with extractives from different parts of Cerbera odollam trees. Particles of rubber-wood (Hevea brasiliensis) treated with extracts of leaf, fruit, wood, bark, flower, and seed of Cerbera odollam were used to manufacture panels in laboratory conditions. Two types of adhesive, namely melamine urea formaldehyde and phenol resorcinol formaldehyde were used as binder for the panels. Treated panels had higher resistance against powder post beetle in laboratory as well as field exposures. Both thickness swelling and internal bond strength values of treated samples satisfied requirements for P4 Type particleboards stated in European Standards (EN 312). It appears that such extractives possess potential to enhance resistance of particleboard against insect damage in tropical countries.

Antibacterial Activity of Different Biomass Components of Cerbera odollam and their Potential to Be Used as New Preservative for Wood Based Products

Cerbera odollam’s tree parts were extracted with methanol and further fractionated using n-hexane, ethyl acetate and ethanol, followed by antibacterial assay against Bacillus subtilis, Bacillus licheniformis, Escherichia coli and Pseudomonas aeruginosa. Hexane soluble parts from flower, fruit, leaf, wood, bark and ethyl acetate soluble part from bark showed antibacterial activity against Bacillus subtilis. Hexane soluble parts from leaf and bark and ethyl acetate soluble parts from wood showed antibacterial activity against Bacillus licheniformis. All fractions appeared ineffective on Escherichia coli and Pseudomonas aeruginosa. Screened extracts were analysed using FTIR. Experiments were continued with impregnation of methanolic extracts of Cerbera odollam into Melamine-urea formaldehyde (MUF) particleboards, Phenol-resorcinol formaldehyde (PRF) particleboards and solid wood samples followed by exposure to wood-boring beetles and natural decaying.