The effect of heartwood extracts from Acacia mangium (heartrot-susceptible) and A. auriculiformis (heartrot-resistant) was examined on the growth of wood rotting fungi with in vitro assays. A. auriculiformis heartwood extracts had higher antifungal activity than A. mangium. The compounds 3,4',7,8-tetrahydroxyflavanone and teracacidin (the most abundant flavonoids in both species) showed antifungal activity. A. auriculiformis contained higher levels of these flavonoids (3.5- and 43-fold higher, respectively) than A. mangium. This suggests that higher levels of these compounds may contribute to heartrot resistance. Furthermore, both flavonoids had strong 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity and laccase inhibition. This suggests that the antifungal mechanism of these compounds may involve inhibition of fungal growth by quenching of free radicals produced by the extracellular fungal enzyme laccase.

The heartwood of Acacia mangium is vulnerable to heart rot and this is the first study to investigate the role of heartwood extractives in its susceptibility. Acacia auriculiformis was compared with A. mangium because it is rarely associated with heart rot. The heartwood extracts of both species were dominated by three flavonoids (2,3-trans-3,4¢,7,8-tetrahydroxyflavanone, teracacidin, and 4¢,7,8,-trihydroxyflavanone), which were purified and identified by nuclear magnetic resonance spectroscopy. The latter compound has not been previously reported in A. mangium and evidence for melacacidin is also newly reported. The mass spectrometric (MS) behavior of these compounds is given, for example teracacidin does not form molecular ions by either electrospray ionization or atmospheric-pressure chemical ionization. The nature of Acacia tannins was compared to quebracho tannin (composed of profisetinidins) using oxidative cleavage to enable MS detection but a negative reaction was obtained for both, which suggests the Acacia tannins may also be of the 5-deoxy proanthocyanidin type. The concentration of flavanones was less when A. mangium heartwood was decayed but the amount of proanthocyanidins was only slightly reduced and therefore these compounds may be more resistant to degradation by heart rot fungi. We found that the total phenol content of A. auriculiformis was about fivefold that of A. mangium, and, while preliminary, this provides evidence for a role played by phenolic extractives in heart rot resistance of these Acacia species.

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Superoxide dismutase-like activity of crude Eucalyptus globulus extracts obtained from new wound wood was measured using the water-soluble tetrazolium salt (WST)-1 assay. This in vitro assay determined the activity of superoxide radicals scavenging in a xanthine oxidase system. The 50% inhibition (IC 50 ) of formazan formation was estimated for fractionated samples and purified compounds isolated from the crude wound wood extract, i.e. engelitin and pedunculagin. Standards of gallic acid and pentagalloyl glucose were also measured. Fraction II as well as the compounds pentagalloyl glucose and pedunculagin showed the highest levels of antioxidant activity. Subsequent analysis of fraction II by high-performance liquid chromatography (HPLC) coupled with negative ion electrospray mass spectrometry revealed the fraction to be dominated by hydrolysable tannins including pedunculagin, di-, tri-and tetragalloylglucoses. These preliminary results provide some evidence for an antioxidant role of secondary metabolites in tree wound repair and defence.

A Novel Acylated Quercetin Tetraglycoside from Oolong Tea (Camelia sinensis) extracts. -(MIHARA, R.; MITSUNAGA*, T.; FUKUI, Y.; NAKAI, M.; YAMAJI, N.; SHIBATA, H.; Tetrahedron Lett. 45 (2004) 26, 5077-5080; Fac. Bioresour., Mie Univ., Tsu, Mie 514, Japan; Eng.) -Mais 42-221

No abstract

The inhibitory effects of 50% aqueous ethanol extracts obtained from 36 tropical woody plants species on glucosyltransferase (GTase) activity were studied. Out of the 36 species examined, those obtained from kapur (Dryobalanops sp.), a species growing in Kalimantan (Indonesia), showed the highest level of GTase inhibition. Kapur extracts were further subjected to fractionation using column chromatography (LH-20 gel, cellulose and C-18 silica gel column). LH-20 gel provided the most successful method of fractionation. The separated fractions showed positive with Folin-Ciocalteau's reagent and negative with vanillin-HCl reagent, indicating that the main constituents of the active fractions were polyphenols but not proanthocyanidin (condensed tannins). Results of the assay for protein precipitating ability with bovine serum albumin (BSA) solution suggested these polyphenols have strong protein-precipitating ability. The predominant compound produced after acid hydrolysis was ellagic acid, indicating that the GTase-inhibitory components were mainly ellagitannins. Two polyphenolic compounds referred to as compounds 1 and 2 were isolated from the water eluate fraction with LH-20 gel column, and these compounds showed comparatively strong GTaseinhibitory activities and relatively low molecular weight. Using a combination of two-dimensional, 1 H and 13 C nuclear magnetic resonance analysis, compound 1 was identified as 4-methoxy-2-[tetrahydro-3,4,5-trihydroxy-6-(hydroxymethyl)pyran-2-yl]-a-resorcylic acid d-lactone (ber genin), and 2 was identified as 4-O-(a-rhamnopyranosyl) ellagic acid (eschweilenol C). Bergenin has been previously isolated from the roots of Bergenia crassifolia, and eschweilenol C has been isolated from the bark of Eschweilera coriacea. Both compounds were found in kapur for the first time.

The deactivating of mite allergens was investigated using lignophenols, which are polymers with a lightbeige appearance that were synthesized directly from lignocellulose with a phase-separation system. Various applications of lignophenols, instead of the photochemical solar cell dye-sensitized with lignophenol, have been reported. In the present study, lignophenols were applied for the deactivation of mite allergens.