Synthesis and biological evaluation of alkoxycoumarins as novel nematicidal constituents.

We synthesized all of the monomethoxycoumarins, 5-alkoxycoumarins and their derivatives, and investigated their nematicidal activity against the phytopathogenic nematode, Bursaphelenchus xylophilus. Among the compounds, 5-ethoxycoumarin showed the highest nematicidal activity. Furthermore, 5-ethoxycoumarin was comparatively harmless against both the brine shrimps, Artemia salina, and the Japanese killifish, Oryzias latipes.

Antinematodal activities of ingenane diterpenes from Euphorbia kansui and their derivatives against the pine wood nematode (Bursaphelenchus xylophilus).

Under the bioassay-guided method, two diterpenes, 3-O-(2",3"-dimethylbutanoyl)-13-O-dodecanoylingenol (1) and 3-O-(2",3"-dimethylbutanoyl)-13-O-decanoylingenol (2) isolated from Euphorbia kansui, showed a pronounced antinematodal activity against the nematode Bursaphelenchus xylophilus at the same minimum effective dose (MED) of 5 microg per cotton ball and still displayed antinematodal activity at a dose of 2.5 microg per cotton ball. Compounds 3-6 were obtained, and the structure of the new compound 6 was elucidated based on 1D- and 2D-NMR analyses and physicochemical data. Preliminary structure-biological activity relationships of ingenane-type compounds were deduced.

Three antinematodal diterpenes from Euphorbia kansui.

Three compounds, 20-O-acetyl-[3-O-(2'E,4'Z)-decadienoyl]-ingenol (1), 20-O-acetyl-[5-O-(2'E,4'Z)-decadienoyl]-ingenol (2) and 3-O-(2'E,4'Z)-decadienoylingenol (3), were isolated from Euphorbia kansui under the bioassay-guided method. Each compound showed the same antinematodal activity against the nematode, Bursaphelenchus xylophilus, at a minimum effective dose (MED) of 5 microg/cotton ball.

Synthesis and antinematodal activity of 3-n-alkylphenols.

Several 3-alkylphenols including 3-undecylphenol, which was isolated from a Sumatran rainforest plant, were synthesized to investigate their antinematodal activity against the phytopathogenic nematodes, Bursapherencus xylophilus. A three-step synthesis involving the treatment of 2-cyclohexen-1-one with the Grignard reagent, oxidation of the resulting 1-alkyl-2-cyclohexen-1-ol and subsequent aromatization of 3-alkyl-2-cyclohexen-1-one successfully afforded such phenols. Among the 3-alkylphenols, 3-nonylphenol showed the highest activity, while 3-decylphenol and 3-undecylphenol also showed high activity.

Distribution and persistence of emamectin benzoate at efficacious concentrations in pine tissues after injection of a liquid formulation.

In an earlier paper the authors reported the creation of a novel emamectin benzoate 40 g litre(-1) liquid formulation (Shot Wan Liquid Formulation). The injection of this formulation exerted a preventative effect against the pine wilt disease caused by the pine wood nematode, Bursaphelenchus xylophilus (Steiner & Buhrer) Nickle, and this effect lasted for at least 3 years. The present study was carried out to show experimentally that the marked effect of this formulation was due to the presence and persistence in pine tissues of sufficient amounts of emamectin benzoate to inhibit nematode propagation. A cleanup procedure prior to quantitative analysis of emamectin benzoate by fluorescence HPLC was devised. The presence of the compound in concentrations sufficient to inhibit nematode propagation in the shoots of current growth and its persistence for 3 years explained the marked preventative effect. Non-distribution of emamectin benzoate in some parts of the lower trunk suggested that the formulation should be injected at several points for large trees in order to distribute the compound uniformly to lower branches.

Development and preventative effect against pine wilt disease of a novel liquid formulation of emamectin benzoate.

Injection of the poorly water-soluble emamectin benzoate (EB) into pine trunks required the development of an efficient liquid formulation. For injection into big trees in forests a good rate of injection and a high active content were required. Tests on the viscosity and EB-solubilizing ability of 14 various solubilizers in diethylene glycol monobutyl ether (DGMBE) led to the selection of Sorpol SM-100PM as the solubilizer of the formulation. Relationships between the solubilizing ability and amounts of Sorpol SM-100PM and DGMBE relative to that of EB, and between the concentration of the latter and the viscosity or the injection rate of the formulation led to a novel 40 g litre(-1) emamectin benzoate formulation (Shot Wan Liquid Formulation), which was composed of EB (40), Sorpol SM-100PM (120), DGMBE (160) and distilled water (50 g litre(-1)) in methanol. Injection of this formulation at a dose of 10 g EB per unit volume of pine tree prevented over 90% of the trees from wilting caused by pine wood nematode, and this preventative effect continued for 3 years. Neither discolouration of the leaves nor injury around the injection hole on the trees was observed after injection of the formulation.

Antifungal garcinia acid esters from the fruits of Garcinia atroviridis.

Two new garcinia acid derivatives, 2-(butoxycarbonylmethyl)-3-butoxycarbonyl-2-hydroxy-3-propanolide and 1',1"-dibutyl methyl hydroxycitrate, were isolated from the fruits of Garcinia atroviridis guided by TLC bioautography against the fungus Cladosporium herbarum. The structures of these compounds were established by spectral analysis. The former compound represents a unique beta-lactone structure and the latter compound is most likely an artefact of garcinia acid (= hydroxycitric acid). Both compounds showed selective antifungal activity comparable to that of cycloheximide (MID: 0.5 microg/spot) only against C herbarum at the MIDs of 0.4 and 0.8 microg/spot but were inactive against bacteria (Bacillus subtilis, methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli), other fungi (Alternaria sp., Fusarium moniliforme and Aspergillus ochraceous) including the yeast Candida albicans.