Plant-derived natural products exhibiting activity against formosan subterranean termites (Coptotermes formosanus).

The Formosan subterranean termite, Coptotermes formosanus Shiraki, is among the most devastating termite pests. Natural products derived from plant extracts were tested in a discovery programme for effective, environmentally friendly termite control agents. Among the natural products tested, vulgarone B (isolated from Artemisia douglasiana Besser), apiol (isolated from Ligusticum hultenii (Fern.) Calder & Taylor) and cnicin (isolated from Centaurea maculosa Lam.) exhibited significantly higher mortalities than in untreated controls in laboratory bioassay. These compounds are present at high levels in their respective plant sources and also possess other biological activities such as phytotoxic and antifungal properties.

Antibacterial activity of components from Lomatium californicum.

The isolation, characterization and bioactivity testing of compounds from Lomatium californicum (Nutt.) are described. Ethyl acetate and hexane extracts of the roots of L. californicum were subjected to vacuum liquid chromatography (VLC), flash column chromatography (FCC) and separation by normal- and reverse-phase high-performance liquid chromatography (HPLC). Six compounds were isolated successfully and characterized by 1D and 2D nuclear magnetic resonance (NMR) experimentation. The bioactivity of the known compounds (+)-falcarindiol, coniferyl ferulate, ferulic acid and (Z)-ligustilide were confirmed against the Gram-positive bacteria Bacillus subtilis and Staphylococcus aureus. The known compounds senkyunolide I and trans-neocnidilide were also isolated but in too small a quantity for similar testing.

Phytotoxic and antifungal compounds from two Apiaceae species, Lomatium californicum and Ligusticum hultenii, rich sources of Z-ligustilide and apiol, respectively.

The seeds of two Apiaceae species, Ligusticum hultenii and Lomatium californicum, were investigated. Preliminary bioassays indicated that methylene chloride extracts of seeds of both species contained selective phytotoxic activity against monocots and antifungal activity against Colletotrichum fragariae. Active constituents were isolated by bioassay-guided fractionation, and the structures were elucidated by NMR and GC-MS as apiol and Z-ligustilide, isolated from L. hultenii and L. californicum, respectively. Apiol and Z-ligustilide had I50 values of about 80 and 600 microM, respectively, for inhibition of the growth of Lemna paucicostata. The methylene chloride (CH2Cl2) extracts of the seeds and the isolated and purified compounds were tested against the 2-methylisobomeol-producing cyanobacterium (blue-green alga) Oscillatoria perornata, and the green alga Selenastrum capricornutum. The CH2Cl2 extracts of both Apiaceae species and apiol were weakly toxic to both species of phytoplankton, while Z-ligustilide was toxic to both with a lowest complete inhibitory concentration (LCIC) of 53 microM. Seeds of L. californicum and L. hultenii were found to be rich sources of Z-ligustilide (97 mg/g of dry seed) and apiol (40 mg/g of dry seed), respectively.

Polyol monoterpenes and sesquiterpene lactones from the Pacific Northwest plant Artemisia suksdorfii.

Five new polyol monoterpenes (1-5) and seven new sesquiterpene lactones (6-12), along with five previously identified compounds, were isolated from the aerial parts of Artemisia suksdorfii. The structures of the new compounds were established by high-field NMR techniques (1H, 13C, 1H-1H DEPT, COSY, HMQC, and HMBC) and in case of 6 confirmed by X-ray analysis.

Molluscicidal activity of vulgarone B against ram's horn snail (Planorbella trivolvis).

The ram's horn snail (Planorbella trivolvis (Say)) is an intermediate host for a digenetic trematode (Bolbophorus confusus (Krause) Dubois) that has recently been discovered to be a significant problem in commercial channel catfish (Ictalurus punctatus Raf) production ponds in the Mississippi Delta region in the USA. In these catfish ponds, the digenetic life cycle of this parasitic trematode involves two intermediate hosts, the ram's horn snail and the channel catfish, and the final host, the American white pelican (Pelecanus erythrorhynchos Gmelin). One approach to eradicate this problem is to disrupt the life cycle of the parasitic trematodes by eliminating the snails. During our search for natural-product-based molluscicides to control the snails in the catfish ponds, vulgarone B, isolated from the steam distillate of the aerial parts of the plant Artemisia douglasiana Besser (Asteraceae), was found to be active towards the snails with a LC50 of ca 24 microM. Channel catfish toxicity studies indicated a LC50 of ca 207 microM. Vulgarone B may be an environmentally acceptable alternative for snail control in aquaculture.

Vulgarone B, the antifungal constituent in the steam-distilled fraction of Artemisia douglasiana.

Antifungal activity of the steam distilled essential oil fraction of Artemisia douglasiana was detected by bioautography on silica gel TLC plates against three Colletotrichum spp. The active principle was isolated by bioassay-directed fractionation using column chromatography followed by crystallization and was characterized as vulgarone B by 1H and 13C NMR and GC-MS. Antifungal activity of vulgarone B was further evaluated using 96-well microtiter assay against Colletotrichum acatatum, C. fragariae, C. gloeosporioides, and Botrytis cinerea. In addition, the antifungal activity of vulgarone B and verbenone, and their corresponding alcohols was tested by bioautography and microtiter assay. Structure-activity studies revealed that the alpha, beta-unsaturated carbonyl functionality is a prerequisite for the antifungal activity of these mono and sesquiterpene ketones. This is the first report of antifungal activity of vulgarone B. The yield of essential oil from A. douglasiana is about 0.6-0.8% by weight of the dry material, including plant stems.

Antifungal constituents of the essential oil fraction of Artemisia dracunculus L. Var. dracunculus.

The isolation and structure elucidation of antifungal constituents of the steam-distilled essential oil fraction of Artemisia dracunculus are described. Antifungal activities of 5-phenyl-1,3-pentadiyne and capillarin against Colletrotichum fragariae, Colletrotichum gloeosporioides, and Colletrotichum acutatum are reported for the first time. The relative abundance of 5-phenyl-1,3-pentadiyne is about 11% of the steam-distilled oil, as determined by GC-MS. Methyleugenol was also isolated and identified as an antifungal constituent of the oil.

Molluscicidal and antifungal activity of Erigeron speciosus steam distillate.

The steam-distilled fraction of the aerial parts of Erigeron speciosus (Lindl) DC was tested for activity against strawberry plant pathogenic fungi Botrytis cinerea Pers ex Fr, Colletotrichum acutatum Simmonds, C fragariae Brooks, C gloeosporioides (Penz) Penz & Sacc, and the intermediate host snail Planobdella trivolvis that harbors the trematode, Bolbophorus confusus, that infests and causes severe infections in pond-raised catfish in the Mississippi Delta region of the USA. Bioautography on silica TLC plates demonstrated antifungal activity in the steam distillate. Preliminary bioassays of the steam distillate indicated the presence of phytochemicals toxic to P trivolvis. The bioactive compounds methyl 2Z, 8Z-deca-2,8-diene-4,6-diynoate and its 2E, 8E isomer were isolated by bioassay-guided fractionation and chromatographic techniques and identified by 1H NMR spectroscopy.