Nematocidal activity

The demonstration that a-terthienyl had nematocidal activity in vitro and that the activity was light-dependent created an interesting puzzle 

The importance of finding effective nematocides for crop protection amply justifies the synthesis and testing of analogs of compounds with demonstrated activity. Thus, for example, many 2,2 -bithiophenes, trithiophenes, 1,2-dithienylethenes, and analogs where other rings such as benzene, thiazole and pyrazole replace the thiophene nucleus were synthesized and tested on nematodes 118, 243, 245). The photosensitizing properties of some of these compounds were also investigated in vitro 113). 

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Nematocidal activity. Water extract of the dried fruit, in cell culture at a concentration of 10 mg/mL, and methanol extract at a concentration of 1 mg/mL, were active on Toxacara canis . ... 

Kondo. Nematocidal activity of some DC158 anthelmintics, traditional medicines, and spices by a new assay method using larvae of Toxocara canis. Shoyakugaku Zasshi 1989 43(4) 279-287. DC159... 

ZO200 Kiuchi, F., M. Hioki, N. Nakamura, N. Miyashita, Y. Tsuda, and K. Kondo. Screening of crude drugs used in Sri Lanka for nematocidal activity on the larva of Toxocaria canis. Shoyakugaku Zasshi 1989 43(3) 288-293. 

While compounds 27 and 29 lack nematocidal activity, we found 23 to be more active than MFA. 

Due to the enhanced nematocidal activity observed following the introduction of a methyl group at C14 [32, Fig. (8)], its effect on C15 was next investigated. 

While compound 36 demonstrated excellent nematocidal activity, the epimer 41 at the same concentration was totally inactive. Perhaps the conformation of the G-ring relative to the hydroxyl group is more important than the chirality of the methyl group at Cl5. To further... 

Scale up studies of a second potential candidate yielded the desired 36 and a small amount of a less polar compound, characterized as the 2-desoxo derivative 49 [Fig. (15)]. The excellent nematocidal activity of 49 encouraged us to attempt the selective reduction of the C-ring carbonyl in MFA (1), to yield 52. Reduction of 1 with three or ten equivalents of LAH yielded 50 (carbonyl reduced in ring F) and 51 (carbonyls reduced in rings C and F) respectively, both lacking nematocidal activity we were unable to synthesize 52. 

To follow up the excellent nematocidal activity of 49, PHA was selectively reduced with the alane-NMe2Et complex to furnish 53, albeit in only a 5% yield [Fig. (16)]. 

An Oceanapia sp. collected off the northern Rottnest Shelf, Australia, has yielded three novel dithiocyanates, thiocyanatins A-C (623-625). The structures were determined by spectroscopic analysis and confirmed by total synthesis. The thiocyanatins contain an unprecedented dithiocyanate functionality and an unusual 1,16-difunctionalised n-hexadecane carbon skeleton. They possess nematocidal activity [496]. 

Triclabendazole is a very potent anthelminthic used against all stages of liver flukes in sheep, goats, and cattle at dosages of 10-12 mg/kg bw. This drug does not exhibit nematocidal activity and is not teratogenic. 

Addition product 72 from 2-azidobenzothiazole (71) was claimed to have anthelmintic and nematocidal activity.483 Refluxing EP with... 

Several years later Gommers found that in the presence of light (sun light or UV-A), the nematocidal activity of a-terthienyl increased (LD10o... 

A new curcuminoid, cyclocurcumin, possessing nematocidal activity, was isolated from the mother liquor by repeated purification as a yellow gum (Kiuchi et al, 1993). It had the same molecular formula as curcumin, but differed in structure by an intramolecular Michael addition of the enol-oxygen to the enone group. The chemical structures of these components are given in Fig. 6.2. 

Kiuchi, F., Goto, Y., Sugimoto, N., Akao, N., Kondo, K. and Tsuda, Y. (1 993) Nematocidal activity of turmeric synergistic action of curcuminoids. Chemical and Pharmaceutical Bulletin 41, 1 640-1643. 

Dihydro-2//-thieno[3,4-c]pyrazoI-3-yIcarbamates show insecticidal, acaricidal and nematocidal activity. 

Triazophos is a broad-spectrum insecticide and acaricide with some nematocidal activity. It is used for control of aphids, beetles, foliar-feeding larvae, fruit flies, leafhoppers, leafminers, scales, soil insects, whiteflies, and nematodes in fruits, vegetables, and ornamentals. Its oral LD50 in rats is 57-59 mg/kg. 

Watanabe I, Koike K, Satou T, Nikaido T (1999) Nematocidal Activity of Picrodendrins against a Species of Diplogastridae. Biol Pharm Bull 22 1310... 

The total extract of the rhizomes of Curcuma longa showed nematocidal activity against second stage larvae of dog roundworm Toxocara canis) (107). Inactivity of the pure components (1, 40, 41, 44) in contrast to activity of mixtures in various proportions prompted Kiuchi and associates to postulate synergism of the constituents. Itokawa et al. reported that the extract oi Alpinia qfficinarum inhibited the contraction of guinea pig ileum (26) induced by BaCl2 and histamine at 0.1 mg/ml concentration. 

Methyldihydropinosylvin from the bark of Firms strobes was demonstrated to be nematocidal to inactivate the pinewood nematode [460]. Synthesized perrottetin and derivatives showed nematocidal activity against Caenorhabditis elegans and Nippostrongylus brasiliensis. Some had ICso values even lower than 1 pg/mL [442],... 

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