Abamectin as a pesticide for agricultural use.

The avermectins are a family of macrocyclic lactones, produced by the soil organism Streptomyces avermitilis, which were discovered in the mid-1970's as a direct result of a screening effort for natural products with anthelmintic properties. Avermectin B1 (abamectin), the major component of the fermentation, also showed potent activity against arthropods in preliminary laboratory evaluations and was subsequently selected for development to control phytophagous mites and insect pests on a variety of agricultural and horticultural crops worldwide. Major applications for which abamectin is currently registered include uses on ornamental plants, citrus, cotton, pears and vegetable crops at rates in the range of 5 to 27 grams abamectin per hectare as a foliar spray. Abamectin has shown low toxicity to non-target beneficial arthropods which has accelerated its acceptance into Integrated Pest Management (IPM) programs. Extensive studies have been conducted to support the safety of agricultural uses of abamectin to man and the environment. Abamectin is highly unstable to light and has been shown to photodegrade rapidly on plant and soil surfaces and in water following agricultural applications. Abamectin was also found to be degraded readily by soil microorganisms. Abamectin residues in or on crops are very low, typically less than 0.025 ppm, resulting in minimal exposure to man from harvesting or consumption of treated crops. In addition, abamectin does not persist or accumulate in the environment. Its instability as well as its low water solubility and tight binding to soil, limit abamectin's bioavailability in non-target organisms and, furthermore, prevent it from leaching into groundwater or entering the aquatic environment.

Antibacterial N-[omega,omega'-bis(alicyclic and aryl)-sec-alkyl]-1,3-diamino-2-propanol dihydrochloride salts.

A series of 14 antibacterial N-[omega,omega'-bis(cycloalkyl, bicyclo[2.2.1]heptyl, and substituted phenyl)-sec-alkyl]-1,3-diamino-2-propanol dihydrochloride salts were synthesized as potential topical antiseptics and disinfectants. Four derivatives which were particularly effective against Pseudomonas aeruginosa encompassed the three diverse ring-type substituents and an 8-n-pentadecyl moiety. The calculated Hansch hydrophobic parameter (pi) for the N-substituents of the more efficient compounds were in the range 7.0--9.0 and correlated with minimal inhibitory activity as a parabola for all of the products under the assay conditions. The potencies against Gram-positive and other Gram-negative bacteria were comparable to benzalkonium chloride and chlorhexidine.

Antibacterial N-[omega, omega'-bis(alicyclic and aryl)-sec-alkyl]poly(methylene)triamine and -tetramine hydrochloride salts.

A series of antibacterial N-(omega, omega'-(cycloalkyl, bicyclo[2.2.1]heptyl, and alkyl-substituted phenyl)-sec-alkyl]poly(methylene)triamine and -tetramine hydrochloride salts were synthesized in an effort to develop efficient, nonsystemic inhibitors, particularly for Pseudomonas aeruginosa. In the 1,5,9-triazanonane group, 3 of 16 compounds were effective at 8--10 micrograms/mL against pseudomonads. Efficiency appeared more dependent upon lipophilicity of the nitrogen substituent than other characteristics represented by the three types of rings. A parabolic relationship was observed for the entire set between the hydrophobic parameter, pi, of the lipoidal moiety and minimal inhibitory concentration. One of 16 tetramines, 1-[1,5-bis(3,3-dimethyl-2-norbornyl)-3-pentyl]-1,5,9,13-tetraazatridecane tetrahydrochloride (26f), ranked similarly. An additional two compounds in each series were superior to several commercial cationic detergents in the control of the Gram-negative bacteria. None was inhibitory at up to 200 micrograms/mL for Proteus vulgaris.

Methyl 6-(phenylsulfinyl)imidazo[1,2-a]pyridine-2-carbamate, a potent, new anthelmintic.

A series of methyl imidazo-[11,2-a]pyridine-2-carbamates was synthesized for anthelmintic testing. The preparation of this class of compounds was simplified by utilization of a novel one-step condensation of the appropriately substituted 2-aminopyridine and methyl chloroacetylcarbamate. The most potent compound, methyl 6-(phenylsulfinyl)-imidazo[1,2-a]pyridine-2-carbamate, was orally effective against a broad range of helminths in sheep and cattle, at a dosage of 2.5 mg/kg. Limited trials in swine and dogs demonstrated anthelmintic activity at higher dosages. Limited observations in sheep and cattle indicated that, in both species, a single oral dose of 200 mg/kg was well tolerated.