Helmut Mrozik

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Eprinomectin (MK-397 or 4"-epi-acetylamino-4"-deoxy-avermectin B1) is a novel avermectin selected for development as a topical endectocide for all cattle, including lactating dairy cows. Herein, we show its anthelmintic, insecticidal and miticidal activity. To determine its anthelmintic capabilities, eprinomectin was tested topically on Jersey calves at(More)
The avermectins and, to a lesser extent, the milbemycins, have revolutionized antiparasitic and antipest control over the last decade. Both avermectins and milbemycins have macrocyclic lactone structures that are superimposable, they are produced by the same genus of soil dwelling organisms, they have the same mode of action, they exert this action against(More)
Eprinomectin (MK-397 or 4"-epi-acetylamino-4"-deoxy-avermectin B1) is a novel avermectin selected for development as a topical endectocide for all cattle, including lactating cows. The initial efficacy assessments were made in sheep to identify subclasses of the avermectin/milbemycins that possessed inherent activity against a spectrum of nematode(More)
Eprinomectin has been approved for use as a topically applied endectocide for beef and dairy cattle. To determine if eprinomectin has utility as an injectable anthelmintic, it was titrated at 0.05, 0.1, and 0.2 mg/kg s.c. against adult (Trial 1) and at 0.05, 0.1, 0.14, and 0.2 mg/kg s.c. against immature (Trial 2) stages of lung and gastrointestinal(More)
Xenopus laevis oocytes were injected with mRNA isolated from the free-living nematode Caenorhabditis elegans and the activation and potentiation of a glutamate-sensitive chloride current by a series of avermectin analogs and milbemycin D were determined. There was a strong correlation between the EC50 value determined for current activation in oocytes, the(More)
A new class of insecticidal and antiparasitic agents, 4″-amino-4′-deoxy avermectins, has been developed by chemical modification of avermectin B1. The most effective of these compounds are 1500-fold more potent than avermectin B1 (abamectin) against the beet armywormSpodoptera exigua and show similar potency against other lepidopteran larvae.
Few studies have examined activity against trematodes for the avermectin/milbemycin class of anthelmintics. To gain insight into this, 12 different members of the avermectin/milbemycin mode of action class were tested against juvenile Fasciola hepatica in a mouse model. The compounds chosen were Avermectin A1, Avermectin A2, Avermectin B1, Avermectin B2,(More)
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(More)
A series of gem-difluoro-avermectin derivatives was synthesized from the corresponding ketones at positions 4", 4', 13, and 23 using diethylaminosulfur trifluoride (DAST). These fluorinated avermectins exhibit potent antiparasitic activity in a new Haemonchus contortus larval assay and are equipotent to ivermectin. In addition, 23-gem-difluoro-ivermectin(More)