Potential of some monoterpenoids and their new N-methyl carbamate derivatives against Schistosomiasis snail vector, Biomphalaria alexandrina.

Some monoterpenoids and their corresponding new N-methyl carbamate derivatives were used to study their molluscicidal effect on Biomphalaria alexandrina, the snail-vector of Schistosoma mansoni in Egypt. Improving the efficacy of the tested monoterpenoids and/or their corresponding carbamates by either piperonyl butoxide (PBO) or triton X-100 (TX) was also performed. Thymol, β-citronellol, carvacrol, and geraniol exhibited high molluscicidal activity against the snails.

Structure-activity relationships of philanthotoxin analogs and polyamines on N-methyl-D-aspartate and nicotinic acetylcholine receptors.

The effects of varying the structure of philanthotoxin (PhTX) were investigated on binding of the channel blockers: [3H]perhydrohistrionicotoxin (H12-HTX) to the nicotinic acetylcholine receptor (nACh-R) of Torpedo electric organ and [3H]MK-801 [( 3H]-5-methyl-10,11-dihydro-5H-dibenzocyclo-hepten-5,10-imine maleate) to the N-methyl-D-aspartate receptor (NMDA-R) of rat brain cortex. The four moieties of PhTX (tyrosine, butyrate, spermine and the terminal amino group) were modified or conjugated resulting in 36 compounds. Although the potencies of the PhTX analogs on both receptors were higher with increasing lipophilicity and the polyamine chain length, there was considerable divergence between the two receptors' channels in the structural activity requirements for blockade by PhTX analogs.

Actions of the insecticide 2(nitromethylene)tetrahydro-1,3-thiazine on insect and vertebrate nicotinic acetylcholine receptors.

The nitromethylene heterocyclic compound 2(nitromethylene)tetrahydro)1,3-thiazine (NMTHT) inhibits the binding of [125I]alpha-bungarotoxin to membranes prepared from cockroach (Periplaneta americana) nerve cord and fish (Torpedo californica) electric organ. Electrophysiological studies on the cockroach fast coxal depressor motorneuron (Df) reveal a dose-dependent depolarization in response to bath-applied NMTHT. Responses to ionophoretic application of NMTHT onto the cell-body membrane of motorneuron Df are suppressed by bath-applied mecamylamine (1.

Allosteric inhibition of nicotinic acetylcholine receptors of vertebrates and insects by philanthotoxin.

The effects of pure philanthotoxin (PhTX), a component of the venom of the wasp Philanthus triangulum, were studied on nicotinic acetylcholine receptors (nAChRs) of vertebrates and insects so as to compare their sensitivities and the mechanism of action of PhTX. Electrophysiological techniques were used on frog muscles and cockroach thoracic ganglia and biochemical techniques were applied to membranes from Torpedo electric organ and honeybee brain. PhTX (1-20 microM) inhibited reversibly the indirectly elicited muscle twitch and reduced the endplate current peak amplitude and its decay time constant in a concentration-dependent manner.

(+/-)alpha-Phenyl-beta-(3,4-dimethoxy)- and (+/-)alpha-phenyl-beta -(3,4-dihydroxy)phenethylamines: potential probes for nicotinic acetylcholine receptor-ion channel molecule from torpedo electric organ.

The synthesis of some N-methyl, N-alkyl derivatives of (+/-)alpha-phenyl-beta-(3,4-dimethoxy)- and (+/-)alpha-phenyl-beta-(3,4-dihydroxy)-phenethylamines was achieved. These compounds were shown to bear certain structural features of acetylcholine (ACh), as well as phencyclidine (PCP). The latter was reported to act as a specific probe for the nicotinic ACh receptor-ion channel molecule from Torpedo electric organ.