Ion-channel block in insect muscle fibre membrane by the venom of the digger wasp, Philanthus triangulum F.

Philanthotoxin-343 attenuates retinal and optic nerve injury, and protects visual function in rats with N-methyl-D-aspartate-induced excitotoxicity

“…PhTX-433 is the natural compound isolated from the venom sac of the female wasp, Philanthus triangulum , mainly found in the Sahara Desert. The compound, first discovered by T. Piek and colleagues, contains a butyryl/tyrosyl/polyamine structure and exerts glutamate receptor-blocking properties including antagonism towards the NMDA receptors [ 21 – 23 ]. Subsequently, its analogue, known as PhTX-343 (numerals denote the number of methylenes between the amino group of the spermine moiety from left to right) was synthesized and shown to retain the pharmacological properties [ 18 , 20 , 24 , 25 ].…”

Structure and synthesis of a potent glutamate receptor antagonist in wasp venom.

“…Quisqualate-sensitive glutamate receptors are distributed widely in excitable tissues of multicellular animals (9), and recent studies of the effects of the venoms of certain wasps and spiders on vertebrate and invertebrate neurons and muscle fibers suggest that one source of antagonists for this class of receptor might be found in the venoms of some species of predaceous arthropods (10)(11)(12)(13)(14)(15). The solitary digger wasp Philanthus triangulum F., which is a sphecid wasp that preys on honeybees, manufactures a venom that blocks glutamate receptors on locust skeletal muscle (14,15 (16) and extrajunctional glutamate D-receptors (17) of locust leg muscle, most of which are quisqualate-sensitive (18). We have purified this toxin from the wasp venom, identified its chemical structure, and synthesized the pure toxin, philanthotoxin 433 (PTX-433), which is a potent inhibitor of the neurally evoked twitch contraction of locust skeletal muscle.…”

Insect Venoms and Toxins

“…The first indication for a postsynaptic effect of the venom was found by May, T. and Piek, T. (1979) who showed that, in the locust retractor unguis muscle, the venom antagonizes bath-applied and iontophoretically evoked glutamate potentials. The view that Philanthus venom blocks open ion channels was born out of the results of May, T. and and Piek, T. et al (1980b) and confirmed for (S-PTX, using the metathoracic extensor tibiae muscle of the locust and iontophoretically applied glutamate currents and patch clamp techniques (Clark, R. et al, 1981(Clark, R. et al, , 1982) (see chapter 3, Figs 32-36, for a detailed description). Although the effect was reversible the shift in the glutamate dose-response curves showed that the antagonism was not competitive (Fig.…”

“…Note the reversible decrease in amplitude and the seeming decrease in frequency (see also Fig. The venom of P. triangulum collected in Egypt showed a more pronounced effect on amplitude (Figs 12 and 13) than the venom of wasps collected in Europe (Piek, T. et al, 1980a). amount of acetylcholine (Piek, T., 1982b, Piek, T. et al, 1980a, 1983b, the most obvious effects are on the skeletal neuromuscular transmission in insects (Piek, T., 1966, Piek, T. et al, 1971.…”

“…The bee unit (BU) is defined as the activity of a P. triangulum venompreparation, injected in equal amounts into ten honeybee workers, causing five of these bees to remain paralysed for at least 1 h (Piek, T. et al, 1971). amount of acetylcholine (Piek, T., 1982b, Piek, T. et al, 1980a, 1983b, the most obvious effects are on the skeletal neuromuscular transmission in insects (Piek, T., 1966, Piek, T. et al, 1971. The signals were recorded on tape with a bandwidth of 500 Hz (upper control) and fed into the computer with a bandwidth from 0.02 to 100 Hz (lower control).…”