Paralytic and insecticidal toxins from the funnel web spider, Hololena curta.

One peptide and ten acylpolyamine toxins (curtatoxins) were purified and identified from venom of Hololena curta. The acylpolyamines consist of six different polyamines which are amidated with three different aromatic acids: (3-indolyl)acetic, (4-hydroxy-3-indolyl)acetic and 2.5-dihydroxybenzoic acids. These acylpolyamines instantly paralyze lepidopteran larvae following injection. The most potent insecticidal peptide in H. curta venom contains 38 amino acids and is lethal at 4 micrograms/g when injected into Manduca sexta larvae.

Identification of metabolites of ampicillin using liquid chromatography/thermospray mass spectrometry and fast atom bombardment tandem mass spectrometry.

Mass spectrometry is combined with liquid chromatography (LC/MS) and mass spectrometry (MS/MS) to identify ampicillin and two known metabolites--ampicillin penicilloic acid and ampicillin piperazine-2,5-dione--in human urine samples. Identifications were based on the fact that the metabolites or degradation products contain a substructure of ampicillin. In addition, two previously unidentified components in human urine samples were detected, corresponding to newly discovered metabolites or degradation products of ampicillin. Different chromatographic retention times in the LC mass spectra indicated two different compounds. However, the tandem mass spectra of these two components were similar, suggesting that they are stereoisomers. The use of LC/MS and MS/MS confirmed that the unknown components are the (3S,5R) and (3S,5S) epimers of ampicillin penilloic acid. Further study showed that only one of the components was eliminated from the body; the other arises from interconversion to the epimer in a urine sample. It is speculated that the component produced in vivo is the (3S,5R) epimer of ampicillin penilloic acid.

Tandem mass spectrometric studies of the fragmentation of penicillins and their metabolites.

The fragmentation of two penicillins, ampicillin and amoxicillin, and their principal metabolites has been studied by a combination of liquid chromatography/thermospray mass spectrometry and tandem mass spectrometry. A high-resolution tandem mass spectrometer was used to obtain chemical ionization, fast-atom bombardment, and collision-induced dissociation mass spectra. Structural information and fragmentation mechanisms have been deduced from ions in the mass and collision spectra. This knowledge is useful in the analysis and identification of metabolites of ampicillin and related drugs in human body fluids.

Structures of paralytic acylpolyamines from the spider Agelenopsis aperta.

The structures are given for five paralytic acylpolyamines from the venom of the funnel web spider, Agelenopsis aperta. The acyl moieties are derived from (3-indolyl)acetic acid, (4-hydroxy-3-indolyl)acetic acid, and 4-hydroxybenzoic acid. The polyamine portions of the toxins are novel. Three toxins (AG489, AG505, and AG452) contain 1, 5, 9, 13, 18, 22-hexaazadocosane which is unique as a natural polyamine because of its length and hydroxylation at the 5-aza position. The polyamine portions of two other alpha-agatoxins (AG488 and AG504) are unusual also, containing guanidinooxy moieties.

In vitro metabolism of N-(5-chloro-2-methylphenyl)-N'-(2-methylpropyl)thiourea: species comparison and identification of a novel thiocarbamide-glutathione adduct.

The in vitro metabolism of SDZ HDL 376, a thiocarbamide developed for the treatment of atherosclerosis, was investigated in rat, dog, monkey, and human liver microsomes, as well as in rat and human liver slices. [14C]SDZ HDL 376 was extensively metabolized in all the species except human. In rat liver microsomes an S-oxide was the major metabolite. In human and monkey microsomes, carbon hydroxylation was favored. The NADPH-dependent oxidation of SDZ HDL 376 resulted in covalent binding to microsomal protein. Addition of GSH to the incubations decreased protein binding in a concentration-dependent manner and resulted in a novel SDZ HDL 376-GSH adduct. Adduct formation required NADPH and was mediated predominantly by cytochrome P450. Inhibition of cytochrome P450 by 1-aminobenzotriazole resulted in a 95% decrease in adduct formation, while heat inactivation of flavin-containing monooxygenases resulted in a 10% decrease. Unlike other thiocarbamides which form disulfide adducts with GSH, the SDZ HDL 376 adduct contained a thioether linkage as characterized by LC/MS/MS and reference to a synthetic standard. Reactions performed with [35S]GSH resulted in a [35S]SDZ HDL 376-GSH adduct, demonstrating the sulfur was derived from GSH. Adduct formation was faster in rat microsomal reactions compared to human microsomes. Other structurally unrelated thiocarbamides (phenylthiourea, methimazole, 2-mercaptobenzimidazole, 2-mercaptoquinazoline, and 2-propyl-6-thiouracil) did not form similar adducts in rat liver microsomes supplemented with GSH. Therefore, the GSH adduct of SDZ HDL 376 is unique for this type of thiocarbamide. These results suggest that the bioactivation and detoxification of SDZ HDL 376 differ significantly from other thiocarbamides. Furthermore, the in vitro formation of S-oxides and GSH adducts in rat hepatic tissue, and ring hydroxylation and glucuronidation in human hepatic tissue, suggests rats may be more susceptible to the toxicity of SDZ HDL 376 compared to humans.