Fred M. Schell

COMPARISON OF EARTHWORM- AND FISH-DERIVED CHEMICALS ELICITING PREY ATTACK BY GARTER SNAKES (Thamnophis)

Materials eliciting increased tongue flicking and prey attack in garter snakes were isolated from both earthworm and fish prey. New extraction methods based on chloroform-methanol mixtures are valuable adjuncts to the more typical aqueous preparations. Both high- and low-molecular weight components from earthworms and fish were active. The similarity between the active chemicals in these two classes of prey was established using several methods of analysis. These included chromatography, carbohydrate and amino acid analyses, and nuclear magnetic resonance.

N-chloramine rearrangements. The use of cyclobutylamine as a pyrrolideine precursor.

Abstract Exposure of N-chloro-N-cyclobutyl-3,4-dimethoxyphenethylamine to silver ion in benzene results in efficient ring expansion to a pyrrolideine that can be trapped via Pictet-Spengler reaction.

Characterization of volatile, hydrophobic cyclodextrin derivatives as thin films for sensor applications

Abstract Successful development of chemical sensors and multi-sensor arrays critically depends on the availability of appropriate coatings. In the present studies, we synthesized hydrophobic and thermally stable cyclodextrin (CD) derivatives and, using a physical vapor deposition method, successfully deposited them on surfaces as thin films. 13 C NMR and FT-IR spectroscopy verified that while heptakis(6-O-tert-butyldimethylsilyl-2,3-di-O-methyl)cyclomaltoheptaose (DMe-CD) remained chemically intact after the deposition, heptakis(6-O-tert-butyldimethylsilyl-2,3-di-O-acetyl)cyclomaltoheptaose (DAc-CD) showed some variations. The hydrophobicity and refractive indices of the prepared thin films were determined using, respectively, contact angle measurements and ellipsometry. Selectivity patterns of the prepared CD films with respect to a series of analytes were defined using surface plasmon resonance. Because the chemical structure of the DAc-CD derivatives is compromised during the PVD process and any structural change may affect the selectivity of these thin films, additional attention should be given to the PVD process. In addition, thin films of the DMe-CD derivative were tested as protective coatings on silver island films for sensors based on surface enhanced Raman spectroscopy (SERS). The observed kinetics of SERS signals indicates that medium molecular weight analytes are able to rapidly diffuse through the CD films and reach the underlying silver islands.

Responses by king snakes (Lampropeltis getulus) to chemicals from colubrid and crotaline snakes

Four litters of king snakes (Lampropeltis getulus), a snake-eating species, were tested for responses to chemicals from colubrid and crotaline snakes. King snakes presented with swabs rubbed against the dorsal skin of living snakes and with swabs treated with methylene chloride extracts of shed snake skins tongue-flicked more to swabs from a northern copperhead (Agkistrodon contortrix), a crotaline, than to swabs from some colubrid snakes or to blank swabs. Six out of 10 king snakes in one litter attacked and attempted to ingest swabs treated with snake skin chemicals, implicating these chemicals as feeding stimuli for these ophiophagous snakes. Ingestively naive king snakes presented with plain air and snake odors in an olfactometer tongue-flicked more to snake odors. This study and others suggest that crotaline and colubrid snakes can be distinguished by chemical cues.

Synthesis of N-Benzoyl-4-oxo-1,2,3,4-Tetrahydropyridine and its Ethylene Ketal

Abstract Recently we had need for large quantities of N-benzoyl-4-oxo-1,2,3,4-tetrahydropyridine (1), its ethylene ketal derivative 7, and potentially other N-acyl derivatives. Prior to our initial studies, the N-carboethoxy derivative 2 had been prepared by sodium borohydride reduction of N-carboethoxy-4-pyridone.1.

Structure of the lactam of guanidinoglutaric acid (N-Amidinoglutamic acid)

Abstract Glutamic acid forms a lactam on boiling in water to form pyroglutamic acid (pGlu). This compound is a pyrrole derivative. N-Amidinoglutamic acid (guanidinoglutaric acid) also forms a lactone on boiling in aqueous solution (pyroamidinoglutamic acid, pAGlu). It was previously proposed that this reaction took the same pathway to form a pyrrole derivative (Formula I). It was observed that the chemical behavior of pAGlu was inconsistent with the proposed structure. For this reason, the 13C NMR spectrum of pAGlu was compared with that of pGlu. These spectra showed a significant difference in the environment of the carboxyl carbons of the two structures. This observation favored an alternative structure for the lactam of guanidinoglutaric acid, which was an imidazole with the carboxyl carbon at the end of propionic acid side chain (Formula II). The pAGlu was then studied by mass spectrometry. Conventionalmass spectrometry did not supply adequate data to distinguish between Formulas I and II for the lactam. However, when the mass analyzer ion kinetic energy spectrum of the lactam of guanidinoglutaric acid was obtained, four prominent fragments of masses which supported the imidazole structure (Formula II) were observed. These could not have been formed readily from Formula I. This imidazole structure is similar to that of creatinine. Like creatinine, the lactone forms a water-insoluble picrate, and gives an alkaline picrate color (Jaffe reaction), with an absorption spectrum similar to that of creatinine. Formula II is consistent with the observation that a strong alkali is required to acylate the lactone, forming a diacyl derivative. With Formula I, only a monoacyl derivative would be expected to form. It is concluded that the structure of the lactam of guanidinoglutaric acid is, 2-imido-4-oxo-5-(3′-propane acid) tetrahydroimidazole.

Analysis of chemicals from earthworms and fish that elicit prey attack by ingestively naive garter snakes (Thamnophis).

Materials previously shown to elicit increased tongue-flicking and prey attack in garter snakes (Thamnophis sirtalis) were isolated from both earthworms (Lumbricus terrestris) and fish (Pimephales promelas). Both high- and low-molecular-weight components from earthworms and fish stimulated attacks and increased tongue-flicking in previously unfed neonate garter snakes relative to distilled water controls. Earthworm collagen was also effective, but even concentrated fractions were less effective than raw extract. Conflicting reports on the effectiveness of collagen suggest that the salient chemical(s) is a smaller molecule tightly bound to collagen and resisting standard purification methods.

Synthesis of pyrrolizidine and indolizidine ring systems via N-chloramine rearrangement

Abstract The silver ion induced rearrangement of bicyclic N-chloramines is reported. In addition to the expected reaction, oxidation of the rearrangement products was observed in two cases.