Peter A. Cockrum

Pyrrolizidine alkaloids inDanaus plexippus L. andDanaus chrysippus L.

Danaus plexippus L. andDanaus chrysippus L. have been found to store pyrrolizidine alkaloids obtained from adult food plants and it is suggested that the alkaloids contribute to the unpalatability of the butterflies to potential predators.

Corynetoxins causative agents of annual ryegrass toxicity; their identification as tunicamycin group antibiotics

The corynetoxins, formed in galled seeds of Lolium rigidum(annul ryegrass) occupied by Corynebacterium rathayi and responsible for annual ryegrass toxicity, are identified as new members of the tunicamycin group of antibiotics.

High-performance liquid chromatograpic comparison of the tunicaminyluracil-based antibiotics corynetoxin, tunicamycin, streptovirudin and MM 19290

Abstract Resolution of the components of tunicaminyluracil-based antibiotics by reversed-phase high-performance liquid chromatography is described. Two systems are employed using a silica-based ODS bonded-phase support, and gradient elution with either water—methanol or wate—methanol—tetrahydrofuran as mobile phase. The ternary mixture reduces analysis time by a factor of 4 whilst retaining resolution, however the increase in background absorption due to introduction of tetrahydrofuran reduces optimum detector sensitivity about sixteen-fold. Both systems are capable of separating the homologues within individual antibiotics and further resolving them into their anteiso-, iso - or normal-isomers as defined by the termination of the fatty acid portion of their structure. The resultant reproducible pattern of peaks in the chromatograms, and the retention time changes associated with catalytic reduction, have allowed assignment of structures to previously unrecognized or unidentified components in all antibiotics studied, e.g. , the 23 components identified in MM 19290, and have permitted correlation of the various nomenclatures published for tunicamycin components.

Structure elucidation of phomopsin A, a novel cyclic hexapeptide mycotoxin produced by Phomopsis leptostromiformis

Phomopsin A, the main mycotoxin isolated from cultures of Phomopsis leptostromiformis and the cause of lupinosis disease in animals grazing infected lupins, is a cyclic hexapeptide containing 3-hydroxyisoleucine, 3,4-didehydrovaline, N-methyl-3-(3-chloro-4,5-dihydroxyphenyl)-3-hydroxyalanine, E-2,3-didehydroaspartic acid, E-2,3-didehydroisoleucine, and 3,4-didehydroproline; its 13C n.m.r. spectrum was completely assigned and the amino-acid sequence established unambiguously by extensive heteronuclear 13C-{1H} selective population inversion n.m.r. experiments.

LUPINOSIS: CHEMICAL PROPERTIES OF PHOMOPSIN A, THE MAIN TOXIC METABOLITE OF Phomopsis leptostromiformis

I. ABSTRACT Phomopsin A, the main toxic metabolite of Phomopsis leptostromiformis responsible for lupinosis, has an empirical formula approximately C33H44N5O13Cl. There are 3 acidic centers per molecule which are probably phenolic, β-diketone or ββ-triketone in nature. Ultraviolet, infrared, and nuclear magnetic resonance spectra are described. These and the mild acid hydrolysis of phomopsin A to oxalacetic acid and an amine suggest that the metabolite is related to tenuazonic acid.

Male scent-organ chemicals of the vine moth,Phalaenoides glycinae Lew. (Agaristidae)

Extracts of the male brush-organs of the vine moth,Phalaenoides glycinae Lew., have been found to contain 2-phenylethanol and 2-phenyl-2-phenylethanolacetate.

Curassavine, an alkaloid from Heliotropium curassavicum Linn. with a C8 necic acid skeleton

Curassavine, the major alkaloid of Heliotropium curassavicum Linn. is shown to be an ester of trachelanthamidine with 3-carboxy-4-methylhexane-2,3-diol (homoviridifloric acid), the first example of a monocarboxylic necic acid with a C8 skeleton; the minor alkaloids, coromandalin and heliovicine are esters of trachelanthamidine with (+)-viridifloric and (–)-trachelanthic acids, respectively, the former providing the first example of natural occurrence of a (+)-viridiflorate.