Solenopsis conjurata

Venoms from the fire ants Solenopsis invicta and 5. geminata are free of detectable histamine but possess histamine-release activity. This activity can account for the edema, itch, redness, warmth, and possibly the pain and burning sensations resulting from fire ant stings. And it can be attributed to the piperidines which constitute the major component of the venom. It has actually been proved that 6-methyl-2-n-undecylpiperidines (Ic and Id), components of S. geminata, possess the histamine-release activity (75). Due to some of the above-mentioned various activities the piperidine alkaloids play roles as defensive compounds. In addition to 2-alkyl-6-methylpiperidines, their N-methyl derivatives (3) are found in S. pergandei, S. carolinensis, and S. conjurata, and 1-piperideine derivatives (6 and 7) in S. sp. A (Puerto Rico) and S. xyloni (Table I). 

Solenopsis (Diplorhoptrum) conjurata and some other thief ants contain indo-lizidines and/or piperidines (Tables I and II). (5Z,8 )-3-Heptyl-5-methylpyr-rolizidine (48) has also been shown to be contained in the thief ant Solenopsis xenovenenum (Table IV). The poison glands of Aphaenogaster fulva and A. tennesseensis contain the tobacco alkaloid anabaseine (8), which functions as an attractant in A. fulva (Table I) (26). 

Stractures of 3-alkyl-5-methylindolizidines, found in thief ants, Solenopsis species (Table II), arrived at by gas chromatographic and mass spectral analysis were confirmed by coinjection and direct comparison with the synthetic sample. Indolizidine 15a from S. conjurata exhibits characteristic peaks at miz 152 (M — CHj) and 138 (M — C2H5, a base peak) as well as a parent peak at m/z 167 in the mass spectram. It corresponds to an isomer of 3-ethyl-5-methylindolizidine (15) which was prepared as a mixture of four stereoisomers by reductive amination of triketone 391 with ammonium acetate-sodium cyanoborohydride and sodium borohydride (Scheme 47). 

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