LSU Historical Dissertations and Theses

1990

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry

Nikolaus H. Fischer

Abstract

As part of an investigation into the allelopathic interactions of members of the Florida scrub community of plants, the release of allelochemicals by the Florida wild rosemary, Ceratiola ericoides (Empetraceae) was monitored. Aqueous extracts of whole leaves, water-rinses of leaves, aqueous litter extracts, and aqueous soil extracts were monitored monthly, or twice monthly in the summer months, for the dihydrochalcone ceratiolin, its decomposition product hydrocinnamic acid, the microbial degradation product of hydrocinnamic acid, acetophenone, and trans-cinnamic acid. High performance liquid chromatography was used to quantify the four compounds. The amounts of ceratiolin, hydrocinnamic acid, acetophenone, and trans-cinnamic acid in the leaf extracts varied seasonally; the largest amounts were observed in the months of September and October. These months are in the midst of the rainy season in the Florida scrub. Observed amounts of the four analytes in the leaf mists were much lower, and there was no seasonal variation. The soil and litter extracts also contained hydrocinnamic acid in varying amounts; the maximum concentrations again occurred in the late summer. The efficiency of extraction of exogenously applied hydrocinnamic acid to scrub soil was determined to be dependant on the level at which the compound was applied, and ranged from 18% at a level of 1 $\mu$g/g soil to 79% at a level of 64 $\mu$g/g soil in non-sterile soil. In sterile soil, the recovery was 91%, 78%, and 80% for levels of 2 $\mu$g/g, 4$\mu$g/g, and 8$\mu$g/g soil respectively. Allelochemicals that were released into the environment as volatile compounds were collected by dynamic headspace sampling and trapping on Tenax TA adsorbent. Thermal desorption and cryogenic focusing were utilized to introduce the compounds into a capillary column for analysis by gas chromatography-mass spectrometry. The volatile compound composition of whole leaves varied seasonally. Among the more abundant compounds were ethyl acetate, 3-methyl-1-butanol, and 1-hexanol. Of the volatile compounds collected from the litter and soil, 1-octene, 3-methyl-1-butanol, and 3-octanol were the most abundant.

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