University of St. Thomas' 2004 Research Symposium, Abstract Three

University of St. Thomas featuring:

Performing a GC/MS Technique to Study Secondary Metabolites of Lichens*...

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This experiment continues with the study of secondary metabolites in lichens. However, the experimenters did not primarily focus on the bioactivity of various fractions (the metabolites) extracted from the experiment, but rather, they were interested in identifying the different kinds of secondary metabolites in lichens and to determine their structures. In order to do this, they used the lichens of the genus Ramalina, which were collected from Spain, and then pulverized them in liquid nitrogen. After this, the pulverized lichens were extracted with acetone and were then further separated into ether soluble and insoluble fractions. Once the fractions were derivatized with BSTFA to cap the –OH and –COOH groups, they were then analyzed by the gas chromatography mass spectrometry (GC/MS). Electron and chemical ionizations were used along with several reagent gases like isobutene. (Oviedo commented that they could have used ammonia in the experiment, but didn't.)

In addition to these experimental procedures, the experimenters compared these possible matches to the metabolites that were already known and identified in previous lichen samples by taking note of the molecular weights (measured in Daltons) and major fragment ions of the fractions. The experimenters used a chart of the various known and identified metabolites to perform this procedure in order to identify the structures of the metabolites. Furthermore, the experimenters also found many other structures of metabolites that were found in their sample of lichens that were not previously reported yet. However, possible structures were proposed, and hopefully, future experiments would be conducted.

Literature Cited

Oviedo C, Cocciani R. Electron and chemical ionization mass spectrometry characterization of secondary metabolites extracted from lichens. 2004 UST Research Symposium; 2004 Apr 16; Houston (TX) at Crooker Center: [the program booklet], pg. 29.

--Reviews by Kathy Nguyen, 2004.

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* The full-length abstract is not displayed for public view, because it is compiled in the UST's 2004 Research Symposium program booklet. For more information on what the Research Symposium is, please visit the site: The UST Research Symposium.

University of St. Thomas' 2004 Research Symposium, Abstract Two

University of St. Thomas featuring:

Performing a Base Deuterium on C7 Ketones*...

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This organic lab experiment was based on a previous experiment in that the previous experiment involved six isomeric ketones, whereas this experiment has extended to the acyclic C7 ketones. A ketone is a class of organic compounds that have a carbonyl group linked to a carbon atom in each of two hydrocarbon radicals. In this experiment, a student is given the mass spectra of the undeuterated C7 ketones and a sample of one of them on which to perform a base deuterium (an isotope of hydrogen which has one neutron) exchange reaction. The molecular ion given from the gas chromatography mass spectrometry (GC/MS) was used to determine the number of hydrogens that were replaced by deuteriums. Furthermore, the location of the deuteriums in the molecule was determined by the change of the MS fragmentation pattern.

Based on those two pieces of information, the experimenter was expected to identify the possible saturated acyclic (having an open chain structure) heptanones he/she has and explained the fragmentation patterns. In addition to this, using a 50/50 mixture of D2O and CH3OD allowed the C6 ketones the full deuterium exchange on all thirteen C7 ketones, and the HP G1800A with the auto-sampler provided the results to this experiment. The main purpose of this lab experiment was to illustrate and understand fundamental chemistry concepts such as catalysis, the use of stable isotopes, and knowing extraction methods and mass spectrometry to name a few.

Literature Cited

Abdul-latif M, Abraham S. GC/MS applications in the undergraduate organic lab: deuterium exchange in isomeric acyclic C7 ketones revisited. 2004 UST Research Symposium; 2004 Apr 16; Houston (TX) at Crooker Center: [the program booklet], pg. 7.

--Reviews by Kathy Nguyen, 2004.

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* The full-length abstract is not displayed for public view, because it is compiled in the UST's 2004 Research Symposium program booklet. For more information on what the Research Symposium is, please visit the site: The UST Research Symposium.

University of St. Thomas' 2004 Research Symposium, Abstract One

University of St. Thomas featuring:

Defense Mechanisms of Lichens*...

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Lichens are made up of 93% fungi and 7% algae; both of these microscopic organisms observe a symbiotic relationship. Although lichens produce many secondary metabolites, these chemicals do not pertain to regular metabolic processes, but instead, they play an important ecological role by being involved with antimicrobial and antibiotic activities and offering protection against the environment. Lichens not only add organic nitrogen to the ecosystem, but they also help make the growth and succession of plants possible after a burnt forest or a volcanic eruption, for example.

The purpose of this experiment was to study the defense mechanisms of lichens against some type of encroachment. The experimenters used an analogue of rhodocladonic acid called anthraquinone, which is one of the secondary metabolites of lichens, in order to further study its bioactivity and to determine its effects on mitosis.

In general, the experimenters found that b-tubulin, one of the components of microtubules (which are responsible for the alignment of the chromosomes on the metaphase plate), were not affected by anthraquinone. They also tested this metabolite on kinetochore proteins called dynein and kinesin and found that these were affected instead. The experimenters also noted that the stages of metaphase and anaphase were abnormal in that there was no distinct alignment of the chromosomes across the metaphase plate, but rather, these chromosomes were situated randomly on the plate. In addition to these results, the experimenters noted that anthraquinone decreased inhibition of germination and root malformation.

Literature Cited

Aguilar D, Oviedo R, Cervantez C. Examining the disruptive effects of an anthraquinone analogue on mitosis. 2004 UST Research Symposium; 2004 Apr 16; Houston (TX) at Crooker Center: [the program booklet], pg. 8.

--Reviews by Kathy Nguyen, 2004.

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* The full-length abstract is not displayed for public view, because it is compiled in the UST's 2004 Research Symposium program booklet. For more information on what the Research Symposium is, please visit the site: The UST Research Symposium.