Summary
Major: Chemistry
Faculty Mentors: Dr. Christopher Jefferey
Research Topic: Effect of Polysaccharide Environments on Ultraviolet Photoprotection by Anthraquinones
Abstract: Many classes of compounds found in organisms have proven to be effective UV sunscreens. Despite these efforts, very little is known about how these pigment molecules dissipate the absorbed energy and how this dissipation is affected by the particular chemical environment the pigment is localized within the organism. One such pigment is vulpinic acid, which is found in the outer cortex of wolf lichen, Letharia vulpina, embedded in a polysaccharide matrix. Our research group has demonstrated that the optical screening ability of this pigment is highly dependent on its specific chemical environment to function. Under high-energy UV exposure, vulpinic acid took ~13 times longer to degrade in a biomimetic polysaccharide environment compared to its isolated crystalline state. This significant increase in stability points to the contribution of the specific pigment-polysaccharide interaction to confer extreme UV tolerance to these organisms. Previous studies of UV blocking molecules have considered many classes of protective microbial pigments as probable UV protectants, including anthraquinones. It is possible that all such sunscreen molecules will have a form of intra- or intermolecular mechanisms associated with their ability to dissipate the absorbed energy. The dependence of the pigment photostability on the polysaccharide is proposed to be due to its ability to facilitate a proton transfer in vulpinic acid that otherwise cannot happen internally. Proton transfer is an efficient pathway to dissipate UV energy, much like commercially available sunscreens. Comparatively, anthraquinones can efficiently transfer a proton internally through a 6-atom transition state. Given this case, I hypothesize that the photostability of anthraquinone pigments will be less dependent on the polysaccharide medium than the vulpinic acid. I will study the photostability of common anthraquinone pigments in a polysaccharide matrix and compare it to the previous study results from the Jeffrey Research Group. This research could unveil new biosignatures for the detection of life on other planets, as well as improve the development of radiation-resistant materials and biological countermeasures to support human missions to deep space.
New Scholar: 2021 cohort
Graduating with a Baccalaureate Degree: 2024