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Lessons in photoprotection from nature’s sunscreens : an investigation of photoactive motifs in synthetic molecules
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Cowden, Adam M. (2023) Lessons in photoprotection from nature’s sunscreens : an investigation of photoactive motifs in synthetic molecules. PhD thesis, University of Warwick.
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Official URL: http://webcat.warwick.ac.uk/record=b3948331
Abstract
At present there are only a few UVA (315-400 nm) absorbers available for sunscreen formulations even though such compounds are essential for effective protection against the harms of solar radiation. The four major aims of this research are 1) to understand how the naturally occurring photoprotective motif (N/O=C-C=C-N-) can be scaffolded into synthetic molecules, 2) to propose new molecules for the global bank of UVA filters that is available to sunscreen manufacturers, 3) to characterise how a subset of molecules disperse excess energy after they are energetically excited by light, and 4) to investigate a natural product pathway in bacteria to produce new ‘natural’ and ‘unnatural’ sunscreens. These aims are achieved by a combination of experiment and theory, covering the natural product molecules, synthetic analogues and new hybrid sunscreens.
• In Chapter 1 an introduction is presented with reference to photochemical theory.
• In Chapter 2, the materials and methods used are in this work are detailed with reference to all relevant spectra in the Appendix.
• Both Chapters 3 and 5 refer to MAAs, a family of molecules characteristic of high UV marine environments. In Chapter 3 it is studied how sunscreen active ingredients absorb light and then relax from excite d energetic states by dispersing excess energy in primarily non - radiative ways. In Chapter 5, the modification of a biosynthetic pathway of exemplar MAA, shinorine , is explored.
• In Chapter 4, it is shown how new hybrid molecules, designed by combining avobenzone and cinnamate moti fs , match or exceed the photostability of industry standard avobenzone in polar, non - protic solvents.
A complete picture of sunscreening ability must consider the long - and short - term behaviour of molecules during and after interaction with light. The longer time studies in solar - like conditions track the fate of molecules on the minute to hour timescale; while ultrafast transient absorption spectroscop ies on the femto - to nanosecond scale are used to track the energy flow shortly after photoexcitation , complemented by computational models. In short, this work contributes to the understanding of sunscreening molecules and adds new compounds to our photoprotectant library. The techniques used to quantify photoprotection could be extended towards near - to - life conditions. The synthetic methods could be optimised to further improve the yields and scope . The molecular biology approach could be expanded to include a range of control s , an improved understanding of the limits of detection and other enzymes of interest.
Item Type: | Thesis (PhD) | ||||
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Subjects: | Q Science > QD Chemistry | ||||
Library of Congress Subject Headings (LCSH): | Sunscreens (Cosmetics), Ultraviolet radiation -- Physiological effect, Mycosporine-like amino acids, Biomolecules, Photochemistry | ||||
Official Date: | February 2023 | ||||
Dates: |
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Institution: | University of Warwick | ||||
Theses Department: | Department of Chemistry | ||||
Thesis Type: | PhD | ||||
Publication Status: | Unpublished | ||||
Supervisor(s)/Advisor: | Stavros, Vasilios G. ; Corre, Christophe ; Wills, Martin | ||||
Sponsors: | Molecular Analytical Science Centre for Doctoral Training | ||||
Format of File: | |||||
Extent: | multiple pagings : illustrations (some colour) | ||||
Language: | eng |
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