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Adam Cowden

"In the MSc year I completed two projects that involved the isolation of natural products: firstly the characterisation of a range of carbohydrates from wood and plant material, and secondly a family of molecules called mycosporines that were extracted from marine algae, and appear to function as "Nature's very own sunscreen". I chose to continue the latter project into a 3-year PhD, focussing on mycosporine-like amino acids from seaweeds, synthesising molecules with similar properties and attempting to unravel their unique photodynamics on the nano to femto-second timescale with ultrafast laser spectroscopy."

MSc Mini-Project 1 (May-June 2019): Analysis of Enzymatic Degradation Products of Lignin by FT-ICR Mass Spectrometry

Lignin chemical structure superimposed on natural lignin sources

A selection of the major chemical linkages found in the natural biopolymer, lignin, superimposed on three natural sources including wood lamella and Alfalfa.

I investigated the microbial conversion of the lignin residue extracted from plant cells into high-value chemicals using purified enzymes. The oxidative depolymerisation of lignocellulosic biomass is thought to offer the best (and even only) renewable feedstock for aromatic carbon molecules and is an alternative to unsustainable fossil fuel refining. For 10 weeks, I incubated various lignin extracts with five known bacterial lignocellulose-active enzymes (e.g. SpMnSOD1, DyP1B, DyPB Ct, LigE and DHLHD2) in different combinations in order to bio-transform two pre-extracted lignins: 1) Kraft lignin and 2) GreenValue® lignin. I observed low molecular weight aromatic products in the cultures and analysed them by reverse phase liquid chromatography (RP-HPLC). And, for the first time in the Bugg Group, ultrahigh resolution mass spectrometry (FT-ICR MS) was evaluated as a technique to observe the chemical changes that take place during the bio-transformations. The final report concluded that direct infusion FT-ICR MS in negative ion detection mode is a suitable, advanced technique to monitor intermediate, oligomeric products formed during lignin enzymatic breakdown. The identification of degradation products from the transformation of polymeric lignin and an understanding the substrate specificity of particular enzymes will help to decipher the metabolic pathways for microbial lignin breakdown, improve our knowledge of the enzymology of native lignin metabolism and inform biocatalytic lignin valorisation strategies.

Link to Bugg Group (PI: Prof. T. Bugg)

A graphical method for analysing the large data sets obtained from high resolution mass spectra. A detailed section is chosen that demonstrates chemical changes to the lignin following enzymatic digestion
(Left) Van Krevelen diagram of GreenValue® lignin extracts after three different enzymatic digests. (Middle) Detail comparing the control (without enzyme, in orange) with the digest (with a two-enzyme combination, in purple). (Right) Annotated van Krevelen diagram generated from a generic organosolv lignin preparation control. Annotations are the transformation in chemical space that links the identified compounds and assignments are confirmed by extrapolating to the intercept with either axis.
MSc Mini-Project 2 (July-September 2019): Microbial Sunscreens: Mycosporines, For a Better Life

A selection of mycosporine derivatives that have been found in marine species

A selection of mycosporine derivatives that have been found in marine species (including marine algae and cyanobacteria)

I will investigate mycosporines and their mycosporine-like amino acid derivatives, MAAs. These are a family of structurally and chemically related compounds that absorb radiation from the solar ultraviolet radiation (UVR) spectrum and exhibit fast relaxation dynamics while remaining stable in vitro. The pair of conformational isomers usujirene and palythene are algal imino-mycosporines with optical density maxima at wavelengths 357 and 360 nm respectively, which are useful parameters for UVA absorbers. Computational studies using time-dependent density functional theory (TD-DFT) have predicted that these potential sunscreen molecules can interconvert (photoisomerise) following excitation by absorption of a photon, perhaps explaining the very efficient non-radiative dispersion of excited state energy. In addition, a cluster of four genes (Ava_3855-3858) was previously identified in the genome of cyanobacteria that encodes the enzymes that can convert a natural sugar, sedoheptulose-7-phosphate (7-SHP), to the di-substituted imino-MAA, shinorine. I aim to extract and purify these and other molecules of interest from species of seaweed, like Palmaria palmata, or from genetically transformed E. coli cultures using advanced liquid chromatography (RP-HPLC) methods. This study will also provide synthetic precursors for the the chemo-enzymatic synthesis under investigation by the Corre Group in the School of Life Sciences (SLS, Warwick) with the aim to produce promising UV filters. Eventually we hope to be able to produce a wide range of synthetic analogues with adjusted properties in collaboration with the Wills Group in the School of Chemistry, also at Warwick. All of the syntheses will be accompanied by time-resolved ultrafast laser spectroscopy at the Warwick Centre for Ultrafast Spectroscopy (WCUS) to monitor the events in the excited state following UV irradiation. With a resolution of around 20 femtoseconds we can begin to monitor directly for the first time the super fast photodynamics of these molecules.

Link to Stavros Group (PI: Prof. Vas Stavros)

Link to Corre Group site (PI: Dr. Christophe Corre)

Link to Wills Group site (PI: Prof. Martin Wills)

Gene cluster and biosynthetic pathway to some MAAs, steady-state photostability studies and UV spectra obtained of the first synthetic analogue made in the lab

(Left) Genes and enzymes of the biosynthetic pathway to some MAAs (Bottom right) steady-state photo-stability studies using, and (Top right) UV spectra obtained of the first synthetic analogue made in the lab
Previous experience:

MChemX (Hons) from the University of Edinburgh (Sep 2013- July 2018)

I completed my undergraduate Masters in Chemistry with a Year Abroad at Edinburgh. Final year compulsory courses included: Properties and Reactions of Matter, Bio-macromolecules, Advanced Organic Synthesis, Chemical Medicine, and Techniques and Concepts in Inorganic Chemistry. Key modules and skills that have aided my current research: peri-cyclic reactions, organometallic compounds, solid-phase peptide synthesis, carbon-ligand multi-bonding, small molecule activation, natural product synthesis, metals in medicine, protein-protein interactions, molecular magnetism, reaction dynamics and cyclic voltammetry.

The scope of my Honours project (2017/18) was to improve the synthesis of key monomers with amine (Troeger's Base-type) linkers. Previous reaction schemes relied on time-consuming separations and produced the monomer in poor yield. The polymeric product of the scheme has been proposed as a permeable and selective membrane for gas separation and/or storage material that was able to exceed the then current state-of-the-art Robeson limit (2008).

Research placement (Year 4), the University of Bologna, Italy:

I undertook research at the Department of Chemistry "Giacomo Ciamician", leading to a publication in open-access journal Biomimetics of a paper entitled "The Antioxidant Activity of Quercetin in Water Solution". The antioxidant activity of naturally occurring quercetin was investigated by combining differential oxygen-uptake kinetic measurements and B3LYP/6311+g (d,p) calculations. The results helped to rationalise quercetin’s reactivity with peroxyl radicals and its importance as a nutritional antioxidant in vivo and for biomimetic applications. Link to paper: Biomimetics 2017, 2(3), 9;