A greener route to citrus-derived therapeutics: What a new bromination method changes

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Undergraduate students at Penn State Brandywine developed an environmentally friendly and easy method to synthesize compounds from plant-derived molecules for potential use in therapeutics. Their work, conducted under the supervision of Penn State Brandywine Assistant Professor of Chemistry Anna Sigmon, was published in a special issue of the journal ACS Omega titled "Undergraduate Research as the Stimulus for Scientific Progress in the U.S."

Co-author Maria Englert, who graduated from Penn State in 2025, became involved with Sigmon's research on the recommendation of another mentor and said she learned far more than she expected.

"The more we worked through the reactions and discussed methodologies with each other, the more chemistry felt like an art form—something that requires creativity, intuition and a tenacious approach to problem-solving," she said. "This experience taught me that progress in research is shaped by collaboration, careful observation and a willingness to rethink your approach."

In this study, the research team added the crystalline compound copper(II) bromide to ethyl acetate, a solvent with multiple applications, including removing nail polish. The materials reacted in a process called α-bromination, with bromine atoms from the copper bromide reconstituting themselves into a range of flavanones, a sub-class of molecules often found in citrus fruits with anti-inflammatory and other medicinally beneficial properties.

"This research provides a simple and selective approach to α-bromination of flavanones using milder reagents and greener conditions than many traditional methods," Sigmon said. "It demonstrates how undergraduate-driven research can contribute meaningfully to sustainable organic chemistry."

The multi-year project engaged undergraduate students in all phases of the research process, including reaction design and optimization, compound synthesis, purification and structural characterization. The students also partnered with collaborators at the Huck Institutes of the Life Sciences at Penn State University Park to characterize the newly synthesized brominated flavanones.

Paper co-authors Tatiana N. Laremore, director of proteomics and mass spectrometry at the Huck Institute of the Life Sciences; Hemant Yennawar, director of the X-ray Crystallography Facility at the Eberly College of Science; and Christy George, assistant research professor at the Eberly College of Science, collected data via a variety of instruments at Huck, including nuclear magnetic resonance (NMR) spectroscopy, high-resolution mass spectrometry (HRMS), tandem electrospray ionization mass spectrometry (ESI-MS/MS) and X-ray crystallography.

Laremore assisted with analysis of the ESI-MS/MS data; Yennawar collected and analyzed the X-ray crystallography data; and George acquired the NMR data. Their expertise and access to specialized instrumentation were essential, Sigmon said, as these capabilities are not available at Penn State Brandywine.

Students at the center of the work

Sameer Aggroia, who graduated from Penn State in 2025, became involved with the research after attending Brandywine's Exhibit for Undergraduate Research Enterprise and Creative Accomplishment (EURECA) and seeing a poster related to the project.

"I already knew that research of any kind is not very easy," he said. "There are going to be setbacks and there are going to be mistakes that are made. … There were numerous times when a reaction did not work, and some reactions even brought me back to my starting material somehow, but that is chemistry research."

Gracie Clare Guerin, who graduated from Penn State in 2025, became involved with the research after asking Sigmon about opportunities she could take part in on campus. She noted how her time researching with Sigmon solidified what she wanted to do post-graduation.

"I wasn't sure if I wanted to go into research, but after working with Dr. Sigmon, I knew that's what I wanted to do when I graduated," she said. "I'm now working as a full-time research technician in a medical research lab at the Children's Hospital of Philadelphia. … This was my first experience in research, so it was important for my development as a researcher. Dr. Sigmon helped me develop my skills in problem-solving and precision."

Undergraduate research at Penn State Brandywine

Sigmon said she hopes the experience helps students understand the realities of scientific research while preparing them for future careers.

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"I hope this experience helps students understand the true nature of research in chemistry, which requires patience and extensive trial and error experimentation, while also giving them practical skills that prepare them for careers in the life sciences or for graduate studies," she said.

The students involved encouraged Brandywine undergraduate students to seek research opportunities early. "Research allows you to apply what you're learning in lectures to real-world problems, which helped me truly connect and understand the material in a deeper way," Englert said. "It encourages curiosity, initiative and independent thinking, and while the challenges may be demanding, the process of working through them is incredibly rewarding and transformative."

Guerin agreed. "It's okay if you don't like it or if you want to change your goals," Guerin said. "I switched the type of research I was doing a bunch of times before I really figured out what I want to do, and I still got so much out of those experiences."

Aggroia recommended giving research a try, even if it ends up not being a career path for someone. "Undergraduate research is an incredible experience that gives you a head start in whatever your career may be," Aggroia added. "Obviously, some students may enjoy research as much as I did, while others may not like it at all. They won't know until they have tried it, so I say give it a shot, at least for one semester."

Publication details

Anna J. Sigmon et al, A Green, Facile Method for Selective α-Bromination of Flavanones, ACS Omega (2025). DOI: 10.1021/acsomega.5c07396

Journal information: ACS Omega

Provided by Pennsylvania State University