Evaluating the Antibacterial Effects of Capsaicin Extract from Capsicum annuum on Kanamycin-Resistant Escherichia coli
Article By: Amani Benamor
Sometimes, breakthroughs don’t begin with the perfect hypothesis - but a spicy misunderstanding.
In a project part of their premedical Biology coursework, where curiosity met a bit of chemical confusion, three PM1 students, Alhussein Alaswad, Loaie Hassan, and Mohammed Eid, may have stumbled upon an interesting lead in the fight against antibiotic-resistant bacteria. Early in their first semester, the group was tasked with choosing an organic compound to test for antimicrobial activity against different types of bacteria. The team posed a question: what if capsaicin, the fiery molecule behind the heat in chili peppers, could affect kanamycin-resistant E. coli?
Unfortunately, It doesn’t.
This experiment investigated the antibacterial activity of extracts from Capsicum annuum (red chili pepper) against both wild-type and kanamycin-resistant strains of Escherichia coli. Capsaicin was obtained through ethanol-based extraction from dried pepper samples, yielding a thick, hydrophobic solution. Contrary to the initial hypothesis, the resistant E. coli displayed significantly larger zones of inhibition than the wild-type strain.
This unexpected result suggests that the resistance mechanism for kanamycin may increase bacterial vulnerability to certain phytochemicals, such as capsaicin. A statistical analysis confirmed the observed difference in inhibition zone sizes. The findings point to a potential inverse relationship between antibiotic resistance and susceptibility to plant-derived antimicrobials, warranting further investigation into the genetic and molecular mechanisms involved.
Reflecting on the process, Loaie explained,
Eid added,
“We didn’t just learn lab skills like pipetting and plating. We learned how to fail, reassess, and repeat. Our first few attempts didn’t show clear results, so we had to adjust the exact concentration, refine our disc diffusion technique, and stay patient—sometimes staying late into the evening to rework the setup.”
“Capsaicin was incredibly difficult to work with. It’s sticky, nonpolar, and hard to dissolve. Getting it into a usable form took real persistence.”
The group hopes their findings can be a springboard for future studies isolating specific compounds within C. annuum and determining their precise mechanisms of action against resistant bacterial strains. As resistance to synthetic antibiotics continues to rise, their project serves as a timely reminder that solutions may lie in nature—and in the curiosity of students willing to explore it.
