Probing medicinal plants for novel antimicrobial compounds

Level of Education of Students Involved


Faculty Sponsor

Danielle Orozco-Nunnelly


Arts and Sciences



ORCID Identifier(s)


Presentation Type

Poster Presentation

Symposium Date

Spring 4-27-2023


According to the World Health Organization, infectious diseases account for three of the top ten global causes of death. Antimicrobial drug discovery to treat such illnesses surged in mid-twentieth century but has sharply declined in recent years. At the same time, antimicrobial-resistant “superbug” infections are on the rise. Plants produce a robust supply of novel metabolic compounds including many antimicrobial agents. However, with the advent of modern antibiotic drugs, natural plant-derived antibiotic sources have largely been left unexplored. Therefore, our work is focused on screening poorly explored medicinal plants in the hopes of discovering novel antimicrobial drugs. To do this, we have been testing extracts of various plants found in the Valpo medicinal garden for their effects against twelve bacterial and fungal microbes of interest. To date, methanol and hexane extracts of both aerial and reproductive portions of 8 plants have been screened, with three plants showing especially promising activities. Both raspberry leaf and yarrow flower methanol extracts were seen to inhibit growth of both Gram-positive and Gram-negative bacteria, with little activity against the fungal organisms tested. Chokeberry leaf methanol extracts had similar trends, but with overall less activity. Moreover, we are currently working to separate the methanolic chokeberry leaf and raspberry leaf crude extracts using column chromatography to eventually determine the specific compounds responsible for these antibacterial activities. These data highlight the importance of plants as an invaluable pharmaceutical resource at a time when antimicrobial drug discovery has plateaued.

Biographical Information about Author(s)

We are a group of undergraduate biology students working in the lab of Dr. Orozco-Nunnelly. Our research focuses on testing plant extracts against various bacteria and fungi of interest to identify novel antimicrobial compounds. The research process involves macerating plant material, incubating it with a solvent (usually hexane or methanol), purifying the extract, and testing it using an antimicrobial disc diffusion assay against over a dozen unique prokaryotic and eukaryotic cell lines. Our lab partners with Dr. Pruet's organic chemistry lab to help analyze the compounds within the plant extracts and to produce derivative compounds based on specific phytocompounds we have previously identified.

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