Joanne Huang

Student: Joanne Huang

Project: Anti-bacterial and Anti-toxin Activities of Catechins | View Poster (PDF)

Institution: Lehigh University

Major: Chemical and Biomolecular Engineering

Advisor: Angela Brown


Aggregatibacter actinomycetemcomitans (A.a.) is a Gram-negative bacterium that is associated with aggressive forms of periodontal disease. The bacterium releases a leukotoxin (LtxA) that allows the bacteria to evade the immune response of the host by targeting white blood cells. Catechins found in green tea have been found to inhibit the growth of some bacteria, and recent studies are showing evidence of its potential in controlling oral infections. However, the mechanism of this inhibitory activity is not yet known. In these experiments, we studied the interaction between LtxA and catechins using confocal microscopy and circular dichroism (CD) spectroscopy. Six types of catechin were tested: epicatechin (EC), epicatechin gallate (ECG), epigallocatechin gallate (EGCG), gallocatechin gallate (GCG), epigallocatechin (EGC), and catechin (C). We found that five out of the six catechins inhibited the activity of LtxA. Galloylated catechins were most influential in preventing the binding between LtxA and giant unilamellar vesicles (GUVs), and these same five catechins inhibited the activity of LtxA in THP-1 cells. Incubation of LtxA with catechin resulted in a change in the secondary structure of the toxin, preventing LtxA binding to cholesterol. These results indicate that catechins have the ability to inhibit the toxic activity of A.a. by changing the secondary structure of its leukotoxin.

About Joanne Huang

Joanne Huang is a senior student studying Chemical Engineering at Lehigh University. She is a Clare Boothe Luce Research Scholar and performs undergraduate research in Dr. Angela Brown’s lab. She has been studying the interactions between catechins and Aggregatibacter actinomycetemcomitans bacterium. Outside of academics, Joanne is a gryphon for an upperclassmen themed community, where she collaborates with other gryphons and plans various events for students. Joanne is also involved in InterVarsity Christian Fellowship where she facilities discussions about faith, organizes events, and encourages the formation of genuine relationships.

Lehigh Engineering Undergraduate Research Symposium

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