Inhibition of multidrug-resistant bacteria by Civil War plant medicines Open Access

Dettweiler, Micah John (2017)

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A shortage of conventional medicine during the American Civil War (1861-1865) led Confederate physicians to use preparations of native plants as medicines. Francis Porcher, a southern botanist, compiled in 1863 a book of native medicinal plants, including plants used in Native American traditional medicine. In this project, Porcher's book was consulted. Samples from three plant species which he used for the formulation of antiseptics, Liriodendron tulipifera, Aralia spinosa, and Quercus alba, were collected in Lullwater Preserve, Atlanta, Georgia. Chemical extracts of these plant samples were tested for the ability to inhibit growth, biofilm production, and quorum sensing in three species of multidrug-resistant pathogenic bacteria.

Bulk plant specimens were dried and ground to a powder. Chemical extraction for each was performed via sonication in methanol, then each extract was either partitioned or fractionated by column chromatograph to create 19 samples. Samples were dissolved in DMSO (10 mg/mL) and tested at concentrations ranging from 2-256 µg/mL for growth inhibition and biofilm inhibition of Staphylococcus aureus, Klebsiella pneumoniae, and Acinetobacter baumannii. Samples 617B (hexane partition), 619 (bark extract), and 619F2 (tannin fraction) displayed the most growth inhibition of S. aureus with MIC90 < 256 µg/mL, and extracts 619, 619F2, and 620 (gall extract) displayed growth inhibition of K. pneumoniae and A. baumannii. Extracts 616 (leaf extract), 616F1 (non-tannin fraction), 618B (hexane partition), 619F2, 620, and 621 (bark extract) displayed biofilm inhibition of S. aureus at sub-MIC50 concentrations.

The extracts from the three plants showed activity in growth inhibition, biofilm inhibition, and quorum quenching of drug-resistant bacteria.The data herein suggest that these plant extracts represent promising natural product compositions for antibiotic drug development.

Table of Contents

Abstract iv

Chapter 1: Introduction 1

Chapter 2: Literature Review 6

Chapter 3: Materials and Methods 13

Chapter 4: Results 22

Chapter 5: Discussion 38

References 44

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