The oral microbiome represents an extremely diverse environment that harbors many species of bacteria; over 700 different species have been identified overall. These organisms may be either commensal or pathogenic, and reside in multi-species communities of bacterial biofilms. As such, these bacteria may be 100-1000 times less susceptible to antibiotic treatment than their planktonic counterparts. One pathogenic organism that exists as a biofilm in the oral cavity is Streptococcus mutans, the main etiologic agent contributing to dental caries. Recently, the myxobacterial natural product carolacton was isolated and shown to be lethal to S. mutans cells in a biofilm at low (10 nM) concentration. As part of an endeavor to take inspiration from natural products to develop new therapeutics to combat biofilms, our group became interested in carolacton. This dissertation describes research conducted into the synthesis and biological evaluation of carolacton. Total synthesis enabled the biological evaluation of carolacton as well as several analogs. A novel compound was identified that was shown to elicit a phenotypic response from S. mutans that was different from that elicited by carolacton. In an effort to uncover novel simplified carolacton derivatives that maintain bioactivity and/or act via a different mechanism, we have exploited the power of diverted total synthesis in order to obtain a 1st-generation library of carolacton analogs. By leveraging a common intermediate that we were then able to diversify, we have obtained a library of simplified aryl analogs. Preliminary testing of these analogs has revealed a compound that inhibits growth and formation of S. mutans biofilms. This research has enabled us to obtain compounds that will serve to guide future drug discovery efforts, as well as act as tool compounds to help identify novel drug targets in S. mutans biofilms. / Chemistry

Ever since traditional medicine developed thousands of years ago, humans have looked to natural substances as remedies for maladies. Today, many isolation and natural product chemists have begun revisiting ancient folk medicines in an attempt to isolate the compound(s) responsible for effective treatment. In addition to the examination of traditional remedies, the secondary metabolites of many newly discovered species, especially bacteria, get tested against a wide array of pathogenic cells. Isolated from the myxobacterium Sorangium cellulosum, the secondary metabolite carolacton was discovered to be lethal to Streptococcus mutans cells transitioning to the biofilm state. This was a significant finding since S. mutans is the main causative agent of dental caries, the most prevalent chronic childhood and adolescent disease worldwide. Herein, our efforts to design, synthesize, and biologically evaluate a 16-member library of carolacton-inspired analogs is described. In addition to natural product inspired research, two projects borne from a target-oriented templated approach are also described. The first, the synthesis of the antitumor compound FRAX-1036, was completed as part of a collaboration with the Chernoff group at Fox Chase Cancer Center to provide them with more material for murine testing. The second, the synthesis of macrocycles for the formation of atomically precise membranes, was conducted using spiroligomer building blocks and unnatural amino acids to furnish a triangle-shaped macrocycle via solution and solid phase techniques. This dissertation highlights the usefulness of the techniques of diverted total synthesis and building block synthesis in organic chemistry. / Chemistry