Synthesis, Evaluation and Applications of Biologically Significant Molecules and their Analogues

Synthetic chemists are always looking for challenging problems to solve. Design and synthesis of novel molecules that can act as agents of chemical and biological modification are one of the foremost goals of a synthetic chemist. This dissertation describes advances and efforts made in this area.

Obesity is one of the critical problems of the modern age. Molecules that can remediate this condition are highly sought after. The first chapter of this dissertation describes synthetic strategies explored to prepare these valuable natural products along with their structural and stereochemical analogues to study structure and activity relationships (SAR). This method gives easy access to the preparation of several complex natural products. This could eventually result in discovery of potent medicines for different diseases.

Similarly, development of novel synthetic strategies was carried out in order to understand the role of autoinducer 2 (AI-2) in quorum sensing and is described in chapter 2. Quorum sensing is the way bacteria communicate with each other using small signaling molecules. AI-2 is a small molecule produced by a variety of bacteria and is proposed to be a universal quorum sensing signal. 4,5-dihydroxy-2,3-pentadione (DPD), which is a precursor to AI-2, and analogues were synthesized and utilized in studies designed to probe their role in quorum sensing. In addition, the effect of AI-2 on dual species mutualistic biofilm formation in a model dental plaque system is also discussed.

The facile detection and efficient quantification of DPD has been a great challenge to researchers due to its chemical and physical properties. Chapter 3 of this dissertation discusses the development of optical sensors for the selective detection of DPD.

Chapter 4 lists the experiments carried out to shed light on the role and mechanism of AI-2 in other biological systems such as the immune system and oxidative stress along with quorum sensing. It was deduced that autoinducer-2 suppresses the immune system by the interruption of cytokine signaling, implying that the autoinducer plays a protective role during host colonization.