Chemistry Projects 2011
From the Periodic Table to the Kitchen #4 - Investigation of household chemicals for
incorporation into the middle and high school curricula
Faculty Mentors - Drs. Samuel Hudson, David Saiki
All too often, chemistry and chemical research is seen as a mysterious activity relegated to obscure labs using black-box type instruments not to really be understood by the public or especially students. The purpose of this project has been to strip-away some of the veils that get in the way of understanding this "central science." In this project, students and teachers will develop a series of demonstrations and experiments that use cheap, commonly available items that ably demonstrate many scientific principles. In addition, teachers and students will work together to create a lab manual to take back to school and home. This manual will address California Science Standards for each demonstration and is intended to be a resource that teachers and take and use in the classroom. This year's demonstrations include experiments that cover topics such as: Clock Reactions, Crushing Cans, Egg in a Bottle, Disappearing Ink, Sunken Ice Cubes, Cartesian Divers, Low-Temperature Boiling, Fog Machines, and Chemical Fountains. Participants in this project will also be able to suggest additional experiments.
Metabolic Profiling of Peppers (Capsicum sps) and Evaluation of Capsaicinoids as Potential Antibiotics
Faculty Mentor - Dr. Roy LaFever
Peppers have been used extensively throughout modern human history. The plants and fruit have been utilized in myriad of ways related to both culinary and medicinal uses. Peppers produce a variety of secondary natural products. In particular, pepper fruit accumulates several compounds known as capsaicinoids. The predominant capsaicinoid is the compound capsaicin, which is the major "heat producing" component of pepper extracts. Although capsaicin has been well studied there are few reports regarding biological activities of the other capsaicinoids or unrelated metabolites found in peppers. The focus of this research is two-fold. First to examine the constituents of several pepper species through chemical means, and secondly to screen the pepper extracts for important biological activities. This type of research is ideally suited for a small group, or team. A group of secondary students and a team leading educator will cultivate peppers in the greenhouse and produce extracts from the plants for chemical analysis. This analysis will identify and quantify the isolated constituents in preparation for carrying out biological activity assays. The assays will examine antibacterial activity and antioxidant potential of the pepper extracts. The skills obtained from this research will include basic chemical skills and laboratory techniques as well as hands-on experience utilizing sophisticated analytical instrumentation. In addition, the assays designed to screen for biological activities will expose the team to a highly interdisciplinary project that bridges the disciplines of chemistry, biochemistry, and biology.
Can Computers Fuel Hydrogen Vehicles?
Faculty Mentor - Tiffany Pawluk
Many methods for the production of hydrogen are currently available, including the commonly used process of steam reformation of natural gas containing methane. In this steam reformation process, methane is first converted to syngas, a mixture of H2 and CO over a supported metal catalyst. The potential of transition metal catalysts such as platinum, iridium and palladium have been studied both experimentally and theoretically. In particular, iridium shows promise for methane dehydrogenation on surfaces and cations. However, studies utilizing neutral gas phase atoms or clusters are lacking. This project will use modern computational methods to determine the reaction pathway for hydrogen dissociation from methane molecules supported on iridium nanoparticle clusters. Participants will learn popular computational methods that scientists around the world use to complement experimental work. Can computers fuel hydrogen vehicles? The research of this summer project will be a step in the right direction.
Pharmacophore-Guided Design and Synthesis of Dopamine D3 Receptor Ligands
Faculty Mentor - Dr. Laura Serbulea
The dopamine D3 receptor has been recognized to play an important role in various neurological and psychiatric disorders, due to its preferential distribution in distinct areas of the central nervous system associated with emotional and cognitive functions. Numerous studies have shown that D3 selective antagonists induce beneficial antipsychotic activity without significant extrapyramidal side effects and are potential therapeutic drugs in the treatment of schizophrenia and cocaine addiction, while D3 receptor agonists have potential in treatment of L-dopa induced dyskinesia in Parkinson’s disease. Although numerous D3 receptor ligands have been developed in the past decade, only few compounds display high affinity, sufficient selectivity over the D2 or other aminergic receptors, and possess a satisfactory pharmacological profile. Several groups have reported computational homology modeling for dopamine receptors, using high resolution X-ray crystal structure of bovine rhodopsin as template. Wang et al. performed docking of 29 structurally diverse ligands on homology modeled D3 receptor and proposed a pharmacophore model containing three hydrogen bonding centers, an aromatic region, an alicyclic ring and a salt bridging site.
The new D3 receptor ligands have been designed such that contain all structural features proposed in Wang’s pharmacophore model. In order to confer some rigidity to the ligands, a tricyclic structure of the ligands has been envisioned. The amine nitrogen is contained in a piperidine ring, which holds a meta- or para-substituted phenyl ring at C4, while the amine nitrogen is connected via a methylene or ethylene linker to a saturated five or six membered ring:
R1 is either a substituted cyclopentanone or cyclohexanone residue, and R2 represents small sized hydrogen donors or acceptors. Computational docking experiments will be carried out to get insight into the binding interactions of the designed ligands to the receptor and estimate their potency. The results from docking studies will be used for further structural refinement of proposed ligands.
In the synthesis of the R1-P-R2 ligands, the arylpiperidine core is obtained by a palladium catalyzed Suzuki coupling of aryl boronic acid derivatives and 4-piperidone derived triflates. Coupling of the arylpiperidine core with R1 containing aldehydes via sodium triacetoxyborohydride mediated reductive amination will complete the synthesis of the proposed ligands. Finally, well-established and validated binding assays will be used for determination of the activity (as agonists or antagonists), affinity and selectivity of the proposed compounds for the D3 receptor.
Synthesis of Naturally-Occurring Antimalarial Agents
Faculty Mentor - Dr. Danielle Solano
Every year approximately 250 million cases of malaria and one million malaria-related deaths are reported worldwide. While several antimalarial drugs are available, new strains of malarial parasites have recently emerged that are resistant to current treatments. Thus there is a need for the development of more effective antimalarial drugs. Natural products isolated from living organisms often provide a source of inspiration in drug discovery. Venturamide A and Venturamide B (below) are natural products that were recently isolated from the marine cyanobacterium Oscillatoria sp. Both of these cyclic molecules are reported to have potent antimalarial properties. This project will utilize synthetic organic chemistry and techniques used in drug discovery to work towards the synthesis of these natural products. This research will pave the way for the design of new, antimalarial drug-like molecules.
