Associate Professor of Chemistry
Assistant Professor, Kansas State University, Manhattan KS
Postdoctoral Associate, The Ohio State University, Columbus, OH
Ph.D., University of Missouri-Columbia, Columbia, MO
Synthetic organic chemistry, physical organic chemistry, photochemistry, biological/medicinal chemistry, materials chemistry, computational chemistry.
Our laboratory is providing versatile and robust strategies to unique classes of N-fused heterocycles and evaluating their optoelectronic and biological properties by experimental and computational methods. We are also synthesizing and evaluating a new class of compounds based on tetrazolethione scaffold for application in photoactivated DNA damage via biradicals.
Rayat Research Group
Bridgehead-Nitrogen Fused Heterocyclic Systems
Heterocycles with a nitrogen atom at the ring fusion exhibit interesting photophysical and biological properties. Our laboratory is developing new, concise and low cost strategies to construct challenging unique bridgehead nitrogen-containing fused heterocyclic scaffolds with the goals of applying these scaffolds in designing tunable organic semiconductors, fluorescent DNA probes and topoisomerase inhibitors. The syntheses of these N-fused heterocycles involve two sequential intramolecular cyclizations from hetero-enyneallenes in the presence of a hydrogen halide generated in situ from a Lewis acid and trace water. To our knowledge, there are no direct methods available in the literature for their synthesis and our research group has found quick ways to access these unique and highly complex yet elegant heterocyclic systems with finely tuned electronic and optical properties.
Photoactivated DNA Cleaving Agents
Photodynamic therapy (PDT) is a therapeutic treatment that employs a combination of drug and light to selectively kill cancer cells. This method is approved for the treatment of a wide variety of cancers (e.g. skin, bladder, cervical, lung and esophageal cancers), precancerous lesions and age-related macular degeneration. We are developing a new class of chemical compounds, based on enynyl-1H-tetrazole-5(4H)-thione as potential prodrugs for use in PDT. These compounds are expected to cause damage via a pathway different from the clinically approved method of treatment using PDT, and therefore will help address some of the limitations associated with traditional PDT. Our hypothesis is depicted in the schematic shown above. Once the prodrug is accumulated in the target tissue, the exposure of tumor cells to light will activate the drug and produce toxic species (biradicals) which will ultimately cause damage by cutting the DNA strands (abstraction of H-atoms from the sugar phosphate backbone of the DNA). The destruction of DNA of the tumor cell will lead to cell death.
One-Pot Cascade Approach to Phenanthridine-Fused Quinazoliniminiums from Heteroenyne-Allenes. Alawode, O. E.; Naganaboina, V. K.; Liyange, T.; Desper, J.; Rayat, S. Org. Lett. 2014, 16, ASAP.
Controlling Molecular Tautomerism Through Supramolecular Selectivity. Epa, K.; Aakeroy, C, B; Desper, J.; Rayat, S.; Chandra, K. L.; Cruz-Cabeza, A. J. Chem. Comm. 2013, 49, 7929-7931.
An easy entry into 2-halo-3-aryl-4(3H)-quinazoliniminium halides from heteroenyne-allenes. Naganaboina, V. K.; Chandra, K. L; Desper, J.; Rayat, S., Org. Lett. 2011, 13, 3718–3721.
Bioactivity of Synthetic 2-Halo-3-aryl-4(3H)-quinazoliniminium Halides in L1210 Leukemia and SK-BR-3 Mammary Tumor Cells In Vitro. Perchellet J. –P. H.; Waters, A. M.; Perchellet, E. M.; Naganaboina, V. K.; Chandra, K. L.; Desper, J.; Rayat, S., Anticancer Res. 2011, 31, 2083-2094.
Clean photodecomposition of 1-methyl-4-phenyl-1H-tetrazole-5(4H)-thiones to carbodiimides proceeds via a biradical. Alawode, O.; Robinson, C.; Rayat, S. J. Org. Chem. 2011, 76, 216–222.
Synthesis and antiproliferative evaluation of 5-oxo and 5-thio derivatives of 1,4-diaryl tetrazoles. Gundugola, A. S.; Chandra, K. L.; Perchellet, E. M.; Waters, A. M.; Perchellet, J. –P. and Rayat, S. Bioorg. Med. Chem. Lett. 2010, 20, 3920–3924.
Electronic properties of 1-methyl-4-phenyl-1H-tetrazole-5(4H)-thiones: An experimental and theoretical study. Sundeep Rayat, Radhika Chabbra, Olajide Alawode and Aditya S. Gundugola. J. Mol. Struct. 2009, 933, 38-45.
Intermolecular interactions in the crystal structures of substituted tetrazolones. Sundeep Rayat, Olajide Alawode and John Desper. CrystEngComm. 2009, 1892-1898.
Nitrosative cytosine deamination. An exploration of the chemistry emanating from deamination with pyrimidine ring- opening. Sundeep Rayat, Ming Qian, and Rainer Glaser. Chem. Res. Tox. 2005, 18, 1211-1218.
5-Cyanoimino-4-oxomethylene-4,5-dihydroimidazole and 5-Cyanoamino-4-imidazolecarboxylic Acid Intermediates in Nitrosative Guanosine Deamination. Evidence from 18O-Labeling Experiments. Sundeep Rayat, Papiya Majumdar, Peter Tipton, and Rainer Glaser. J. Am. Chem. Soc. 2004, 126, 9960-9969.
Nitrosative Guanine Deamination. Ab Initio Study of Deglycation of N-Protonated 5-Cyanoimino-4-Oxomethylene-4,5-Dihydroimidazoles. Sundeep Rayat, Zhengyu Wu, and Rainer Glaser. Chem. Res. Tox. 2004, 17, 1157-1169.
4-Oxomethylene-5-Cyanoimino-4,5-Dihydroimidazole and Nitrosative Guanine Deamination. A Theoretical Study of Geometries, Electronic Structures and N-Protonation. Sundeep Rayat and Rainer Glaser. J. Org. Chem. 2003, 68, 9882-9892.
Nitrosative Adenine Deamination: Facile Pyrimidine Ring-Opening in the Deamination of Adenine. Brian Hodgen, Sundeep Rayat and Rainer Glaser. Org. Lett., 2003, 5, 4077-4080.
Theoretical Studies in DNA Base Deamination 2. Ab Initio Study of Linear, Unimolecular Dediazoniation Paths. Rainer Glaser, Sundeep Rayat, Michael Lewis, Man-Shick Son, Sarah Meyer. J. Am. Chem. Soc. 1999, 121, 6108-6119.