B.S., Guru Nanak Dev University, Amritsar, India (1991-1994)
M.S., Guru Nanak Dev University, Amritsar, India (1994-1996)
Ph.D., University of Missouri-Columbia, Columbia, MO (1997-2003)
Postdoctoral Associate, The Ohio State University, Columbus, OH (2003-2005)
Office Phone: 785-532-6660
Lab Phone: 785-532-6257
Rayat Group Website
Photoactivated DNA Cleaving Agents
We are investigating a new class of compounds based on the “enynyl-1H-tetrazole-5(4H)-thione” framework, for use as prodrugs in Photodynamic therapy. Upon light activation, these compounds are expected to cause tissue damage through the generation of biradicals
and subsequent hydrogen atom abstraction from the sugar phosphate backbone of the DNA. This mode of destruction differs significantly from the conventional PDT approach where photodamage occurs through the formation of singlet oxygen and hence, addresses several limitations associated with the clinically approved mode of cancer treatment using PDT.
Bridgehead Nitrogen-Containing Fused Heterocycles
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 otherwise challenging unique bridgehead nitrogen-containing fused heterocyclic scaffolds with the goals of applying these scaffolds in designing tunable organic light emitting diodes (OLEDs), fluorescent DNA probes and topoisomerase inhibitors. The syntheses of these N-fused heterocycles involve two sequential intramolecular cyclizations from aza-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 a quick way to access these unique and highly complex yet elegant heterocyclic systems with finely tuned electronic and optical properties.
Deamination of Catecholamine Neurotransmitters and Oxidative Stress in Parkinson’s Disease
Dopamine and norepinephrine are the catecholamine neurotransmitters in brain areas concerned with movement, emotional behavior, arousal, reward, and regulation of sleep and mood. The principal neuropathlogical feature of Parkinson’s disease is the selective and progressive degeneration of dopamine and norepinephrine-containing neurons as a result of oxidative stress. Oxidative stress could result from (1) the monoamine oxidase-mediated oxidation and autoxidation of catecholamines, which leads to the formation of cytotoxic quinones and reactive oxygen species (ROS), (2) the cysteinyl-catecholamine adducts, formed by the reaction of cysteine and quinones that also lead to the formation of ROS, (3) exposure to reactive nitrogen species (RNS) that leads to the formation of cytotoxic nitrated catecholamines and, (4) interaction of dopamine with cytotoxic and mutagenic agent glyoxal, which results in the production of toxic adducts.
The reactivity of these catecholamines towards various RNS has not been extensively studied. It is well known that dinitrogen trioxide N2O3, a RNS derived from nitric oxide, causes deamination of the exocyclic amino groups of DNA bases which has dire consequences on human body. The catecholamines, dopamine and norepinephrine, are also characterized by a primary amino group and what effect N2O3 might impose on these neurotransmitters is unknown. Nitrosative deamination of catecholamines represents a critical and yet
unexplored pathway of neurodegeneration in PD. Our laboratory is interested in investigating the deamination of catecholamines under nitrosative stress followed by adduct formation with biomolecules which will be evaluated for their toxicity against nerver cell models.
- Naganaboina, V. K.; Chandra, K. L; Desper, J.; Rayat, S. An easy entry into 2-halo-3-aryl-4(3H)-quinazoliniminium halides from heteroenyne-allenes, Org. Lett. 2011, 13, 3718–3721.
- Perchellet J. –P. H.; Waters, A. M.; Perchellet, E. M.; Naganaboina, V. K.; Chandra, K. L.; Desper, J.; Rayat, S.
Bioactivity of Synthetic 2-Halo-3-aryl-4(3H)-quinazoliniminium Halides in L1210 Leukemia and SK-BR-3 Mammary Tumor Cells In Vitro, Anticancer Res. 2011, 31, 2083-2094.
- Alawode, O.; Robinson, C.; Rayat, S. Clean photodecomposition of 1-methyl-4-phenyl-1H-tetrazole-5(4H)-thiones to carbodiimides proceeds via a biradical, J. Org. Chem. 2011, 76, 216–222.
- Gundugola, A. S.; Chandra, K. L.; Perchellet, E. M.; Waters, A. M.; Perchellet, J. –P. and Rayat,S. Synthesis and antiproliferative evaluation of 5-oxo and 5-thio derivatives of 1,4-diaryl tetrazoles, Bioorg. Med. Chem. Lett. 2010, 20, 3920–3924.
- Rayat, S.; Chabbra, R; Alawode, O.; Gundugola, A. S. Electronic properties of 1-methyl-4-phenyl-1H-tetrazole-5(4H)-thiones: An experimental and theoretical study, J. Mol. Struct. 2009, 933, 38–45.
- Rayat, S.; Alawode, O.; Desper, J. Intermolecular interactions in the crystal structures of substituted tetrazolones, CrystEngComm. 2009, 13, 1892-1898..