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John P. Toscano
Johns Hopkins University Phone: 410.516.6534 PhD - Yale University Most photochemical reactions take place through very short-lived intermediates such as singlet or triplet excited states, radicals, carbenes, nitrenes, and nitrenium ions. A thorough understanding of these intermediates is not only of basic scientific concern, but also has direct relevance to many critical issues in photochemistry and photobiology. The Toscano group's main research interests involve the application of time-resolved spectroscopic techniques to the study of these intermediates with particular emphasis on the use of newly developed methods in time-resolved infrared (TRIR) spectroscopy. In the area of photobiology, we are presently involved in the development of novel photochemical precursors to nitric oxide (NO). NO is an important bioregulator that is involved in the control of neurotransmission, blood clotting, and blood pressure. In addition, NO has been shown to kill cancerous tumor cells. Thus, previous research has focused on the development of drugs that can deliver NO efficiently and selectively, e.g., to tumor cells without dramatically affecting other bioregulatory processes.
Diazeniumdiolates (1) are an interesting class of NO-releasing drugs. Recent efforts to make diazeniumdiolates more effective pharmaceuticals have concentrated on using derivatives of such compounds to deliver NO specifically to a targeted site. In collaboration with Dr. Larry K. Keefer, head of the Laboratory of Comparative Carcinogenesis at the Frederick Cancer Research and Development Center of the National Cancer Institute, we have begun to develop photochemical precursors to diazeniumdiolates that can be used as effective NO-releasing agents. Since initial experiments in other laboratories with classical photoprotecting groups gave unexpected and disappointing results, we are presently clarifying reaction pathways so that more efficient phototriggered drugs based on the release of diazeniumdiolates can be rationally designed. In addition, if diazeniumdiolates are to enjoy routine medical use, their basic photochemistry must be understood so that phototoxicity issues may be anticipated and avoided. |
Organic Chemistry