Project Significance:
β-Lapachone (β-LA) is an ortho-naphthoquinone obtained from the heartwood of Tabebuia avellanedae, which is mainly found in Brazil. β-LA has been extensively studied due to its anticancer properties. β-LA has been found to inhibit the growth of sarcoma tumors in mice and to be cytotoxic to leukemia cells and human cancers such as breast, colon, prostate, and lung. The mechanism of the observed cytotoxicity in cancer cells appears to be due to NAD(P)H quinine oxidoreductase-1 performing a two-electron reduction of β-LA to produce its hydroquinone, which may then generate reactive oxygen species to induce DNA damage that can lead to cell death. Therefore, there has been some research effort conducted on the photoreactions of β-LA.
Although a number of studies have examined β-LA in organic solvents, the phototoxicity mechanism of β-LA toward cancers cells remains poorly understood because the organic solution conditions are very different from those of the biological environment. Therefore, it will be useful to investigate the photophysics and photochemistry of β-LA in aqueous solutions that are more relevant to the actual solvent environment biological systems.
Results Achieved:
I had used femtosecond and nanosecond transient absorption (fs-TA and ns-TA) and nanosecond time-resolved resonance Raman (ns-TR3 ) spectroscopic methods to investigate the early events taking place for β-LA after photoexcitation in aqueous solutions. As far as we know, this is the first time that fs-TA, ns-TA, and ns-TR3 experiments have been performed on β-LA in different acetonitrile (MeCN)/H2O mixture solutions in order to investigate the role of water on the excited states, intermediates, and dynamics of reactive intermediates that are involved in the photochemistry of β-LA.
