Light as a source of full aromatization and hydroxylation of 7-methoxy-1-methyl-3,4-dihydro-2H-pyrido[3,4-b]indole alkaloid: oxygen partial pressure as a key modulator of the photoproducts distribution

F. A. O. RASSE-SURIANI; ERRA-BALSELLS, R; M.P. DENOFRIO,; T. SCHMIDT DE LEóN,; F. VILLARRUEL; F.S. GARCIA-EINSCHLAG; F.M. CABRERIZO.

JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY

ELSEVIER SCIENCE SA

Lugar: Amsterdam; Año: 2019 vol. 199

1011-1344

AbstractFull-aromatic and partially hydrogenated â-carboline (âC) derivatives constitute a group of alkaloids widely distributedin a great variety of living systems. In plants and bacteria, tetrahydro-âCs are the primary product of the Pictet-Spengler enzymatically catalyzed condensation. Tetrahydro-âC skeleton is further modified giving rise to the formationof a vast set of derivatives including dihydro- and full-aromatic âCs. However, in most of the cases, the later processesstill remain unclear and other sources, such as photo-triggered reactions, deserve to be explored. In this context, thephotophysic and photochemistry of 7-methoxy-1-methyl-3,4-dihydro-2H-pyrido[3,4-b]indole or harmaline (Hlina) inaqueous solution is reported herein. UV-visible absorption and fluorescence emission spectroscopy coupled withmultivariate data analysis (PARAFAC), HPLC and HRESI-MS techniques were used for both quantitative andqualitative analysis. The formation singlet oxygen and hydrogen peroxide reactive oxygen species (ROS) wasquantified and their role together with the influence of pH and oxygen partial pressure on the photochemicaldegradation of HlinaH+ was assessed. We report herein the first study on photochemical full-aromatization of adihydro-âC derivative. These results can shed some light on the âCs biosynthesis and role in living systems.