Comprehensive chemometric analysis of β-carbolines alkaloids

FEDERICO A. O. RASSE-SURIANI; FRANCO M. CABRERIZO; ROSA ERRA-BALSELLS; FERNANDO S. GARCÍA EINSCHLAG

Villa Carlos Paz

Congreso; XIII ELAFOT (Encuentro Latinoamericano de Fotoquímica y Fotobiología; 2017

Derivated of β-carboline (βC) alkaloids has were found in a wide range of species [1-4]. In mammals, they have an exogenous (diet) [1] and endogenous origin (biosynthesis) [2]. In particular, N-methyl-βCs has been reported as potential pathogenetic factors in Parkinson?s disease, inhibitors of acetylcholinesterase enzyme, neuroprotective and neuron-differentiating agents, antimicrobial compounds, and DNA intercalators in vitro [3a-e]. So despite the established importance of N-methyl-βCs and related βCs, the molecular bases of the mechanisms involved on the above mentioned processes still need to be addressed. In this regard, a deep knowledge of fundamental aspects related to their spectroscopic, chemical and photophysical properties represents a key starting point. It is known that for βCs the latter properties strongly depend on the chemical molecule structure, as well as on the nature of the environment (solvent) and its pH [4]. In consequence, each specific βC derivative deserves special attention, particularly for better assessing the correlation between alkaloid acid-base species and their physico-chemical properties. Hence, we have systematically investigated photophysical properties of norharmane (nHo) and their N-methylated derivatives (Scheme 1), in aqueous solution, paying special attention not only on the equilibrium and/or species dominant in physiologically relevant pH-conditions but also under highly alkaline conditions. As in many cases the species involved have a high degree of spectral overlap and the extraction of information is not possible with traditional analysis tools (univariate data), the use chemometric methods (multivariate analysis techniques) was exploited for interpretation and analysis of the spectroscopyc data, providing qualitative and quantitative information about equilibria and species involved.βCs are naturally occurring secondary metabolites that deserve to be explored in several fields of biology because they might represent an interesting alternative as fluorescent tracers endowed with unique photophysical properties. The results of the present work would contribute to understand the photophysical behavior of βCs in biological environments and, therefore, to further elucidate the roles played by these alkaloids in a wide range of biological systems. In addition, this study also shows that multivariate analysis provides a reliable tool for tracking bioactive compounds in natural product extracts.