Do planar alkaloids from Strychnos usambarensis intercalate into the DNA helix?

Photophysical and Photochemical Properties of Naturally Occurring normelinonine F and Melinonine F Alkaloids and Structurally Related N(2)‐ and/or N(9)‐methyl‐β‐carboline Derivatives

“…(6) As it was described for other related β Cs , due to their planar chemical structure, nor melinonine F and melinonine F interact with cell‐free DNA. Such interaction involves a partial intercalation of the indolic ring of the β C molecule into the stacked base‐pairs, placing the N‐methylpyridinium cationic ring in a protic environment (methyl substituent at position 2 (N‐2) in pyridoindole moiety) .Despite the established importance of N‐methyl‐ β Cs for the abovedescribed biological processes, molecular basis of the mechanisms involved remains unclear. If further insight is to be gained, then fundamental aspects related to spectroscopic, chemical and photophysical properties of N‐methyl‐ β Cs need to be addressed.…”

“…It is known that for β Cs, the latter properties strongly depend on molecular structure, as well as on the nature of the environment (solvent) and pH . To the best of our knowledge, only partial information regarding the spectroscopic characteristics of few quaternary β Cs has been reported . Moreover, the characterization of the species present under highly alkaline aqueous conditions (pH > 13) is rather scarce or, in many cases, null.In the present work, we have systematically investigated the chemical and photochemical properties of a selected group of quaternary N‐methyl‐ β ‐carbolinium iodide salts (Scheme ), in aqueous solution, paying special attention not only to the equilibrium and/or species dominant in physiologically relevant pH conditions but also under highly alkaline conditions.…”

“…(6) As it was described for other related bCs (43)(44)(45), due to their planar chemical structure, normelinonine F and melinonine F interact with cell-free DNA. Such interaction involves a partial intercalation of the indolic ring of the bC molecule into the stacked base-pairs, placing the N-methylpyridinium cationic ring in a protic environment (methyl substituent at position 2 (N-2) in pyridoindole moiety) (46).…”

“…It is known that for bCs, the latter properties strongly depend on molecular structure, as well as on the nature of the environment (solvent) and pH (47)(48)(49)(50)(51)(52). To the best of our knowledge, only partial information regarding the spectroscopic characteristics of few quaternary bCs has been reported (46,(53)(54)(55). Moreover, the characterization of the species present under highly alkaline aqueous conditions (pH > 13) is rather scarce or, in many cases, null.…”

Ground‐ and Excited‐State Hydrogen Bonding in the Diazaromatic Betacarboline Derivatives

“…These rings are the structural units of numerous naturally occurring alkaloids that possess a wide range of biological and pharmacological properties [34][35][36][37][38][39][40][41][42][43][44][45]. Also, some of them have been proposed as fluorescence standards [26,27], their fluorescence activity being highly sensitive to the solvent [46,47].…”