Quantifying Non‐Covalent Binding Interactions between Tobacco Alkaloids and Cyclodextrin Using Mass Spectrometry and the Application in Cigarette Smoke

Abstract

The host-guest inclusion complexes between cyclodextrin (CD) and five tobacco alkaloids (TAs), namely 1-(4-Nitrophenyl) piperazine (NHK), nicotinamide (NAm), nornicotine (NCt), DL-Anabasine (DL-ABs), and nicotinic acid (NTa), were explored via electrospray ionization mass spectrometry (ESI-MS). The MS results of these CD complexes confirmed the 1 : 1 stoichiometry of the host-guest assemblies formed. The binding constants of the complexes were studied to quantify the interactions between TAs and CDs. The binding constants (lgK R ) of [CD-NHK + H] + were first obtained via ESI-MS titration as a reference; the values obtained were 4.26, 4.11, and 4.03 for [α-, β-, and γ-CD + NHK + H] + , respectively. The binding constants for other CD complexes were then acquired via competitive ESI-MS based on the reference binding constants. The gas-phase binding affinity of the CD complexes was probed by collision-induced dissociation, which indicated the same variation trend as their binding constants, i. e. bigger binding constant results in better kinetic stability of the complex. Finally, considering the non-toxicity and cost-effectiveness of β-CD, it was applied to practical samples of mainstream cigarette smoke (MSS) and the aforementioned special m/z values were identified as the [β-CD + TA + H] + complexes using tandem mass spectrometry. Our results reveal that β-CD could effectively extract TAs and some other ingredients from the MSS during smoking. Therefore, applying CDs such as β-CD in hookah or even in cigarette filter tips might be a potentially promising strategy to extract some harmful components of MSS to reduce the harm caused to the smoker.