Modulation in prototropism of the photosensitizer Harmane by host:guest interactions between β-cyclodextrin and surfactants

Simple naturally occurring β-carboline alkaloids – role in sustainable theranostics

This review is a brief treatise on some simple β-carboline alkaloids that are abundantly available in plants, animals and foodstuff. These alkaloids are well known for their pharmacological action as well as their allelopathic behaviour. The focus of this review is on sustainable use of naturally occurring compounds in safeguarding human health and protecting our environment at large i.e. the prospective applications of these molecules for Sustainable Theranostics. The review commences with an initial introduction to the β-carboline alkaloids, followed by an outlay of their geographical distribution and natural abundance, then the basic structure and building units of the simplest β-carboline alkaloids have been mentioned. This is followed by a discussion on the important methods of extraction from natural sources both plants and animals. Then the foundation for the use of these alkaloids in Sustainable Theranostics has been built by discussing their interesting photophysics, interactions with important biological molecules and an extensive survey of their therapeutic potential and allelopathic behaviour. Finally the review ends with a silver lining mentioning the future prospective applications of these alkaloids with special relevance to sustainability issues.

Targeting Natural Polymeric DNAs with Harmane: An Insight into Binding and Thermodynamic Interaction Through Biophysical Approach

DNA is one of the major molecular targets for a broad range of anticancer drugs. Hence, interaction studies involving cellular DNA and small molecules can be highly beneficial as they often lead to rational and efficient drug design. In this study, the binding interaction of Harmane (a naturally occurring, bioactive indole alkaloid) with two natural polymeric DNAs, that is, Calf thymus (CT) DNA and Herring testis (HT) DNA has been elucidated using biophysical techniques. A ground state, 1:1 complexation, was revealed by steady-state fluorescence spectroscopy. The thermodynamic profile and energetics of the associated reaction were evaluated by temperature-dependent fluorescence spectroscopy. The spontaneity of the binding was confirmed by the negative ΔG° values in both cases. Negative enthalpy change, along with stronger positive entropic contribution, indicated the dominant electrostatic nature of the interaction and finally the entropy-driven exothermic binding process throughout. Salt-dependent studies further demonstrated the significant contribution of electrostatic interactions in ligand binding toward DNA. Infrared data substantiated the structural information of the said interactions, leading to the exploration of the structure-function relationship.

Supramolecular interaction of a cancer cell photosensitizer in the nanocavity of cucurbit[7]uril: A spectroscopic and calorimetric study

The interaction of small biologically active molecules in the nanocavity of supramolecular host is very interesting and thriving research area. In the presence of supramolecular host the absorption and emission properties of small biologically active molecules were modulated several folds compared to bulk solution. In this study we have investigated the supramolecular interaction of a cancer cell photosensitizer molecule harmane in the presence of cucurbit[7]uril (CB7) as host in aqueous buffer solution (pH∼7.2). We have used steady state absorption, emission and time resolved fluorescence spectroscopy techniques. The thermodynamics of the binding between harmane in the nanochannel of CB7 were studied by using isothermal titration calorimetry (ITC) method. The emission properties of harmane are modulated several fold in the presence of CB7. ITC study indicates that the complexation between harmane and CB7 are enthalpically favourable.