Excited-state dynamics of imiquimod in aqueous solutions

Takkella, Dineshbabu; Sharma, Sudhanshu; Martínez‐Fernández, Lara; Gavvala, Krishna

doi:10.1016/j.jphotochem.2022.113998

Cited by 5 publications

(2 citation statements)

References 29 publications

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“…The second one (pKa = 7.3) was calculated using the Henderson–Hasselbach equation by extrapolating to zero methanol concentration the apparent pKa measured in water–methanol solutions [ 6 ]. The third paper [ 24 ] reports a pKa of 6.8 based on spectroscopic analysis in water at different pH, and it was attributed to quinoline nitrogen. Interestingly, this value is not significantly different from the experimental value determined in this work.…”

Section: Resultsmentioning

confidence: 99%

Imiquimod Solubility in Different Solvents: An Interpretative Approach

Sorgi,

Sartori,

Germani

et al. 2024

Pharmaceutics

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Imiquimod (IMQ) has been successfully formulated to date mainly as semi-solid lipophilic formulations for topical application. In this study, we investigated the solubility of IMQ in solvents suitable for developing innovative formulations in the form of powder obtained, for instance, by spray drying; thus, water, ethanol, methanol, acetone, acetonitrile, and dimethyl sulfoxide were tested at different temperatures. Temperature variations, stirring intensity, and the contact time between IMQ and the solvent greatly affected the evaluation of IMQ equilibrium solubility. The attainment of the solid–liquid equilibrium requires 13 days starting from solid IMQ and 2 days from a cooled-down supersaturated IMQ solution. A correlation between IMQ solubility and the solubility parameters of solvents was not found. IMQ solutions in water, ethanol, methanol, acetonitrile, and dimethyl sulfoxide were neither ideal nor regular. The Scatchard–Hildebrand equation does not apply to IMQ solutions because of association phenomena due to intermolecular hydrogen bonds and/or π-stacking, as supported by the hyperchromic effect that was very pronounced in highly polar solvents, such as water, with the increase in temperature. Finally, IMQ solubility values measured in acetone cannot be considered reliable due to the reaction with the solvent, leading to the formation of new molecules.

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Section: Resultsmentioning

confidence: 99%

Imiquimod Solubility in Different Solvents: An Interpretative Approach

Sorgi,

Sartori,

Germani

et al. 2024

Pharmaceutics

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“…Time‐resolved fluorescence decay investigations were performed to investigate and confirm PCAD's interaction with the Pu24T GQ DNA. This lifetime study is sensitive to excited state correlations and offers an accurate indication of a compound's surroundings [17,18] . To analyse PCAD's behaviour in Pu24T GQ DNA conditions, we used the average fluorescence lifetime (τ avg ) rather than individual decay components using tri‐exponential decay data fitting.…”

Section: Resultsmentioning

confidence: 99%

Deciphering Preferential Binding Interaction of Synthetic Pyrido[2,3‐c]Carbazole Alkaloid Derivative (PCAD) with Pu24T G‐quadruplex DNA

Pal,

Bag,

Burman

et al. 2024

ChemistrySelect

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G‐quadruplex DNA (GQ‐DNA) represents one of the most significant non‐canonical nucleic acid configurations. GQ‐DNA producing sequences are found in different important genomic areas, including the promoter islands of numerous oncogenes and human telomere regions. Therefore, GQ‐DNA is a key target for anticancer medicines. GQ‐DNA has a highly variable structure, it is critical to develop ligand molecules that selectively target certain quadruplex sequences. Natural products such as pyridocarbazole alkaloids have grown interest for healthcare and medicinal values and they considered as a valuable source of innovative anticancer medicines among the chemical compounds. In this investigation, we have synthesised and characterized pyrido[2,3‐c]carbazole derivative (PCAD) through NMR and IR spectra and explore the interactions between PCAD and Pu24T GQ (promoter region), h‐TELO GQ (telomere region) and duplex DNA by employing several multi‐spectroscopic analytical techniques. We have found that PCAD preferentially interacts with Pu24T GQ DNA as compared to other DNA sequences. These findings highlights PCAD as an appealing option for targeting the Pu24T promoter region and consequently acting as an anti‐cancer drug. This study also highlights the potential for developing drugs to understand the molecular aspects of GQ DNA recognition and signaling, paving the way for future research on GQ biology.

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