Solubility of Adenine and Kinetin in Water–Ethanol Solutions

Magic-angle spinning NMR spectroscopy provides insight into the impact of small molecule uptake by G-quartet hydrogels

“…Such minute quantities of DMSO likely do not disrupt the hydrogen bonding networks in hydrogels, yet the gel stability is maintained as confirmed by a vial inversion test. The enhanced adenine solubility in GB gels could be related to several mechanisms and hypotheses proposed in the previous studies; for example, alcohol/water or glycol/water binary mixtures enhance the adenine solubility, 62,64 the presence of an amino acid additive such as arginine improves the solubility of adenine in water, 63 and also the presence of dideoxynucleosides augments adenine solubility in water. 75 In particular, it has been hypothesized that the hydrogen bonding interactions between polar OH groups associated with alcohols and adenine moieties dominate as compared to the base stacking of these latter molecules.…”

“…To explore the uptake of neutral guest molecules, we next studied the incorporation of nucleosides into G4ÁM + borate gels. Indeed, nucleobases such as adenine and closely related heterocycles with antiviral action show relatively poor solubility in water (B7 mM) and water/additive binary solutions (B20 mM adenine in the presence of 1 M arginine as an additive), [62][63][64] which poses a challenge for their therapeutic applications. It has been reported that added sugars including ribose 65 and especially galactose and lactose 66 can enhance the solubility of adenine in water by using CH-p interactions 67 that disrupt the base stacking processes that lead to adenine aggregation.…”

“…To examine the nucleobase solubility in GB gels, we employed adenine concentrations over 30 mM, which is well beyond the limit of its solubility in water (B7 mM). [62][63][64] While 32 mM adenine precipitates in H 2 O (Fig. 4, inset photograph), the same concentration of adenine added to a 72 mM G4ÁK + a Errors on the P Q and d CS iso (ppm) are estimated as AE0.01 MHz and 0.1 ppm, respectively.…”

“…75 In particular, it has been hypothesized that the hydrogen bonding interactions between polar OH groups associated with alcohols and adenine moieties dominate as compared to the base stacking of these latter molecules. 62,64 While such noncovalent interactions are anticipated to be relevant in GB gels, the roles of enhanced polarity of the solution phase (due to the borate buffer) of GB gels in enhancing the adenine solubility cannot be ruled out.…”

Structure of N 6-furfurylaminopurine (kinetin) dihydrogenphosphate

“…In order to obtain crystals of kinetin dihydrogenphosphate we prepared a water suspension of kinetin since the solubility of this compound in pure water is very low (Krzaczkowska et al, 2004). Excess orthophosphoric acid was then added (molar ratio of kinetin-to-dihydrogenphosphate ca 1:5), which strongly increased the solubility of kinetin.…”