[en] Solubilities of L-cystine, L-tyrosine, and L-leucine in aqueous NaCl media at 298.15 K have been studied. Indispensable and related solvent parameters such as molar mass, molar volume, etc., were also determined. The results are used to evaluate the standard transfer Gibbs free energy, cavity forming enthalpy of transfer, cavity forming transfer Gibbs free energy and dipole-dipole interaction effects during the course of solvation. Various weak interactions involving solute–solvent or solvent–solvent molecules were characterized in order to find their role on the solvation of these amino acids.

[en] Radiation-induced double-strand modification of DNA was studied in the absence and presence of sodium 1,4-dihydroxy-9,10-anthraquinone-2-sulfonate (NaQSH₂) and its metal (Cu²⁺ and Ni²⁺) complexes in aerated, de-aerated (Argon saturated) and N₂O saturated aqueous media at pH 7.4. Ethidium bromide, an established DNA intercalator was used to estimate DNA remaining after interaction with γ-radiation, by measuring loss of fluorescence of the ethidium bromide–DNA adduct. In de-aerated (Argon saturated) and N₂O saturated aqueous media radiation-induced double-strand modification of calf thymus DNA was comparatively less in presence of NaQSH₂ and its Ni(II) complex than standard control indicating the compounds behaved as radio-protectors. However, in presence of the Cu(II) complex radiation-induced double-strand modification increased significantly. In N₂O saturated medium, double-strand modification of DNA was almost double in all cases than that observed in de-aerated (Argon saturated) medium indicating ^·OH radicals played a major role in modifying DNA. That ·OH radicals were important was verified by repeating experiments using tertiary-butanol that showed significant decrease in DNA modification. Another important observation was in aerated medium NaQSH₂, Ni(II)–NaQSH₂ did not show radioprotection while Cu(II)–NaQSH₂ was an almost equally effective radiosensitizer as that observed in N₂O saturated medium. Role of molecular oxygen as radiosensitizer was thus realized. - Highlights: • γ-radiation induced DNA modification was studied by ethidium bromide fluorescence. • In de-aerated and N₂O saturated medium NaQSH₂ and Ni(II)–NaQSH₂ were radioprotectors. • Cu(II)–NaQSH₂ showed radiosensitization that was attributed to Fenton reactions. • In aerated medium, NaQSH₂ and complexes showed radiosensitization through participation of molecular oxygen. • ·OH had the major role in double strand modification of DNA

[en] Highlights: • Solubility of l-isoleucine and l-serine at aqueous electrolytes solutions was measured from 288.15 to 308.15 K. • The standard transfer Gibbs free energies, enthalpy, entropy of l-isoleucine and l-serine were measured. • The chemical transfer free energies and entropies of l-isoleucine and l-serine were computed. • The stability of l-isoleucine and l-serine in aquo-electrolytes was explained. The solubilities of l-isoleucine and l-serine in aqueous sodium sulfate (Na₂SO₄) and potassium sulfate (K₂SO₄) from 298.15 to 308.15 K are presented. The solubilities are measured by ‘gravimetric’ method. The relative solubility of the amino acids is calculated to explain the salting-in and salting-out effect in the electrolytes solutions. The amino acids solvation thermodynamical parameters are computed. The chemical effects of the transfer Gibbs energies for both the amino acids are estimated by subtracting the cavity effect and dipole-dipole interaction effect from the total transfer energies. The chemical transfer energetics is employed to discuss solute-solvent and solvent-solvent interactions.