Theoretical, Semiempirical, and Experimental Solvatochromic Comparison Methods for the Construction of the α1 Scale of Hydrogen-Bond Donation of Solvents.

Today, the hydrogen bonding donation (HBD) ability parameter of new solvents, α, is generally determined either by the Kamlet-Taft solvatochromic comparison of two probes, Reichardt betaine dye B(30) and 4-nitroanisole, or by the measurement of a single probe (e.g., solvatochromism of an iron coordination complex). This work highlights the shortcomings of these probes and recommends three replacement methods: (a) the theoretical comparison of the experimental and PCM-TD-DFT calculated transition energies ET(30) of B(30), (b) the semiempirical comparison of the experimental and McRae calculated ET(30), and, (c) for ionic liquids, the experimental comparison of ET(30) and ET(33) lying on the lower basicity of the betaine dye B(33) compared to B(30). These methods yield a new HBD parameter, α1, for 101 molecular solvents and 30 ionic liquids. The novelty is emblematic for water, with α1 = 1.54 instead of α (Kamlet-Taft) = 1.17. The solvent parameter α1 is not equivalent to the solute hydrogen-bond acidity parameter α2H, partly because of the self-association of HBD solvents.

Effect of extracts and isolated compounds derived from Retama monosperma (L.) Boiss. on anti-aging gene expression in human keratinocytes and antioxidant activity.

ETHNOPHARMACOLOGICAL RELEVANCE: Moroccan folk medicine treats skin cicatrization with Retama monosperma (L.) Boiss. locally named "Rtem", but the mechanism involved is still not well known. Traditional healers use the plant in small doses as an anthelmintic, disinfectant and an effective abortive. In addition, the cladodes powder mixed with honey is employed as purgative and vermifuge. Equally, the SIRT1 and SIRT3 genes activation and sirtuin proteins expression, which delay cellular senescence, participate in wound healing and skin regeneration especially, SIRT1 the most studied gene, leads to fast skin restoration and cicatrization. AIM OF THE STUDY: In this study, we evaluated the ability of the Retama monosperma (L.)Boiss. flowers and seeds extracts and the isolated compounds in augmenting the SIRT1 and SIRT3 gene expression in HaCaT cells and expressing the antioxidant activity. MATERIALS AND METHODS: We examined for quantitative expression levels of SIRT1 and SIRT3 in HaCaT cell by qRT-PCR and the antioxidant activity by four tests (conjugated diene, TBARS assay, DPPH scavenging activity and H2O2 radical scavenging assay) of diethyl ether extract of flowers (DEF extract) and ethyl acetate extract of seeds (EAS extract) of R. monosperma(L.) Boiss. and the isolated compounds (quercetin, 6-methoxykaempferol, kaempferol and genistein). RESULTS: The screening system by EGFP fluorescence revealed that all samples and resveratrol significantly increase SIRT1 and SIRT3 promoters activities in HaCaT cells with p< 0.05. Furthermore, EAS, quercetin, 6-methoxykaempferol and kaempferol increase significantly (p< 0.05) SIRT1 (3.43, 1.18, 2.62, and 1.72 expression quantity, respectively) and SIRT3 (16.27, 5.01, 3.01, and 6.18 expression quantity, respectively) in HaCaT cells. On the other hand, genistein has a moderate activity on SIRT1 and SIRT3 with 1.43 and 2.04 expression levels. For the antioxidant activity, the EAS and the pure compounds exhibited stronger antioxidant activity than BHT. While DEF and genistein have a moderate antioxidant activity when compared with BHT. CONCLUSIONS: In this study, the expression levels of SIRT1 and SIRT3 in HaCaT cells increase in the presence of extracts of R. monosperma (L.) Boiss. and the pure compounds.

Determination of a solvent hydrogen-bond acidity scale by means of the solvatochromism of pyridinium-N-phenolate betaine dye 30 and PCM-TD-DFT calculations.

Empirical parameters of solvents describing their hydrogen-bond (HB) acidity (e.g., the Kamlet-Taft α parameter) are often difficult to determine for new solvents because they are not directly related to a single definition process. Here, we propose a simple method based on one probe, the betaine dye 30, and one reference process, the solvatochromism of this dye, measured by its first electronic transition energy, ET(30). These ET(30) values are calculated within the time-dependent density functional theory framework, using a polarizable continuum solvent model (PCM). The part of ET(30) values that is not included in the PCM calculation is taken as the HB component of the measured ET(30) values, allowing us to deduce a solvent HB acidity parameter α1. The validity of this simple model is assessed by good linear correlations between α1 and a variety of solute properties mainly depending on the solvent's HB acidity. The quality of fit observed with α1 is at least comparable with that obtained by previous solvent HB acidity scales. The simplicity of our method is illustrated by the determination of α1 and of its companion, the electrostatic solvent parameter ES, for some new green solvents derived from glycerol.