Dielectric constant is an important property which is widely utilized in many scientific fields and characterizes the degree of polarization of substances under the external electric field. In this work, a structure–property relationship of the dielectric constants (ε) for a diverse set of polymers was investigated. A transparent mechanistic model was developed with the application of a machine learning approach that combines genetic algorithm and multiple linear regression analysis, to obtain a mechanistically explainable and transparent model. Based on the evaluation conducted using various validation criteria, four- and eight-variable models were proposed. The best model showed a high predictive performance for training and test sets, with R² values of 0.905 and 0.812, respectively. Obtained statistical performance results and selected descriptors in the best models were analyzed and discussed. With the validation procedures applied, the models were proven to have a good predictive ability and robustness for further applications in polymer permittivity prediction.

In the present study, six known compounds were investigated that were isolated from the aerial parts of plant Dianthus helenae Vved. The structures of these compounds were identified as polypodine B (1), 2,3,20,22-diacetonide-20-hydroxyecdysone (2), 20-hydroxyecdysone (3), cyasterone (4), α-ecdysone (5) and 2-deoxy-α-ecdysone (6). Their structures were confirmed by NMR-, ESI-MS, and IR-spectroscopy. The compounds (5) and (6) are reported for the first time from this species. Furthermore, compounds (2) and (4) were isolated for the first time from the Caryophyllaceae family. In addition, all these phytoecdysteroids were investigated for a nootropic activity. Thus, the total phytoecdysteroids-containing preparation at a dose of 25 mg/kg increases two times the motor activity, an approximate reaction – four times and exploratory behavior − 1.4 times compared to control animals. Graphical Abstract

A number of iridoids and triterpene acids, such as pulchelloside, sesamoside, shanshiside methyl ester, barlerin, gypsogenin acid and acetate of gypsogenic acid were isolated from the aerial part of Phlomis linearifolia and their structures were confirmed by NMR, mass and IR spectroscopy. In addition, the hepatoprotective potential of iridoid fraction from P. linearifolia aerial parts was tested against CCl₄ induced fibrosis in rats. The iridoid fraction not only prevented the manifestation of the hepatotoxic effect of CCl₄, but rather quickly eliminated the effects of developing intoxication. The hepatoprotective activity of the SI was confirmed to be effective and exceeds knows drug carsil. Supplemental data for this article can be accessed at https://doi.org/10.1080/14786419.2019.1677650. Graphical Abstract

This study reports the isolation of iridoids and cycloartane glycosides from the aerial parts of Phlomoides labiosa Bunge. Six compounds were isolated and the chemical structures were identified as phlorigidoside С (1), 8-O-acetylharpagide (2), shanzhiside methyl ester (3), cyclosiversioside A (4), cyclosiversioside E (5), and cyclosiversioside C (6). Compounds 4-6 are reported for the first time in this plant. In addition, anti-inflammatory and analgesic activities of iridoid fraction were studied. The sum of iridoids (SI) with intragastric administration is 5.2 and 52.5 times less toxic, than such market drugs as analgin and diclofenac sodium, respectively. In terms of the latitude of analgesic action (LD50/ED50), the SI exceeds analgin by 19.2 times and diclofenac sodium by 16 times. The anti-inflammatory and analgesic activities of the sum of iridoids were confirmed to be effective and nontoxic, and exceed known drugs diclofenac sodium and analgin (metamizole sodium). Graphical Abstract