Winter plants acclimate to frost mainly during the autumn months, through the process of cold acclimation. Global climate change is causing changes in weather patterns such as the occurrence of warmer periods during late autumn or in winter. An increase in temperature after cold acclimation can decrease frost tolerance, which is particularly dangerous for winter crops. The aim of this study was to investigate the role of brassinosteroids (BRs) and BR analogues as protective agents against the negative results of deacclimation. Plants were cold-acclimated (3 weeks, 4 °C) and deacclimated (1 week, 16/9 °C d/n). Deacclimation generally reversed the cold-induced changes in the level of the putative brassinosteroid receptor protein (BRI1), the expression of BR-induced COR, and the expression of SERK1, which is involved in BR signal transduction. The deacclimation-induced decrease in frost tolerance in oilseed rape could to some extent be limited by applying steroid regulators. The deacclimation in plants could be detected using non-invasive measurements such as leaf reflectance, chlorophyll a fluorescence, and gas exchange monitoring.

• Keywords
• 24-epibrassinolide, 28-homocastasterone, BRI1, CO2 assimilation, COR, SERK, brassinosteroid analogues, chlorophyll a fluorescence, frost tolerance, leaf reflectance,
• MeSH
• Acclimatization * MeSH
• Brassica napus * physiology   metabolism   MeSH
• Brassinosteroids * metabolism   MeSH
• Plant Leaves metabolism   physiology   MeSH
• Cold Temperature * MeSH
• Gene Expression Regulation, Plant * MeSH
• Seasons MeSH
• Plant Proteins metabolism   MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Brassinosteroids * MeSH
• Plant Proteins MeSH

A series of novel acridine N-acylhydrazone derivatives have been synthesized as potential topoisomerase I/II inhibitors, and their binding (calf thymus DNA—ctDNA and human serum albumin—HSA) and biological activities as potential anticancer agents on proliferation of A549 and CCD-18Co have been evaluated. The acridine-DNA complex 3b (-F) displayed the highest Kb value (Kb = 3.18 × 103 M−1). The HSA-derivatives interactions were studied by fluorescence quenching spectra. This method was used for the calculation of characteristic binding parameters. In the presence of warfarin, the binding constant values were found to decrease (KSV = 2.26 M−1, Kb = 2.54 M−1), suggesting that derivative 3a could bind to HSA at Sudlow site I. The effect of tested derivatives on metabolic activity of A549 cells evaluated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide or MTT assay decreased as follows 3b(-F) > 3a(-H) > 3c(-Cl) > 3d(-Br). The derivatives 3c and 3d in vitro act as potential dual inhibitors of hTopo I and II with a partial effect on the metabolic activity of cancer cells A594. The acridine-benzohydrazides 3a and 3c reduced the clonogenic ability of A549 cells by 72% or 74%, respectively. The general results of the study suggest that the novel compounds show potential for future development as anticancer agents.

• Keywords
• HSA binding, acridine, benzohydrazide, ctDNA, spectroscopic study,
• MeSH
• Acridines chemistry   MeSH
• Topoisomerase II Inhibitors pharmacology   MeSH
• Intercalating Agents MeSH
• Humans MeSH
• Serum Albumin, Human chemistry   MeSH
• Antineoplastic Agents * chemistry   MeSH
• Binding Sites MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Acridines MeSH
• Topoisomerase II Inhibitors MeSH
• Intercalating Agents MeSH
• Serum Albumin, Human MeSH
• Antineoplastic Agents * MeSH

The metabolism of brassinosteroid leads to structural modifications in the ring skeleton or the side alkyl chain. The esterification and glycosylation at C-3 are the most common metabolic pathways, and it has been suggested that conjugate brassinosteroids are less active or inactive. In this way, plants regulate the content of active brassinosteroids. In this work, the synthesis of brassinosteroid 24-norcholane type analogs conjugated at C-3 with benzoate groups, carrying electron donor and electron attractant substituents on the aromatic ring, is described. Additionally, their growth-promoting activities were evaluated using the Rice Lamina Inclination Test (RLIT) and compared with that exhibited by brassinolide (used as positive control) and non-conjugated analogs. The results indicate that at the lowest tested concentrations (10-8-10-7 M), all analogs conjugated at C-3 exhibit similar or higher activities than brassinolide, and the diasteroisomers with S configuration at C-22 are the more active ones. Increasing concentration (10-6 M) reduces the biological activities of analogs as compared to brassinolide.

• Keywords
• 24-norcholane, Rice Lamina Inclination Test, analogs, benzoate esters, brassinosteroids, conjugated in C-3, synthesis,
• MeSH
• Benzoates chemistry   pharmacology   MeSH
• Brassinosteroids chemical synthesis   chemistry   pharmacology   MeSH
• Molecular Conformation MeSH
• Plant Growth Regulators chemical synthesis   chemistry   pharmacology   MeSH
• Oryza drug effects   metabolism   MeSH
• Stereoisomerism MeSH
• Dose-Response Relationship, Drug MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Benzoates MeSH
• Brassinosteroids MeSH
• Plant Growth Regulators MeSH

Brassinosteroids are a class of plant hormones that regulate a broad range of physiological processes such as plant growth, development and immunity, including the suppression of biotic and abiotic stresses. In this paper, we report the synthesis of new brassinosteroid analogues with a nitrogen-containing side chain and their biological activity on Arabidopis thaliana. Based on molecular docking experiments, two groups of brassinosteroid analogues were prepared with short and long side chains in order to study the impact of side chain length on plants. The derivatives with a short side chain were prepared with amide, amine and ammonium functional groups. The derivatives with a long side chain were synthesized using amide and ammonium functional groups. A total of 25 new brassinosteroid analogues were prepared. All 25 compounds were tested in an Arabidopsis root sensitivity bioassay and cytotoxicity screening. The synthesized substances showed no significant inhibitory activity compared to natural 24-epibrassinolide. In contrast, in low concentration, several compounds (8a, 8b, 8e, 16e, 22a and 22e) showed interesting growth-promoting activity. The cytotoxicity assay showed no toxicity of the prepared compounds on cancer and normal cell lines.

• Keywords
• brassinosteroid, cytotoxicity, nitrogen-containing steroid, organic synthesis, plant bioassay,
• MeSH
• Arabidopsis drug effects   growth & development   MeSH
• Brassinosteroids chemical synthesis   chemistry   pharmacology   MeSH
• Nitrogen chemistry   MeSH
• Molecular Structure MeSH
• Chemistry Techniques, Synthetic * MeSH
• Plant Development drug effects   MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Brassinosteroids MeSH
• Nitrogen MeSH