Unreported ent-rosane diterpenes from Croton niveus Jacq. (Euphorbiaceae). Cytotoxic activity and docking studies.

From the bioactive extract of the euphorbiaceous Croton niveus Jacq., three previously unreported ent-rosane diterpenes have been isolated and characterized by conventional methods, in addition to the known compounds lupeol, cajucarinolide and some phytosterols. Two of the ent-rosane diterpenes displayed activity against HCT-15 and PC-3 cancer cell lines, and the results of docking calculations of these compounds with NF-κB and STAT3 receptors agreed with the proposed mode of action of diterpenes against PC-3 cells.

3ß-Palmitoyloxy-olean-12-ene analogs from Sapium lateriflorum (Euphorbiaceae): Their cytotoxic and anti-inflammatory properties and docking studies.

Ten compounds, including a new anti-inflammatory acyl triterpene, 3ß-palmitoyloxy-1ß,11α-dihydroxy-olean-12-ene, were isolated from the bioactive organic extract prepared from the leaves of Sapium lateriflorum (syn: S. nitidum). The isolated compounds were screened for their cytotoxic activity against selected human cancer cell lines and did not display significant activity. They were also evaluated as anti-inflammatory agents in mouse models (TPA-induced edema in the ear and in a carrageenan-induced paw edema model). The results indicated that the new compound, 3ß-palmitoyloxy-1ß,11α-dihydroxy-olean-12-ene, was the compound with major anti-inflammatory activity similar to that of indomethacin, being the hydroxyl at C-11 important for the observed activity. The results of docking studies of the 3ß-palmitoyloxy esters of olean-12-ene with NF-κB and with COX-2 receptors were consistent with possible molecular mechanisms of the anti-inflammatory activity.

Ovine oocytes display a similar germinal vesicle configuration and global DNA methylation at prepubertal and adult ages.

Epigenetic mechanisms are thought to be involved in the reduced developmental capacity of early prepubertal ewe oocytes compared to their adult counterparts. In this study, we have analyzed the global DNA methylation pattern and in vitro meiotic and developmental competence of oocytes at the germinal vesicle (GV) stage obtained from adult and 3-month-old donors. All oocytes were aspirated from antral follicles with a diameter ≥3 mm, and DNA methylation on 5-methylcytosine was detected by immunofluorescence using an anti-methyl cytosine antibody. The main global chromatin configuration pattern shown by both prepubertal and adult ovine oocytes corresponded to condensed chromatin localized close to the nuclear envelope (the SNE pattern). Immunofluorescence showed that a global bright nuclear staining of 5-methylcytosine (5-mC) occurred in all germinal vesicle stage oocytes and matched the propidium iodide staining pattern. The total fluorescence intensity values of lamb GVs were not lower than those observed in adult GVs. The meiotic competence and cleavage rates were similar in adult and prepubertal oocytes, however, the developmental competence of embryos to reach blastocysts was higher for adult oocytes than lamb oocytes (p<0.0001). In conclusion, our results indicate that adult-size oocytes derived from 3 to 4 month old prepubertal ewes show similar GV morphology and DNA methylation staining patterns to those obtained from adult animals, despite exhibiting a lower developmental competence.

Genetic analysis reveals a complex regulatory network modulating CBF gene expression and Arabidopsis response to abiotic stress.

Arabidopsis CBF genes (CBF1-CBF3) encode transcription factors having a major role in cold acclimation, the adaptive process whereby certain plants increase their freezing tolerance in response to low non-freezing temperatures. Under these conditions, the CBF genes are induced and their corresponding proteins stimulate the expression of target genes configuring low-temperature transcriptome and conditioning Arabidopsis freezing tolerance. CBF2 seems to be the most determinant of the CBFs since it also regulates CBF1 and CBF3 expression. Despite the relevance of CBF genes in cold acclimation, little is known about the molecular components that control their expression. To uncover factors acting upstream of CBF2, mutagenized Arabidopsis containing the luciferase reporter gene under the control of the CBF2 promoter were screened for plants with de-regulated CBF2 expression. Here, the identification and characterization of five of these mutants, named acex (altered CBF2 expression), is presented. Three mutants show increased levels of cold-induced CBF2 transcripts compared with wild-type plants, the other two exhibiting reduced levels. Some mutants are also affected in cold induction of CBF1 and CBF3. Furthermore, the mutants characterized display unique phenotypes for tolerance to abiotic stresses, including freezing, dehydration, and high salt. These results demonstrate that cold induction of CBF2 is subjected to both positive and negative regulation through different signal transduction pathways, some of them also mediating the expression of other CBF genes as well as Arabidopsis responses to abiotic stresses.

Antioxidant aryl-prenylcoumarin, flavan-3-ols and flavonoids from Eysenhardtia subcoriacea.

Antioxidant activity (AOA) assay-guided chemical analysis, using a rat pancreas homogenate model, of aerial parts from Eysenhardtia subcoriacea, led to isolation of the new compound subcoriacin (3-(2'-hydroxy-4',5'-methylendioxyphenyl)-6-(3''-hydroxymethyl-4''-hydroxybut-2''-enyl)-7-hydroxycoumarin) together with the known substances: (+)-catechin, (-)-epicatechin, (+)-afzelechin, eriodictyol, (+)-catechin 3-O-beta-D-galactopyranoside and quercetin 3-O-beta-D-galactopyranoside as bioactive constituents. The structure of the compound was determined from 1D and 2D NMR spectroscopic analyses. Additional known constituents were characterized. The bioactive compounds showed also moderate to strong radical scavenging properties against diphenylpicrylhydrazyl radical (DPPH). In addition, subcoriacin, (+)-catechin, (-)-epicatechin and (+)-afzelechin improved the reduced glutathione levels in rat pancreatic homogenate.

Arabidopsis CBF1 and CBF3 have a different function than CBF2 in cold acclimation and define different gene classes in the CBF regulon.

The C-repeat-binding factor (CBF)/dehydration-responsive element-binding factor (DREB1) proteins constitute a small family of Arabidopsis transcriptional activators (CBF1/DREB1B, CBF2/DREB1C, and CBF3/DREB1A) that play a prominent role in cold acclimation. A fundamental question about these factors that remains to be answered is whether they are functionally equivalent. Recently, we reported that CBF2 negatively regulates CBF1 and CBF3 expression, and that CBFs are subjected to different temporal regulation during cold acclimation, which suggested this might not be the case. In this study, we have analyzed the expression of CBF genes in different tissues of Arabidopsis, during development and in response to low temperature, and characterized RNA interference (RNAi) and antisense lines that fail to accumulate CBF1 or/and CBF3 mRNAs under cold conditions. We found that CBF1 and CBF3 are regulated in a different way than CBF2. Moreover, in contrast to CBF2, CBF1 and CBF3 are not involved in regulating other CBF genes and positively regulate cold acclimation by activating the same subset of CBF-target genes. All these results demonstrate that CBF1 and CBF3 have different functions than CBF2. We also found that the CBF regulon is composed of at least two different kind of genes, one of them requiring the simultaneous expression of both CBF1 and CBF3 to be properly induced. This indicates that CBF1 and CBF3 have a concerted additive effect to induce the whole CBF regulon and the complete development of cold acclimation.

CBF2/DREB1C is a negative regulator of CBF1/DREB1B and CBF3/DREB1A expression and plays a central role in stress tolerance in Arabidopsis.

CBF/DREB1 (C-repeat-binding factor/dehydration responsive element-binding factor 1) genes encode a small family of transcriptional activators that have been described as playing an important role in freezing tolerance and cold acclimation in Arabidopsis. To specify this role, we used a reverse genetic approach and identified a mutant, cbf2, in which the CBF2/DREB1C gene was disrupted. Here, we show that cbf2 plants have higher capacity to tolerate freezing than WT ones before and after cold acclimation and are more tolerant to dehydration and salt stress. All these phenotypes correlate with a stronger and more sustained expression of CBF/DREB1-regulated genes, which results from an increased expression of CBF1/DREB1B and CBF3/DREB1A in the mutant. In addition, we show that the expression of CBF1/DREB1B and CBF3/DREB1A in response to low temperature precedes that of CBF2/DREB1C. These results indicate that CBF2/DREB1C negatively regulates CBF1/DREB1B and CBF3/DREB1A, ensuring that their expression is transient and tightly controlled, which, in turn, guarantees the proper induction of downstream genes and the accurate development of Arabidopsis tolerance to freezing and related stresses.