Quinazolinecarboline alkaloid evodiamine as scaffold for targeting topoisomerase I and sirtuins

This paper reports the synthesis of a series of evodiamine derivatives. We assayed the ability to inhibit cell growth on three human tumour cell lines (H460, MCF-7 and HepG2) and we evaluated the capacity to interfere with the catalytic activity of topoisomerase I both by the relaxation assay and the occurrence of the cleavable complex. Moreover, whose effect on sirtuins 1, 2 and 3 was investigated. Finally, molecular docking analyses were performed in an attempt to rationalize the biological results.     

A systematic study of the polyphenolic composition of aqueous extracts deriving from several Cistus genus species: evolutionary relationship

Introduction – Cistaceae is a large family of shrubs widely spread over the Mediterranean area. It includes Helianthemum, Halimium and Cistus genus. Cistus genus contains approximately 20 species distributed in three subgenus. The essential oil of Cistus species has been thoroughly studied, but the polyphenolic composition of the aerial parts of the different Cistus species needs further characterisation. Objective – To perform a comparative analysis of the qualitative and quantitative polyphenolic composition of the aerial parts of the most commonly distributed Spanish Cistus species in order to find a relationship between chemotype and subgenus. Methodology – Thirteen aqueous extracts derived from 10 different Cistus species were analysed by using HPLC with diode array‐detection coupled to electrospray ion trap mass spectrometry technique (HPLC‐DAD‐ESI‐MS/MS). Their major compounds were identified and ellagitannins were quantified. Principal component analysis (PCA) was performed on the most relevant compounds to find out the statistical association between chemotype and variety. Results – Three main groups of compounds were found, i.e. ellagitannins, flavonoids and phenolic acids derivatives. The polyphenolic profile was specific for each species, although the abundance of some compounds also varied depending on the soil type. Whereas C. ladanifer, C. salviifolius, C. populifolius and C. libanotis were specially rich in ellagitannins, C. clusii, C. laurifolius and C. monspeliensis contained significant amounts of flavonoids and much less ellagitannins. In contrast, C. crispus, C. incanus and C. albidus showed a polyphenolic profile mostly based on flavonoids. PCA analysis showed a strong relationship between Cistus subgenus and its chemotype based on the most relevant water‐soluble polyphenolic compounds. Conclusions – Chemical composition of the leaves' aqueous extracts from plants belonging to the Cistus genus is strongly related to their subgenus, in agreement to previous taxonomical and phylogenetic divisions. In contrast, soil and climate are less influencing factors. Leucocistus and Halimioides subgenus showed a higher content in ellagitannins. However, Cistus subgenus had higher flavonoid content. Copyright © 2011 John Wiley & Sons, Ltd.     

The Shc family protein adaptor, Rai, negatively regulates T cell antigen receptor signaling by inhibiting ZAP-70 recruitment and activation

Rai/ShcC is a member of the Shc family of protein adaptors expressed with the highest abundance in the central nervous system, where it exerts a protective function by coupling neurotrophic receptors to the PI3K/Akt survival pathway. Rai is also expressed, albeit at lower levels, in other cell types, including T and B lymphocytes. We have previously reported that in these cells Rai attenuates antigen receptor signaling, thereby impairing not only cell proliferation but also, opposite to neurons, cell survival. Here we have addressed the mechanism underlying the inhibitory activity of Rai on TCR signaling. We show that Rai interferes with the TCR signaling cascade one of the earliest steps--recruitment of the initiating kinase ZAP-70 to the phosphorylated subunit of the TCR/CD3 complex, which results in a generalized dampening of the downstream signaling events. The inhibitory activity of Rai is associated to its inducible recruitment to phosphorylated CD3, which occurs in the physiological signaling context of the immune synapse. Rai is moreover found as a pre-assembled complex with ZAP-70 and also constitutively interacts with the regulatory p85 subunit of PI3K, similar to neuronal cells, notwithstanding the opposite biological outcome, i.e. impairment of PI-3K/Akt activation. The data highlight the ability of Rai to establish interactions with the TCR and key signaling mediators which, either directly (e.g. by inhibiting ZAP-70 recruitment to the TCR or sequestering ZAP-70/PI3K in the cytosol) or indirectly (e.g. by promoting the recruitment of effectors responsible for signal extinction) prevent full triggering of the TCR signaling cascade.     

Predictors of ectopic fat accumulation in liver and pancreas in obese men and women

The aim of the present study was to determine the relationship between body fat distribution, adipocytokines, inflammatory markers, fat intake and ectopic fat content of liver and pancreas in obese men and women. A total of 12 lean subjects (mean age 47.25 ± 14.88 years and mean BMI 22.85 ± 2), 38 obese subjects (18 men and 20 women) with mean age 49.1 ± 13.0 years and mean BMI 34.96 ± 4.21 kg/m2 were studied. Measurements: weight, height, BMI, waist circumference, as well as glucose, insulin, HOMA (homeostasis model assessment of insulin resistance), cholesterol, triglycerides, high-density lipoprotein cholesterol, high sensitivity C-reactive protein, daily energy intake, leptin, and adiponectin. Magnetic resonance was used to evaluate visceral, subcutaneous adipose tissue (SCAT) as well as liver and pancreas lipid content using in-phase and out-of-phase magnetic resonance imaging (MRI) sequence. Obese subjects had significantly higher weight, waist circumference, SCAT, deep SCAT, visceral adipose tissue (VAT), liver and pancreatic lipid content than lean subjects. Obese women had significantly lower VAT, liver and pancreas lipid content regardless of same BMI. In multiple regression analyses, the variance of liver lipid content explained by gender and VAT was 46%. When HOMA was added into a multiple regression, a small increase in the proportion of variance explained was observed. A 59.2% of the variance of pancreas lipid content was explained by gender and VAT. In conclusion, obese men show higher VAT and ectopic fat deposition in liver and pancreas than obese women despite same BMI. Independent of overall adiposity, insulin resistance, adiponectin and fat intake, VAT, measured with MRI, is the main predictor of ectopic fat deposition in both liver and pancreas.     

Synergism of plant-derived polyphenols in adipogenesis: perspectives and implications

Dietary polyphenols may exert their pharmacological effect via synergistic interactions with multiple targets. Putative effects of polyphenols in the management of obesity should be primarily evaluated in adipose tissue and consequently in well-documented cell model. We used Hibiscus sabdariffa (HS), a widely recognised medicinal plant, as a source of polyphenols with a number of salutary effects previously reported. We present here the full characterisation of bioactive components of HS aqueous extracts and document their effects in a model of adipogenesis from 3T3-L1 cells and in hypertrophic and insulin-resistant adipocytes. Aqueous extracts were up to 100 times more efficient in inhibiting triglyceride accumulation when devoid of fibre and polysaccharides. Significant differences were also observed in reactive oxygen species generation and adipokine secretion. We also found that, when polyphenols were fractionated and isolated, the benefits of the whole extract were greater than the sum of its parts, which indicated a previously unnoticed synergism. In conclusion, polyphenols have interactive and complementary effects, which suggest a possible application in the management of complex diseases and efforts to isolate individual components might be irrelevant for clinical medicine and/or human nutrition.     

p300/CBP acetyl transferases interact with and acetylate the nucleotide excision repair factor XPG

Nucleotide excision repair (NER) is an important DNA repair mechanism through which cells remove bulky DNA lesions. Following DNA damage, the histone acetyltransferase (HAT) p300 (also referred to as lysine acetyltransferase or KAT) is known to associate with proliferating cell nuclear antigen (PCNA), a master regulator of DNA replication and repair processes. This interaction, which results in HAT inhibition, may be dissociated by the cell cycle inhibitor p21^CDKN1A, thereby restoring p300 activity; however, the role of this protein interplay is still unclear. Here, we report that silencing p300 or its homolog CREB-binding protein (CBP) by RNA interference (RNAi) significantly reduces DNA repair synthesis in human fibroblasts. In addition, we determined whether p300 and CBP may associate with and acetylate specific NER factors such as XPG, the 3′-endonuclease that is involved in the incision/excision step and is known to interact with PCNA. Our results show that p300 and CBP interact with XPG, which has been found to be acetylated in vivo. XPG is acetylated by p300 in vitro, and this reaction is inhibited by PCNA. Knocking down both p300/CBP by RNAi or by chemical inhibition with curcumin greatly reduced XPG acetylation, and a concomitant accumulation of the protein at DNA damage sites was observed. The ability of p21 to bind PCNA was found to regulate the interaction between p300 and XPG, and an abnormal accumulation of XPG at DNA damage sites was also found in p21^−/− fibroblasts. These results indicate an additional function of p300/CBP in NER through the acetylation of XPG protein in a PCNA–p21 dependent manner.     

Effect of humic acids from Leonardite on the stability of soil aggregates and melon roots under greenhouse conditions

Leonardite is an oxidized form of lignite carbon, which is obtained from fossilized organic materials. Such materials are used for the extraction of humic acids (HA). The result of the addition of HA of organic origin on soil structure is known; however, the effects of adding HA of Leonardite on soil structure have been scarcely investigated. The objectives of this research were (1) to determine the influence of humic acids derived from Leonardite in increasing the aggregate stability of an Aridisol under greenhouse conditions, and (2) evaluate the morphology of the root xylem during the phenological development of melon plants (Cucumis melo L.). Three treatments of HA solution application to the soil were used: soil without solution application (HA0), and application of HA solution to the soil with pH 6 (HA6) or (HA7). Aggregate stability (As) and bulk density (Da) were evaluated as soil variables. Development and quantification of xylem area were studied on plants. There were significant differences in aggregate stability. Also, there was an increase in the root xylem area, and the best treatment was when AH7 solution was applied. Humic acids derived from Leonardite increased the stability of soil aggregates when plants grew under greenhouse conditions, and fostered the development of xylem conduits during the fruiting stage.