A novel bioresponsive self-immolative spacer based on aza-quinone methide reactivity for the controlled release of thiols, phenols, amines, sulfonamides or amides

A stimuli-sensitive linker is one of the indispensable components of prodrugs for cancer therapy as it covalently binds the drug and releases it upon external stimulation at the tumour site. Quinone methide elimination has been widely used as the key transformation to release drugs based on their nucleofugacity. The usual approach is to bind the drug to the linker as a carbamate and release it as a free amine after a self-immolative 1,6-elimination. Although this approach is very efficient, it is limited to amines (as carbamates), alcohols or phenols (as carbonates) or other acidic functional groups. We report here a self-immolative spacer capable of directly linking and releasing amines, phenols, thiols, sulfonamides and carboxyamides after a reductive stimulus. The spacer is based on the structure of (5-nitro-2-pyrrolyl)methanol (NPYM-OH), which was used for the direct alkylation of the functional groups mentioned above. The spacer is metabolically stable and has three indispensable sites for bioconjugation: the bioresponsive trigger, the conjugated 1,6 self-immolative system and a third arm suitable for conjugation with a carrier or other modifiers. Release was achieved by selective reduction of the nitro group over Fe/Pd nanoparticles (NPs) in a micellar aqueous environment (H2O/TPGS-750-M), or by NADH mediated nitroreductase activation. A DFT study demonstrates that, during the 1,6 elimination, the transition state formed from 5-aminopyrrole has a lower activation energy compared to other 5-membered heterocycles or p-aminobenzyl derivatives. The NPYM scaffold was validated by late-stage functionalisation of approved drugs such as celecoxib, colchicine, vorinostat or ciprofloxacin. A hypoxia-activated NPYM-based prodrug (HAP) derived from HDAC inhibitor ST7612AA1 was also produced, which was active in cancer cells under hypoxic conditions.

Blood biomonitoring of metals in subjects living near abandoned mining and active industrial areas

A human blood biomonitoring campaign to detect the environmental exposure to metals (Cd, Cu, Cr, Mn, Pb and Zn) in 265 subjects was performed in the South-Western part of Sardinia (an Italian island) that is a particular area with a great history of coal and metal mining (Pb/Zn mainly) activities and large industrial structures (as metallurgy). Subjects living near the industrial plant area had geometric means (GM) of blood Cd (0.79 μg/l), Cu (971 μg/l), Mn (12.2 μg/l), and Pb (55.7 μg/l) significantly higher than controls (Cd, 0.47 μg/l; Cu, 900 μg/l; Mn 9.98 μg/l; Pb, 26.5 μg/l) and than people living nearby the past mining sites. Subjects living next to one dismissed mine were statistically higher in blood Cu (GM, 1,022 μg/l) and Pb (GM, 41.4 μg/l) concentrations than controls. No differences were observed in people living in the different mining sites, and this might be related to the decennial disclosure of mines and the adoption of environmental remediation programmes. Some interindividual variables influenced blood biomonitoring data, as smoke and age for Cd, gender for Cu, age, sex and alcohol for Pb, and age for Zn. Moreover, blood metal levels of the whole population were similar to reference values representative of the Sardinian population and acceptably safe according to currently available health guidelines.

Assessment of reference ranges for blood Cu, Mn, Se and Zn in a selected Italian population

The reference ranges for blood Cu, Mn, Se and Zn of 215 adult subjects non-occupationally exposed and living in the Nuoro province (Sardinia, insular Italy) were assessed. Metals were determined by sector field inductively coupled plasma mass spectrometry after microwave-assisted acid digestion of blood. The blood reference ranges estimated as P5-P95 percentiles (geometric mean, GM) were 776-1495μg/L (1036μg/L) for Cu; 4.73-17.0μg/L (8.91μg/L) for Mn; 106-185μg/L (140μg/L) for Se and 4686-8585μg/L (6418μg/L) for Zn. These results were then stratified for sex, age, alcohol consumption, smoking habit and living area. The GM value of Cu was significantly higher in females (1127μg/L) than in males (957μg/L). Age, alcohol intake, smoking habit and residential area did not influence blood Cu. The GM of Mn was significantly higher in females (9.98μg/L) respect to males (8.01μg/L) and in drinkers (9.67μg/L) compared to non-drinkers (8.38μg/L). The other variables did not change the Mn data. Selenium concentrations did not differ significantly as a function of individuals factors. With reference to Zn, males had GM of 6804μg/L and females of 6031μg/L, and more blood Zn was found in subjects consuming alcohol (6618μg/L) respect to abstainers (6155μg/L). In addition, blood Zn was not affected by age, smoking habit and place of living.

Low cadmium concentration in whole blood from residents of northern Sardinia (Italy) with special reference to smoking habits

INTRODUCTION

The present study was initiated to investigate the cadmium concentrations in whole blood of Northern Sardinian, non-occupationally exposed adult subjects. Sardinia is a large Italian island which differs genetically and environmentally from other mainland Italian areas.

METHODS

Two hundred and forty-three adults (157 females and 86 males) were selected in the study area from subjects who were undergoing blood collection for laboratory analysis during the period January 2005-May 2005. Whole blood was analysed by graphite furnace atomic absorption spectrometer equipped with a Zeeman-effect background corrector (Perkin Elmer ZLS5100) and an auto sampler. The adopted analytical procedure uses the Stabilized Platform Temperature Furnace (STPF) technique.

RESULTS

The mean value of Blood Cadmium Concentration (BCdC), expressed as Geometric Mean, was 0.32 pg/l (CI 95%: 0.31-0.34 l) in non-smokers to 034 pg/l (CI 95%: 0.30-0.39 pg/l) in ex-smokers up to 0.47 gg/ll(CI 95%: 0.42-0.53 pg/l) in smokers (p < 0.0001).

DISCUSSION

The results show that BCdC levels in Northern Sardinian non-occupationally exposed adults are lower than levels found in many other regions, including those within Italy. Nevertheless, similar values have been detected in other European countries and cities.

CONCLUSIONS

In relation to other reports in which data were analysed by strata for smoking habit and age, we found similar BCdC values among non smokers. However, Sardinian smokers seem to show lower levels of blood cadmium.

Hypericum perforatumSubspeciesAngustifoliumshows a Protective Activity on the Consequences of Unavoidable Stress Exposure at Lower Doses thanHypericum perforatum Perforatum

Clinical studies have demonstrated that the antidepressant efficacy of Hypericum perforatum extract is comparable to that of classic antidepressants, such as imipramine. The role played by its components, particularly hypericin and hyperforin, has been examined in different experimental models of depression. The present study was carried out in order to verify the hypothesis that hyperforin is the main active antidepressant component. For this purpose we evaluated the activity of a dry extract from a subspecies of H. perforatum, H. perforatum spp. angustifolium, which has a higher hyperforin content than H. perforatum perforatum, in a series of experimental models of depression. The models used are based on the development of hyporeactivity to aversive stimuli induced by unavoidable stress exposure in rats. The extract of H. perforatum angustifolium presented an efficacy that was similar to that obtained with a treatment with imipramine or H. perforatum perforatum. Furthermore, in the models used the H. perforatum angustifolium extract was active at doses eight times lower than those necessary to produce a comparable activity with H. perforatum extract.

Dopamine output in the nucleus accumbens shell is related to the acquisition and the retention of a motivated appetitive behavior in rats

Chronic stress exposure consistently impairs the reactivity to aversive and pleasurable stimuli in rats; these behavioral modifications are associated with a decrease in dopamine output in the nucleus accumbens shell (NAcS). However, when rats that have already acquired an appetitive behavior are exposed to chronic stress, they develop an impaired reactivity to avoidable aversive stimuli while retaining the appetitive behavior. The dissociation between these two behavioral traits was used to study whether the decreased dopaminergic activity in the NAcS was connected to either of the two deficits. Dopamine output was studied through microdialysis as dopamine accumulation following re-uptake inhibition by cocaine. When rats that had previously acquired the appetitive behavior were exposed to chronic stress, they showed a dopaminergic transmission in the NAcS similar to that of controls and significantly higher than that of chronically stressed animals. Thus, dopamine output in the NAcS was consistently associated to the acquisition and maintenance of appetitive behavior, while the expression of a deficit in avoidance appeared to be independent of it.

Animal models for the study of antidepressant activity

Three behavioral paradigms are presented for the study of the mechanism of action of antidepressant treatments and for the screening of new antidepressant drugs. The first model (acute escape deficit) exploits the decreased ability of a rat exposed to an unavoidable stress to avoid a noxious stimulus, and it allows us to evaluate the preventive activity of a treatment on the development of escape deficit. The second paradigm (chronic escape deficit) begins as acute escape deficit, that is then indefinitely sustained by the repeated administration of mild stressors; this model allows us to evaluate the efficacy of a treatment to revert the escape deficit. The third is a model of anhedonia based on the finding that exposure to repeated unavoidable stress prevents the acquisition of an appetitive behavior induced and maintained by a highly palatable food (vanilla sugar) in rats fed ad libitum; this paradigm assesses the efficacy of a treatment to restore an animal's motivation. A long-term (2 to 3 week) treatment with classical antidepressants, such as imipramine or fluoxetine, resulted in a clear-cut preventive and/or revertant activity in the three models.

Long-term lithium administration abolishes the resistance to stress in rats sensitized to morphine

Morphine sensitized rats appear protected from the sequelae of an unavoidable stress: when exposed to stress (after a 7-day morphine wash-out) and then tested for escape, they perform like naive animals. This protection appears similar to that induced by chronic imipramine treatment, as it is antagonized by the inhibition of D(1)-dopamine receptors before exposure to unavoidable stress. Repeated unavoidable stress induces in rats a condition characterized by hyporeactivity to noxious stimuli and reverted by long-term antidepressant treatments, and this state is regarded as an experimental model of depression. The resistance to stress in morphine sensitized rats could be considered as the behavioral counterpart of the sensitivity to stress in control rats, i.e. as a model of mania. The aim of the present study was to validate such a putative model by studying whether the resistance to stress induced by morphine sensitization would respond to a long-term administration of lithium, the reference antimanic drug. Long-term lithium treatment induces in rats a condition of hyporeactivity to noxious stimuli, accompanied by decreased levels of dopamine in the nucleus accumbens shell. In morphine sensitized rats chronic lithium abolished the resistance to stress, but it did not modify the D(1)-dopamine receptor mediated response to morphine, nor did it modify the levels of extraneuronal dopamine in the nucleus accumbens shell. Thus, lithium treatment abolished the resistance to stress in morphine sensitized rats, conferring predictive validity to the paradigm. Moreover, it did so through a mechanism which appeared to be independent of D(1)-dopamine receptor activity.

Implication of Bcl-2 family genes in basal and D-amphetamine-induced apoptosis in preneoplastic and neoplastic rat liver lesions

Molecular mechanisms of basal and D-amphetamine (AMPH)-induced apoptosis were studied in rat liver nodules, 12 (N12) and 30 (N30) weeks after initiation, and in hepatocellular carcinoma (HCC) induced by diethylnitrosamine in rats subjected to resistant hepatocyte model. Basal apoptosis in hematoxylin/eosin- and propidium iodide-stained sections was higher in nodules and HCC than in normal livers. It sharply increased in all tissues 4 hours after AMPH treatment (10 mg/kg), and declined to basal levels at 8 to 12 hours in liver and N12, but remained high up to 18 hours in N30 and HCC. c-myc, Tgf-alpha, p53, and Bcl-X(S) messenger RNA (mRNA) levels were higher, and Bcl-2 mRNA was lower in N12 and/or N30 and HCC than in normal liver. Four hours after AMPH injection, increase in c-myc and decreases in Bcl-2 and Bcl-X(L) mRNAs occurred in all tissues, whereas p53, Bax, and Bcl-X(S) mRNAs increased in N30 and HCC. These changes disappeared in liver and N12 at 18 hours, but persisted in N30 and HCC. c-Myc, P53, Bcl-2, and Bax proteins in normal liver and HCC +/- AMPH showed similar patterns. Tgf-beta1, Tgf-beta-RIII, CD95, and CD95L mRNA levels underwent slight or no changes in any tissue +/- AMPH. Basal Hsp27 expression was high in nodules and HCC, and was stimulated by AMPH in liver and N12, but not in N30 and HCC. These data suggest a role of dysregulation of Bcl-2 family genes and, at least in atypical lesions, of p53 overexpression, in basal and AMPH-induced apoptosis in nodules and HCCs. Hsp27 does not appear to sufficiently protect atypical lesions against apoptosis.

Rats sensitized to morphine are resistant to the behavioral effects of an unavoidable stress

In agreement with the results of other authors, rats sensitized to morphine and challenged with 5 mg/kg of morphine after 7 days of wash-out showed intense stereotyped movements, the expression of which was selectively antagonized by SCH 23390. Sensitized rats were exposed to an unavoidable stress (which consistently produces an escape deficit in control animals) after 3, 7 and 21 days of morphine wash-out. Twenty-four hours after the unavoidable stress, animals were tested for their capacity to escape and their performance was compared to that of control-stressed and naive rats. Morphine sensitization completely prevented the development of escape deficit. This protective effect was similar to that induced by a chronic imipramine treatment and, like the effect of imipramine, it was antagonized by the administration of SCH 23390 before the unavoidable stress. However, it was not affected by the administration of naloxone. Moreover, when rats presenting a clear-cut escape deficit, induced by a 10-day treatment with SKF 38393, were exposed to the morphine sensitization protocol, a complete recovery of their capacity to avoid a noxious stimulus was observed. Finally, the down-regulation of both the number of D(1)-dopamine receptors and of the coupled adenylyl cyclase activity in the pre-frontal cortex (PFC) produced by long-term SKF 38393 administration was reverted by the superimposed morphine sensitization. Thus, the condition of morphine sensitization appears to share several common effects with chronic imipramine treatment.

Efficacy of an Hypericum perforatum (St. John's wort) extract in preventing and reverting a condition of escape deficit in rats

The treatment of unselected depressed patients with an hydro-alcoholic extract of Hypericum perforatum has been reported to have an efficacy similar to that of classical antidepressants. In the present report, the effects of H. perforatum were studied on three animal models of depression: (i) an acute form of escape deficit (ED) induced by an unavoidable stress; (ii) a chronic model of ED, which can be maintained by the administration of mild stressors on alternate days; (iii) a model of anhedonia based on the finding that repeated stressors prevent the development of an appetitive behavior induced by vanilla sugar in satiated rats fed ad libitum. H. perforatum acutely protected animals from the sequelae of unavoidable stress; such an effect was partially prevented by the administration of SCH 23390 or (-)-pindolol. Moreover, H. perforatum reverted the ED maintained by repeated stressors and preserved the animal's capacity to learn to operate for earning a positive reinforcer. It was concluded that H. perforatum contains some active principle(s) endowed with antidepressant activity.