Radiolytic transformation of 2,2',4'-trihydroxychalcone

Radiolysis of 2,2',4'-trihydroxychalcone, a natural antioxidant present in fruit and vegetables, was performed in ethanol in the absence or in the presence of dioxygen. The degradation process of chalcone was followed in de-aerated solution by HPLC, NMR, FAB-LSIMS mass spectroscopy and analytical TLC. Under anaerobic conditions, six new products (three couples of diastereoisomers) were identified. Four of them kept the chalcone skeleton with OCH(2)CH(3), CH(OH)CH(3) and H substitutions on C(alpha) and C(beta). Thus the target was the alpha-beta double bond on which ethanol radicals were added. The two other compounds were formed in a second stage and exhibited a cyclization between the substituent on C(beta) and the carbonyl group. In the presence of dioxygen, these reactions were prevented and chalcone was protected. This study was the first step toward understanding of the behavior chalcone in irradiated fruits and vegetables.     

The effect of limited hydrolysis with Neutrase and ultrafiltration on the anti-adipogenic activity of soy protein

Limited hydrolysis of isolated soy protein (ISP) with Neutrase for 4 h to obtain the hydrolysate (NH4h) revealed the ability to suppress glycerol-3-phosphate dehydrogenase (GPDH) activity and relative lipid accumulation (RLA) in 3T3-L1 cells during differentiation. Lower GPDH activity or RLA indicates higher anti-adipogenic activity. Sequentially fractionating NH4h with 30–1 kDa (kilo-daltons) molecular weight cut-off (MWCO) membranes to obtain the 1 kDa concentrate resulted in further enhancing its anti-adipogenic activity in the cells. The GPDH activity significantly decreased from 280 to 100 U/mg protein (p < 0.05). When comparing the high-performance size-exclusion chromatography (HPSEC) profiles, the most active peptide for the anti-adipogenic activity was primarily composed of peptides with molecular weight between 1300 and 2200 Da. The in vitro effect of gastrointestinal protease on the anti-adipogenic activity of 1 kDa concentrate was also investigated. The results suggested that gastrointestinal proteases have very little effect on anti-adipogenic activity of the concentrate. According to the Western immunoblot analysis, 1 kDa concentrate inhibits adipogenesis by affecting the expression of peroxisome proliferators-activated receptor γ (PPARγ) and the CCAAT/enhancer binding protein α (C/EBPα) during 3T3-L1 cells differentiation.     

Carcinogenesis with the insecticide rotenone

Rotenone is an insecticide which has been used extensively for a long time, and is now widely used in the U.S.A. and other industrialized countries. Rotenone is used mainly as an agricultural insecticide, household garden insecticide and water plant pesticide. Through these uses, rotenone may now be reaching the human male and female in these countries in substantial amounts, carried by fresh or cooked vegetables, consumed fish and drinking water. A review of the existing published reports and unpublished official documents dealing with the capacity of rotenone to induce neoplastic, paraneoplastic and preneoplastic lesions in the rat is presented here. It is strongly suggested that rotenone is carcinogenic to the rat (at doses from 2 to 25 parts per million continuously in food, or from 0.8 to 2.5 mg/kg weight for 1 to 4 months by oral administration), above all, when the rats receive deficient diets, especially those poor in riboflavin. Rotenone carcinogenesis, among other things, seems to exhibit a peculiar dose response pattern, which could be explained by its possible hormonal mechanism of action. Further studies to assess definitively the role of rotenone as a possible environmental carcinogen are proposed as being highly necessary.     

A new approach to procyanidins synthesis with potent anti-adipogenic effects

Convenient structure modification of (+)-catechin (1) induced by nonthermal dielectric barrier discharge (DBD) plasma treatment afforded three novel methylene-linked flavan-3-ol oligomers, methylenetetracatechin (2), methylenetricatechin (3), and methylenedicatechin (4), together with two known catechin dimers, bis 8,8′-catechinylmethane (5) and bis 6,8′-catechinylmethane (6). The structures of the three new catechin oligomers 2–4 with methylene bridges were elucidated by detailed 1D- and 2D-NMR analysis, and the absolute configurations were established by the observation of circular dichroism (CD). The novel products 2 and 3 showed significantly enhanced anti-adipogenic capacities against both pancreatic lipase and differentiation of 3T3-L1 preadipocytes compared to the parent (+)-catechin.     

Design, synthesis and cytotoxic activity of novel spin-labeled rotenone derivatives

Three series of novel spin-labeled rotenone derivatives were synthesized and evaluated for cytotoxicity against four tumor cell lines, A-549, DU-145, KB and KBvin. All of the derivatives showed promising in vitro cytotoxic activity against the tumor cell lines tested, with IC(50) values ranging from 0.075 to 0.738μg/mL. Remarkably, all of the compounds were more potent than paclitaxel against KBvin in vitro, and compounds 3a and 3d displayed the highest cytotoxicity against this cell line (IC(50) 0.075 and 0.092μg/mL, respectively). Based on the observed cytotoxicity, structure-activity relationships have been described.     

Radiolytic signature of Z-DNA.

Ionizing radiations induce various damages in DNA via the hydroxyl radical OH. generated by the radiolysis of water. We compare here the radiosensitivity of B- and Z-DNA, by using a Z-prone stretch included in a plasmid. In the supercoiled plasmid, the stretch is in the Z-form, whereas it is in the B-form when the plasmid is relaxed. Frank strand breaks (FSB) and alkali-revealed breaks (ARB) were located and quantified using sequencing gel electrophoresis. We show that B- and Z-DNA have the same mean sensitivity towards radiolytic attack, for both FSB and ARB. Nevertheless, the guanine sites are more sensitive, and the cytosine sites less sensitive in Z- than in B-DNA, leading to a characteristic signature of the Z-form. The comparison of experiments with the outcome of a Monte Carlo simulation of OH. radical attack suggests that transfer of initial damage from a guanine base to its attached sugar or the adjacent 3' cytosine is more important in Z-DNA than in B-DNA.     

Berberine exerts anti-adipogenic activity through up-regulation of C/EBP inhibitors, CHOP and DEC2

Berberine exerts an anti-adipogenic activity that is associated with the down-regulation of C/EBPα and PPARγ. Stimulation of AMP-activated kinase (AMPK) caused by inhibition of mitochondrial respiration has been suggested to underlie such molecular regulation. In the present study, we show that berberine up-regulated the expression of two different sets of C/EBP inhibitors, CHOP and DEC2, while down-modulating C/EBPα, PPARγ and other adipogenic markers and effectors in differentiating 3T3-L1 preadipocytes and mature adipocytes. Data also suggested that the berberine-induced up-regulation of CHOP and DEC2 was attributable to selective activation of an unfolded protein response (UPR) and modified extracellular environment, respectively. As a result, the anti-adipogenic activity of berberine was diminished remarkably by adjusting the differentiation culture media and limitedly but consistently by knockdown of CHOP expression. Together, up-regulation of C/EBP inhibitors appears to underlie the berberine-induced repression of C/EBPα and PPARγ and, so, the inhibition of adipogenesis.     

Lymphocyte transformation and transmembrane potential depressors

Potassium and rubidium at high concentrations, as well as valinomycin, gramicidin, and ouabain, inhibit the PHA-induced synthesis of DNA. They act primarily at an early step in the G 1 period. All these inhibitors have in common a tendency to depress the transmembrane potential suggesting a relationship between the potential and lymphocyte transformation.     

Novel nicotine analogues with potential anti-mycobacterial activity

Tuberculosis (TB) is the second leading lethal infectious disease in the world after acquired immuno deficiency (AIDs). We have developed a series of twenty-five novel nicotine analogues with de-addiction property and tested them for their activity against Mycobacterium tuberculosis (MTB). In an effort to increase the specificity of action and directing nicotine analogues to target MTB, four promising compounds were further optimized via molecular docking studies against the Dihydrofolate reductase of MTB. After lead optimization, one nicotine analogue [3-(5-(3fluorophenyl)nicotinoyl)-1-methylpyrrolidin-2-one] exhibited minimum inhibitory concentration of 1 μg/mL (2.86 nM) against M. tuberculosis (H37Rv strain), a human pathogenic strain of clinically significant importance. Pharmacokinetic analysis of [3-(5-(3fluorophenyl)nicotinoyl)-1methylpyrrolidin-2-one] with lowest MIC value via oral route in Wistar rats revealed that at a dosage of 5 mg/kg body weight gave a maximum serum drug concentration (C_max) of 2.86 μg/mL, T_max of one hour and a half-life (T_1/2) of more than 24 h and Volume of distribution (V_d) of 27.36 L. Whereas the parenteral (intra venous) route showed a C_max of 3.37 μg/mL, T_max of 0.05 h, T_1/2 of 24 h and V_d equivalent to 23.18 L. The acute oral toxicity and repeated oral toxicity studies in female Wistar rats had an LD₅₀ > 2000 mg/kg body weight. Our data suggests that nicotine derivatives developed in the present study has good metabolic stability with tunable pharmacokinetics (PK) with therapeutic potential to combat MTB. However, further in vivo studies for anti-tuberculosis activity and elucidation of mode of action could result in more promising novel drug for treating MTB. To the best of our knowledge this is the first report revealing the anti-mycobacterial potential of nicotine analogue at potential therapeutic concentrations.     

5-Fluorouracil-cisplatin adducts with potential antitumor activity

Using 5-fluorouracil (5-FU) and cis-diamminedichloroplatinum(II) (cisplatin, CDDP) as starting compounds, 5-FU-cisplatin adducts cis-[Pt(NH(3))(2)(HFU)Cl] (1) and cis-[Pt(NH(3))(2)(HFU)(2)] (2) were prepared. The obtained complexes were characterized by IR, ES-MS and 1H NMR spectroscopy. Complex 1 reacted with guanosine-5'-monophosphate (5'-GMP) and gave rise to a stable mixed-ligand complex cis-[Pt(NH(3))(2)(HFU)(GMP)] (3), whereas 2 did not undergo a similar reaction. In vitro cell growth inhibition tests of complexes 1 and 2 exhibited moderate antitumor activities against the melanoma B16-BL6 cell line. This work provides the basis for a potential alternative for the combinational use of 5-FU and CDDP in cancer therapy.     

New chitosan derivatives with potential antimicrobial activity

A series of four water-soluble chitosan derivatives differing in molecular mass, hydrophobicity, and charge was synthesized and tested for the intensity of their effects on Gram-negative and Gram-positive bacteria. It was shown that the tested compounds allowed the penetration of ethidium bromide into the bacteria, which showed increased permeability of their cell walls under the effect of chitosans. The tolerance to various chitosan derivatives differed in Gram-negative and Gram-positive bacteria. The Gram-negative bacteria were the most responsive to high-molecular chitosan and the Gram-positive ones, to N-,O-carboxypropylchitosan, whereas high-molecular chitosan had little effect. Research on the correlation between the structure and activity of the studied compounds revealed that depolymerization of chitosan reduced, and introduction of hydrophobic substantives in chitosan molecule significantly enhanced its permeability effect on bacterial cell walls. The obtained results provide a basis for the construction of new chitosan derivatives with antimicrobial activities.     

Constituents of Quinchamalium majus with potential antitubercular activity

Antitubercular bioassay-guided fractionation of the dichloromethane extracts of the above-ground biomass and roots of Quinchamalium majus led to the identification of six known constituents, betulinic acid (1), daucosterol (2), 5,7-dihydroxyflavone (3), oleanolic acid (4), (-)-2S-pinocembrin (5), and ursolic acid (6), for the first time in this species. Their chemical structures were determined on the basis of spectroscopic evidence and chemical transformation methods. All of these compounds along with additional 11 analogues were evaluated for their antitubercular potential against Mycobacterium tuberculosis in a microplate alamar blue assay, and the primary structure-activity relationships (SARs) for 4 and 6 were discussed. In addition, all the isolates were tested for cytotoxicity against African green monkey Vero cells in order to evaluate for their selectivity potential.     

Plasma-induced dimerization of phloridzin as a new class of anti-adipogenic agents

Phloridzin is a natural phloretin glucoside found in several parts of apple trees and is an attractive target for structural modification as novel pharmaceutical agent. Nonthermal dielectric barrier discharge (DBD) plasma-induced structural changes in dihydrochalcone phloridzin (1) resulted in the isolation of three new methylene-bridged dihydrochalcone dimers, methylenebisphloridzin (2), deglucosylmethylenebisphloridzin (3), and methylenebisphloretin (4), along with phloretin (5). The chemical structures of these newly generated compounds were elucidated by interpretation of their spectroscopic data. The new phloretin dimer 4 connected by a methylene linkage exhibited significantly improved anti-adipogenic properties against pancreatic lipase as well as differentiation of 3T3-L1 preadipocytes compared to the parent compound phloridzin.     

Phosphoinositide kinase activity and transformation

We have used the DNA tumor virus polyoma as a model system to examine whether the phosphatidylinositol (PI) turnover pathway is a critical target for transforming gene products. Polyoma-infected cells show elevated levels of polyphosphoinositides and polyphosphoinositols, and a PI kinase activity is associated with middle T antigen, a transforming gene product of polyoma virus. In anti-T immunoprecipitates from polyoma-infected or -transformed cells, comparisons of wild-type and polyoma mutants defective for transformation show a strong correlation between middle T-associated PI kinase activity and transforming ability. Middle T has previously been found to associate at the plasma membrane with pp60 c-src and to activate it as a tyrosine kinase. c-src itself does not appear to phosphorylate PI; however, the middle T/pp60 c-src tyrosine kinase activity may be important for activation of PI kinase. Ammonium orthovanadate, a tyrosine phosphatase inhibitor, elevates the middle T/pp60 c-src-associated PI kinase activity. We propose that middle T/pp60 c-src activates a PI kinase and modulates PI turnover in vivo by tyrosine phosphorylation.     

Radiolytic Studies of Naphthalene in the Presence of Water

Naphthalene is an interesting candidate to study in the framework of organic delivery to planetary surfaces as well as in the origin of life. Additionally, naphthalene is of environmental interest, because of its chronic and acute effects on living systems, such as humans and animals (e.g. moths). Naphthalene has been well studied in both fields. In this paper we give an overview of radiolytic studies of naphthalene in the presence of both liquid water and water ice. From our review it appears that OH radicals are formed both in liquid water and in interstellar ices and that these radicals play a considerable role in the degradation of naphthalene. However, it also appears that upon irradiation of naphthalene in liquid water, hydrogen peroxide, a species that accelerates naphthalene degradation, is formed. Based on this review we suggest that the role of hydrogen peroxide in interstellar ices should be further investigated.     

Coenzyme Q10 reduces the toxicity of rotenone in neuronal cultures by preserving the mitochondrial membrane potential

Defects in mitochondrial energy metabolism due to respiratory chain disorders lead to a decrease in mitochondrial membrane potential (DeltaPsim) and induce apoptosis. Since coenzyme Q10 (CoQ10) plays a dual role as an antioxidant and bioenergetic agent in the respiratory chain, it has attracted increasing attention concerning the prevention of apoptosis in mitochondrial diseases. In this study the potential of CoQ10 to antagonize the apoptosis-inducing effects of the respiratory chain inhibitor rotenone was explored by video-enhanced microscopy in SH-SY5Y neuroblastoma cells. The cationic fluorescent dye JC-1 which exhibits potential-dependent accumulation in mitochondria was used as an indicator to monitor changes in DeltaPsim. The relative changes in fluorescence intensity after incubation with rotenone for 15 minutes were calculated. Pre-treatment with CoQ10 (10 or 100 microM) for 48 h led to a significant reduction of rotenone-induced loss of DeltaPsim. These results suggest, that cytoprotection by CoQ10 may be mediated by raising cellular resistance against the initiating steps of apoptosis, namely the decrease of DeltaPsim. Whether these data may provide new directions for the development of neuroprotective strategies has to be investigated in future studies.