Oxidative stress resistance through blocking Hsp60 translocation followed by SAPK/JNK inhibition in aged human diploid fibroblasts

The stress‐activated protein kinase/c‐Jun N‐terminal kinase (SAPK/JNK) pathway is a well‐known senescence‐related stress activated protein kinase. Multiple environmental stresses induce programmed cell death, such as apoptosis. Normal human diploid fibroblast (HDF) cells have a limited life span in vitro, halting proliferation after a fixed number of cell divisions. Aged passage HDF showed resistance to oxidative stress involving heat shock proteins (Hsp60) through a mechanism involving the translocation of Hsp60 from the mitochondria to the cytosol. The present study showed that the translocation of Hsp60 from the mitochondria to the cytosol followed by high levels of p‐SAPK/JNK activation as a result of oxidative stress was observed in the young cells only. The inhibition of SAPK/JNK activation by SP600125 under oxidative stress almost completely blocked the translocation of Hsp60 in both young and aged cells. This suggests that aged HDF cells are resistant to oxidative stress by blocking the translocation of Hsp60 from the mitochondria to the cytosol followed by SAPK/JNK inhibition. Overall, the mechanism of resistance by oxidative stress in aged cells is induced by blocked of the translocation of Hsp60 followed by SAPK/JNK inactivation. Copyright © 2008 John Wiley & Sons, Ltd.     

(−)-Cryptocaryalactone and (−)-deacetylcryptocaryalactone-germination inhibitors from Cryptocarya moschata seeds

(?)-Cryptocaryalactone (6-[2-acetoxy-4-phenyl-3-butenyl]-5,6-dihydro-2-pyranone) and (?)-deacetylcryptocaryalactone (6-[2-hydroxy-4-phenyl-3-butenyl]-5,6-dihydro-2-pyranone) isolated from Cryptocarya moschata seeds are natural germination inhibitors. Applied at 0.004 M, the second compound completely arrested germination of velvetleaf (Abutilon theophrasti) and decreased the germination rate of soybeans, but did not appear to affect corn. The first compound was not as effective; 0.004 M reduced velvetleaf germination 50%.     

Subchronic exposure to high-dose ACE-inhibitor moexipril induces catalase activity in rat liver

The long-term clinical effects of ACE-inhibitors have similarities with those of both fibrates and glitazones, activators of peroxisome proliferator activator receptor (PPAR) alpha and gamma, respectively. The antioxidant enzyme catalase, a heme protein that degrades hydrogen peroxide, is found at high concentrations in peroxisomes. Catalase activity is one of the recognized surrogate markers indicative of PPAR activation in the rat liver. The purpose of the study was to establish the effect of moexipril on catalase activity and to compare it with the effect of both saline controls and that of the known PPAR agonist clofibrate (positive control). Three groups of seven rats were used. All substances were applied i.p. daily for 5 days, followed by a 2-day break. The cycle was repeated eight times. After the final cycle (day 56) the animals were sacrificed and liver tissue collected. The number of catalase positive cells in both moexipril group (95% CI 57–61) and clofibrate group (95% CI 72–80) is higher than in controls (95% CI 3–16) (p ≤ 0.01). The number of catalase positive cells in the clofibrate group is higher than in the moexipril group (p ≤ 0.01). High-dose subchronic exposure to the ACE-inhibitor moexipril induces catalase activity in the rat liver to an extent comparable to fibrates. We suggest that some of the long-term advantages of ACE inhibitor use – beyond mere BP lowering – might be due to a PPAR mediated effect. (Mol Cell Biochem xxx: 159–163, 2005)     

Characterization and <Emphasis Type="Italic">in vitro</Emphasis> expression patterns of extracellular degradative enzymes from non-pathogenic binucleate <Emphasis Type="Italic">Rhizoctonia</Emphasis> AG-G

Many filamentous fungi produce an array of extracellular enzymes that acting in cell walls release elicitors of the plant defense response These enzymes may therefore be important in biocontrol applications. The aim of this study was to characterize extracellular degradative enzymes produced by a non-pathogenic binucleate isolate of Rhizoctonia AG-G. The fungus was grown in liquid culture supplemented with pectin, polygalacturonic acid or glucose as a carbon sources and filtrates of the culture media were analyzed for the detection of pectinolytic and glucan hydrolytic enzymes. Using only pectin as a carbon source, secretion of polygalacturonases and methylesterases was found. When the liquid medium was supplemented with polygalacturonic acid, only polygalacturonase activity was detected. However, when glucose was used as carbon source -1,3 and -1,6 glucanases activities were detected, using laminarin and pustulan as substrates, but none of the pectinolytic activities were found. These enzymes were partially purified and characterized. The -(1,3)(1,6) glucanase and polygalacturonase enzymes showed to be active against cell wall polysaccharides from potato sprouts. These enzymes may have an important role in fungus-plant cell wall interaction. This is the first study about the production of extracellular enzymes by non-pathogenic binucleate Rhizoctonia AG-G.     

Inhibitory effect of inducible nitric oxide synthase inhibitors on DMBA-induced hamster buccal–pouch squamous-cell carcinogenesis

We investigated the effects of two NOS inhibitors (AG and l-NAME) on DMBA-induced hamster buccal-pouch carcinogenesis. Six hundred Syrian golden hamsters were split into two divisions (I and II); divisions split into three groups (experimental groups A and B, control group C); and each group into subgroups of 20 (A1-A6, B1-B6 and C1-C3). The pouches of animals in groups A1-A3 were painted first with AG of differing concentrations (10, 20, and 30 micromol/ml) and then 30 min later with DMBA (0.5%), thrice weekly for 9 weeks. Subgroups A4-A6 only received AG treatment. Groups B1 to B6 were similarly treated with l-NAME. Animals in division II were treated in the same manner for 13 weeks. Post-mortem analysis revealed that both inhibitors can suppress the development of epithelial dysplasias and squamous-cell carcinomas. An associated increase in the numbers of epithelial hyperplasias was paralleled by a decrease in iNOS protein expression. This animal model can be employed to evaluate the potential use of iNOS inhibitors as novel therapeutic tools for oral squamous-cell carcinogenesis.     

Performance of bean bruchids Callosobruchus maculatus and Zabrotes subfasciatus (Coleoptera: Bruchidae) reared on resistant (IT81D-1045) and susceptible (Epace 10) Vigna unguiculata seeds: relationship with trypsin inhibitor and vicilin excretion

Callosobruchus maculatus (Cm) and Zabrotes subfasciatus (Zs) were reared on resistant (IT81D-1045) and on susceptible (Epace 10) cowpea seeds. The emergence of adult insects, total developmental period (TDP) and excretion of trypsin inhibitor and vicilin were determined for both bruchid populations. Parameter evaluation showed that the Zs populations emerged from both seeds had no significant differences in emergence and TDP. The Cm population raised from resistant seeds had lower emergence (5.6+/-1.3%) and delayed TDP (46+/-1.25 days) than those emerged from susceptible seeds. The excretion of defense proteins showed that Zs reared in resistant seeds excreted 1.7 times more trypsin inhibitor, but this did not affect emergence or TDP. Furthermore, Cm population emerged from resistant seeds excreted 7 times higher vicilin and 0.4 times less trypsin inhibitor than that emerged from susceptible seeds. These results indicate that vicilins from resistant seeds are involved to significantly longer TDP (46 days) and also drastic reduction of insect emergence ( approximately 5%) of C. maculatus.     

Synthesis and activity of N-acyl azacyclic urea HIV-1 protease inhibitors with high potency against multiple drug resistant viral strains

As part of our efforts to identify potent HIV-1 protease inhibitors that are active against resistant viral strains, structural modification of the azacyclic urea (I) was undertaken by incorporating acyl groups as P₁′ ligands. The extensive SAR study has yielded a series of N-acyl azacyclic ureas (II), which are highly potent against both wild-type and multiple PI-resistant viral strains.