Hormetins, antioxidants and prooxidants: defining quercetin-, caffeic acid- and rosmarinic acid-mediated life extension in C. elegans

Quercetin, Caffeic- and Rosmarinic acid exposure extend lifespan in Caenorhabditis elegans. This comparative study uncovers basic common and contrasting underlying mechanisms: For all three compounds, life extension was characterized by hormetic dose response curves, but hsp-level expression was variable. Quercetin and Rosmarinic acid both suppressed bacterial growth; however, antibacterial properties were not the dominant reason for life extension. Exposure to Quercetin, Caffeic- and Rosmarinic acid resulted in reduced body size, altered lipid-metabolism and a tendency towards a delay in reproductive timing; however the total number of offspring was not affected. An indirect dietary restriction effect, provoked by either chemo-repulsion or diminished pharyngeal pumping was rejected. Quercetin and Caffeic acid were shown to increase the antioxidative capacity in vivo and, by means of a lipofuscin assay, reduce the oxidative damage in the nematodes. Finally, it was possible to demonstrate that the life and thermotolerance enhancing properties of Caffeic- and Rosmarinic acid both rely on osr-1, sek-1, sir-2.1 and unc-43 plus daf-16 in the case of Caffeic acid. Taken together, hormesis, in vivo antioxidative/prooxidative properties, modulation of genetic players, as well as the re-allocation of energy all contribute (to some extent and dependent on the polyphenol) to life extension.

Therapeutic hypothermia attenuates acute lung injury in paraquat intoxication in rats

AIM OF THE STUDY

Paraquat intoxication induces acute lung injury and numerous fatalities have been reported. The mechanism of toxic effect of paraquat is oxidative injury and inflammation. Therapeutic hypothermia has been known to have antioxidant and anti-inflammatory effects. This study was designed to evaluate the effect of therapeutic hypothermia on paraquat intoxication.

METHODS

Male Sprague-Dawley rats were given 50 mg/kg of paraquat intraperitoneally and divided into the normothermia (36-38°C) group and the hypothermia (30-32°C) group after 1h of paraquat administration. The hypothermia group underwent 2 h of hypothermia followed by 2 h of rewarming. In the survival study, mortality was observed for 24 h after paraquat administration. An in the second experiment, lung tissues and plasma were harvested at 6 h after paraquat administration.

RESULTS

The 12 h survival rate was significantly higher in the hypothermia group than in the normothermia group (100% vs. 50%, p<0.05), but survival rates for 24 h were not different. Acute lung injury score was lower in the hypothermia group than in the normothermia group (p<0.05). Thmalondialdehyde contents of lung tissues, plasma interleukin-6 and nitrite/nitrate concentrations were significantly decreased in the HT group compared to the NT group (p<0.05).

CONCLUSION

Therapeutic hypothermia delayed early mortality and attenuated acute lung injury in paraquat intoxication.

Chymase is Activated in the Pulmonary Inflammation and Fibrosis Induced by Paraquat in Hamsters

The involvement of chymase has been implicated in fibrotic response to tissue injuries. Besides its direct action, chymase indirectly promotes fibrotic response by generating angiotensin (Ang) II from Ang I. In the present study, we examined whether chymase and angiotensin converting enzyme (ACE), that also generates Ang II, were activated in the pulmonary inflammation and fibrosis induced by paraquat (PQ) in hamsters. In an acute PQ intoxication group, PQ was administered subcutaneously and the lungs were excised four days after administration. In a chronic PQ intoxication group, PQ was administered at the same dose once a week for six weeks. The lungs were excised five weeks after the last administration. On dissection, alveolar hemorrhage and capillary stasis were found in the acute PQ intoxication group while interstitial pulmonary fibrosis was found in the chronic PQ intoxication group. The pulmonary tissue chymase activity was elevated in both intoxication groups when compared with a respective age-matched, vehicle (saline)-administered group. Pulmonary tissue ACE activity, on the other hand, decreased in both intoxication groups. These data suggested that activated chymase may be involved in the establishment of PQ-induced pulmonary fibrosis in hamsters.

Changes in the fatty acid composition and hydroxyproline content in rat lung in relation to collagen synthesis after paraquat administration

OBJECTIVES

Effect of paraquat on the fatty acid composition (weight percentage) of rat lung was studied with particular reference to the change of hydroxyproline content in the course of paraquat-induced dysfunction and subsequent repair.

METHODS

Eight-week-old male Wistar rats were administered paraquat at 20 mg/kg body weight subcutaneously, and the wet weight, hydroxyproline content and fatty acid composition of lungs of each group rats were analyzed at 2, 7, 14 or 28 days after treatment, respectively.

RESULTS

The percentage of palmitic acid (C16:0), arachidonic acid (C20:4) and docosahexaenoic acid (C22:6) significantly increased, and the percentage of oleic acid (C18:1) and the ratio of monounsaturated fatty acids/saturated fatty acids (M/S) significantly decreased comparing to control on day 28 after paraquat administration. The time-course of each fatty acid was observed for 28 days after paraquat administration. M/S ratio decreased after paraquat administration up to the 28th day, but the polyunsaturated fatty acids/saturated fatty acids (P/S) ratio decreased during the first 7 days, followed by a increase, and then reached higher level than the 0 day control at the 28th day. Hydroxyproline also increased between the 14th and the 28th days. Eicosapentaenoic acid (C20:5) had once increased during the first 2 days and decreased gradually, while C20:4 maintained high level in this period. C22:6 increased after paraquat administration and maintained high level up to the 28th day. This result indicated that desaturation and elongation in n-3 series fatty acids were accelerated after paraquat treatment, and consequently C20:5 was rapidly converted into C22:6 and decreased.

CONCLUSIONS

Paraquat might cause elevation of unsaturated fatty acids, espe- cially C20:4 but not C20:5 by the stimulation of the fatty acid desaturase system, and could consequently stimulate local collagen synthesis by C20:4 metabolites in the healing stage.

Spectra interference between diquat and paraquat by second derivative spectrophotometry

A rapid and accurate method, combining solid-phase extraction and second-order derivative spectrophotomety approaches, is developed for the simultaneous determination of diquat (DQ) and paraquat (PQ) in blood, tissue and urine samples. Supernatant resulting from the precipitation of protein (with trichloroacetic acid) in plasma and tissue or Amberlite IRA-401 resin treated urine are passed through a mini-column packed with Wakogel gel (Silica gel). Analytes are then eluted with a non-organic solvent, 0.2mol/l HCl solution containing 2mol/l NH(4)Cl. UV spectrum of the eluent in 220-350nm range provides effective screen to detect the presence of DQ and/or PQ. In the presence of DQ or PQ alone, the analyte present is quantitated by conventional zero- or second-order derivative spectrophotometry. The calibration curve in the 0.1-5.0mg/l range for either analyte obeys Beer's law. When both DQ and PQ are present, their concentrations are determined by the peak amplitudes of their respective second-derivative spectra after the addition of alkaline dithionite reagent. Interference is negligible when the DQ/PQ concentration ratio is within the 5.0-0.2 range. Using a 2-ml of sample size, the detection limits for DQ and PQ in plasma are 0.02 and 0.005mg/l. The corresponding detection limits for urine samples (10ml sample size) are 0.004 and 0.001mg/l. Recoveries of DQ and PQ in triplicate plasma and urine samples spiked with 0.5mg/l of analytes are 93 and 85%. The precision of the proposed method resulting from triplicate study of spiked urine samples varies from 3.2 to 4.6% at 0.5mg/l of DQ and PQ, respectively.