Cytochrome P450cam-catalyzed oxidation of a hypersensitive radical probe.

trans-1-Phenyl-2-vinylcyclopropane, a hypersensitive radical probe, is oxidized by cytochrome P450cam (CYP101) to a diastereomeric mixture of the corresponding epoxide (81%), (trans-2-phenylcyclopropyl)acetaldehyde (6%), and trans-5-phenyl-2-penten-1,5-diol (13%). trans-5-Phenyl-2-penten-1-ol and (trans-2-phenylcyclopropyl)ethane-1,2-diol are not detectably formed. Authentic standards of all the products have been synthesized and used to establish the identities (or the absence) of the metabolites. Studies with [18O]H2O demonstrate that the oxygens at positions 1 and 5 in the rearranged diol derive from molecular oxygen and water, respectively. Catalytic turnover of the enzyme is required for product formation from the olefin, but incubation of the epoxide metabolite with the enzyme, or with buffer alone, yields both the aldehyde and the rearranged diol products. The absence of trans-5-phenyl-2-penten-1-ol implies that the lifetime of the putative radical intermediate is so short that its existence as a discrete entity is questionable. A cationic intermediate is unlikely but cannot be excluded because the same metabolites are formed in a secondary reaction, even at pH 8.0, from the epoxide. The results provide no evidence for the involvement of radicals or cations in the epoxidation reaction, in agreement with results on the oxidation of olefins in organic solvents by metalloporphyrin catalysts.     

The induction of chromosomal damage in rat hepatocytes and lymphocytes II. Alkylation damage and repair of rat-liver DNA after diethylnitrosamine,dimethylnitrosamine and ethyl methanesulphonate in relation to clastogenic effects

Rat-liver DNA alkylation by diethylnitrosamine (DEN), dimethylnitrosamine (DMN) and ethyl methanesulphonate (EMS) was studied in an attempt to relate chromosome-damaging effects of these agents (the formation of micronuclei in hepatocytes; see preceding paper) to specific alkylation patterns. No correlation was observed between the induction of micronuclei and liver DNA N-alkylation, measured as 3- and 7-alkyl-purines. O⁶-Alkylguanine is probably not involved in micronucleus induction because it is lost from DNA too rapidly to explain the much more persistent clastogenic effects. In contrast, both the initial amounts of alkylphosphotriesters and the persistencies of these products roughly paralleled the respective effects on micronucleus induction. The possible involvement of alkylphosphotriesters or other O-alkylation products of comparable stabilities is discussed. Results with DMN suggest that part of the primary DNA methylation damage is converted into a secondary (DNA) lesion and that both the primary and secondary lesion(s) contribute to the process of micronucleus formation.     

Constituents of the essential oil of Lavandula latifolia

Thirty components were identified in Lavandula latifolia essential oil (spike oil). One of the compounds, espliegol (δ-terpineol), is a new natural product.     

Some meteorological conditions associated with forest fires in Galicia (Spain)

The present paper offers data on the effect of certain meteorological parameters on the outbreak of forest fires in Galicia (Spain). In a day-to-day analysis, the values of the stability of the air column and the saturation deficit at the lower levels are related to the number of fires occurring in the following 24 h.     

Maximal lactate steady state in rats submitted to swimming exercise.

The higher concentration during exercise at which lactate entry in blood equals its removal is known as 'maximal lactate steady state' (MLSS) and is considered an important indicator of endurance exercise capacity. The aim of the present study was to determine MLSS in rats during swimming exercise. Adult male Wistar rats, which were adapted to water for 3 weeks, were used. After this, the animals were separated at random into groups and submitted once a week to swimming sessions of 20 min, supporting loads of 5, 6, 7, 8, 9 or 10% of body wt. for 6 consecutive weeks. Blood lactate was determined every 5 min to find the MLSS. Sedentary animals presented MLSS with overloads of 5 and 6% at 5.5 mmol/l blood lactate. There was a significant (P<0.05) increase in blood lactate with the other loads. In another set of experiments, rats of the same strain, sex and age were submitted daily to 60 min of swimming with an 8% body wt. overload, 5 days/week, for 9 weeks. The rats were then submitted to a swimming session of 20 min with an 8% body wt. overload and blood lactate was determined before the beginning of the session and after 10 and 20 min of exercise. Sedentary rats submitted to the same acute exercise protocol were used as a control. Physical training did not alter the MLSS value (P<0.05) but shifted it to a higher exercise intensity (8% body wt. overload). Taken together these results indicate that MLSS measured in rats in the conditions of the present study was reproducible and seemed to be independent of the physical condition of the animals.