Lovastatin and simvastatin are modulators of the proteasome

Lovastatin and simvastatin are HMG-CoA reductase inhibitors widely used as antihyperlipidemic drugs, which also display antiproliferative properties. In the present paper, we provide evidence that both lovastatin and simvastatin are modulators of the purified bovine pituitary 20 S proteasome, since they mildly stimulate the chymotrypsin-like activity and inhibit the peptidylglutamylpeptide hydrolyzing activity without interfering with the trypsin-like activity. However, those effects are only observed when the closed ring forms of the drugs are used, while the opened ring form of lovastatin acts as a mild inhibitor of the chymotrypsin like activity. The closed ring form of lovastatin is much more potent as a cytotoxic agent on the Colon-26 (C-26) colon carcinoma cell line than the opened ring form, which is only mildly cytostatic. Moreover, neither the cytotoxic effects nor the effects on 20 S proteasome activities are prevented by mevalonate, which by itself inhibits the trypsin-like activity of the proteasome. Neither the opened ring nor the closed ring form of lovastatin induces an accumulation of ubiquitin-protein conjugates, which is observed after treatment with lactacystin, a selective proteasome inhibitor. In contrast with the opened ring form of lovastatin, the closed ring form induces the disappearance of detectable p27(kip1) from C-26 cells. Altogether, our results indicate that the closed ring form of lovastatin induces cytotoxic effects independent of its HMG-CoA inhibiting activity, however, those effects are mediated by a complex modulation of proteasome activity rather than by inhibition of the 20 S proteasome.     

Biotechnological production and applications of statins

Statins are a group of extremely successful drugs that lower cholesterol levels in blood; decreasing the risk of heath attack or stroke. In recent years, statins have also been reported to have other biological activities and numerous potential therapeutic uses. Natural statins are lovastatin and compactin, while pravastatin is derived from the latter by biotransformation. Simvastatin, the second leading statin in the market, is a lovastatin semisynthetic derivative. Lovastatin is mainly produced by Aspergillus terreus strains, and compactin by Penicillium citrinum. Lovastatin and compactin are produced industrially by liquid submerged fermentation, but can also be produced by the emerging technology of solid-state fermentation, that displays some advantages. Advances in the biochemistry and genetics of lovastatin have allowed the development of new methods for the production of simvastatin. This lovastatin derivative can be efficiently synthesized from monacolin J (lovastatin without the side chain) by a process that uses the Aspergillus terreus enzyme acyltransferase LovD. In a different approach, A. terreus was engineered, using combinational biosynthesis on gene lovF, so that the resulting hybrid polyketide synthase is able to in vivo synthesize 2,2-dimethylbutyrate (the side chain of simvastatin). The resulting transformant strains can produce simvastatin (instead of lovastatin) by direct fermentation.     

Inhibition of rat brain prostaglandin D synthase by 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors

The effect of lovastatin, simvastatin and pravastatin, which are competitive inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, was tested on PGD synthase purified to apparent homogeneity from the rat brain. Lovastatin and simvastatin, which reportedly cause insomnia in vivo, inhibited the PGD synthase activity dose-dependently and showed an IC50 value of 100 and 75 microM, respectively. On the other hand, pravastatin, which does not cause insomnia, showed no significant effect at 100 microM and only a slight effect up to 500 microM.     

Effect of lovastatin on acyl-CoA: cholesterol O-acyltransferase (ACAT) activity and the basolateral-membrane secretion of newly synthesized lipids by CaCo-2 cells.

Lovastatin, a potent competitive inhibitor of 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase activity, was used to study the regulation of cholesterol metabolism and the basolateral-membrane secretion of triacylglycerol and cholesterol in the human intestinal cell line CaCo-2. At 0.1 microgram/ml, lovastatin decreased 3H2O incorporation into cholesterol by 71%. In membranes prepared from cells incubated with lovastatin for 18 h, HMG-CoA reductase activity was induced 4-8-fold. Mevalonolactone prevented this induction. In intact cells, lovastatin (10 micrograms/ml) decreased cholesterol esterification by 50%. The reductase inhibitor decreased membrane acyl-CoA:cholesterol O-acyltransferase (ACAT) activity by 50% at 5 micrograms/ml. ACAT inhibition by lavastatin was not reversed by adding excess of cholesterol or fatty acyl-CoA to the assay. Lovastatin, in the presence or absence of mevalonolactone, decreased the basolateral secretion of newly synthesized cholesteryl esters and triacylglycerols. Lovastatin also inhibited the esterification of absorbed cholesterol and the secretion of this newly synthesized cholesteryl ester. Lovastatin is a potent inhibitor of cholesterol synthesis in CaCo-2 cells. Moreover, it is a direct inhibitor of ACAT activity, independently of its effect on HMG-CoA reductase and cholesterol synthesis.     

Tissue-selective acute effects of inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A reductase on cholesterol biosynthesis in lens

Inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, the key enzyme that regulates cholesterol synthesis, lower serum cholesterol by increasing the activity of low density lipoprotein (LDL) receptors in the liver. In rat liver slices, the dose-response curves for inhibition of [14C]acetate incorporation into cholesterol were similar for the active acid forms of lovastatin, simvastatin, and pravastatin. The calculated IC50 values were approximately 20-50 nM for all three drugs. Interest in possible extrahepatic effects of reductase inhibitors is based on recent findings that some inhibitors of HMG-CoA reductase, lovastatin and simvastatin, can cause cataracts in dogs at high doses. To evaluate the effects of these drugs on cholesterol synthesis in the lens, we developed a facile, reproducible ex vivo assay using lenses from weanling rats explanted to tissue culture medium. [14C]Acetate incorporation into cholesterol was proportional to time and to the number of lenses in the incubation and was completely eliminated by high concentrations of inhibitors of HMG-CoA reductase. At the same time, incorporation into free fatty acids was not inhibited. In marked contrast to the liver, the dose-response curve for pravastatin in lens was shifted two orders of magnitude to the right of the curves for lovastatin acid and simvastatin acid. The calculated IC50 values were 4.5 +/- 0.7 nM, 5.2 +/- 1.5 nM, and 469 +/- 42 nM for lovastatin acid, simvastatin acid, and pravastatin, respectively. Thus, while equally active in the liver, pravastatin was 100-fold less inhibitory in the lens compared to lovastatin and simvastatin. Similar selectivity was observed with rabbit lens. Following oral dosing, ex vivo inhibition of [14C]acetate incorporation into cholesterol in rat liver was similar for lovastatin and pravastatin, but cholesterol synthesis in lens was inhibited by lovastatin by as much as 70%. This inhibition was dose-dependent and no inhibition in lens was observed with pravastatin even at very high doses. This tissue-selective inhibition of sterol synthesis by pravastatin was likely due to the inability of pravastatin to enter the intact lens since pravastatin and lovastatin acid were equally effective inhibitors of HMG-CoA reductase enzyme activity in whole lens homogenates. We conclude that pravastatin is tissue-selective with respect to lens and liver in its ability to inhibit cholesterol synthesis.     

Lovastatin inhibits bone marrow-derived dendritic cell maturation and upregulates proinflammatory cytokine production

Statins are a group of hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors which are most effective as lipid lowering agents, and are currently extensively used clinically. Recently, it was also shown that statins affect the immune response. We investigated the effects of lovastatin on the maturation and functional changes of bone marrow-derived dendritic cells (BM-DC). Lovastatin inhibited MHC class II and CD40 expression on DC in a dose-dependent manner, but had lesser effects on CD16, CD80, CD86, and CD11b expression. Nuclear extracts of lovastatin treated DC had decreased NF-kappaB DNA binding activity. Although antigen capture capacity of DC was not affected by lovastatin, the T-cell stimulatory activity of DC was inhibited. Lovastatin up-regulated DC pro-inflammatory cytokine production induced by LPS as measured by intracellular cytokine staining, ELISA and cDNA microarrays. Mevalonate, added in vitro, prevented these effects. These results indicate that lovastatin may inhibit BM-DC maturation and up-regulate cytokine production through a mevalonate dependent pathway, and may cause adverse effects on either innate or adaptive immunity.     

An esterase is involved in geraniol production during palmarosa inflorescence development

Total incorporation of exogenously administered [2-14C]acetate into essential oil of palmarosa (Cymbopogon martinii) was found to be relatively higher than that of either [U-14C]sucrose or [U-14C]glucose during inflorescence development. Among the major essential oil constituents, biogenesis of geranyl acetate was much higher than that of geraniol. Alkaline hydrolysis of [14C]labeled geranyl acetate revealed that the majority of the label incorporated into geranyl acetate was present in the geraniol moiety, indicating that only newly synthesized geraniol gets acetylated to form geranyl acetate. Geranyl acetate cleaving esterase (GAE) activity followed a similar pattern during both in vivo and in vitro inflorescence development, with maximum activity at immature inflorescence stages, suggesting the involvement of GAE in geraniol production during inflorescence development. Five esterase isozymes (Est-A to E) were detected in the enzymic fraction of palmarosa inflorescence and all showed GAE activity, with Est-B being significantly increased during inflorescence development. The role of GAE in geraniol production and improving the palmarosa oil quality is discussed.     

Hydrolysis of synthetic esters by the antibacterial agent in serum

Yotis, William W. (Loyola University, Chicago, Ill.). Hydrolysis of synthetic esters by the antibacterial agent in serum. J. Bacteriol. 91:488-493. 1966.-An antistaphylococcal serum agent was assayed colorimetrically, manometrically, and titrimetrically for esterase activity. p-Nitrophenol acetate, triacetin, l-lysine methyl and ethyl ester, and norleucine methyl ester were hydrolyzed by the antistaphylococcal agent. Acetylcholine and benzoylcholine esters, triolein, tristearin, and p-tosylarginine methyl ester were not attacked by this agent. With p-nitrophenol acetate as substrate, optimal activity occurred at pH 7.4. Incubation at 60 C for 30 min reduced drastically the esterase activity of the antistaphylococcal agent, and incubation at 75 C for 30 min abolished the esterase activity of this agent. Almost complete inhibition of esterase activity was observed with 0.001 m HgCl(2), ZnSO(4), and ethylenediaminetetraacetic acid (EDTA). EDTA inhibition could be reversed by the addition of CaCl(2), but not MgCl(2). Cysteine reversed the inhibition of HgCl(2). NaF, atoxyl, diisopropyl fluorophosphate, quinine, and physostigmine did not influence the esterase activity of the antibacterial agent. The demonstration of esterase activity of both the antistaphylococcal agent and coagulase may shed further light on the reported ability of coagulase to neutralize the antistaphylococcal activity of this agent, or the prevention of absorption of the agent on the staphylococcal cell surface. In addition, the colorimetric procedure described in this report may be a convenient tool in assaying the potency of the antistaphylococcal agent.     

Esterases from Bacillus subtilis and B. stearothermophilus share high sequence homology but differ substantially in their properties

A novel esterase from Bacillus subtilis (BsubE) was cloned, functionally expressed in Escherichia coli and biochemically characterized. BsubE shows high homology (74% identity, >95% homology) to an esterase from the thermophilic B. stearothermophilus (BsteE). Both enzymes were efficiently expressed in E. coli, using a L-rhamnose-expression system [11,500 units/l (BsteE), 3,400 units/l (BsubE)] and were purified by Ni-nitrilotriacetic acid chromatography, yielding specific activities of 70 units/mg (BsteE) and 40 units/mg (BsubE), as determined by the hydrolysis of p-nitrophenyl acetate. Despite the high homology, both esterases revealed remarkable differences in their properties. As expected, the esterase from the thermophilic organism showed significantly higher temperature stability. Whereas BsteE showed highest activity at 65-70 degrees C, BsubE was almost inactivated at 50 degrees C. Moreover, both enzymes showed quite different substrate patterns in the hydrolysis of various esters. Whilst the B. subtilis esterase accepted esters with a branched alcohol moiety well, the B. stearothermophilus esterase was more useful in the hydrolysis of substrates with a sterically demanding carboxylic acid group. BsteE showed excellent enantioselectivity ( E>100) in the kinetic resolution of menthyl acetate and even accepted the bulky menthyl benzoate as substrate ( E=19). In contrast, BsubE converted 1-phenethylacetate with higher selectivity ( E>150 vs E=8).     

Effects of lovastatin on biliary lipid secretion and bile acid metabolism in humans

Lovastatin, an inhibitor of HMG-CoA reductase, lowers cholesterol saturation of bile. To determine the mechanism of this effect and further define the role of cholesterol synthesis in regulation of biliary lipid metabolism, we studied ten human volunteers in a control period and again after 5-6 weeks on lovastatin, 40 mg b.i.d. Mean sterol production from acetate in mononuclear leukocytes fell from 1.18 to 0.84 pmol/min per 10(6) cells on lovastatin (P less than 0.02). Concomitantly there was reduction in mean biliary secretion of cholesterol from 143 to 96 mumol/h (P less than 0.02). On lovastatin, mean pool size of bile acids by the Lindstedt method fell from 3193 to 2917 mumol (one-sided P = 0.05) and mean pool size by the one-sample method fell from 5158 to 4091 mumol (P less than 0.002). Lovastatin had no effect on mean fractional turnover rate of either cholic acid (0.77 vs. 0.74 day-1) or chenodeoxycholic acid (0.51 vs. 0.54 day-1). Mean total bile acid synthesis was lower on lovastatin (1443 vs. 1240 mumol/day), but the difference did not quite achieve statistical significance. In humans, inhibition of cholesterol synthesis by lovastatin lowers biliary cholesterol saturation by reducing cholesterol secretion into bile. Bile acid pool size, and perhaps bile acid synthesis, are also reduced by this inhibition.     

Identification of a coronavirus hemagglutinin-esterase with a substrate specificity different from those of influenza C virus and bovine coronavirus

We have characterized the hemagglutinin-esterase (HE) of puffinosis virus (PV), a coronavirus closely related to mouse hepatitis virus (MHV). Analysis of the cloned gene revealed approximately 85% sequence identity to HE proteins of MHV and approximately 60% identity to the corresponding esterase of bovine coronavirus. The HE protein exhibited acetylesterase activity with synthetic substrates p-nitrophenyl acetate, alpha-naphthyl acetate, and 4-methylumbelliferyl acetate. In contrast to other viral esterases, no activity was detectable with natural substrates containing 9-O-acetylated sialic acids. Furthermore, PV esterase was unable to remove influenza C virus receptors from human erythrocytes, indicating a substrate specificity different from HEs of influenza C virus and bovine coronavirus. Solid-phase binding assays revealed that purified PV was unable to bind to sialic acid-containing glycoconjugates like bovine submaxillary mucin, mouse alpha1 macroglobulin or bovine brain extract. Because of the close relationship to MHV, possible implications on the substrate specificity of MHV esterases are suggested.     

Lipophilic but not hydrophilic statins selectively induce cell death in gynaecological cancers expressing high levels of HMGCoA reductase

Recent reports have suggested that statins induce cell death in certain epithelial cancers and that patients taking statins to reduce cholesterol levels possess lower cancer incidence. However, little is known about the mechanisms of action of different statins or the effects of these statins in gynaecological malignancies. The apoptotic potential of two lipophilic statins (lovastatin and simvastatin) and one hydrophilic statin (pravastatin) was assessed in cancer cell lines (ovarian, endometrial and cervical) and primary cultured cancerous and normal tissues. Cell viability was studied by MTS assays and apoptosis was confirmed by Western blotting of PARP and flow cytometry. The expressions of key apoptotic cascade proteins were analysed. Our results demonstrate that both lovastatin and simvastatin, but not pravastatin, selectively induced cell death in dose‐ and time‐dependent manner in ovarian, endometrial and cervical cancers. Little or no toxicity was observed with any statin on normal cells. Lipophilic statins induced activation of caspase‐8 and ‐9; BID cleavage, cytochrome C release and PARP cleavage. Statin‐sensitive cancers expressed high levels of HMG‐CoA reductase compared with resistant cultures. The effect of lipophilic statins was dependent on inhibition of enzymatic activity of HMG‐CoA reductase since mevalonate pre‐incubation almost completely abrogated the apoptotic effect. Moreover, the apoptotic effect involved the inhibition of synthesis of geranylgeranyl pyrophosphate rather than farnesyl pyrophosphate. In conclusion, lipophilic but not hydrophilic statins induce cell death through activation of extrinsic and intrinsic apoptotic cascades in cancerous cells from the human female genital tract, which express high levels of HMG‐CoA reductase. These results promote further investigation in the use of lipophilic statins as anticancer agents in gynaecological malignancies.     

A continuous spectrophotometric assay for the determination of diamondback moth esterase activity

Conventional methods to determine esterase activity from insects are composed of a three-step process where the enzyme is allowed to hydrolyze a 1-naphthyl acetate substrate, that reaction is quenched by a SDS detergent, and then a Fast Blue B dye complex is formed with 1-naphthol, the product of 1-naphthyl acetate hydrolysis. These methods measure dye-product complex rather than the product, 1-naphthol. A new assay is presented that continuously monitors the formation of 1-naphthol with the hydrolysis of an esterase substrate. The esterase activity was determined as the slope of the linear regression change in absorbance over time at 320 nm. The continuous assay provides a simple, rapid, and sensitive method for measuring esterases extracted from a single diamondback moth in 1-10 min. The detection limit of the assay is approximately 0.6 microM 1-naphthol. The 1-naphthol product from the esterase reaction was confirmed by HPLC analysis. According to the assay, the K(m) and V(max) values of the esterase were 28 +/- 2 microM and 6.0 +/- 0.1 microM/min, respectively, at 37 degrees C for 1-naphthyl acetate. The K(i) value was 9 +/- 2 microM using azadirachtin, an insecticide from neem tree, Azadirachta indica (A.Juss). Azadirachtin was a reversible competitive inhibitor of the esterase activity.     

Lovastatin is a potent inhibitor of cholecystokinin secretion in endocrine tumor cells in culture

Lovastatin prevents isoprene synthesis thereby affecting the structural organization of proteins involved in protein transport and secretion. Lovastatin at 1 microM decreases CCK 8 secretion by over 50% in WE cells and in CCK 8 expressing AtT20 cells. At 10 microM CCK 8 secretion was inhibited by two thirds and at 100 microM, cytotoxic effects were observed in both cell types. Addition of mevalonate does not restore CCK secretion and stimulation of secretion by forskolin is also partially inhibited. Cellular content of CCK 8 and pro-CCK were not altered in either of these cell lines except at 100 microM lovastatin. Our results clearly demonstrate that lovastatin at 1 microM strongly inhibits CCK 8 secretion at multiple levels while having little or no effect on its synthesis. This effect on secretion may be partly responsible for the adverse gastrointestinal side effects of lovastatin in patients.     

Tissue selectivity of the cholesterol-lowering agents lovastatin, simvastatin and pravastatin in rats in vivo

Tissue selectivity of lovastatin, simvastatin and pravastatin was determined in male rats. Peak levels of active drug were found in all tissues examined between 0.5 and 2 hours after oral administration. The area under the curve describing 24 hour exposure of the tissues to drug indicated that the drugs were preferentially concentrated in the liver. However, the concentration of pravastatin was approximately 50% that of either lovastatin or simvastatin in the liver and 3-6 times higher in peripheral tissues. These studies demonstrate that the hydrophobic prodrugs, lovastatin and simvastatin show greater selectivity than the hydrophilic agent pravastatin towards the liver which is the target organ for inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A reductase.     

Lovastatin inhibits the growth and survival pathway of phosphoinositide 3-kinase/protein kinase B in immortalized rat brain neuroblasts

We previously showed that lovastatin, an HMG-CoA reductase inhibitor, suppresses cell growth by inducing apoptosis in rat brain neuroblasts. Our aim was to study intracellular signalling induced by lovastatin in neuroblasts. Lovastatin significantly decreases the phosphoinositide 3-kinase (PI3-K) activity in a concentration-dependent manner. Expression of p85 subunit and its association with phosphotyrosine-containing proteins are unaffected by lovastatin. Lovastatin decreases protein kinase B (PKB)/Akt phosphorylation, and its downstream effectors, p70^S6K and the eukaryotic initiation factor 4E (eIF4E) regulatory protein 1, 4E-BP1, in a concentration-dependent manner, and reduces p70^S6K expression. Lovastatin effects are fully prevented with mevalonate. Only the highest dose of PI3-K inhibitors that significantly reduce PI3-K kinase activity induces apoptosis in neuroblasts but to a lower degree than lovastatin. In summary, this work shows that treatment of brain neuroblasts with lovastatin leads to an inhibition of the main pathway that controls cell growth and survival, PI3-K/PKB and the subsequent blockade of downstream proteins implicated in the regulation of protein synthesis. This work suggests that inactivation of the antiapoptotic PI3-K appears insufficient to induce the degree of neuroblasts apoptosis provoked by lovastatin, which must necessarily involve other intracellular pathways. These findings might contribute to elucidate the molecular mechanisms of some statins effects in the central nervous system.     

Biosynthesis and biotechnological production of statins by filamentous fungi and application of these cholesterol-lowering drugs

Hypercholesterolemia is considered an important risk factor in coronary artery disease. Thus the possibility of controlling de novo synthesis of endogenous cholesterol, which is nearly two-thirds of total body cholesterol, represents an effective way of lowering plasma cholesterol levels. Statins, fungal secondary metabolites, selectively inhibit hydroxymethyl glutaryl-coenzyme A (HMG-CoA) reductase, the first enzyme in cholesterol biosynthesis. The mechanism involved in controlling plasma cholesterol levels is the reversible inhibition of HMG-CoA reductase by statins, related to the structural similarity of the acid form of the statins to HMG-CoA, the natural substrate of the enzymatic reaction. Currently there are five statins in clinical use. Lovastatin and pravastatin (mevastatin derived) are natural statins of fungal origin, while symvastatin is a semi-synthetic lovastatin derivative. Atorvastatin and fluvastatin are fully synthetic statins, derived from mevalonate and pyridine, respectively. In addition to the principal natural statins, several related compounds, monacolins and dihydromonacolins, isolated fungal intermediate metabolites, have also been characterized. All natural statins possess a common polyketide portion, a hydroxy-hexahydro naphthalene ring system, to which different side chains are linked. The biosynthetic pathway involved in statin production, starting from acetate units linked to each other in head-to-tail fashion to form polyketide chains, has been elucidated by both early biogenetic investigations and recent advances in gene studies. Natural statins can be obtained from different genera and species of filamentous fungi. Lovastatin is mainly produced by Aspergillus terreus strains, and mevastatin by Penicillium citrinum. Pravastatin can be obtained by the biotransformation of mevastatin by Streptomyces carbophilus and simvastatin by a semi-synthetic process, involving the chemical modification of the lovastatin side chain. The hypocholesterolemic effect of statins lies in the reduction of the very low-density lipoproteins (VLDL) and LDL involved in the translocation of cholesterol, and in the increase in the high-density lipoproteins (HDL), with a subsequent reduction of the LDL- to HDL-cholesterol ratio, the best predictor of atherogenic risk. The use of statins can lead to a reduction in coronary events related to hypercholesterolemia, but the relationship between benefit and risk, and any possible interaction with other drugs, must be taken into account.     

Esterase activity in summer population of sunn pest, Eurygaster integriceps Put. (Hemiptera: Scutelleridae)

A key constraint on increasing wheat production in Iran and some neighbouring countries is Sunn pest which cause severe damage to vegetative growth stage of plant in the early season. It also feeds on wheat grain in late growth stage of plants thus damaged wheat grains loose their bakery properties. Because of injecting protease enzymes into the grain during feeding, enzymes degrade gluten proteins and cause rapid relaxation of dough which results in the production of bread with poor volume and texture. Organophosphorus insecticides are the main pesticides used to control the insect pest. However, suitable reduction in pest population has not been achieved partly due to resistance to pesticides. Esterase plays crucial roles in insect physiology and detoxifies a broad range of xenobiotics including insecticides. Enhanced esterase activity is a major mechanism if insecticide resistance and has been detected in a number of insects. To evaluate esterase activity adult bugs were collected from wheat field in Karaj area of Iran and transferred to the laboratory. For biochemical assay, two adult bugs (either males or females) were homogenized in 500 microl Na-phosphate buffer pH 7.2. The homogenates were centrifuged at 14000 g for 10 minutes at 4 degrees C. The supernatants as the enzyme source were pooled and stored at -20 degrees C for later use. For enzyme assay, 300 microl of supernatant was mixed with equal volume of substrates (30 mM alpha-naphthyl acetate or 30 mM beta-naphthyl acetate) and incubated at 30 degrees C for 30 minutes. Then, 50 microl of fast blue solution (150 mg fast blue B in 15 ml distilled water plus 35 ml 5% SDS) was added and esterase activity was determined in a spectrophotometer at 595 nm. Data showed that there are no differences in esterase activity between male and female. However, There was significant differences between hydrolysis of substrates, alpha-naphthyl acetate and beta-naphthyl acetate. Insect esterase hydrolyzes alpha-naphthyl acetate much more than beta-naphthyl acetate.     

Statins as coronary vasodilators in isolated bovine coronary arteries--involvement of PGI2 and NO

Here we studied direct vasodilation induced by statins in isolated bovine coronary arteries. In rings of coronary bovine arteries preconstricted with prostaglandin F(2 alpha) (3 x 10(-8) - 10(-5)), lovastatin, simvastatin, atorvastatin and cerivastatin (3-30 microM) but not pravastatin induced concentration-dependent vasodilation. Removal of endothelium diminished response to simvastatin, cerivastatin and atorvastatin (30 microM) (67.4+/-4.56 vs. 22.7+/-8.14%, 96.9+/-2.27% vs. 54.5+/-6.86%, 67.4+/-4.01% vs. 34.6+/-5.66%, respectively). In presence of L-NAME (300 microM) or indomethacin (5 microM) responses to simvastatin, atorvastatin and cerivastatin, were also partially diminished. In contrast, lovastatin-induced vasorelaxation was not significantly affected by removal of endothelium (35.6+/-4.19% vs. 28.8+/-5.24%) or by pretreatment with L-NAME or indomethacin. In summary, with the exception of pravastatin, statins act as coronary vasodilators. Simvastatin, cerivastatin and atorvastatin but not lovastatin induced vasodilation displayed endothelium dependent- and endothelium-independent components. The endothelium-dependent effect of statins was mediated by NO and PGI(2), while the mechanism of smooth muscle cells-dependent component remains to be determined.