[alpha]-Asarone inhibits HMG-CoA reductase, lowers serum LDL-cholesterol levels and reduces biliary CSI in hypercholesterolemic rats.
Our results showed that [alpha]-asarone was an inhibitor of hepatic HMG-CoA reductase and that the administration of [alpha]-asarone at 80 mg/kg body wt. for 8 days decreased serum cholesterol by 38% (p < 0.001) in hypercholesterolemic rats. This [alpha]-asarone treatment affected mainly the serum LDL-cholesterol levels, leaving serum HDL-cholesterol lipoproteins unaffected, with a consequent decrease of 74% in the LDL/HDL ratio. In addition, [alpha]-asarone especially stimulated bile flow in hypercholesterolemic rats (60%), increasing the secretion of bile salts, phospholipids and bile cholesterol. The drug also reduced the cholesterol levels of gallbladder bile, whereas the concentration of phospholipids and bile salts increased only slightly, leading to a decrease in the cholesterol saturation index (CSI) of bile in the hypercholesterolemic rats. This CSI decrease and the increase in bile flow induced by [alpha]-asarone may account for the cholelitholytic effect of [alpha]-asarone. It seems that [alpha]-asarone induced clearance of cholesterol from the bloodstream and that the excess of hepatic cholesterol provided by LDL-cholesterol is diverted to bile sterol secretion via a bile choleresis process. The inhibition of HMG-CoA reductase and the increase in bile flow induced by [alpha]-asarone, as well as the decrease in the CSI, could then explain the hypocholesterolemic and cholelitholytic effects of [alpha]-asarone.
Key words: [alpha]-asarone, HMG-CoA reductase inhibitor, hypocholesterolemic, lipoproteins, CSI, bile flow
A native plant from Yucatan, Mexico, called 'yumel' (Guatteria gaumeri Greenman; Annonaceae) has been used as a bark infusion in traditional medicine for the treatment of gallstones (Martinez, 1992). Because cholesterol is the major component of gallstones and this plant has been used to dissolve and eliminate these cholesterol gallstones (Martinez, 1992), a hypocholesterolemic effect was suspected. In accordance with this hypothesis, it was reported that an aqueous-alcoholic extract of G. gaumeri was effective in reducing serum cholesterol in rabbits (Sanchez-Resendiz et al. 1980). Soon after this, Mandoki and his group found that the active principle of G. gaumeri was [alpha]-asarone, (2,4,5-trimethoxy-1-propenylbenzene), since this substance isolated via steam distillation of the dried ground bark of G. gaumeri was able to decrease rat and human serum levels of cholesterol (Mandoki et al. 1980). [alpha]-asarone has also been isolated from this plant using a hexane extraction procedure (Enriquez et al. 1980), and several methods for its synthesis have also been reported (Seshadri and Thiruvengadam, 1950; Diaz et al. 1990), along with methods for the synthesis of [alpha]-asarone isomers (Poplawski et al. 2000). Despite the hypocholesterolemic (Gomez et al. 1987; Garduno et al. 1997) and cholelitholytic (Gomez et al. 1987) effects of [alpha]-asarone being confirmed, the mechanisms of these pharmacological effects of [alpha]-asarone have not yet been established. Therefore, in this investigation, we studied the effect of [alpha]-asarone on the activity of hepatic 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA reductase), the rate-limiting enzyme in cholesterol biosynthesis, and on the balance between circulating lipoproteins-cholesterol level and bile secretion, as well as on the levels of cholesterol, phospholipids and bile salts secreted in bile, in order to find evidences to support a possible mechanism of action of [alpha]-asarone related to its hypocholesterolemic and cholelitholytic effects in hypercholesterolemic rats.
* Materials and Methods
Cholesterol, [alpha]-asarone (2,4,5-trimethoxy-1-propenylbenzene), sodium cholate, sodium pentobarbital, NADPH, NAD, cholestyramine, [sup.14]C-HMGCoA, EDTA, dithiothreitol, bovine serum albumin, Tris-HCl, and 3-[alpha]-hydroxysteroid dehydrogenase were obtained from Sigma Chemical Co. All other chemicals used were of the highest commercially-available grade.
Animals and diet
Fifty male Wistar rats (15 week-old rats, raised in our own breeding unit), divided into five groups, were placed at random in metalcages (5 rats per cage) under normal lighting conditions, with free access to food and water. Two control groups received standard pellet diet and two groups received a hypercholesterolemic diet (standard pellet diet supplemented with 1% cholesterol, 0.2% sodium cholate and 5% olive oil). Four experimental groups were constituted (10 rats per group): normolipemic, normolipemic/[alpha]-asarone-treated, hypercholesterolemic and hypercholesterolemic/[alpha]-asarone-treated. The fifth group (10 rats) was acclimated to an alternate 12-h light-dark cycle for a period of 2-3 weeks. The animals were fed rat chow ad libitum, with containing 5% cholestyramine, for 7 days prior to sacrifice at the mid-dark period, which is the diurnal high point of HMGCo A reductase activity of rat liver microsomes.
In the present study, changes produced by [alpha]-asarone in various biochemical parameters affecting serum cholesterol-lipoproteins levels were determined in normal and hypercholesterolemic rats. The [alpha]-asarone, dissolved in corn oil, was injected subcutaneously at a dose of 80 mg/kg body wt./day for the treated groups, over 8 days at 8:00, after the rats were weighed. At the end of the treatment, all rats were anesthetized with sodium pentobarbital (5 mg/100 g body wt.). The abdomen was opened by a midline incision and bile was collected from the common bile duct cannulated with polyethylene tubing (Clay Adams No. 10). Bile was collected for 60 min and the bile flow, as well as the amount of bile acids, phospholipids, and cholesterol secretions in the bile were determined. In addition, blood was obtained by abdominal aorta puncture and allowed to clot, and serum was collected from all the animals to determine cholesterol and cholesterol-lipoproteins. These animals were fasted overnight prior to blood collection to allow proper evaluation of cholesterol and lipoproteins. Finally, these animals were killed by decapitation and their livers were removed immediately and weighed.
Serum cholesterol and lipoproteins were measured using enzymatic procedures and commercial kits. Serum cholesterol levels and cholesterol in HDL were determined using kits from Lakeside (the monotest cholesterol CHOD-PAP). Cholesterol in LDL was determined using kits from Boehringer Mannheim (the cholesterol-LDL method PSV).
Bile analysis and cholesterol saturation index (CSI)
Total bile acid concentration was estimated by an enzymatic method using 3-[alpha]-hydroxy-steroid dehydrogenase (Duane et al. 1993). Cholesterol concentrations in bile were measured using a commercial kit, as mentioned previously. Phospholipid concentrations were determined via enzymatic method using a comercial kit from BioMerieux. Bile CSI was determined using Carey's critical tables (Carey, 1978).
Isolation and assay of HMG-CoA reductase Microsomes were prepared from livers of the rats maintained on rat chow containing 5% cholestyramine for 7 days. HMG-CoA reductase was solubilized from the microsomes following the method of Heller and Shrewsbery (1976) and purified through the second ammonium sulfate precipitation step as described by Kleinsek et al. (1977). The enzyme preparation was stored at -80[degrees]C in 100 [micro]l aliquots. Prior to use, the enzyme was activated at 37[degrees]C for 30 min. The assay was similar to that described by Beg et al. (1977). The reaction mixture contained in 100 [micro]l: 0.14 M potassium phosphate buffer, pH 6.8; 0.18 M KCl; 3.5 mM EDTA, pH 7.0; 10 mM dithiothreitol; bovine serum albumin at 0.1 mg/ml; 0.04 [micro]Ci of [sup.14]C-HMG-CoA (New England Nuclear; 57.6 mCi/mmol) and 8 [micro]g partially purified enzyme (specific activity 14 nmol [min.sup.-1] [mg.sup.-1]) with or without inhibitor. After incubation for 5 min at 37[degrees]C, the reaction was initiated with 0.2 mM NADPH, and terminated with 20 [micro]l of 5 M HCl. After an additional incubation for 30 min at 37[degrees]C to allow for complete lactonization of the product mevalonate, the mixture was passed over a 0.5 x 5-cm column containing 100-200 mesh Bio-Rex, chloride form (Bio-Rad), which was equilibrated with distilled water. With this resin the unreacted [sup.14]C-HMG-CoA was adsorbed and the product, [sup.14]C-mevalonolactone, was eluted with 3 ml of distilled water directly into scintillation vials. After the addition of 15 ml Aquasol II (New England Nuclear), radioactivities of the samples were measured.
Data from these studies were statistically analyzed using the student's t-test. Values of lipid concentrations and of LDL- and HDL-cholesterol concentrations were expressed as mean [+ or -] SE.
Effect of [alpha]-asarone on levels of serum total cholesterol
After feeding the rats for 8 days with hypercholesterolemic diet, mean serum total cholesterol increased by 40%, from 65.03 [+ or -] 2.3 mg/dl, in rats with normal pelleted diet, and to 92.12 [+ or -] 3.81 mg/dl (Table I) in hypercholesterolemic control rats. Under our experimental conditions, [alpha]-asarone treatment had no effect on the levels of cholesterol in normolipemic rats. In contrast, in rats with high cholesterolemia, [alpha]-asarone reduced this cholesterolemia significantly. Thus, in serum, the levels of cholesterol were 38% lower in the [alpha]-asarone treated hypercholesterolemic rats than in the untreated hypercholesterolemic rats (Table 1).
Effect of [alpha]-asarone on the levels of serum lipoproteins, LDL cholesterol and HDL cholesterol
After [alpha]-asarone-treatment, no changes in the serum levels of LDL cholesterol and HDL cholesterol were observed in normolipemic rats versus untreated control. In the hypercholesterolemic rats, mean serum LDL cholesterol levels declined 78.6%, from 11.21 [+ or -] 2.4 to 2.39 [+ or -] 0.61 mg/dl, and no significant changes were detected in HDL cholesterol (44.78 [+ or -] 3.49 vs 36.71 [+ or -] 3.50). In consequence, the net result was a decrease in the LDL/HDL ratio of 74% (Table 1), indicating that the most important hypocholesterolemic effect of [alpha]-asarone concerned the LDL cholesterol more than the HDL cholesterol levels.
Inhibition of HMG-CoA reductase by [alpha]-asarone
The effect of [alpha]-asarone on the activity of HMG-CoA reductase, the rate-limiting enzyme in cholesterol biosynthesis, was also investigated. As shown in Fig. 1, [alpha]-asarone inhibits the HMG-CoA reductase activity and the concentration of [alpha]-asarone required for 50% inhibition of the enzymatic activity was 2.5 mM.
[FIGURE 1 OMITTED]
Effect of [alpha]-asarone on bile flow and biliary lipid secretion
The [alpha]-asarone (80 mg/kg body wt.) was injected daily into normolipemic and hypercholesterolemic rats and after 8 days of treatment the rats were anesthetized with sodium pentobarbital and equipped with catheters in the bile duct. Bile was then collected for 60 min and the bile flow and the amount of bile acids, phospholipids, and cholesterol secreted in bile were determined. We found that bile flow was accelerated significantly (60%) in the [alpha]-asarone treated hypercholesterolemic rats, from 1.30 [+ or -] 0.11 to 2.08 [+ or -] 0.09 [micro]l/min/g liver. In normolipemic rats, the stimulation of bile flow was only 20%, from 1.24 [+ or -] 0.05 to 1.48 [+ or -] 0.08 (Fig. 2). These increases in bile flow consequently increased biliary lipid secretions especially in hypercholesterolemic rats (Fig. 3).
[FIGURES 2-3 OMITTED]
Biliary lipid concentration and cholesterol saturation index
Subsequently, we also investigated whether administration of [alpha]-asarone influenced biliary lipid concentration and CSI. We found that the biliary concentration of cholesterol in the [alpha]-asarone-treated hypercholesterolemic rats decreased in comparison with that of the hypercholesterolemic control rats (0.80 [+ or -] 0.06 versus 0.6 [+ or -] 0.04 mM, p < 0.05). The concentration of bile acids and phospholipids in the bile were increased significantly in the ([alpha]-asarone-treated hypercholesterolemic rats, from 11.43 [+ or -] 0.52 to 13.18 [+ or -] 0.53 mM (p < 0.025) for bile acids and from 2.94 [+ or -] 0.13 to 3.66 [+ or -] 0.19 for the phospholipids (p < 0.005) (Table 2), leading to a reduction of the CSI from 1.08 [+ or -] 0.02 in the hypercholesterolemic control group, to 0.76 [+ or -] 0.05 (p < 0.005) in the [alpha]-asarone-treated hypercholesterolemic group (Table 2). In normolipemic rats this short-term administration of [alpha]-asarone did not significantly change the biliary lipids concentrations or the CSI (Table 2).
In this investigation, we evaluated the effect of [alpha]-asarone on several biochemical parameters related to the hypocholesterolemic (Gomez et al. 1987; Garduno et al. 1997) and cholelitholytic effects (Gomez et al. 1987) of this substance. In an effort to find evidence to support the possible mechanism of action of [alpha]-asarone, various biochemical parameters affecting serum cholesterol levels were determined in normal and hypercholesterolemic rats. We focused on the inhibition of HMG-CoA reductase, the rate-controlling enzyme in cholesterol biosynthesis, as well on the balance between circulating lipoprotein-cholesterol levels, bile flow and on levels of cholesterol, phospholipids and bile salts secreted in bile. We tested the effect of [alpha]-asarone administered over a short period of time (8 days) that was adequate for the study of possible changes in HDL-cholesterol and LDL-cholesterol metabolism.
We found for the first time that [alpha]-asarone was an active inhibitor of HMG-CoA reductase. We also found that the administration of [alpha]-asarone, for a short period of time, decreased by approximately 40% the total serum cholesterol in hypercholesterolemic rats. This ([alpha]-asarone treatment affected mainly the serum levels of LDL cholesterol, while the serum HDL cholesterol levels were not affected. These findings suggest strongly that the LDL receptor pathway is also operating in these hypercholesterolemic rats. It was also found that the short-term [alpha]-asarone treatment had no effect on the levels of total serum cholesterol in normolipemic rats. These results are in agreement with those reported previously by others (Spady and Cuthbert, 1992; Roach et al. 1993) suggesting that rats have a strong ability to maintain serum cholesterol levels.
In humans, the low-density lipoproteins normally account for two thirds of plasma cholesterol content (Lusis, 2000). When liver or extrahepatic tissues require more cholesterol, there is an increase in the number of LDL receptors on the cell surface, which remove more LDL from plasma via the LDL receptor pathway (Brown and Goldstein, 1986). Conversely, when the need for cholesterol diminishes, LDL-receptor synthesis decreases. This hepatic LDL-receptor pathway is the dominant mechanism for controlling plasma LDL levels in humans and the liver is therefore the key organ in the maintenance of whole body cholesterol homeostasis in most mammals, including human beings (Brown and Goldstein, 1986). Under our experimental conditions in which there was an extensive lowering of serum LDL cholesterol without effect on the absolute amount of HDL cholesterol, the net result was a decrease in LDL/HDL ratio of 74%. These experiments suggest strongly that the [alpha]-asarone-induced reduction in serum cholesterol levels arises mainly from an increased hepatic uptake of LDL-cholesterol lipoproteins induced by the inhibition of HMG-CoA reductase.
Because in humans the greater part of the cholesterol in the body is synthesized de novo, mostly in the liver, the search for drugs to inhibit cholesterol biosynthesis has long been pursued as a means to lower levels of plasma cholesterol. As high levels of serum LDL cholesterol are also correlated with an increased occurrence of atherosclerosis (Lusis, 2000; Hensley and Mansfield, 1999), the therapy for hypercholesterolemia is focused mainly on the induction of LDL receptors in the liver. This process is usually accomplished through inhibition of cholesterol synthesis with HMG-CoA reductase inhibitors (Corsini et al. 1995; Wierzbicki, 2001). Lovastatin, pravastatin, atorvastatin and simvastatin, are some HMG-CoA reductase inhibitors that are effective in lowering serum LDL-cholesterol lipoproteins. In humans, reduction of LDL-cholesterol levels in the range of 20 to 40% are attained routinely using these agents (Wierzbicki, 2001; Vivancos-Mora et al. 1999). In this study using hypercholesterolemic rats we observed a higher decrease in serum LDL-cholesterol levels (78%). Because in rats, LDL cholesterol is not the predominant serum lipoprotein, further studies must be performed to investigate the hypocholesterolemic activity of [alpha]-asarone in an animal more comparable to humans in terms of the lipoprotein profile, in which the predominant serum lipoproteins are the LDL cholesterol (Lusis, 2000).
The major route of excretion of cholesterol is its conversion to bile acids (cholate and chenodeoxycholate) which occurs only in the liver (Arias et al. 1988). Therefore, we investigated whether administration of [alpha]-asarone influenced biliary secretion. The experiments showed that [alpha]-asarone treatment stimulated bile flow in both control and hypercholesterolemic rats. The increase in bile flow observed in [alpha]-asarone-treated hypercholesterolemic rats (60%) cannot be attributed only to the hypercholesterolemic diet, because the short-term administration of [alpha]-asarone also induced a small (20%) but significant (p < 0.05) increase in bile flow in normolipemic rats. The drug significantly stimulated the secretion of bile salts, phospholipids and bile cholesterol, particularly in rats with high cholesterolemia. These effects could be understood on the basis of an increase in the intrahepatic cholesterol flux with [alpha]-asarone treatment. The excess of hepatic cholesterol, as suggested indirectly by our findings with LDL-cholesterol serum levels is diverted to bile secretion, probably due to the direct substrate stimulation of 7-[alpha]-hydroxylase, the rate-limiting enzyme of bile acid synthesis (Vlahcevic et al. 1991), by cholesterol as it was demonstrated in rats (Straka et al. 1990), or the induction of this enzyme by cholesterol at the transcriptional level, also demonstrated in rats (Jones et al. 1992).
In addition, our results also showed that [alpha]-asarone has a particular action in the liver, as this substance stimulated bile flow, inducing bile clearance of excess cholesterol from circulating LDL cholesterol, in the form of bile salts and cholesterol. Bile is a micellar solution the predominant lipids of which are bile acids, the phospholipid lecithin, and cholesterol. The fatty-acid chains of lecithin which form the center of these micelles act as a solvent for cholesterol which is completely insoluble in water (Carey and Small, 1970). Because patients who have cholesterol gallstones have bile that is more saturated or supersaturated with cholesterol than normal subjects, bile saturated or supersaturated with cholesterol is considered as an important first event in the pathogenesis of cholesterol gallstones (Small, 1970). Because in most studies of the effect of HMG-CoA reductase inhibitors on bile composition, the CSI of duodenal bile reduced (Duane et al. 1988; Hoogerbrugge et al. 1990), we also tested this possible effect in the [alpha]-asarone-treated rats, showing that [alpha]-asarone also produced a reduction in the CSI, especially in hypercholesterolemic rats. The drug reduced the cholesterol level of gallbladder bile, whereas the concentration of bile salts and phospholipids (lecithin) were only slightly increased, leading to a decrease in the CSI of hypercholesterolemic rats. This decrease in the CSI and the increase in bile flow induced by [alpha]-asarone may account for the cholelitholytic effect of [alpha]-asarone (Gomez et al. 1987). The increase in bile flow induced by [alpha]-asarone will ensure continual bathing of gallstones with unsaturated bile, and in accordance with Danzinger et al. (1972), if unsaturated bile entered the gallbladder and rapidly took up cholesterol from the liquid phase of stones until saturated with cholesterol, the stones should be dissolved in a few weeks.
These effects of [alpha]-asarone are in agreement with those obtained previously with other HMG-CoA reductase inhibitors like lovastatin (Mitchell et al. 1991), simvastatin (Duane et al. 1988) and pravastatin (Smith et al. 1992), because they decrease biliary cholesterol concentrations and CSI, leading to gallstone dissolution (Smith et al. 1992).
The findings obtained under our experimental conditions showed that [alpha]-asarone induced clearance of cholesterol from the blood stream and the excess of hepatic cholesterol provided by LDL cholesterol is diverted to bile sterol secretion by a bile-choleresis process. These findings suggest via [alpha]-asarone exerts its hypocholesterolemic effect by a mechanism other than the sole inhibition of cholesterol synthesis, possibly by stimulating cholesterol and bile salt secretion via the biliary tract in previously hypercholesterolemic rats. These results are comparable to those obtained with crilvastatin in hypercholesterolemic rats (Clerc et al. 1993). Thus, the inhibition of HMG-CoA reductase and the increase in bile flow induced by [alpha]-asarone, as well as the decrease in the CSI can explain the hypocholesterolemic (Gomez et al. 1987; Garduno et al. 1997) and cholelitholytic effects of [alpha]-asarone (Gomez et al. 1987). These results were clearly due to the drug, because the body weight of the rats, whether treated with [alpha]-asarone or not (did not change, the diet intake thus being unchanged).
Table 1. Serum total cholesterol and lipoprotein cholesterol distribution in rats. Serum cholesterol (mg/dl) Rats Treatment Total (80 mg/kg body wt./day) Normolipemic (n = 10) no-treatment 65.03 [+ or -] 2.3 Normolipemic (n = 10) [alpha]-asarone 62.00 [+ or -] 3.1 Hypercholesterolemic (n = 10) no-treatment 92.12 [+ or -] 3.81 ([dagger]) Hypercholesterolemic (n = 10) [alpha]-asarone 56.83 [+ or -] 3.91 ([dagger][dagger]) Serum cholesterol (mg/dl) Rats Treatment LDL cholesterol (80 mg/kg body wt./day) Normolipemic (n = 10) no-treatment 8.39 [+ or -] 2.50 Normolipemic (n = 10) [alpha]-asarone 8.36 [+ or -] 0.40 Hypercholesterolemic (n = 10) no-treatment 11.21 [+ or -] 2.4 Hypercholesterolemic (n = 10) [alpha]-asarone 2.39 [+ or -] 0.61 ([dagger][dagger] [dagger]) Serum cholesterol (mg/dl) Rats Treatment HDL cholesterol (80 mg/kg body wt./day) Normolipemic (n = 10) no-treatment 37.82 [+ or -] 2.50 Normolipemic (n = 10) [alpha]-asarone 38.10 [+ or -] 1.80 Hypercholesterolemic (n = 10) no-treatment 44.78 [+ or -] 3.49 Hypercholesterolemic (n = 10) [alpha]-asarone 36.71 [+ or -] 3.50 Results are expressed as means [+ or -] S.E., p showed the difference between the [alpha]-asarone-treated and the non-treated groups. ([dagger]) p < 0.005 versus normolipemic no-treatment. ([dagger][dagger]) P < 0.005 versus hypercholesterolemic no-treatment. ([dagger][dagger][dagger])p < 0.005 versus hy-percholesterolemic no-treatment, n = number of rats per group. Table 2. Biliary lipid concentration and cholesterol saturation index (CSI) in normolipemic and hypercholesterolemic rats. Biliary lipid concentration (mM) Rats Treatment Cholesterol (80 mg/kg body wt./day) Normolipemic (n = 10) no-treatment 0.40 [+ or -] 0.03 Normolipemic (n = 10) [alpha]-asarone 0.49 [+ or -] 0.02 * Hypercholesterolemic (n = 10) no-treatment 0.80 [+ or -] 0.06 Hypercholesterolemic (n = 10) [alpha]-asarone 0.60 [+ or -] 0.04 * Biliary lipid concentration (mM) Rats Treatment Bile acids (80 mg/kg body wt./day) Normolipemic (n = 10) no-treatment 5.33 [+ or -] 0.96 Normolipemic (n = 10) [alpha]-asarone 16.36 [+ or -] 0.98 Hypercholesterolemic (n = 10) no-treatment 11.43 [+ or -] 0.52 Hypercholesterolemic (n = 10) [alpha]-asarone 13.18 [+ or -] 0.53 ([dagger]) Biliary lipid concentration (mM) Rats Treatment Phospholipids (80 mg/kg body wt./day) Normolipemic (n = 10) no-treatment 2.30 [+ or -] 0.21 Normolipemic (n = 10) [alpha]-asarone 3.16 [+ or -] 0.15 ([double dagger]) Hypercholesterolemic (n = 10) no-treatment 2.94 [+ or -] 0.13 Hypercholesterolemic (n = 10) [alpha]-asarone 3.66 [+ or -] 0.19 ([section]) Rats Treatment CSI (80 mg/kg body wt./day) Normolipemic (n = 10) no-treatment 0.82 [+ or -] 0.04 Normolipemic (n = 10) [alpha]-asarone 0.78 [+ or -] 0.04 Hypercholesterolemic (n = 10) no-treatment 1.08 [+ or -] 0.02 Hypercholesterolemic (n = 10) [alpha]-asarone 0.76 [+ or -] 0.05 ([section] Results are expressed as means [+ or -] S.E. p, showed the difference between the [alpha]-asarone-treated and the non-treated groups. * p < 0.05. ([dagger]) p < 0.025. ([double dagger]) p < 0.01. ([section]) p < 0.005. n = number of rats per group.
This work was supported partially by research grants from the Coordinacion General de Estudios de Posgrado e Investigacion del Instituto Politenico Nacional (CGEPI-IPN), Mexico. R.P.L., B.I. and W. C. are fellows of the COFAA, IPN, and A.S.J. is a fellow of the PIFI, IPN.
Arias IM, Jakoby WB, Popper H, Schachter D, Shafritz DA (1988) The liver, Biology and pathobiology. Raven Press. N.Y.
Beg ZH, Stonik JA, Brewer HB (1977) Purification and characterization of 3-hydroxy-3-methylglutaryl coenzyme A reductase from chicken liver. FEBS Lett 80: 123-129
Brown MS, Goldstein JL (1986) A receptor-mediated pathway for cholesterol homeostasis. Science 232: 34-47
Carey MC, Small DM (1970) The characteristics of mixed micellar solution with particular reference to bile. Am J Med 49: 590-608
Carey MC (1978) Critical tables for calculating the cholesterol saturation of native bile. J Lipid Res 19: 998-1026
Clerc T, Jomier M, Chautan M, Portugal H, Senft M, Pauli A, Laruelle C, Morel O, Lafont H, Chanussot F (1993) Mechanism of action in the liver of crilvastatin: a new hydroxymethylglutaryl-coenzyme A reductase inhibitor. Eur J Pharm. 235: 59-68
Corsini A, Raiteri M, Soma MR, Bernini F, Fumagalli R, Paoletti R (1995) Pathogenesis of atherosclerosis and the role of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors. Am J Cardiol 76: 21-28
Danzinger RG, Hofmann AF, Schoenfield LJ, Thistle JI (1972) Dissolution of cholesterol gallstones by chenodeoxycholic acid. N Engl J Med 286: 1-8
Diaz F, Contreras I, Flores R, Tamariz J, Labarrios F, Chamorro G, Munoz H (1990) An efficient synthesis of alpha asarone. Org Prep Proc Int 23: 133-138
Duane WC, Hunningnake DB, Freeman ML, Pooler PA, Schlojner L, Gebhurd RL (1988) Simvastatin, a competitive inhibitor of HMG CoA reductase lowers cholesterol saturation index of gallbladder bile. Hepatology 8: 1147-1150
Duane WC, Levitt MD, Elson SKJ (1993) Facilitated method measurement of biliary secretion rates in healthy human. J Lipid Res 34: 859-863
Enriquez RG, Chavez MA, Jauregui F (1980) Propenylbenzenes from Guatteria gaumeri. Phytochemistry 19: 2024-2425
Garduno L, Salazar M, Salazar S, Morelos ME, Labarrios F, Tamariz J, Chamorro GA (1997) Hypolipidaemic activity of alpha-asarone in mice. J Ethnopharmacol 55: 161-163
Gomez C, Chamorro G, Chavez MA, Martinez G, Salazar M, Pages N (1987) Effect de l'alpha-asarone sur hypercholesterolemic et la cholelitiasis experimentales. Plant Med Phytother 21: 279-284
Heller RA, Shrewsbery MA (1976) 3-hydroxy-3-methylglutaryl coenzyme A reductase from rat liver. J Biol Chem 251: 3815-3822
Hensley WJ, Mansfield CH (1999) Lipoproteins, atherogenicity, age and risk of myocardial infarction. Aust N Z Public Health 23: 174-178
Hoogerbrugge VD, Linden N, de Rooy FWM, Jansen H, van Blankenstein M (1990) Effect of pravastatin on biliary lipid composition and bile synthesis in familiar hypercholesterolemia. Gut 31: 348-350
Jones MP, Pandak WM, Heuman DM, Chang JY, Hylemon PB, Blahcevic ZR (1992) Cholesterol 7-alpha-hydroxylase: evidence for transcriptional regulation by cholesterol or metabolic products of cholesterol in the rat. J Lipid Res 34: 385-892
Kleinsek A, Ranganathan S, Porter JW (1977) Purification of 3-hydroxy-3-methylglutaryl-coenzyme A reductase from rat liver. Proc Natl Acad Sci (USA) 74: 1431-1435
Lusis AJ (2000) Atherosclerosis. Nature 407: 233-241
Mandoki JJ, Krumm-Heller C, Vega-Noverola J, Wong-Ramirez C, Arriaga C, Roa R, Rubio C, Mendoza-Patino N (1980) Isolation of [alpha]-asarone from the bark of Guatteria gaumeri (Elemuy) and the study of its hypocholesterolemic effect. IV National Congress of Pharmacology, University of Yucatan. Merida, Yucatan, Mexico
Martinez M (1992) Las plantas medicinales de Mexico. 6a ed. Mexico. Ed. Botas
Mitchell JC, Logan GM, Stone BG, Duane NC (1991) Effect of lovastatin on biliary secretion and bile acid metabolism in humans. J Lipid Res 32: 71-78
Poplawski J, Lozowicka B, Dubis AT, Lachowska B, Witkowski S, Siluk D, Petrusewicz J, Kaliszan R, Cybulski J, Strzalkowska M, Chilmoneczyk Z (2000) Synthesis and hypolipidemic and antiplatelet activities of alpha-asarone isomers in humans (in vitro), mice (in vivo), and rats (in vivo). J Med Chem 43: 3671-3676
Roach PD, Balasubramaniam S, Hirata F, Abbey M, Szanto A, Simons LA, Nestel PJ (1993) The low-density lipoprotein receptor and cholesterol synthesis are affected differently by dietary cholesterol in the rat. Biochim Biophys Acta 1170: 165-172
Sanchez-Resendiz J, Lerdo de Tejada A, Gonzalez-Vite J, Guzman R, Tinoco A, Karchmer S (1980) Accion hipocolesterolemiante de Guatteria gaumeri. Med Trad 3: 20-22
Seshadri TR, Thiruvengadam TR (1950) A new synthesis of asarone. Proc Ind Acad Sci 32A: 110-113
Small DM (1970) The formation of gallstones. Adv Intern Med 16: 243-264
Smith OJ, Erkelens DW, Von Berger Henegorwen GP (1992) Successful dissolution of cholesterol gallstones during treatment with pravastatin. Gastroenterol 103: 1068-1070
Spady DK, Cuthbert JA (1992) Regulation of hepatic sterol metabolism in the rat. Parallel regulation of activity and mRNA for 7 alpha-hydroxylase but not 3-hydroxy-3-methyglutaryl coenzyme A reductase or low density lipiprotein receptor. J Biol Chem 267: 5584-5591
Straka MS, Junker LH, Zacarro L, Zogg DR, Dueland S, Everson GT, Davis RAJ (1990) Substrate stimulation of 7-alpha-hydroxylase, an enzyme located in the cholesterol-poor endoplasmic reticulum. J Biol Chem 265: 7145-7149
Vivancos-Mora J, Leon-Colombo T, Monforte-Dupret C (1999) Hypolipemic treatment in the prevention of atherosclerotic plaque complications. Rev Neurol 29: 857-863
Vlahcevic ZR, Heuman DM, Hylemon PB (1991) Regulation of bile acid synthesis. Hepatology 13: 590-600
Wierzbicki AJ (2001) Atorvastatin. Expert Opin Pharmacother 2: 819-830
C. Wong, Departamento de Bioquimica, Escuela Nacional de Ciencias Biologicas, Instituto Politecnico Nacional, Apartado Postal 4-129, Admon. 4, Mexico City, 06401, Mexico
Tel. and Fax: ++52-5-57-29-60-00 ext 62321; e-mail: email@example.com
L. Rodriguez-Paez, M. Juarez-Sanchez, J. Antunez-Solis, I. Baeza, and C. Wong
Departamento de Bioquimica, Escuela Nacional de Ciencias Biologicas, Instituto Politecnico Nacional, Mexico City, Mexico
|Printer friendly Cite/link Email Feedback|
|Title Annotation:||cholesterol saturation index|
|Author:||Rodriguez-Paez, L.; Juarez-Sanchez, M.; Antunez-Solis, J.; Baeza, I.; Wong, C.|
|Publication:||Phytomedicine: International Journal of Phytotherapy & Phytopharmacology|
|Date:||Jun 1, 2003|
|Previous Article:||Effect of Azadirachta indica on paracetamol-induced hepatic damage in albino rats.|
|Next Article:||Modulatory effect of Urtica dioica L. (Urticaceae) leaf extract on biotransformation enzyme systems, antioxidant enzymes, lactate dehydrogenase and...|