الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 183 |  |  |
| | | from | 183 | | |
Abstract
High cholesterol diet is regarded as a crucial factor in the development of hypercholesterolemia, atherosclerosis and ischemic heart disease. Cardiovascular disease is the primary cause of mortality in the world. In recent years, great efforts have been focused on natural compounds and herbal constituents without toxic effects to provide novel therapeutic agents for hypercholesterolemia.
Therefore, this study was carried out to evaluate the protective effects of steroidal saponins extracted from fenugreek and asparagus, and triterpenoidal saponins extracted from soapwort and licorice against hypercholesterolemia induced by feeding of rats on a high cholesterol diet. The present study was also aimed to compare between the efficacies of both types of saponins (steroidal and triterpenoidal) in these plant extracts against hypercholesterolemia in rats. In order to achieve these objectives, the following biological experiment was carried out:
Thirty six male Albino rats of Wistar strain weighing about 100g were obtained from the farm of experimental animals in Helwan, Cairo, Egypt. The rats were housed under normal laboratory conditions. The rats had free access food and water ad libitum during the experiment period. The rats were randomly divided into 6 groups (n = 6), and the first one was fed on a basal diet and served as a normal control group. The other groups of rats were fed on a high cholesterol diet formulated form cholesterol (1%), bile salts (0.25%) and coconut butter (15%) instead of equal percentages of corn starch in the basal diet. The second group of rats received the high cholesterol diet without any plant extract and served as a negative control group. The other four groups of rats were fed on the high cholesterol diet plus various plant (fenugreek, asparagus, soapwort and licorice) extracts during the experiment period (6 weeks). The various plant extracts were administered orally for the rats by using a stomach tube every day at a dose of 250 mg/kg body weight. The protective effect of various saponin extracts were monitored through assays of total cholesterol (TC) and triglycerides (TG) in blood, liver tissues and feces of the rats as well as other blood biochemical analyses and histological examinations of liver tissues. The obtained results can be summarized as follows:
1. Effect of saponin extracts on the lipid profile in serum of rats affected with hypercholesterolemia.
The results showed a significant (P<0.05) increase in the levels of total cholesterol (TC), triglycerides (TG), low density lipoprotein cholesterol (LDL), very low density lipoprotein cholesterol (VLDL), and a significant (P<0.05) decrease in the level of high density lipoprotein cholesterol (HDL) in serum of rats treated with HCD only in negative control compared to normal control. The protective effects of various saponin extracts (fenugreek, asparagus, soapwort and licorice) were proved by decreasing the levels of TC, TG, LDL and VLDL, and increasing the level of HDL to approach their normal values in serum of rats administered these plant extracts. No significant (P<0.05) differences were noticed among the protective effects of all investigated plant extracts against hypercholesterolemia in rats. It means that both types of saponins (steroidal and triterpenoidal) exhibited approximately the same efficiency in their protective effects against hypercholesterolemia.
2. Effect of saponin extracts on the lipid profile in liver of rats affected with hypercholesterolemia.
The results revealed a significant (P<0.05) increase in the levels of total cholesterol (TC) and triglycerides (TG) in liver of rats treated with HCD only in normal control compared to negative control. The protective effects of various saponin extracts (fenugreek, asparagus, soapwort and licorice) were established by obtaining the levels of TC and TG near to their normal values in liver of rats administered these plant extracts. It can be observed that saponins extracted from fenugreek and licorice were effective than those extracted from asparagus and soapwort in lowering of triglycerides in liver of rats administered these plant extracts.
3. Effect of saponin extracts on the lipid profile in feces of rats affected with hypercholesterolemia.
The data indicated a significant (P<0.05) increase in the levels of total cholesterol (TC) and triglycerides (TG) in feces of rats treated with HCD plus various plant extracts compared to normal and negative controls. The inhibition of cholesterol absorption from the intestine, and the inhibition of pancreatic lipase induced by saponin extracts led to decrease of absorbed cholesterol and fats from the intestine into blood circulation and liver, and increase the excretion of cholesterol and fats in feces of rats fed on these plant extracts. The data also illustrate that total cholesterol contents in feces of rats that received steroidal saponins extracted from fenugreek and asparagus were significantly higher than those in feces of rats that received triterpenoidal saponins extracted from soapwort and licorice. Conversely, triglycerides contents in feces of rats that received steroidal saponins extracted from fenugreek and asparagus were significantly lower than those in feces of rats that received triterpenoidal saponins extracted from soapwort and licorice.
4. Effect of saponin extracts on the liver profile of rats affected with hypercholesterolemia.
The data showed a significant (P<0.05) increase in the levels of all liver enzymes (AST, ALT, ALP and GGT) of rats treated with HCD only in negative control compared to normal control. The protective effects of various saponin extracts (fenugreek, asparagus, soapwort and licorice) were established by occurrence the levels of these enzymes near to their normal values in serum of rats administered these plant extracts. The data also demonstrate that the activities of ALP enzyme in serum of rats that received steroidal saponins extracted from fenugreek and asparagus were comparable to those in serum of rats of control group, and frequently lower than those in serum of rats that received triterpenoidal saponins extracted from soapwort and licorice. There were no significant (P<0.05) differences in the levels of total bilirubin (TB) and total protein (TP) in serum of rats of all treatments compared to negative and positive controls during the experiment period.
5. Effect of saponin extracts on the heart profile of rats affected with hypercholesterolemia.
The results demonstrated a significant (P<0.05) increase in the levels of CPK and LDH in serum of rats treated with HCD only in negative control compared to normal control. The protective effects of various saponin extracts (fenugreek, asparagus, soapwort and licorice) were evidenced by appearance the levels of CPK and LDH enzymes near to their normal values in serum of rats administered these plant extracts.
6. Effect of saponin extracts on the blood sugar level of rats affected with hypercholesterolemia.
The data showed a significant (P<0.05) increase in the levels of serum glucose of rats treated with HCD only in negative control (161.3 ± 7.3 mg/dl) compared to normal control (110.6 ± 9.2 mg/dl). The protective effects of various saponin extracts (fenugreek, asparagus, soapwort and licorice) were established by occurrence the glucose level near to their normal values in serum of rats administered these plant extracts.
7. Effect of saponin extracts on the kidney profile of rats affected with hypercholesterolemia.
There were no significant (P<0.05) differences in the levels of urea, creatinine and uric acid in serum of rats for all treatments compared to normal and negative controls. It means that hypercholesterolemia induced by feeding on HCD did not cause any adverse effects on kidney tissues during the experiment period (6 weeks).
8. Effect of saponin extracts on the liver histology of rats affected with hypercholesterolemia.
Liver of rat from normal control group showed the normal histological structure of hepatic lobule. However, liver of rats from negative control group which affected with hypercholesterolemia revealed fatty change of hepatocytes and sinusoidal leukocytosis. Liver of rats treated with asparagus showed slight activation of kupffer cells, whereas most examined sections from this group revealed no histopathological changes. Moreover, liver of rats treated with licorice showed no histopathological changes except cytoplasmic vacuolization of centrilobular hepatocytes in few examined sections. Liver of rats treated with soapwort showed binucleation of hepatocytes, whereas most cases from this revealed no histopathological changes. Some examined sections from rats treated with fenugreek revealed cytoplasmic vacuolization of hepatocytes and slight activation of kupffer cells whereas other sections showed no histopathological changes.