Benificial Effect of Allium sativum and Allium tuberosum on Experimental Hyperlipidemia and Atherosclerosis – a Comparative Evaluatio








ABSTRACT :-
43 guinea pigs were fed cholesterol (0.5g per kg. body weight) for an initial period of four weeks. Cholesterol was then discontinued and they were divided into three groups. Group I (n=7) was fed stock diet while group II (n=18) was given 2 gm. per kg. body weight of alliums sativum daily for 4 weeks. Group III (n=18) was supplemented by alliums tuberosum species of garlic (2gm/kg. body weight) daily for 4 weeks period. In present study both the species of garlic (A Sativum, A tuberosum) showed significant hypolipidemic activity as they reduces serum cholesterol, triglyceride, L.D.L.C & atherogenic Index in hyperlipidemic guineapigs (p<.01). The significant rise in HDLC level was not observed. On comparison between alliums sativum & alliums tuberosum it was found that allium tuberosum very significantly reduced serum cholesterol & serum triglycerided, LDL-C & atherogenic index (P<.05). Allium tuberosum species of garlic was found more potent (p<.05) then allium sativum in reducing severity of atherosclerosis. In view of this it can be concluded that allium tuberosum species of garlic might be a beneficial hypolipidemic & antiatheroselerotic agent.




INTRODUCTION :-
Naturally occurring Sulphur containing compounds present in the Allium family may influence plasma cholesterol and atherosclerosis1. These substances are found especially in garlic, onion and leeks, the most prominent of these being garlic2. The garlic preparations showed significant reduction on serum cholesterol levels in clinical3 as well as experimental studies4.
Allium Sativum has been reported to exhibit beneficial effects in atherosclerosis and ischemic heart disease in experimental animals and human beings5-6.
Most commonly used species of garlic in India is Allium Sativum, while Allium tuberosum species is mainly consumed and cultivated in south-east Asia, China and north-east part of India. Since these plants form the constituent of customary diet in Indian & Chinese food, their chronic ingestion is safe and is expected to be of benefit largely in persons prone to hyperlipidemia and atherosclerosis. Till now no study has been carried out to compare the beneficial effect of these two species of garlic against hyperlipidemia hence this study was under taken to discover the relative potency of these agents with respect to their anti-hyperlipidemic effect & curative potential against atherosclerosis.

MATERIAL & METHODS :-
The study was conducted in healthy guinea pigs of either sex weighing 510 + 42 gm. These were randomly divided into three groups. Group I (n=7), Group II (n=18), Group III (n=18). In all three groups experimental hyperlipidemia was induced by feeding cholesterol (500 mg/kg body wt. per day) in 5 ml milk, for 4 weeks. After – that cholesterol feeding was stopped & group II & group III animals were supplemented with (4gm/kg. body weight per day) of Allium Sativum & Allium tuberosum species of garlic, respectively for 4 weeks. The garlic bulbs were pealed off & crushed in sufficient water & homogenized in blender before tube feeding to the animals.
While group – I animals were given 1 ml of normal saline for 4 weeks period.
All the animals were anesthetized with pentobarbiton (35 mg/kg i.p.) and fasting blood samples were collected carefully from the right ventricle of heart. The blood samples were collected at on set of study, at 4 weeks duration & finally at the end of study that is at 8 weeks period, for the estimation of serum cholesterol7, S. triglyceride8, LDL-C, HDL-C9, VLDL-C & atherogenic index.
At 8 weeks duration Aortae were excised & studied for atherosclerotic lesions which were graded as per the method described by Duff & Mc Millan10. The method of grading was open. All the animals received a common stock diet (bran & fresh vegetables) & water adilib for the period of study. The result’s were analyzed by ANOVA & Newman-Keuls procedure & Fisher’s exact probability test.


RESULT :
EFFECT ON SERUM CHOLESTEROL, TRIGLYCERIDE, LDLC, HDL-C, VLDL-C, & ATHEROGENIC INDEX :
Table 1 – illustrated the effect of normal saline feeding & treatment with crushed Allium Sativum & Allium tuberosum on hyperlipidemic guinea pigs. On comparison with group-I both the species of garlic produce significant reduction in serum cholesterol, triglycerides, LDL-C & atherogenic index (P<.01). There was no significant rise in HDLC level. On comparison between Allium Sativum & Allium tuberosum species of garlic it was found that Allium Tuberosum very significantly reduces serum cholesterol, S.triglyceride, LDL-C & atherogenic index (P<.05).
EFFECT ON ATHEROSCLEROTIC LESIONS :
The distribution of grades of atherosclerotic lesions in all the 3 groups is shown in Table-2. Since these grades do not confirm to a normal distribution curve, a non parametric test (Fisher’s exact probability test) was applied to analyse the result11. For this, each set of result’s was arbitrarily arranged in to two groups, group A containing 0 to II grades and group B containing III & IV grades. The result’s of both the groups were compared & the probability of difference was calculated. Allium tuberosum & sativum was found to reduce the development of atherosclerotic lesions induced by atherogenic diet (P<.01). On comparison between these two species of garlic, Allium tuberosum was found more potent (P<.05) then Allium Sativum in reducing atherosclerosis.
TABLE -1
EFFECT OF ALLIUM SATIVUM & ALLIUM TUBEROSUM ON LIPID PROFILE OF HYPERLIPIDEMIC GUINEA-PIGS
GroupLipid Profile Parameters Group –I(n=7) Normal Saline feeding Group –II(n=18) A. Sativum feeding Group –III (n=18) A. Tuberosum feeding Result of ANOVA test
S. Cholesterol 94.49+ 8.71 60.17*+ 14.31 46.70** + 12.90 F(2,40)=235.11P<.01
S. Triglyceride 91.84+ 5.86 65.61*+ 11.36 57.53**+12.28 F(2,40)=23.92P<.01
HDL-C 11.43+ 0.98 12.22+ 1.40 12.78+ 1.70 F(2,40)=2.18P>.05
LDL-C 64.70+ 7.70 34.82+ 13.09 22.42**+ 10.62 F(2,40)=34.80P<.01
VLDL-C 18.37+ 1.17 13.13*+ 2.30 11.5+ 2.46 F(2,40)=-5.26P>.05
Atherogenic# Index 5.70+ 0.91 2.94*+ 1.26 1.75**+ 0.85 F(2,40)=35.26P<.01

For – Comparison between different groups Newman-Keuls procedure was applied

* P < .05 on comparison to group- I.
** P < .05 on comparison to group-II & group-I
# Atherogenic Index = LDL-C/ HDL-C

TABLE – 2
EFFECT OF A. SATIVUM AND A. TUBEROSUM ON GRADES OF ATHEROSCLEROSIS IN HYPERLIPIDEMIC GUINEA-PIGS

Group No. of animals showing atherosclerosis
Grades
0 I II III IV
A B
Group – I 0 0 3 3 1
Group – II * 0 5 7 6 0
Group – III ** # 0 9 6 3 0

Fisher’s exact probability test is applied for p value :-
* p = .009 ** p = .007 on comparison to group-I.
# p = .012 on comparison to group II.
DISCUSSION : -
Hyperlipidemia is one of the major risk factor for the
development of atherosclerosis. It is associated with high rate of cardiovascular morbidity & mortality. Various agents, which affect hyperlipidemia, are still not used for prevention or cure of atherosclerosis because of their potential toxicity and intolerance.
Garlic has been reported to minimize the adverse effects of hyperlipidemia12 and is well tolerated as it forms one of the important constituents of kitchen recipes in India. Bordia and verma13 as well as jain14 have shown the reversibility of cholesterol induced experimental atherosclerosis in rabbits by garlic.
Among the risk factors identified for coronary artery disease, lipids are of utmost importance. Risk of coronary artery disease is proportional to the antecedent, Cholesterol level.15 Garlic contains sulphur containing compound allin, which is converted to active ingredient 'allicin' when the garlic bulb is crushed. This compound has an inhibitory effect upon the key enzymes involved in cholesterol biosynthesis, such as HMG-CoA reductase 16. Hypocholesterolemic effect of garlic is exerted by decrease in hepatic cholesterogenesis, where as the triacylglycerol lowering effect appears to be due to inhibition of fatty acid synthesis, by mallic enzymes, fatty acid synthatase, & glucose -6 phosphate dehydrogenase17 Garlic helps to prevent lipid implantation on the arterial wall18. Orekhov19 suggested that garlic powder extract inhibited lipid synthesis both in normal & atherosclerotic cells cultured in vitro from human aortic cell. Jain20 suggested that garlic may act by increasing the excretion of cholesterol end products and by affecting it's synthesis in the liver. Aqueous garlic extract also made the LDL significantly resistant to oxidation, it may be one of the powerful mechanism accounted for the benefits of garlic in athero- sclerosis.21 Garlic also prevents fall of HDL, which is nonatherogenic and transfers cholesterol from the periphery to the liver22. Yeh etal.17 shows that water soluble sulphur compounds of garlic like s-allylcysteine, s-ethylcysteine, & s-propylcystein inhibited the cholesterol synthesis significantly on comparison to lipid soluble sulphur compounds of garlic which inhibited cholesterol synthesis slightly .
In the present study too, both the species of garlic( Allium sativum and allium turberosum) showed significant hypolipidemic activity as they reduces serum cholesterol, triglyceride, LDL in hyperlipidemic guineapigs. But the significant rise in HDL was not observed. These agents were also found to confer protection against atherogenic diet induced atherosclerosis. The most potent amongst these two species was found to be allium tuberosum for reduction of hyperlipidemia & athoerosclerosis.
In view of this it can be concluded that Allium tuberosum might be a beneficial hypolipidemic & anti- atherosclerotic agent.

REFERENCES :
1 Banerjee SK, Maulik SK. Effect of garlic on cardio- vascular disorders: a review. Nutr j 2002; 1(1): 4.
2 Block, E. The chemistry of garlic and onion. Sci Am 1985; 252 : 114-119.
3 Andrianova IV, Demidova OM, Medvedeva LA, et al. Correction of hyperlipidemia with Allicor ( Article in Russion ) Klin Med ( Mosk ) 2004; 82(4) : 56-8.
4 Chetty KN, Calahan L, Harris KC etal . Garlic attenuates hypercholesterolemic risk factors in olive oil fed rats and high cholesterol fed rats. Pathophysiology 2003; 9(3) : 127-132.
5 Bordia A Verma SK. Effect of garlic feeding on regression of experimental atherosclerosis in rabbits. Artery 1980; 7(5): 428-37.
6 Arora RC, Arora S, Gupta RK. The long term use of garlic in ischaemic heart disease. Atherosclerosis 1981; 40: 175-179.
7 Allain CC, Poon LS, Chan CSG, et al. Enzymatic determination of total serum cholesterol. Clin Chem. 1974; 20: 470.
8 Fossati P, Prencipe L. Clin Chem. 1982; 28:2077.
9 Finely PR, Schifman RJ, Lichti DA. Cholesterol in high density lipoprotein; use of Mg/ PTA in it’s enzymatic measurement. Clin Chem 1978; 24 (6): 931-3.
10 Duff GL, Mcmillan GC. The effect of alloxan diabetes on experimental cholesterol athero- sclerosis in the rabbit I The inhibition of experimental cholesterol athersclerosis in alloxan diabetes. II The effect of alloxan diabetes on the retrogression of experimental cholesterol athero sclerosis. J Exp Med 1976; 64:1509-1515.
11 Seisgul S In: “ Non- parametric statistics for Behavioral Sciences” New York: McGraw Hill Book Co, Inc; 1956 pp 96-98.
12 Bordia A, Bansal HC, Arora SK, et al. Effect of the essential oil (active principle) of garlic on serum cholesterol, plasma fibrinogen, whole blood coagulation time and fibrinolytic activity in alimentary lipaemia. J Assoc Phys Ind .1974;22:267-270.
13 Bordia A, Verma SK. Garlic on the reversibility of experimental atherosclerosis. Ind Heart J 1978,30:47-50.
14 Jain RC. Onion and garlic in experimental cholesterol induced atherosclerosis. Ind J Medical Res 1976; 64:1508-1515.
15 Kannel WB, William PC, Gorden T, et al. Serum cholesterol and lipoproteins and the risk of coronary heart disease. Ann Int Med 1971; 74:1-12.
16 Schulz V, Hansel R, Tyler V, et al. Rational phytotherapy: A physician’s guide 5th ed. Berlin: Springer Verlag; 2004.
17 Yeh YY, Liu L Cholesterol lowering effect of garlic extracts and organosulfur compounds: Human and animal studies. J Nutr. 2001; 131(3s): 389s-93s.
18 Abramovitz D, Gavri S, Harats D, et al. Allicin induced decrease in formation of fatty streaks (athesosclerosis) in mice fed a cholesterol rich diet. Coronary Artery Disease 1999:10:515-519.
19 Orekhov, AN, Grunwald J. Effect of garlic on atherosclerosis. Nutrition 1997; 13:656- 663.
20 Jain RC. Onion and garlic in experimental cholesterol induced athersclerosis. Ind J Medical Res 1976; 64:1508-1515.
21 Lau Benjamin, HS. Suppression of LDL oxidation by garlic. J Nutr 2001; 131(3s) : 9585-9885.
22 Bordia A, Varma SK, Khabia BL, et al. The effect of active principle of garlic and oninon on blood lipids and experimental atherosclerosis in rabbits and their comparison with clofibrate. J Assoc Phys Ind 1977; 25:509-516.