Investigation of antihypertensive mechanism of garlic in 2K1C hypertensive rat
Introduction
Garlic (Allium sativum L.) has long and widely been used not only as a flavoring agent but also as a folk medication.
There is compelling evidence, suggesting various pharmacological properties of garlic opposing microbial infection, thrombosis, hypertension, hyperglycemia, hyperlipidemia, cancer as well as being a healing agent (Pedraza-Chaverri et al., 1998).
Garlic preparations contain a wide variety of organosulfur compounds in which allicin is the most notable and it is responsible for the characteristic garlic odor. Allicin and other thiosulfinates are found in crushed, chewed or chopped garlic when cellular membrane is disrupted. This brings the precursor compound Allicin (S-allyl-l-cysteine sulfoxide) in contact with the enzyme “Allinase” (Jansen et al., 1989, Yu et al., 1989).
Several reports have also suggested that fresh garlic extract has protective actions against cardiovascular disorders including: stroke, coronary artery disease, arteriosclerosis and hypertension (Bordia et al., 1977, Bordia et al., 1978, Chutani and Bordia, 1981). These beneficial effects have partly been attributed to its ability to inhibit platelet aggregation and thromboxane formation (Bordia, 1978, Makheia et al., 1979, Samson, 1982). Blood pressure lowering effect of garlic has been reported not only in spontaneously hypertensive rats (Foushee et al., 1982, Samson, 1982), 2K1C rats (Al-Qattan et al., 1999) and hypertensive patients (Zheziang Institute of Traditional Chinese Medicine, 1986) but also in normotensive animals (Banerjee, 1979).
Various mechanisms for antihypertensive effect of garlic are being reported including: hyperpolarization of human coronary artery by opening K+ channels as well as stimulation of nitric oxide synthesis (Pedraza-Chaverri et al., 1998) causing vasodilatation.
The rennin–angiotensin–aldosteron system (RAAS) plays an important role in the control of cardiovascular homeostasis affecting both blood pressure and fluid volume and is one of the most important etiological candidates in hypertension (Sealy and Laragh, 1995). It is now well documented that all the components of this enzymatic pathway may reside within several individual organs or tissues such as kidneys, lung, heart and vascular smooth muscle cells (Dzau, 1988). The presence of angiotensin-converting enzyme (ACE) and other components of rennin–angiotensin system in arteries indicates that angiotensin II can be locally formed in the arterial wall, inducing both structural and functional changes in hypertension (Saavedra et al., 1992) and plays an important role in elevation of peripheral vascular resistance (Li et al., 1997). It has been known that arterial ACE is high in both genetic (Nakata et al., 1987, Nakamura et al., 1988) and experimental (Miyazaki et al., 1988) models of hypertension in rat and it is correlated with elevation of blood pressure (Nakata et al., 1987). Moreover, ACE inhibitors are one of the widely used antihypertensive drugs in the treatment of patients with essential and renovascular hypertension (Unger et al., 1990).
Using herbal medications instead of chemical drugs because of minor side effects have always been one of the wishes of human being for years. In spite of important role of garlic in prevention and controlling cardiovascular disorders, its precise mechanism of action is unknown.
The present study, therefore, investigated the antihypertensive mechanism of garlic in 2K1C hypertensive rats by measurement of circulatory and local ACE activity in aorta, heart, kidney and lung.
Section snippets
Animals
Thirty-two normotensive age matched male Wistar rats with a body weight ranging between 180–220 g were selected and divided into four groups of eight rats including: unoperated group “CTL”, sham-operated group “SHAM”, hypertensive group “H” and garlic-treated hypertensive group “GT”.
The rats were kept for 2 weeks before induction of hypertension at normal physical conditions (22–25 °C, 25–35% humidity and regular day/night cycle) and fed with standard diet and tap water.
Induction of 2K1C hypertension
Following general
Blood pressure measurement
The SBP in “CTL”, “SHAM”, “H” and “GT” groups during the week before surgery were 90±3 mmHg, 89±5 mmHg, 91±4 mmHg and 88±3 mmHg, respectively, which were increased to 91±4 mmHg, 92±3 mmHg, 125±6 mmHg and 126±5 mmHg 4 weeks after surgery (before starting the treatment).
Surgical procedure used for 2K1C produced a rise in SBP in “H” group, which was significantly higher than that of age matched “SHAM” and “CTL” rats (P<0.01, Fig. 1).
There was no significant difference in SBP between “SHAM” and “CTL” group
Discussion
High blood pressure is a risk factor for stroke, coronary heart disease and renal vascular disease. The control of hypertension through diet has been the focal point of public health and mass media attention. The usual method for controlling hypertension is the use of long-term drug therapy. Drugs have many side effects that can complicate the clinical problem. That is why medical professionals and even most of patients prefer herbal medicine and preventive strategies.
Garlic has been used as a
Acknowledgements
The authors would like to thank Cellular and Molecular Research Center of Iran University of Medical Sciences for providing the instruments.
References (29)
- et al.
The antihypertensive effect of garlic (Allium sativum L.) in the rat two-kidney-one-clip Goldblatt model
Journal of Ethnopharmacology
(1999) Effect of garlic on human platlet aggregation in vitro
Atherosclerosis
(1978)- et al.
Effect of essential oil of onion and garlic on experimental atherosclerosis in rabbits
Atherosclerosis
(1977) - et al.
The effect of fried versus raw garlic on fibrinolytic activity in man
Atherosclerosis
(1981) - et al.
Method for determination of angiotensin-converting enzyme activity in blood and tissue by high performance liquid chromatography
Journal of Chromatography
(1982) Effects of dietary garlic on temporal drift on platlet aggregation
Atherosclerosis
(1982)Effect of aqoueuos extract of garlic on arterial blood pressure of normotensive and hypertensive rats
Artery
(1979)- et al.
Effects of essential oil of garlic on serum fibrinolytic activity in patients with coronary artery diseases
Atherosclerosis
(1978) - Dunn, J.M., 1986. The relationship of prostaglandin and thromboxane to the pathophysiology of renal disease and...
Circulating versus local rennin–angiotensin system in cardiovascular homeostasis
Circulation
(1988)
Garlic as a natural agent for the treatment of hypertension: a preliminary report
Cytobios
Characterizations of an alliin lyase preparation from garlic (Allium sativum)
Planta Medica
Effects of onion and garlic extracts on spontaneously hypertensive rats.
Phytotherapy Research
Cited by (82)
Regulation of blood pressure by natural sulfur compounds: Focus on their mechanisms of action
2022, Biochemical PharmacologyIn vitro and in vivo antihypertensive and antioxidant activities of fermented roots of Allium hookeri
2021, Chinese Herbal MedicinesCitation Excerpt :In the present study, the SHR rats treated with ALP, ALM, or AWC had lower plasma ACE activity compared with control rats, and no significant difference in plasma ACE activity was found among the ALP, ALM, or AWC groups (Fig. 5A). Similar to our results, garlic is reported to exert a significant effect in reducing blood pressure in 2K1C hypertensive rats and its antihypertensive effects of garlic is thought to be partly due to inhibition of serum ACE activity (Sharifi, Darabi, & Akbarloo, 2003). NO is one of the most potent vasodilators synthesized in vascular endothelium and the loss of NO bioavailability is a hallmark of hypertension.
Garlic
2020, Nutritional Composition and Antioxidant Properties of Fruits and VegetablesFree amino acids and bioactive peptides profile of Pastırma during its processing
2016, Food Research InternationalThe role of garlic in cardiovascular diseases
2023, Natural Products: An Answer to Cardiovascular Complications