Elsevier

Life Sciences

Volume 71, Issue 5, 21 June 2002, Pages 509-517
Life Sciences

Aged garlic extract enhances production of nitric oxide

https://doi.org/10.1016/S0024-3205(02)01706-XGet rights and content

Abstract

Nitric oxide (NO) controls several physiological functions of the cardiovascular system. Three kinds of NO synthases (NOSs), neuronal constitutive NOS (ncNOS), inducible NOS (iNOS) and endothelial constitutive NOS (ecNOS), were responsible for NO biosynthesis. This study investigated the effect of aged garlic extract (AGE) on NO production by measuring the NO metabolites nitrite and nitrate in the plasma of mice. AGE (2.86 g/kg, p.o.) temporarily increased NO production by 30–40% from 15 to 60 min after administration. The time course of the fluctuation in NO levels in the AGE-treated group was clearly different to that in a group of mice treated with lipopolysaccharides, a typical iNOS inducer. Arginine (63 mg/kg, p.o.) at the equivalent dose of AGE did not increase NO production. However diphenyleneiodonium chloride (1 mg/kg, i.p.), a selective cNOS inhibitor, administered prior to AGE, overcame the effect of AGE. These results indicate that AGE increased NO production by activating cNOS, but not iNOS. The arginine contained in AGE was not responsible for the effect. AGE may be a useful tool for the prevention of cardiovascular disease.

Introduction

Nitric oxide (NO) is an important intercellular and intracellular messenger with a major role in controlling the physiological function of the cardiovascular system [1], [2]. It is synthesized from L-arginine by NO synthases (NOSs) in many of the cells of the cardiovascular system, including endothelial cells, macrophages, smooth muscle cells, platelets and fibroblasts [1]. Three kinds of NOSs, neuronal constitutive NOS (ncNOS), inducible NOS (iNOS) and endothelial constitutive NOS (ecNOS), were recently reported to be responsible for NO biosynthesis in these cells [3]. NO derived from ncNOS and ecNOS was reported to modulate vasomotor tone, the inhibition of platelet or leukocyte aggregation and adhesion to the endothelium, suggesting properties of anti-atherogenicity [1]. The study found that iNOS remained unexpressed until induced by cytokines or lipopolysaccharides in some pathological process such as circulatory shock or inflammation [4], [5].

Since ancient times, people of many different cultures have considered garlic (Allium sativum L.) as a valuable healing agent. Garlic has been used as a cure for various ailments, including heart disease, cancer and infection [6]. Its curative properties have been attributed to its ability to increase physiological levels of NO, which acts as an anti-arteriosclerotic and anti-inflammation agent [7], [8], [9], [10], [11]. It may also reduce damage in diseased blood vessel walls. A large number of pharmacological studies have been reported that aged garlic extract (AGE) possesses anti-hyperlipidemic [12], anti-oxidative [13], [14], [15], cardiovascular [16], [17], [18] and hepato-protective [19], [20], [21] properties.

In this study, we examined the effect of AGE on NO production in mice. As NO is instantaneously oxidized to nitrate and nitrite within the body, we examined by measuring levels of the stable end-products of NO metabolites, nitrite and nitrate, in the plasma of mice after experimental treatment.

Section snippets

Aged garlic extract

AGE was manufactured by Wakunaga Pharmaceutical Co. Ltd. (Osaka, Japan) by slicing garlic cloves (Allium sativum L.) and soaking them in a water-ethanol mixture, which was then naturally extracted/aged for more than 10 months at room temperature. The AGE we used contained approximately 28.6% (w/v, 286 mg/ml) solid material, 0.63% (6.3 mg/ml) arginine and 0.1% S-allylcysteine (calculated on a dry weight basis) as a marker compound for standardization [22].

Chemicals

( ±

Effect of drugs on NO production

Fluctuation in NO production was investigated after administration of AGE, NOR3 and L-NMMA. AGE as well as NOR3, NO donor, significantly increased NO levels in the plasma compared to the control (p < 0.05 and p < 0.01, respectively). On the other hand, the NOS inhibitor L-NMMA significantly reduced NO levels in the plasma compared to the control (p < 0.01, Table 1).

Effect of AGE and LPS on NO production

We examined the effect of AGE on NO production over time. AGE significantly increased NO levels in the plasma at 15 (by 44%, p <

Discussion

In the present study, we investigated NO production in the body by surveying stable NO metabolites in the blood. We confirmed that levels of NO metabolites are related to the presence of NO donor or NOS inhibitor. Both AGE and NO donor significantly show increasing NO levels (Table 1). AGE rapidly increased NO production about 30–40% after administration and was returned to the basal value at 2 h after administration (Fig. 1). The period for this rapidly response was supported by the result

References (39)

  • M. Steiner et al.

    A double-blind crossover study in moderately hypercholesterolemic men that compared the effect of aged garlic extract and placebo administration on blood lipids

    Am. J. Clin. Nutr.

    (1996)
  • M. Steiner et al.

    Aged garlic extract, a modulator of cardiovascular risk factors: a dose-finding study on the effects of AGE on platelet functions

    J. Nutr.

    (2001)
  • S. Maeda et al.

    Effects of exercise training of 8 weeks and detraining on plasma level of endothelium-derived factors, endothelin-1 and nitric oxide, in healthy young humans

    Life Sci.

    (2001)
  • S. Moncada et al.

    Nitric oxide: physiology, pathophysiology, and pharmacology

    Pharmacol. Rev.

    (1991)
  • R.M. Palmer et al.

    Nitric oxide release accounts for the biologic activity of endothelium-derived relaxing factor

    Nature

    (1987)
  • J.F. Kerwin et al.

    Nitric oxide: a new paradigm for second messengers

    J. Med. Chem.

    (1995)
  • I. Das et al.

    Potent activation of nitric oxide synthase by garlic: a basis for its therapeutic applications

    Curr. Med. Res. Opin.

    (1995)
  • H.E. von der Leyen et al.

    Gene therapy inhibiting neointimal vascular lesion: in vivo transfer of endothelial cell nitric oxide synthase gene

    Proc. Natl. Acad. Sci. U. S. A.

    (1995)
  • J.P. Cooke et al.

    Antiatherogenic effects of L-arginine in the hypercholesterolemic rabbit

    J. Clin. Invest.

    (1992)
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