Eikai Kyo

Immunomodulatory Effects of Aged Garlic Extract

Using various kinds of models, we examined the effects of aged garlic extract (AGE) on immune functions. In the immunoglobulin (Ig)E-mediated allergic mouse model, AGE significantly decreased the antigen-specific ear swelling induced by picryl chloride ointment to the ear and intravenous administration of antitrinitrophenyl antibody. In the transplanted carcinoma cell model, AGE significantly inhibited the growth of Sarcoma-180 (allogenic) and LL/2 lung carcinoma (syngenic) cells transplanted into mice. Concomitantly, increases in natural killer (NK) and killer activities of spleen cells were observed in Sarcoma-180--bearing mice administered AGE. In the psychological stress model, AGE significantly prevented the decrease in spleen weight and restored the reduction of anti-SRBC hemolytic plaque-forming cells caused by the electrical stress. These studies strongly suggest that AGE could be a promising candidate as an immune modifier, which maintains the homeostasis of immune functions; further studies are warranted to determine when it is most beneficial.

Aged garlic extract enhances production of nitric oxide

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.

Immunomodulation and antitumor activities of Aged Garlic Extract.

We found that Aged Garlic Extract (AGE) could be a significant immuno-potentiator, and could exhibit anti-tumor activities through immune modulation. Consequently, AGE stimulated the proliferation of mouse spleen cells and the release of cytokines, such as IL-2, TNF-alpha and IFN-gamma, increased NK activities, and enhanced phagocytosis of peritoneal macrophages. AGE treatment also stimulated the reactivity of lymphocytes in response to cytokines or mitogens. AGE was far superior to PSK in IL-2 induction, but slightly inferior to PSK in nitric oxide induction. AGE, as effectively as PSK (Krestin), significantly inhibited the growth of Sarcoma-180 (allogenic) and LL/2 lung carcinoma (syngenic) cells transplanted into mice. Concomitantly, increases in NK and killer activities of spleen cells were observed in Sarcoma-180 bearing mice treated with AGE. These results strongly suggest that AGE is as effective as PSK, and could serve as a potent biological response modifier on NK cells and T lymphocytes, and subsequently inhibit the growth of transplanted tumors.

Aged Garlic Extract Maintains Cardiovascular Homeostasis in Mice and Rats

Nitric oxide (NO) plays an important role in controlling the physiological functions of the cardiovascular system. However, toxic peroxynitrite is produced by the reaction of NO with superoxide. We investigated the effect of aged garlic extract (AGE) on NO production, and on oxidative stress induced by peroxynitrite. A single dose of AGE temporarily increased NO production by 30-40% between 15 and 60 min after administration to mice. The time course of the fluctuation in NO levels in the AGE-treated group clearly differed from that in a group treated with an inducible NO synthase (iNOS) inducer. A selective constitutive NOS (cNOS) inhibitor overcame the effect of AGE. These results indicate that AGE increases NO production by activating cNOS, but not iNOS. In another experiment, the addition of AGE to a rat erythrocyte suspension reduced the rate of peroxynitrite-induced hemolysis in a concentration-dependent manner, suggesting that AGE protects erythrocytes from membrane damage induced by peroxinitrite. Because an increase in NO derived from cNOS and protection against peroxynitrite are important factors in the prevention of cardiovascular disease, our data strongly suggest that AGE could be useful in preventing cardiovascular diseases associated with oxidative stress or dysfunctions of NO production.

Prevention of psychological stress-induced immune suppression by aged garlic extract

We determined the effect of Aged Garlic Extract (AGE) on damage caused to immune function by a psychological stress using a communication box. After four days of a psychological stress, a decrease in spleen weight and spleen cells was observed in the psychological stress-exposed mice as compared normal mice (non-stress). AGE significantly prevented the decreases in spleen weight and cells. Additionally, AGE significantly prevented the reduction of hemolytic plaque-forming-cells in spleen cells and anti-SRBC antibody titer in serum caused by this psychological stress. Moreover, a reduction in NK activities was observed in the psychological stress-exposed mice as compared with normal mice (non-stress), whereas NK activities in the AGE administered mice were almost the same as normal mice (non-stress). These results indicate that psychological stress qualitatively and quantitatively impairs immune function, and that AGE is extremely useful for preventing psychologically-induced damage.

Anti-allergic effects of aged garlic extract.

To examine the effect of Aged Garlic Extract (AGE) on the function of mast cells and activated T lymphocytes, we adopted the in vitro histamine release system, the in vivo IgE mediated skin reaction system and the in vivo late phase reaction system. Consequently, at 1.25, 2.5, and 5.0% (v/v), AGE dose-dependantly inhibited the antigen specific histamine release by mouse anti-TNP monoclonal antibody and TNP-BSA hapten carrier complex against rat basophil cell line RBL-2H3 by 50, 80, and 90 percent, respectively. In the IgE mediated skin reaction system, repeated or single intragastric administration of AGE (10 ml/kg), decreased by 25-45% the antigen specific ear swelling which was induced by a picryl chloride ointment applied to the ear of mice also given an intravenous administration of anti-TNP antibody IgE ascites. In the late phase reaction system, repeated or single intragastric administration of AGE (10 ml/kg) suppressed by 45-55% the antigen specific ear swelling induced by a secondary challenge to the ear of mice given a picryl chloride ointment seven days prior. These results suggest that AGE application could modify, directly or indirectly, the function of mast cells, basophils and activated T lymphocytes which play a leading role in allergic cascade reactions including inflammation.

Aged Garlic Extract Inhibits Development of Putative Preneoplastic Lesions in Rat Hepatocarcinogenesis

A unique garlic preparation, aged garlic extract (AGE), was examined for its modifying effect on diethylnitrosamine (DEN)-induced neoplasia of the liver in male F344 rats, using the medium-term bioassay system based on the 2-step model of hepatocarcinogenesis. Carcinogenic potential was scored by comparing the numbers and areas of induced glutathione S-transferase placental form (GST-P)-positive hepatocellular foci. GST-P-positive foci were significantly decreased in rats treated with AGE at doses of 2, 5, and 10 mL/kg, i.g., 5 times per week during the promotion phase. In addition, to clarify the mechanism underlying the inhibitory effect of AGE, the effect of AGE on hepatocellular proliferation was evaluated using partially hepatectomized rats as a liver-regeneration model. The bromodeoxyuridine-labeling indices in the livers of the AGE group were significantly lower than those in the control group at 24 h, the maximum proliferation period after partial hepatectomy. These findings indicate that AGE inhibited the development of putative preneoplastic lesions in rat hepatocarcinogenesis, involving a slowing in the proliferation rate of liver cells after partial hepatectomy.

Effect of garlic and garlic preparations on physiological and psychological stress in mice

The effect of several kinds of garlic preparations such as raw garlic juice (RGJ), heated garlic juice (HGJ), processed garlic powder (PGP) and aged garlic extract (AGE) on both physiological and psychological stress were investigated using four stress models in mice: forced swimming test, mechanical treadmill running, immobilization stress test, and a cooling rewarming test. RGJ was shown to be effective only at a low dose in the forced swimming test, whereas the effect was reduced at a high dosage. HGJ and PGP demonstrated no antistress effects. In contrast, AGE was shown to be effective in all of the stress tests.

Aged garlic extract inhibits peroxynitrite-induced hemolysis

Abstract Nitric oxide (NO), which is synthesized by constitutive NO synthase (cNOS), plays important roles in physiological functions of the cardiovascular system. However, NO, which is synthesized by inducible NOS, is detrimental when it reacts with superoxide to form peroxynitrite. Peroxynitrite is recognized as a powerful oxidant, and results in vascular or tissue damage. We have previously reported that aged garlic extract (AGE) enhances NO production through cNOS stimulation. In the present study, we determined the effect of AGE, its fractions or constituents on peroxynitrite-induced hemolysis using rat erythrocytes. Incubation of rat erythrocytes with peroxynitrite (300 μM) for 30 min at 37°C caused 4-fold hemolysis. AGE (0.14–0.57 %w/v) added to an erythrocyte suspension was found to reduce peroxynitrite-induced hemolysis in a concentration-dependent manner. Of the AGE fractions, a polar fraction and a low-molecular-weight fraction both suppressed the hemolysis to the same degree as that seen with AGE. S-Allylcysteine, one of the major compounds in AGE, also reduced hemolysis at 1–10 mM dose-dependently. These data indicate that AGE and its compounds protect erythrocytes from membrane damage induced by peroxynitrite, suggesting that AGE could be useful for prevention of cardiovascular diseases associated with oxidative stress or dysfunction of NO production.

Garlic as an immunostimulant

For over 5000 years, garlic has acquired a worldwide reputation in folklore as a formidable prophylactic and therapeutic medicinal agent [1–3]. More than three thousand publications in this century have confirmed the efficacy of this herb in the prevention and treatment of a variety of diseases, acknowledging and validating the traditional uses.