The pharmacokinetic behavior of S-allylcysteine (SAC), one of the biologically active transformation products from garlic, was investigated after oral administration to rats, mice, and dogs. SAC was rapidly and easily absorbed in the gastrointestinal tract and distributed mainly in plasma, liver, and kidney. The bioavailability was 98.2, 103.0, and 87.2% in rats, mice, and dogs, respectively. SAC was mainly excreted into urine in the N-acetyl form in rats; however, mice excreted both SAC and the N-acetyl form. The half-life of SAC was longer in dogs than in rats and mice.

We investigated the pharmacologic activities of four garlic preparations, raw garlic juice (RGJ), heated garlic juice (HGJ), dehydrated garlic powder (DGP) and aged garlic extract (AGE). The study used three animal models, i.e., testicular hypogonadism (hypospermatogensis and impotence) induced by warm water treatment, intoxication of acetaldehyde and growth of inoculated tumor cells. RGJ was found to be effective only in recovery of testicular function. The efficacy of HGJ was observed in three models; however, it did not improve impotence. DGP was effective in recovery of spermatogenesis and stimulated acetaldehyde detoxification. Significant beneficial effects of AGE were found in all three models. Although all four garlic preparations significantly enhanced natural killer (NK) and killer cell activities of the spleen cells of tumor-bearing mice, only AGE and HGJ inhibited the growth of inoculated tumor cells. These results suggest that different types of garlic preparations have different pharmacologic properties, and among the four garlic preparations studied, AGE could be the most useful garlic preparation.

S-1-propenyl-l-cysteine (S1PC) is a stereoisomer of S-allyl-l-cysteine (SAC), an important sulfur-containing amino acid that plays a role for the beneficial pharmacological effects of aged garlic extract (AGE). The existence of S1PC in garlic preparations has been known since the 1960’s. However, there was no report regarding the biological and/or pharmacological activity of S1PC until 2016. Recently, we performed a series of studies to examine the chemical, biological, pharmacological and pharmacokinetic properties of S1PC, and obtained some interesting results. S1PC existed only in trace amounts in raw garlic, but its concentration increased almost up to the level similar of SAC through aging process of AGE. S1PC showed immunomodulatory effects in vitro and in vivo, and reduced blood pressure in a hypertensive animal model. A pharmacokinetic study revealed that S1PC was readily absorbed after oral administration in rats and dogs with bioavailability of 88–100%. Additionally, S1PC had little inhibitory influence on human cytochrome P450 activities, even at a concentration of 1 mM. Based on these findings, S1PC was suggested to be another important, pharmacologically active and safe component of AGE similar to SAC. In this review, we highlight some results from recent studies on S1PC and discuss the potential medicinal value of S1PC.

Maternal sound stress (800 Hz; 77 dB, every other minute for 15 min/day, from day 10 to 18 of gestation), combined with forced swimming stress (15 min/day), was found to cause potentiation of sound-induced loss of locomotor activity, referred to as emotional behavior, of male offspring, but not that of female offspring, at 4 weeks of age. Maternal stress also caused an increase in the total number of errors by male, but not female offspring in the water-maze test at 6 weeks of age. These effects of stress on emotional behavior and learning behavior were abolished when dams were pretreated with buspirone (30 min before the stress, from day 8 to 18 of gestation). Thus, prenatal stress might have sex-dependent effects on emotional behavior and learning ability of neonatal rats.

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