The pharmacokinetic behavior of allixin (3-hydroxy-5-methoxy-6-methyl-2-penthyl-4H-pyran-4-one) was investigated in an experimental animal, mice. Allixin was administered using an inclusion compound because the solubility of allixin in aqueous solution is very low. The allixin content in serum and in the organs of administered animals was analyzed by liquid chromatography (LC)-MS. Most of the administered allixin disappeared within 2 h, and the bioavailability of allixin was estimated to be 31% by obtained area under the blood concentration-time curve (AUC). The metabolites of allixin were studied using the metabolic enzyme fraction of liver and liver homogenate. Several new peaks corresponding to allixin metabolites were observed in the HPLC chromatoprofile. The chemical structure of the metabolites was investigated using LC-MS and NMR. Three of them were identified as allixin metabolites having a hydroxylated pentyl group.

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.

Tautomycin isolated fromStreptomyces spiroverticillatus is an inhibitor of protein phosphatases 1 and 2A. Tautomycin induced hyperphosphorylation of cytokeratin peptides in human keratinocytes (PHK 16-I cells) 30 times less strongly than did okadaic acid. Repeated applications of tautomycin (30 μg, 40 nmol/application) did not induce tumor promotion in a two-stage carcinogenesis experiment on mouse skin initiated with 7,12-dimethylbenz[a]anthracene, whereas okadaic acid (1 μg, 1.2 nmol/application) as a control induced tumor promotion strongly. As for mucosa or rat glandular stomach, tautomycin induced ornithine decarboxylase 4 h after intubation into the stomach. The tumor-promoting activity of tautomycin was next studied in the glandular stomach initiated withN-methyl-N′-nitro-N-nitrosoguanidine (MNNG). Administration of tautomycin in the diet (1 mg rat−1 day−1), from week 9 to week 52 of the experiment, inhibited rather than enhanced tumor development in the glandular stomach initiated with MNNG. The percentages of tumor-bearing rats of the groups treated with MNNG plus tautomycin, MNNG alone, and tautomycin alone were 20.0%, 40.6%, and 0% respectively in week 52. The reason for the absence of tumor-promoting activity of tautomycin was studied in relation to tumor necrosis factor α (TNFα), an endogenous tumor promoter. We found that tautomycin neither enhanced TNFα mRNA expression in mouse skin nor induced TNFα release in a human stomach cancer cell line (KATO III cells), whereas okadaic acid did both. These results indicate that not all inhibitors of protein phosphatases are tumor promoters, and suggest that tumor promotion of the okadaic acid class of compounds is mediated by TNFα.

A cytosolic fraction of mouse brain gave two peaks of protein kinase activity on DEAE-cellulose column chromatography. The first peak of protein kinase corresponded to protein kinase C. The second peak contained protein kinases that were "activated" dose-dependently by the okadaic acid class tumor promoters, okadaic acid and dinophysistoxin-1. This "activation" was not achieved by other tumor promoters, such as 12-0-tetradecanoyl-phorbol-13-acetate, teleocidin, aplysiatoxin, or palytoxin. In addition, the second peak contained phosphatases. The phosphate liberation from phosphorylated histone type III-S by incubation with the second peak was inhibited by okadaic acid or dinophysistoxin-1, dose-dependently. The resulting apparent "activation" of protein kinases by okadaic acid is indicated and would imply a new pathway of tumor promotion on mouse skin.

Dinophysistoxin‐1, 35‐methylokadaic acid, is a causative agent of diarrhetic shellfish poisoning. The biological activities and tumor‐promoting activity of dinophysistoxin‐1 were studied together with those of okadaic acid and 7‐O‐palmitoyl okadaic acid. Dinophysistoxin‐1 is a skin irritant and induces ornithine decarboxylase in mouse skin with the same potency as okadaic acid. 7‐O‐Palmitoyl okadaic acid induced a lower activity than the other compounds. Dinophysistoxin‐1 inhibited the specific [3H]okadaic acid binding to a participate fraction of mouse epidermis. The binding affinities of dinophysistoxin‐1 and okadaic acid to a particulate fraction were almost the same. Dinophysistoxin‐1 showed a tumor‐promoting activity as strong as that of okadaic acid in a two‐stage carcinogenesis experiment on mouse skin. The percentages of tumor‐bearing mice in the groups treated with 100 μg of 7,12‐dimethylbenz[α]anthracene (DMBA) followed by 5 μg of dinophysistoxin‐1, twice a week, and with DMBA followed by 5 μg of okadaic acid twice a week were 86.7% and 80.0% in week 30, respectively. The average number of tumors per mouse was 4.6 in the former group and 3.9 in the latter. Dinophysistoxin‐1 and okadaic acid act on cells through different pathways from the 12‐O‐tetradecanoylphorbol‐13‐acetate‐type tumor promoters.

S-(1,2-Dicarboxyethyl)glutathione and S-(1,2-dicarboxyethyl)L-cysteine were determined by high performance liquid chromatography after reaction with 2,4-dinitrofluorobenzene. By this method the former could be determined in the range 4.05 mumol/l-815 mumol/l, and the latter in the range 1.45 mumol/l-1.45 mmol/l. The recovery from cattle lens homogenate was 90.0 +/- 3.2% for S-(1,2-dicarboxyethyl)glutathione and 95.3 +/- 3.1% for S-(1,2-dicarboxyethyl)L-cysteine. Using this method S-(1,2-dicarboxyethyl)-glutathione and S-(1,2-dicarboxyethyl)L-cysteine were determined in lenses of several vertebrates and in rat lens during cataract formation by galactose.