A gamma-glutamyl peptide isolated from onion (Allium cepa L.) by bioassay-guided fractionation inhibits resorption activity of osteoclasts

One gram of onion added to the food of rats inhibits significantly (p < 0.05) bone resorption as assessed by the urinary excretion of tritium released from bone of 9-week-old rats prelabeled with tritiated tetracycline from weeks 1 to 6. To isolate and identify the bone resorption inhibiting compound from onion, onion powder was extracted and the extract fractionated by column chromatography and medium-pressure liquid chromatography. A single active peak was finally obtained by semipreparative high-performance liquid chromatography. The biological activity of the various fractions was tested in vitro on the activity of osteoclasts to form resorption pits on a mineralized substrate. Medium, containing the various fractions or the pure compound, was added to osteoclasts of new-born rats settled on ivory slices. After 24 h of incubation, the tartrate-resistant acid phosphatase positive multinucleated cells, that is, osteoclasts, were counted. Subsequently, the number of resorption pits was determined. Activity was calculated as the ratio of resorption pits/osteoclasts and was compared to a negative control, that is, medium containing 10% fetal bovine serum only and to calcitonin (10(-12) M) as a positive control. Finally, a single peak inhibited osteoclast activity significantly (p < 0.05). The structure of this compound was elucidated with high-performance liquid chromatography-electrospray ionization-mass spectrometry, time-of-flight electrospray ionization mass spectrometry, and nuclear magnetic resonance spectroscopy. The single peak was identified as gamma-L-glutamyl-trans-S-1-propenyl-L-cysteine sulfoxide (GPCS). It has a molecular mass of 306 Da and inhibits dose-dependently the resorption activity of osteoclasts, the minimal effective dose being approximately 2 mM. As no other peak displayed inhibitory activity, it likely is responsible for the effect of onion on bone resorption.

Carcinoma ex pleomorphic adenoma in a minor salivary gland: report of a case

BACKGROUND: Carcinoma ex pleomorphic adenoma is exceedingly rare in minor salivary glands of the oral cavity. We present a case of carcinoma ex pleomorphic adenoma (CEPA) of the buccal mucosa in a 47-year-old Turkish patient. The buccal mass was of a size of 1.5 cm located in the left cheek. Pleomorphic adenoma was the tentative diagnosis. METHODS: The tumor was removed under local anesthesia. Histopathologic evaluation revealed a preexisting pleomorphic adenoma associated with adenoid tumor component with tubulo-cystic and papillary or pseudopapillary structures; CEPA was diagnosed. Capsular integrity was incomplete with infiltration by islands of metaplastic/dysplastic epithelium. RESULTS: Secondary surgery of the site was performed. No tumor tissue could be detected in the resection specimen. The patient is free of recurrence since 9 months.