In recent decades, it was found that vitamins affect biological functions in ways other than their long-known functions; niacin is the best example of a water-soluble vitamin known to possess multiple actions. Biotin, also known as vitamin B7 or vitamin H, is a water-soluble B-complex vitamin that serves as a covalently-bound coenzyme of carboxylases. It is now well documented that biotin has actions other than participating in classical enzyme catalysis reactions. Several lines of evidence have demonstrated that pharmacological concentrations of biotin affect glucose and lipid metabolism, hypertension, reproduction, development, and immunity. The effect of biotin on these functions is related to its actions at the transcriptional, translational, and post-translational levels. The bestsupported mechanism involved in the genetic effects of biotin is the soluble guanylate cyclase/protein kinase G (PKG) signaling cascade. Although there are commercially-available products containing pharmacological concentrations of biotin, the toxic effects of biotin have been poorly studied. This review summarizes the known actions and molecular mechanisms of pharmacological doses of biotin in animals and current information regarding biotin toxicity.

Lectins comprise a heterogeneous class of proteins that recognize the carbohydrate moieties of glycoconjugates with high specificity. Numerous studies have shown that lectins are capable of recognizing specific carbohydrate moieties displayed by malignant cells or tissues. The present work was performed to investigate the effects of tepary bean (Phaseolus acutifolius) lectins on proliferation, colony formation, and alteration of DNA synthesis of human malignant cells. Tepary bean lectin showed dose dependent effects on the inhibition of viability as well as on colony formation in two human malignant cells lines (C33-A, Sw480); By contrast, tepary bean lectin only showed significant effects on DNA synthesis on Sw480 cells. Our results provide evidence of the anti- proliferative and cytotoxic effects of the tepary bean lectins on C33-A and Sw480 cells lines.

ISHS I International Symposium on Saffron Biology and Biotechnology CHEMICAL COMPOSITION OF SAFFRON (CROCUS SATIVUS L.) FROM FOUR COUNTRIES

Pharmacological concentrations of biotin have pleiotropic effects. Several reports have documented that biotin supplementation decreases hyperglycemia. We have shown that a biotin-supplemented diet increased insulin secretion and the mRNA abundance of proteins regulating insulin transcription and secretion. We also found enlarged pancreatic islets and modified islet morphology. Other studies have shown that pharmacological concentrations of biotin modify tissue structure. Although biotin administration is considered safe, little attention has been given to its effect on tissue structure. In this study, we investigated the effect of biotin supplementation on hepatic morphology and liver toxicity markers. Male BALB/cAnN Hsd mice were fed a control or a biotin-supplemented diet for 8 weeks. Versus the control mice, biotin-supplemented mice had an altered portal triad with dilated sinusoids, increased vascularity, and bile conducts. Furthermore, we observed an increased proportion of nucleomegaly and binucleated hepatocytes. In spite of the liver morphological changes, no differences were observed in the serum liver damage indicators, oxidative stress markers, or antioxidant enzymes. Our data demonstrate for the first time that biotin supplementation affects liver morphology in normal mice, and that these modifications are not paralleled with damage markers.