Contact sensitizing potential of annatto extract and its two primary color components, cis-bixin and norbixin, in female BALB/c mice.

Abstract

The present studies were performed to examine the contact allergenic effects of an annatto extract (ANT) in female BALB/c mice. ANT at 5-10% induced a greater than threefold increase in lymph node cell proliferation when compared to the control in the LLNA. Moreover, a significant increase in the percent ear swelling at 24h after ANT challenge was observed in the MEST. A significant increase in the percentage of B cells was also observed. To determine which of the two predominant coloring components (norbixin and bixin) in ANT was responsible for the sensitizing effects of ANT, norbixin was subsequently examined, with negative results being observed in both the LLNA and MEST following treatment with norbixin (1-20%). These findings suggested that perhaps bixin was responsible for the positive responses in both the LLNA and MEST following exposure to ANT. Therefore, further studies using a partially purified cis-bixin extract were conducted. Positive responses in both the LLNA and MEST were observed in mice treated with cis-bixin at the concentrations as low as 0.1-0.5%. These results have demonstrated that cis-bixin, but not norbixin, is likely a contact sensitizer and contributes to the contact hypersensitivity effects observed following dermal exposure to ANT in mice.

• Authors: Wimolnut Auttachoat, Dori R Germolec, Matthew J Smith, Kimber L White Jr, Tai L Guo
• Journal: Food and chemical toxicology : an international journal published for the British Industrial Biological Research Association (Food Chem Toxicol) Vol. 49 Issue 10 Pg. 2638-44 (Oct 2011) ISSN: 1873-6351 [Electronic] England
• PMID: 21777644 (Publication Type: Journal Article)
• Copyright: Copyright © 2011 Elsevier Ltd. All rights reserved.

Chemical References

• Food Coloring Agents
• Plant Extracts
• Carotenoids
• annatto
• bixin
• norbixin

Topics

• Animals
• Bixaceae (toxicity)
• Carotenoids (toxicity)
• Dermatitis, Contact (etiology)
• Female
• Flow Cytometry
• Food Coloring Agents (toxicity)
• Local Lymph Node Assay
• Mice
• Mice, Inbred BALB C
• Plant Extracts (toxicity)
• Random Allocation