Some Natural and Synthetic Antioxidants as Stabilizers of beta-Carotene Conversion into Vitamin A

S. B. Gomboeva¹, N. N. Gessler^1*, K. B. Shumaev¹, T. I. Khomich², A. G. Moiseenok², and V. Ya. Bykhovskii¹

¹Bakh Institute of Biochemistry, Russian Academy of Sciences, Leninskii pr. 33, Moscow, 117071 Russia; fax: (095) 954-2732; E-mail: inbio@glas.apc.org

²Institute of Biochemistry, Academy of Sciences of Belarus, bulvar Leninskogo Komsomola 50, Grodno, 230009 Belarus.

^* To whom correspondence should be addressed.

Received July 10, 1997; Revision received September 29, 1997

---

The effect of antioxidants (vitamins C and E, quercetin, probucol, butylated hydroxytoluene) on the oxidation of beta-carotene and its conversion into retinal under the influence of beta-carotene 15,15´- dioxygenase (CDO) from rat intestinal mucosa was studied. The activity of CDO decreased in the presence of oxidants. Antioxidants protected both the substrate and the enzyme. The extent of the protection depended on the antioxidant type. The combined injection of antioxidants and beta-carotene to animals completely or partially prevented the inhibition of the intestinal CDO which was caused by products of non-enzymatic oxidation of beta-carotene. Vitamins C and E, which protected the enzyme--substrate complex in vivo and in vitro, were found to be the most efficient protectors of beta-carotene conversion into retinal.

---

KEY WORDS: beta-carotene, beta-carotene 15,15´-dioxygenase, retinal, vitamins A, C, and E, quercetin, probucol, peroxidation, sodium hypochlorite

---