Lipoxygenase and carotenoids: A co-oxidation story

Abstract

Lipoxygenases (LOXs), widely found in plants, fungi, and animals, are a large family of monomeric proteins with non-heme, non-sulphur, iron cofactor containing dioxygenases that catalyze the oxidation of polyunsaturated fatty acids such as linoleic, linolenic and arachidonic acid to yield hydroperoxides. Some LOX isoenzymes have the capacity to co-oxidise also the carotenoids. Carotenid biosynthesis occurs only in bacteria, fungi and plants where they have established functions that include their role as antenna in the light-harvesting proteins of photosynthesis, their ability to regulate light-energy conversion in photosynthesis, as well as the ability to protect the plant from reactive oxygen species, and coloration. In humans, some carotenoids (the provitamin A carotenoids: α-carotene, β-carotene, γ-carotene and the xanthophyll β-cryptoxanthin) are best known for their conversion into vitamin A. Lipoxygenase has negative food-related implications for color, off-flavour and antioxidant status of plant based foods. Up to now, β-carotene seems to attract more attention in developing strategies for food processing to prevent LOX-mediated deteriorations such as oxidation, rancidity, and off-flavor. More research is necessary for transferring the in vitro mechanistic studies on the LOX inhibition in vivo. Other carotenoids like lutein, zeaxanthin, β-cryptoxanthin in pure form as well as in natural extracts could be good candidates for LOX inhibition through their antioxidant action.

Keywords: Lipoxygenase, carotenoids, oxidation

African Journal of Biotechnology Vol. 12(20), pp. 2786-2791