dihydroxycarotenoids

Dihydroxycarotenoids are a class of organic pigments belonging to the broader family of carotenoids. They are characterized by the presence of two hydroxyl (-OH) functional groups attached to the carotenoid backbone. These hydroxyl groups are typically found at specific positions within the polyene chain or on one of the ionone rings, depending on the specific dihydroxycarotenoid.

Naturally occurring dihydroxycarotenoids are synthesized by plants, algae, and some bacteria as accessory pigments in photosynthesis and for photoprotection. They are often found in conjunction with other carotenoids and chlorophylls within chloroplasts and chromoplasts. Their characteristic yellow, orange, and red colors are due to the extended conjugated system of double bonds in their molecular structure, which absorbs light in the blue-green region of the visible spectrum.

Functionally, dihydroxycarotenoids play roles in light harvesting, transferring absorbed energy to chlorophyll for photosynthesis. They also act as antioxidants, scavenging reactive oxygen species that can be generated during photosynthesis or in response to environmental stress. This antioxidant activity helps protect cellular components from oxidative damage.

Examples of dihydroxycarotenoids include certain xanthophylls, such as lutein and zeaxanthin, which are abundant in green leafy vegetables, egg yolks, and the macula of the human eye. These specific compounds are important for vision health. Other dihydroxycarotenoids may be present in various plant tissues, contributing to coloration and offering protective benefits. The exact number and position of hydroxyl groups define the specific identity and properties of each dihydroxycarotenoid.