Carotenoid

Some things are bright colors. They are red, orange, or yellow. These colors come from tiny things in plants and some animals.

You can find them in carrots and pumpkins. They also color the feathers of pink flamingos.

They can even color the scales of fish.

In plants, these colors help catch light. This light helps the plant make food. They also act like a shield to keep the plant safe.

These colors hide in green leaves all summer. In the fall, the green fades away. Then the bright yellows and oranges show up.

Eating these colors is good for us too. They help our eyes see better. They also help keep our bodies healthy.

Carotenoids are natural pigments. They make things look yellow, orange, or red.

You can find them in many foods. Carrots and pumpkins are bright orange because of them.

Some plants, like kale, have them too.

These pigments help plants in two ways. First, they catch light. This light helps the plant make food through photosynthesis. Second, they act like a shield. They protect the plant from damage caused by light.

In the fall, many leaves change color. During summer, green chlorophyll hides the carotenoids. When the green fades, the yellows and oranges appear.

Animals cannot make their own carotenoids. They must eat them to stay colorful. Flamingos get their pink color from the foods they eat.

Salmon and lobsters also use them for color.

Carotenoids are also good for humans. They help our eyes see in low light. They also help our immune systems stay strong. Some carotenoids, like beta-carotene, can turn into vitamin A in our bodies.

Carotenoids are natural pigments that create bright colors in our world. They produce the yellow, orange, and red hues we see in many things.

These pigments are made by plants and algae. They are also found in some bacteria, fungi, and archaea. You can see them in pumpkins, carrots, corn, and tomatoes.

They even color animals like flamingos, salmon, and lobsters. There are over 1,100 different types of carotenoids identified by scientists. These pigments are very important for both plants and animals.

In plants, carotenoids have two main jobs. First, they act as accessory pigments for photosynthesis. They absorb light energy and pass it to chlorophyll.

This helps the plant make food from sunlight. Second, they provide photoprotection for the plant. Light can create damaging species called reactive oxygen species. Carotenoids help by transferring this extra energy away safely. This protects the plant's cells from being harmed by too much light.

Scientists categorize these pigments into two main groups. The first group is called carotenes. These are made only of carbon and hydrogen.

The second group is called xanthophylls. These contain oxygen and are often yellow.

All carotenoids are made from 8 isoprene units. This means they contain 40 carbon atoms. The specific structure of these molecules determines their color. Longer chains of bonds can shift the color toward red. This is why some look pale yellow while others look deep red.

Many people recognize carotenoids through the food they eat. For example, beta-carotene is found in carrots and sweet potatoes. Dried carrots have a very high amount of this pigment. The Vietnamese gac fruit has the highest known amount of lycopene.

In humans, these pigments are essential for health. Some can be turned into vitamin A in the body. They help support vision, especially in low light. They also help the immune system and skin. In the eye, pigments like lutein are found in the macula.

Carotenoids also change how we see nature during different seasons. In the autumn, many tree species show yellow or orange leaves.

This happens because the green chlorophyll disappears. Once the green fades, the hidden carotenoids become visible. This happens in about 15% to 30% of tree species. Animals like flamingos get their color by eating carotenoid-rich foods.

Because animals cannot make these pigments, they must find them in their diet. This makes color a sign of good health in the wild.

Carotenoids are a diverse group of organic pigments that produce vibrant yellow, orange, and red colors.

These pigments are produced by plants, algae, bacteria, archaea, and fungi. They are essential to life because they serve critical roles in energy capture and protection. In plants, they act as accessory pigments to assist chlorophyll during photosynthesis. They also provide photoprotection to prevent cellular damage from intense light. Because most animals cannot synthesize these molecules, they must obtain them through their diet. This makes carotenoids a vital link between the energy captured by plants and the health of animals.

Structurally, carotenoids are derivatives of tetraterpenes. This means they are built from eight isoprene units and contain 40 carbon atoms.

The specific color of a carotenoid is determined by its chemical structure, particularly the length of its conjugated double bonds. These bonds allow the molecule to absorb specific wavelengths of light, typically between 400 and 550 nanometers. This absorption of violet to green light results in the reflected colors of yellow, orange, or red. As the length of the conjugated system increases, the absorption band shifts toward the red end of the spectrum.

Scientists categorize the over 1,100 identified carotenoids into two primary classes. The first class is carotenes, which are pure hydrocarbons containing only carbon and hydrogen.

Common examples include alpha-carotene, beta-carotene, and lycopene. The second class is xanthophylls, which are carotenoids that contain oxygen.

Xanthophylls, such as lutein and zeaxanthin, are often yellow in color. These two classes differ in their polarity and how they behave within lipid membranes. This structural variation allows carotenoids to perform many different functions within a cell.

The mechanism of light harvesting and photoprotection is a complex, two-part process. During photosynthesis, carotenoids absorb photons and transfer that excitation energy to chlorophyll. This is known as singlet-singlet energy transfer, which is a lower energy state transfer. However, light can also produce dangerous reactive oxygen species (ROS) during photosynthesis. To defend against this, carotenoids perform triplet-triplet energy transfer. This higher energy transfer allows the carotenoid to absorb excess energy from triplet chlorophyll. The energy is then moved through the carotenoid's polyene tail to reach a stable, low-energy state.

This process protects the plant's lipids from oxidative damage.

Carotenoids also play a major role in plant signaling and growth. They can signal the production of abscisic acid, a hormone that regulates many plant functions. This includes regulating seed dormancy, embryo maturation, and germination. Abscisic acid also helps plants respond to environmental stress, such as drought or pathogen attacks. In fact, stressors like drought can trigger the accumulation of carotenoids as a protective response. This accumulation enhances the overall resilience of the plant. By managing these signals, carotenoids help plants navigate their life cycles and survive harsh conditions.

In the human diet, carotenoids provide significant health benefits. Some carotenoids, such as beta-carotene, possess vitamin A activity because they can be converted into retinol.

This process is essential for supporting vision, especially in low-light conditions. Carotenoids also support immune function, skin health, and provide antioxidant properties. In the human eye, pigments like lutein, zeaxanthin, and meso-zeaxanthin are found in the macula.

While their role in preventing age-related eye disease is still under clinical research, they remain a focus of study. To improve absorption, humans should consume these pigments with fats, as carotenoids are lipophilic.

Nature displays the impact of carotenoids through striking visual examples. In the autumn, about 15% to 30% of tree species show yellow or orange leaves due to carotenoids.

These colors become visible only after the green chlorophyll degrades. In the animal kingdom, carotenoids are often used as ornamental traits. For example, the diet of flamingos imparts orange colors to their feathers.

Because animals must eat these pigments to obtain them, their brightness can serve as a visible indicator of health. This can influence sexual selection, as animals may choose mates based on these vibrant color signals.