carotenoid
carotenoid
Overview
Carotenoids are a large and structurally diverse class of lipophilic pigments biosynthesized primarily by plants, algae, fungi, and photosynthetic bacteria. Comprising over 750 identified structures, they are subdivided into two principal groups: carotenes, which are pure hydrocarbons (such as β-carotene and lycopene), and xanthophylls, which are oxygenated derivatives (such as lutein, zeaxanthin, and astaxanthin). Their characteristic conjugated polyene backbone renders them potent light-absorbing chromophores, contributing pigmentation ranging from yellow and orange to deep red in fruits, vegetables, and biological tissues. In plants, carotenoids serve as accessory photosynthetic pigments and photoprotective agents; in animals and humans, they fulfill critical roles as precursors to vitamin A (retinoids), lipid-soluble antioxidants, and modulators of immune function. Their capacity to quench singlet oxygen and neutralize reactive oxygen species underpins their well-established role in mitigating oxidative stress, a process implicated in the pathogenesis of cardiovascular disease, Malignant Disease, and metabolic dysfunction–associated steatotic liver disease.
Beyond their antioxidant function, carotenoids interact with a range of intracellular signaling cascades. They have been shown to modulate the PI3K/AKT/mTOR pathway and influence sirtuin 1 activity, positioning them as regulators of cellular energy homeostasis and autophagy. Their inhibitory effects on enzymes such as alpha-glucosidase and amylase alpha 1C underscore their relevance in glycemic control, while interactions with butyrylcholinesterase suggest a neuroprotective dimension. As fat-soluble molecules, their bioavailability is inherently dependent on co-ingested lipids, food matrix properties, and processing conditions—factors that have driven substantial recent research into encapsulation and delivery technologies.
Focus of Latest Publications
Recent publications have examined carotenoids in several nutritional, analytical, and delivery contexts. In the Environmental Determinants of Diabetes in the Young study, carotenoid intake and plasma carotenoid status were assessed alongside retinol and tocopherol measures to investigate associations with the development of islet autoimmunity and progression to type 1 diabetes. A separate review on microalgal biotechnology highlighted carotenoid production as a promising application area for microalgae, particularly in the hot-dry valley regions of southwest China.
Several studies focused on carotenoids in food matrices and their bioaccessibility. In quinoa, in vitro digestion of bitter and nonbitter genotypes showed that saponins did not alter the digestive stability, solubility, bioaccessibility, or micellar efficiency of carotenoids and tococochromanols. In another study, modified mango cotyledon starch was used to microencapsulate a carotenoid-rich pumpkin suspension, and the resulting fortified foods showed matrix-dependent carotenoid bioaccessibility, with yogurt providing the highest bioaccessibility and a 200 mL serving contributing substantially to vitamin A recommended dietary allowance across age groups. Similarly, food-grade bigels based on agar hydrogels and carnauba wax oleogels were developed as carriers for carotenoid-rich extracts from Arthrospira platensis and Scenedesmus obliquus; both hydrogel:oleogel ratio and 3D printing affected digestive stability, micellization, and bioaccessibility, with xanthophyll-rich systems generally performing better than carotene-rich systems.
Other publications explored carotenoids as bioactive constituents in plant extracts and by-product valorization. Leaf extracts from eight fruit tree species were profiled for chlorophylls and carotenoids, and multivariate analysis indicated that carotenoids were associated with antidiabetic activity, while chlorophyll derivatives correlated more strongly with antioxidant and neuroprotective effects. In cherry juice, carotenoids were implicated in aroma formation pathways, alongside pyruvic acid, Amino Acids, and fatty acids. Red guava by-products were also used to extract and nanoencapsulate pulp carotenoids, with peel and seed materials serving as wall components; the resulting nanoparticles showed antioxidant activity, good encapsulation performance, and storage stability, supporting potential use as a liquid dietary supplement dye.
Across these studies, carotenoids were also discussed in broader reviews of natural products and health. One review described carotenoids among bioactive compounds that can modulate autophagy through pathways including AMPK, PI3K/AKT/mTOR, sirtuin 1, and FOXO, with relevance to aging and age-related disease. Overall, the recent literature emphasizes carotenoids as nutritionally important compounds, as targets for improving bioaccessibility and delivery, and as bioactive constituents with potential roles in food, nutraceutical, and health applications.