[Frontiers in Bioscience-Landmark, 6, 171-190, DOI:10.52586/4932] https://www.fbscience.com Review Biosynthesis and extraction of high-value carotenoid from algae Amit Kumar Gupta1, Kunal Seth2, Kirti Maheshwari1, Prabhat Kumar Baroliya3, Mukesh Meena1, Ashwani Kumar4;*, Vandana Vinayak5, Harish1;* 1Department of Botany, Mohanlal Sukhadia University, 313 001 Udaipur, Rajasthan, India, 2Department of Botany, Government Science College, Pardi, 396125 Valsad, Gujarat, India, 3Department of Chemistry, Mohanlal Sukhadia University, 313 001 Udaipur, Rajasthan, India, 4Metagenomics and Secretomics Research Laboratory, Department of Botany, Dr. Harisingh Gour Central University, 470003 Sagar, MP, India, 5Diatom Nanoengineering and Metabolism Laboratory (DNM), School of Applied Sciences, Dr. Harisingh Gour Central University, 470003 Sagar, MP, India TABLE OF CONTENTS 1. Abstract 2. Introduction 3. Carotenoid biosynthesis pathways in algae 4. Chemistry of different carotenoid 5. Extraction of high value carotenoids 6. Application of carotenoids 7. Global carotenoid market 8. Concluding remarks 9. Author contributions 10. Ethics approval and consent to participate 11. Acknowledgment 12. Funding 13. Conflict of interest 14. References 1. Abstract tural features of different carotenoids are elaborated from a chemistry point of view. Furthermore, current understand- Algae possess a considerable potential as bio- ings of the techniques designed for pigment extraction from refinery for the scale-up production of high-value natural algae are reviewed. In the last section, applications of dif- compounds like—carotenoids. Carotenoids are accessory ferent carotenoids are elucidated and the growth potential of pigments in the light-harvesting apparatus and also act as the global market value of carotenoids are also discussed. antioxidants and photo-protectors in green cells. They play important roles for humans, like—precursors of vitamin A, reduce the risk of some cancers, helps in the prevention 2. Introduction of age-related diseases, cardiovascular diseases, improve skin health, and stimulates immunity. To date, about 850 Carotenoids comprehend a group of naturally oc- types of natural carotenoid compounds have been reported curring lipophilic (fat-soluble) pigments. C40 carbon and they have approximated 1.8 billion US$ of global mar- atoms with varying numbers of the double bond (polyene ket value. In comparison to land plants, there are few re- backbone) interlink and forms the basic structure of the ports on biosynthetic pathways and molecular level regu- carotenoid molecule, resulting from the isoprenoid path- lation of algal carotenogenesis. Recent advances of algal way [1, 2]. The discovery of carotenoid has far been de- genome sequencing, data created by high-throughput tech- coded the mystery behind the prismatic and radiant col- nologies and transcriptome studies, enables a better under- ors, we observe in fruits, vegetables, flowers, and leaves. standing of the origin and evolution of de novo carotenoid They are also responsible for the flamboyant coloration in biosynthesis pathways in algae. Here in this review, we animals like flamingos, crustaceans, shells, and fish skin focused on, the biochemical and molecular mechanism as in salmon [3]. In nature, all photosynthetic organisms of carotenoid biosynthesis in algae. Additionally, struc- (cyanobacteria, algae, higher plants), as well as some non- Submitted: 28 March 2021 Accepted: 7 May 2021 Published: 30 May 2021 This is an open access article under the CC BY 4.0 license (https://creativecommons.org/licenses/by/4.0/). © 2021 The Author(s). Published by BRI. 172 photosynthetic organisms such as fungi (Umbelopsis is- ronmental factors like salinity, temperature, irradiance, nu- abellina) and bacteria (Deinococcus-Thermus), have the trition, and growth factors [19]. The foremost, premier, and capability of carotenoid biosynthesis [4, 5]. The sundry rate-limiting step of the biosynthetic pathway is the con- shades of colors in fruits and vegetables, while they undergo densation of two GGPP (Geranyl geranyl pyrophosphate), ripening as well as color change during metamorphosis of to originate phytoene (colorless carotenoid) in presence crab, are also because of carotenoid transitions [6]. From an of PSY (Phytoene synthase) enzyme [20]. Subsequently, aesthetic point of view, carotenoids augment the beauty of an array of sequential desaturations results in the produc- the environment by adding pigmentation to fruits and flow- tion of all-trans lycopene. Major enzymes involved are ers, enhancing the taste of fruits, and adding aromas to the Phytoene desaturase (PDS), ζ-Carotene Isomerase (Z-ISO), flower, which in turn fascinate pollinators and engross seed ζ-Carotene desaturase (ZDS), and Carotenoid isomerase dispersal organisms. (Crt-ISO). The colored sequence from phytoene is as fol- About 850 kinds of carotenoids have been reported lows: phytofluene (colorless), ζ-carotene (green), neu- up to 2018 [7]. They are broadly grouped into two cate- rosporene (orange/yellow), lycopene (red), and γ-carotene gories either on basis of functional properties or chemical (orange). Lycopene then undergoes cyclization by Ly- structure. Functionally, they can be either primary hav- copene ϵ-cyclase (LCY-E), and Lycopene β-cyclase (LCY- ing a vital role in photosynthesis or secondary having a B), forming α-carotene and β-carotene, respectively and role in stress conditions [8]. Based on chemical structure, this step is a critical branch point [21]. α- and β-carotene carotenoids having pure carbon skeleton and are referred to undergoes hydroxylation in presence of EHY (ϵ-carotene as carotenes (cyclized or uncyclized, e.g., α-carotene, β- hydroxylase) and BCH (β-carotene hydroxylase) to form carotene, γ-carotene, lycopene, phytoene) and another, the lutein and zeaxanthin, respectively. β-Cryptoxanthin is an oxygenated carotenes, are known as xanthophylls. Lutein, intermediate product during zeaxanthin formation. Anther- zeaxanthin, astaxanthin, violaxanthin, canthaxanthin, echi- axanthin and violaxanthin are formed by epoxidation and neone, β-cryptoxanthin, fucoxanthin, peridinin, neoxanthin de-epoxidation of zeaxanthin by ZEP (Zeaxanthin epoxi- are some of the well-known xanthophylls [9]. The pres- dase) and VDE (Violaxanthin de-epoxidase), respectively, ence of xanthophyll as fatty acid esters, glycosides, sulfates, making up the xanthophyll cycle. In the cytoplasm, zeaxan- and protein complexes have been reported [10]. Around thin may form adinoxanthin by BKT (β-carotene ketolase) 50 types of carotene and ~800 types of xanthophyll have which in turn forms astaxanthin using the same enzyme by been reported. Carotenoids with more than 45 or 50 car- incorporation of additional keto group. BKT can also act bon atoms are referred to as higher carotenoids, while, with as an intermediate enzyme to β-carotene by adding a keto less-than 40-carbon skeleton are known as apocarotenoids. group to it, resulting in the formation of echinenone and About 40 types of higher carotenoids are reported in ar- canthaxanthin as an intermediate. Neoxanthin synthase en- chaea and about 120 types of apocarotenoids are reported zyme converts violaxanthin into 9-cis neoxanthin [22]. in higher plant and animals. Most carotenoids have a 40- Carotenoids can be stored inside or outside the carbon skeleton [10]. Sweet potato, carrots, pumpkin, apri- chloroplast according to their functional role. Primary pig- cots, cantaloupe, spinach, and broccoli are a rich source of ments are stored inside while secondary pigments remain α-carotene [11]. Lycopene is abundant in tomato, water- outside the chloroplast in lipid globules. Green tissue con- melon, pink grape fruit [12]. β-cryptoxanthin and zeax- serves the accumulation of carotenoids while the levels in anthin are found in peach, papaya, mandarin, orange, and non-green tissues may vary according to the developmen- tangerine [13]. Collards, butternut, raw spinach, corn are tal stage. Though, cell storage capacity, catabolism, and also enriched with zeaxanthin [14]. Lutein, violaxanthin, degradation rate may alter the carotenoid profile [20]. The β-carotene, and neoxanthin are abundant in green leafy veg- phenomenal process of photosynthesis on the whole needs etables [15]. Crocin, crocetin, picrocrocin are the three chlorophyll as a pre-dominant pigment, while carotenoids apocarotenoids present in stigmata of Crocus flower which play a donative role in the overall mechanism of en- provide coloring properties to saffron [16]. ergy transport and conversion [23]. Carotenoids majorly Chloroplast—the green organ of photosynthetic play a dual role, primarily; they act as accessory light- tissue of higher plants, is not only the site of photosynthe- harvesting pigments in photosystem, thereby extending the sis, but also plays an important role in biosynthesis and ac- range of solar radiation (wavelength) which is not ab- cumulation of carotenoid. Stanely and Yuan have reported sorbed by chlorophyll and hence, drive the process of pho- many nuclei encoded membrane proteins, their synthesis in tosynthesis to a greater peak. Secondly, the noteworthy the cytoplasm as polypeptide precursor with amino termi- role of carotenoids is photo protective by dissipating ex- nus extension, directed to the chloroplast, for the biosyn- tra energy and scavenging toxic oxygen molecules. In this thesis of carotenoids [17]. The carotenogenesis pathway way, carotenoids stabilize pigment-protein complexes; and