Carotenoids are quantitatively very prominent among

the substances which render colour - Biochrome. There are

an immense array of carotenoids in the animal kingdom and

so also in the plants. They are present predominantly in

the eye spot of the protozoans, in the body of coelentrates,

sponges and other' organisms. The only clear cut physiological

function they perform/as precursor for vitamin A.

Apart from this though many a varied roles ascribed to them

in the physiology of the organism are highly speculative in

nature. We, at the dawn of revolutionary findings in the

function of carotenoid

Easterson, D C V

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• i . IB^^mmf^-mmmmmmifm^mm'im Proceedings of the Summer Institute in Recent Advances in Finfish and Shellfish Nutrition 11 TO 30 MAY 1987 CENTRAL MARINE FISHERIES RESEARCH INSTITUTE Dr. SALIM ALI ROAD COCHIN-682 031 i Technical Paper - 7 SUMMER INSTITUTE IN RECENT ADVANCES IN FINFISH AND SHELLFISH NUTRITION 11-30 May, 1987 CAROTENOIDS AND THEIR IMPORTANCE IN THE NUTRITION OP FISH AND CRUSTACEANS 'D.C.V, EASTERSON Tuticorin Research Centre of Central Marine Fisheries Research Institute Tuticorin-628 001. Carotenoids are quantitatively very prominent among the substances which render colour - Biochrome. There are an immense array of carotenoids in the animal kingdom and so also in the plants. They are present predominantly in the eye spot of the protozoans, in the body of coelentrates, sponges and other' organisms. jThe only clear cut physio-logical function they perform/as precursor for vitamin A. Apart from this though many a varied roles ascribed to them in the physiology of the organism are highly speculative in nature. We,at the dawn of revolutionsiry findings i»fthe function of carotenoids. BIOCHROMES The following group of biochemics are collectively known as biochromes - 1, Carotenoids, 2. Quinones* 3. Flavonoids, 4. Flavins, 5. Tetrapyrroles, 6. Pterins and 7. Indole pigments. The first four are synthesised de novo only by plants of which the first three contain only carbon, hydrogen and oxygen while the four^n addition nitrogen. Irifiiiv-. i^r-e si'x-.t-.h al&o contain nitrogen and ecu Id "ne synthesised by both plants and animals.' The last viz., indole pigments are melanins and indigoids"vhich are synthesised by the • • 2 •« animals by catabolic degradation of essential amino acids tyrosine and tryptophan. Of these carotenoids are the most diverse and occur in very high quantity. CAROTENOIDS Carotenoids are fat soluble lipochromcs and can be divided into two groups. 1, Carotenes, which are carotenoid hydrocarbons lacking in oxygen ie. are made of carbon and hydrogen only. 2. Xanthophylls, which are oxygen containing alcohol soluble, non-acidic, non-saponifiable carotene derivatives. The xanthophylls are classified as follows (Fox, 1976). 1. Carotenoid alcohols - caroteneIs 2. " ketones - carotenones 3. " alcohol ketones- carotenolones 4. aldehydes - carotenols 5. * ethers - caroten - ethers 6. Esters of carotenoid alcohols - carotenol esters 7. Carotenoid acids and their esters. In Xanthophylls suffix 'Xanthin' is added while for carotenes •carotene*. Eg; Astaxanthin, Q- carotene, tunicarotene. Carotenoids are present in the organisms in two types of complexes, vi?., carotenoproteins - i) pigment is bound to the protein in stoichiometric amounts in non-covalent linkages and ii) dissolved in lipoprotein or lipoglycoprotein component. The central dogma of carotenoid biochemistry is that animals cannot synthesise the pigments de novo but can only alter the molecules by oxidation, as in the conversion of l^r"^z^x:<^M>-,..-xi Into -astaxanthin, ori if the structure is appropriate, by central fission to form vitamin A. Though the first part of the dogma still holds for the latter part 2 new metabolic activities have come to our Icnowledge as exceptions, i) Conversionc5C/2>-rings into^-rings in birds and ii) a change of chirality as in the formation of 3' -epilutein from lutein in fishes (Goodwin, 1984). Though animals lack the carotenoids from protozoa to mairanalia they contain '•.8 capacity to synthesis , v-» „ _ ^ _ _. jnm lia they contain i" carotenoids. ^ '"i^>lH-f ^ t ^ t ^ t t f e h animals and plant, put together have more / xanthophylls^the ifiarxne and freshwater mud contain higher amounts of carotein than xanthophylls. Fox (1979) divides the organisms into the following 5 categories based on their carotenoid nutrition. 1* Carotene selectors: These animals -' ' IO-^ ILA%/ provided with r: . forms of carotenoids,are able to assimilate hydrocarbon type of carotenes, while defaecate xanthophylls txhJL. completely^. Typical examples • ^ i^horse and cattle* The marine detritus eating polychaete Euzpnus mucronata assimi-late and store y^-carotene only. The parasitic crustacean Sacculina carcina too assimilate and store in considerable quantity only 0 - carotene (Fox, 1979). 2. Carotenoid rejectors: There are also animals which assimilate little of carotenoids except for visual pigments from carotenoid rich diets. The exanrples are sheep, goat, swine and also most strains of rabbits. The hag fish (cyclestome) Eptatretus stoutii, the mako shark Isurus glaucus and the chimaerid Hydrolaqus sp. are also carotenoid rejectors. Xanthophyl1 accumulators: These organisms store no carotenes but assimilate alcoholic • •. hydrojq^lated and -.. «.. z^ .* ketonic carotenoids * They convert only a little carotene ingested '3 vitamin A, just sufficient for their needs. Othersiise dispose o^f all carotenes in faeces. The examples «. 4 • . are domestic fowl, most of the fishes and many invertebrates. Non-selectors; These organisms readily assimilate and deposit both carotenes and xanthophylls in the body tissues. Examples are man, frog and octopus. Carptenoid innovators: These assimilate varied kind of carotenoids, oxidises them to yield derivatives. Thus /^-carotene could be converted mono - or dihydroxy-alcohols (Eg: cryptoxanthin, zeaxanthin) or into mono - or dihydroxy -diketo conpwU- (Eg; astaxanthin). Many echinoderms, crustaceans and a few fishes come under this category. Crustaceans; Artemia salina, the brine shrimp c m convert jh- carotene into echinenone and canthaxanthin. Penaeus japonicus and Motapenaeus barbata oxidise /?-carotene to astaxanthin (Pox, 1979). In most crustaceans free astaxanthin fom^s the bulk of the pigment in caraiaace. The pigments are transferred from epidermii^ during moulting to the carapace (Goodwin, 1984). It is observed that during intermoult stages the carotenoid content in the hepato-pancreas^ is very high (unpublished data). In hepato-pancreas the conversion of carotenoids take place. Some crustaceans - Penaeus .) aponicus - can metabolise f^ -carotene to astcixanthin while still others - Panulirus Japonicus, Portunus trituberculatus and Pagurus prideauxi - can meta-bolise upto exhinenone (Fig. 1 and 2). The pigments are transported from hepatopancreas to epidermis through haemoiynnph while the transfer from gut to hepatopancreas is mediated by a carrier protein, structurally similar to apopi:;^ t^ein of ^—- crustacyanin (Goodwin, 1984)* • * 3 • • /Vcarotene -^ 4-Hydroxy- j6 -carotene —^4,4' -Dlhydroxy-^ (isooryptokanthln) (xsozeaiS^'tUinT 4-keto- ^ -carotene 4 -ke to-4 ' -hydros^-p-caro tene ^' a ^ 4,4'-Diketo- M-carotene (Canthaxanthin) Figure - I; y^carotene to echinone and canthaxanthin synthesis is crustaceans (Goodwin, 1934). The carotenoid concentrations within the crustacean can vary very much. In Sergestes corniculum carotenoids are very high in the carapace and hypodermis while very little is present in the eyes. In some euphausids about 94% of the total carotenoids occur in thfe eyes, in Oplophorous spinosus the eggs contain 2447 ug/g carotenoids while the adults only 244 ug/g. In Par^alus borealis and Penaeus _iaponicus y§ carotene is high in the hepatopancreas while astaxanthin is abundant in the carajpace, Amino .acids: It is of interest that Otazu-Abrill, et al. (1982) have found that purified amino acids in the diet especially methionine,(at 8% level) "can elevate carotenoid levels in Palaemon serratus. Methionine and isoleucine paitiu produced stricking increase in carotenoids. However too higheL addition of free amino acids is the food reduced the pigment content. * Evcstalk secretions: Ablation of, eye-stalks in Rithoropanopeus harrisii during <levelo|Mwen.t of ovaries resulted in increase in ovarian weight with accumulation of carotenoids,while if ablatod during the resting period, '- ^-x ovarian weight ijr>cr^a.ii<a(4 •'iijt not the carotenoid content ." :. Removal of eyestalk QISO seems to have a bearing on chromatophores ^ carotene V Zecixanthin P-V Doradexanthin • • 6 • • -V 4- hydroxy- f^ -carotene (Isoqryptoxanthin) 4 .. 4-keto- G -carotene (Exhinenone) 4-keto-4•-hydroxy- A -carotene (4•- Hydroxyechinenone) 4_4»-DiTceto " fii) " carotene (C anthaxanthin) Pho enicoxanthin (Adonirubin) Astaxanthin / Figure- 2: Metabolic pathway from M -carotene to Astaxanthin in crustaceans (Goqdwinn, 1984) and colour change. In Pala^ tv^ n^ serratus pigment granules are reduced with the loss of xanthophyll metabolism. In Uca puqilater bilateral removal results in loss of mobilisation of carotenoids from the hepatopancreas• Bilateral removal lowered the cimountis of esterified axtaxanthin in Dardanus arrosor while in Macrobrachium'rosenberqii increase in both free and esterified astaxanthin was observed, FISHES Carotenoids have been located in skin, muscle, liver, egg, sperm and in buccal mucosa of fishes. It is difficult to give authoritative values for carotenoids in fishes, since carotenoid content is Influenced by dietary availability, In salmon Oncorhynfehus; nerka is the male during spawning 7596 of., tiie carotenoids are in tihe skin while during pre-spawning 98% is concentrated in the muscle. In the testis • • I. • • it is nil. In the female during spawning 85% are in the ovaries, 14% in the skin and 5% in the muscle. During prespavming 90%-are in the muscle, 1% in the'skin and little' in the ovaries. Thus mobilisation of carotenoids vary :..». between sexes and with reproductive cycle. In fishes too as given in the figures 1 & 2 both metabolic of pathways are evident. Much •. j 'the information on this is based on reasonable evidences, yet intermediary links, and mediat^^enzymes are to be studied (Goodwin, 1984). FUNCTIONS ASCRIBED The only major function known is the role of carotenoids in the synthesis of vitamin A, y^  -carotene by breaking at 15-carbon can give rise to two molecules of vitamin A. c>(^ .-carotene, i^-cryptoxanthin and ^-apocarotene -8*-al are active retinol precursors. Thus the two essentials to be a precursor for vitamin A seems i) an unsubstituted M-ring and ii) a side chain of conjugated double bonds at least as long as that in retinol. Zeaxanthin, lutein and ^ -carotene are all 'inactive (Goodwin, 1984). In freshwater fishes desaturation at C*-3 does not destroy activity which is the characteristic of vitamin A2 (dehydroretinol)• But saturation of a double bond in the side chain or removal of a methyl group (eg. at C-13) entirely eliminated the vitamin activity. The usual form of natural carotenoids is all - transform, though some Cis-isomers do exist. The pro- '^-carotene though being a cis-isomer has potency equal to all-trans- '^^-carotene, because one half contain all the structural requirements of vitamin A precursor (Goodwin, 1984). All other functions proposed are just hypothesis^ x^, ST <»n-l:s(. Goodwin (1984) catalogues the following as the supp<;->s£>ci f•mct.lcir.s of carotenoids in crustaceans, perception •« 8 « • of light, electron acceptor,. protective-chromatic adaptation, protect eggs from solar radiation, high temperature, reducing reflectivity, masking luminescence of prey in stomach.and protecting gut wall against digestive enzymes -stabilisation of proteins, stabilisation of chitin, transfer of carotenoprotein pigments, reproduction, and chemo-reception in antennae. Tacon (1981) speculate the following as the possible function of carotenoids in fishes. 1. Antioxidant -P) carotene is 50 times faster as oxygen quencher -.- - ^(j^ oC- tocopherol. 2. Fishes are capab^%: of storing and modifying carotenoids to suit their requirements, whereby indicating some vital necessity for carotenoids other than vitamin'A precursor. 3. Egg astaxanthin in Salmo qairdneri enhances chemotaxis of spermatozoa. 4. In Cyclopterus lumpus there is intensive expenditure of Ccurotenoids in yolk sac also in Salmo trutta. 5. when canthaxanthin is supplemented in the diet of Salmo qairdneri resulted in enhancement of growth and maturation rate, 6. Degree of pigmentation is related to tolerance to various stringent.environmental conditions - low oxygen level, elevated temperature and ammonia levels, 7, Carotenoids may be respiratory in cellular level under adverse oxygen conditions. Eggs deposited in places of low 'oxygen and animals which live in low oxygen localities are more highly pigmented. 8, Though the role of carotene in gametogenesis is not clearly known in animals in certain filamentous fungi (phycomycetes) p -carotene serves as a precursor to ^Jb^ hormone trisporic acid which controls gametogenesis. 9, In fishes it is most likely they are mainly antioxidents since their association with high lipid content site make one to spaaiilate so. QUINONES Though the carotenoids are the subject of discussion it is better that a very brief mention is made of other biochromes. Of the quinones, ubiquinones (Q - coenzymes) belonging to benzoquinone series serve as biocatalysts in cellular respirationi Eventhough they occur almost 'i the anim^ ils, always present in very lav quantities, • In the skeleton of the echinoderms naphthoquinones pigments are present but their physiological role is not established. Vitamins K. and VU '«<- prothrombin and anti-haemorrhagic factorsTaXso related to naphthoquinones. Anthr^uinones are predpminently present in the scale insects. C Po<y ^ <^ 79} FIAVONOIDS Flavonoides are less common than the former.. These could have a role similar to that of vitamin P. Rutin has been found to accelerate the healing from severe X-ray burns and prevents capillary fragility. In the animals subjects to irradiation calcium flavonoids decreased haemorrhagic lesfions and mortality (Fox, 1979). FIAVItys Riboflavin is the most stricking example under this group of biochromes. Riboflavin could be sunthesised by the plants and specially young and tender parts are rich. Riboflavin iiS greenish - fluorescing, water soluble, yellow (when oxidised)^heterocyclic compound and serves as a reversible hydrogen acceptor in the redox systems .Cfb9<' 1*^ /9) 10 TETRAPYRROLES Porphyrins and Bilichrcanes belong to this group. Chlorophylls and haem are porphyrins. Cyanonocobalamin (B ,) is a tetrapyrrole. Biliru^n and the allied bile salts and the blood pigment biliverdin are the examples of bilichromes. (Poc/i'I "79) PTERINS These are polycylic nitrogenous compounds. Pluorescyanin present in fish scales are found to have physiological properties'like accelerating oxygen consu-mption like those of vitamin B^r Xanthopterin is found to stimulate normal cell division but suppresses tumorous growth and also functions as anti-anaemic •<lfc«, INDOLE The melanins, which are black or brown coloured substances common on the skin, fur, scale and feathers. The ink of cephalopods are melanins. Melanins are synthesised by the organism from the amino acid tyrosine while indigoids from oxidation of tryptophan.C^ oiK^ t*^ 79) In aquaculture, by tactful addition of specific biochromes the shell/skin/meat colour of the cultured organism can be modified to suit the aesthetic taste of the consumer market. • • 11 • • LITERATURE CITED Pox, D.L. 1976. Animal Biochromes and Structural Colours, II Edition, University of California Press, Berkeley. Pox, D.L. 1979. Pigment transactions between animals and plants. Biol. Rev., 54: 237-268. Goodwin, T.W, 1984, The Biochemistry of the Carotenoids Vol. 2 - Animals. XVI + 224 pp. II Edition, Chapman and Hall, London. Otazu - Abrill, M., B.J. Martin and H.J. Ceccaldi 1982. Influence of purified amino acids added to artificial diets on metabolism of carotenoid pigments in Palaemon serratus (Crustacea : Decapoda). Aquaculture^ 2.8: 303-309 (French; English abstract) . Tacon, A.G.J, 1981. Speculative review of possible carotenoid function in fish. Prog. Fish. Cult,, 4|(4): 205-208. 

Carotenoids and their importance in the nutrition of fish and crustaceans

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Carotenoids and their importance in the nutrition of fish and crustaceans

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