Capsanthin oxidation

FIGURE 5.3.3B Oxidation to ketocarotenoids, capsorubin, and capsanthin. Enzyme abbreviations and enzyme activities are defined in Table 5.3.1. 

The structure of a new carotenoid, isolated from fruits of the red tomato-shaped paprika, was elucidated to be (3S,5f ,6S,59P)-3,6-epoxy-5,6-dihydro-5-hydroxy-P, carotenes, 6 -dione by spectroscopic analyses and mass spectrometry and was designated as capsanthone 3,6-epoxide. Capsanthone 3,6-epoxide is assumed to be an oxidative metabolite of capsanthin 3,6-epoxide in paprika (Maoka et al., 2001a). 

Eleven apo-carotenoids (1-11), including five new compounds, 4, 6, 9,10 and 11, were isolated from the fruits of the red paprika collected from Japan by Maoka et al. (2001b). The structures of new apocarotenoids were determined to be apo-14 -zeaxanthinal (4), apo-13-zeaxanthinone (6), apo-12 -capsorubinal (9), apo-8 -capsorubinal (10) and 9,9 -diapo-10,9 -retro-carotene-9,9 -dione (11) by spectroscopic analysis. The other six known apocarotenoids were identified to be apo-8 -zeaxanthinal (1), apo-lO -zeaxanthinal (2), apo-12 -zeaxan-thinal (3), apo-15-zeaxanthinal (5), apo-11-zeaxanthinal (7) and apo-9-zeaxanthinone (8), which had not been found previously in paprika. These apocarotenoids were assumed to be oxidative cleavage products of C40 carotenoid, such as capsanthin in paprika. 

Yamano and Ito have used the SnCl2 mediated regio- and stereoselective rearrangement of a cyclohexene oxide to produce a precursor to the natural products capsanthin and capsombin (Scheme 63) <20070BC3207>. 

A large survey of mass spectra of oxygenated carotenoids is reported by Budzikiewicz. He describes some characteristic fragmentation patterns for 5,6- and 5,8-oxides and capsanthin-type end-groups. Elimination of toluene, xylene, and C12H14 has been studied in aromatic and acyclic carotenoids labelled with deuterium at C-7 and C-7 and some with in-chain-oxidized... 

Capsanthin (16) and capsorubin (16a), the colourants in paprika oleoresin, although not produced by commercial synthesis have been prepared in the course of carotenoid studies (ref. 58). Capsanthin has been synthesised from p-citraurin ( 3-hydroxy-p-apo-8 -carotenal ) which is available from zeaxanthin (3R, 3R )-p-carotene-3,3 -diol), by oxidation with potassium permanganate (ref. 59). 

With p-citraurin from natural sources or obtainable semi-syntheticallly by the oxidation of zeaxanthin with permanganate, the same racemic hydroxy ketone derived from (Y) afforded by Claisen condensation, capsanthin as a mixture of diastereoisomers (ref. 61). The process is shown in Scheme 19b. Both capsanthin and capsorubin have yet to be synthesised in optically active form. 

This paper reports the antioxidative effect of capsanthin on the chlorophyll-photosensitized oxidation of soybean oil and selected flavor compounds including 2-ethylfiiran, 2,4.5-trimethyloxazole. and 2,5-dimethyl-4-hydroxy-3(2H)-fiiranone (DMHF), which are unstable when exposed to light in the presence of sensitizer 3,20). The quenching mechanism and kintics of capsanthin on the photosensitized oxidation of soybean oil are also reported. J3-carotene and lutein were used as controls for comparing the antiphotooxidative activity with capsanthin. 

Several other naturally occurring carotenoids that are not considered significant in the human diet have shown potential as cancer chemopreventive agents. These inclnde neoxanthin, fucoxanthin, phytoflnene, ( -carotene, phytoene, crocetin, capsanthin, peridinin, and astaxanthin. The xanthophyll astaxanthin is a powerful antioxidant and has great potential for reducing human disease processes related to oxidative damage." Therefore, it warrants a more detailed discussion as follows. 

The color change in paprika from red to brown, as an example, is due partly to a slow Maillard reaction, but primarily to oxidation of capsanthin (Fig. 3.48) and to some as yet unclear polymerization reactions. 

Fig. 3.48. Oxidative degradation of capsanthin during storage of paprika (according to Philip and Francis, 1971)...

Many spices also contain carotenoids. The composition and changes in concentration of different carotenoids during the ripening process in different species of pepper were studied by use of a binary gradient of water/acetone and a C18 RP column (245-247). An isocratic RP HPLC separation of capsanthin and capsorubin in Capsicum annum paprika and oleoresin on a Merck LiChros-pher 100 C18 5-p.m (0.4 X 25 cm) column with CH3CN/2-propanol/ethyl acetate (80 10 10) has been described (248). The carotenoids in saponified extracts of irradiated and ethylene oxide-treated red pepper were determined by HPLC on... 

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