Chemistry Reference
In-Depth Information
O
O
-
O
P
Na
+
O
-
Na
+
O
-
O
P
O
3.17
Na
+
O
-
Na
+
O
O
P
Na
+ -
O
P
O
O
-
O
Na
Na
+
-
O
Na
+
O
-
3.18
O
O
O
-
Na
+
O
O
O
Na
+ -
O
O
3.19
O
O
O
O
+
NH
3
O
H
NH
3
Cl
-
+
Cl
-
O
+
H
3
N
O
3.20
Cl
-
H
NH
3
+
O
Cl
-
OH
O
O
O
O
O
P
O
O
-
H
HO
OH
Na
+
HO
OH
O
H
O
O
O
P
O
3.21
O
-
HO
O
Na
+
SCHEME 3.7
very successful and resulted in a remarkable number of hydrophilic carotenoids; several are shown
in Schemes 3.7 through 3.9.
Cardax™ (disodium disuccinate astaxanthin,
3.19
), the i rst synthesized hydrophilic compound
in the astaxanthin series, can today be produced in kg amounts by Cardax Pharmaceuticals, Inc.,
Aiea, Hawaii (Frey et al. 2004). A highly hydrophilic astaxanthin dilysine conjugate,
3.20
, although
not outperforming natural crocin,
3.7
, in solubility, surpasses its natural counterpart as colorant. The
lysine conjugate,
3.20
, forms deep red solutions in water and other solvents and, similar to crocin,
3.7
, aggregates only at high concentrations (Nalum Naess et al. 2006, 2007). In both compounds,
3.19
and
3.20
, the conversion of astaxanthin,
3.6
, to more soluble or dispersible compounds resulted
in antioxidant activity in aqueous formulations; however, this antioxidant capacity was primarily
based on the astaxanthin scaffold, and not to the conjugating moieties. Much work and resources
were subsequently devoted to the combination of hydrophilic ascorbic acid,
3.22
, with several caro-
tenoids, in particular astaxanthin,
3.6
. The many difi cult initial attempts i nally succeeded gratify-
ingly in an astaxanthin-vitamin C derivative, using a phosphate group as linker,
3.21
(Lockwood
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