Beta Vulgaris Biomimetic synthesis of betaxanthin plant

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Beta Vulgaris
Biomimetic synthesis of betaxanthin plant
pigments via in situ generation of betalamic acid
from betanin isolated from Beta vulgaris. Adam
S. Thompson and Paul I. Higgs. Department of
Chemistry, The University of Tennessee at
Martin,
Betalamic acid
Betaxanthins
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Plant Pigments Four Classes
Betalains

• chromoalkaloids
• conjugates of the chromophore betalamic acid and
  an amine.
• Betacyanins from L-DOPA derivative (glycosylated)
• betaxanthins from L-amino acids.
• Vacuoles highly water soluble,
• stable in acidic conditions
• but hydrolyze in basic conditions

Betacyanins
Betaxanthins
Betalamic acid
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Biochemical Construction of Betalains
?spontaneous (non-enzymatic) condensation of an
amino acid with betalamic acid (2 steps form
tyrosine via L-DOPA)
Betacyanins
Betaxanthins
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UV-Vis of Betalains
Betaxanthins
Betacyanins
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Tailored Semisynthetic Colorants
Betaxanthins
Betacyanins
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Why?
Natural Pigments gt Natural coloring agents food,
pharmaceuticals ?increasing consumer critique of
synthetic dyes FDC Red 2 Amaranth cake mixes,
fruit-flavoured fillings, jelly crystals can
provoke asthma, eczema and hyperactivity it
caused birth defects and foetal deaths in some
animal tests, possibly also cancer banned in the
USA, Russia, Austria and Norway and other
countries FDC Red 40 Allura, sweets, drinks
and condiments, medications and cosmetics,
synthetic introduced in the early eighties to
replace amaranth which was considered not safe
allura red has also been connected with cancer
in mice banned in Denmark, Belgium, France,
Germany, Switzerland, Sweden, Austria and Norway
Allura
Amaranth
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Extraction of Betacyanins
1. Red beet (homogenized or juiced) macerated
with acidified water (TFA pH 5-6) 2. Filtered,
Separated by Ion Exchange Chromatography with
Amberlite XAD-16. Elution with water (TFA pH 5-6)
followed by methanol gave fractions containing
the vivid red-violet betacyanins
Fractionated betaxanthins and betacyanins
Crude
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HPLC
Beta vulgaris
Betanin
Iso-Betanin
Solvent System A 0.1 (TFA) in H20 B 10
Formic Acid in H20 10A90 B ? 538 nm Flow
rate 1.0 mL/min Hypersil ODS
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Betalains Literature

• Very small scale, very dilute solution, UV
  amounts products not isolated
• Kept in solution, used as is without isolation

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Improved In Situ Generation of Betalamic Acid
?Concentrated betanin solution, excess
NH4OH(aq) 10-15 mins by UV hydrolysis completed
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Condensation of Amino Acids with Betalamic Acid
Gly
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Condensation of Amino acids with Betalamic Acid
Ala
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Condensation of Amino acids with Betalamic Acid
?Current Two down Gly and Ala adducts prepared
as shown by UV (Is the NMR fixed
yet?) ?Foreseeable Future Eighteen more to go!
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Acknowledgements
Dr Paul Higgs Clint Ary Carolyn Nguyen Tiffany
Brewer UTM College of Engineering and Natural
Sciences (CENS) undergraduate research grant UTM
College of Engineering and Natural Sciences
(CENS) Instrument grant purchase of UV-Vis
(Thermoscientific evolution 300)