Cinnamic acid is an iron chelator and has been shown to be beneficial to those
with diabetes a disease which has been found to be closely related to elevated
iron levels in the body.

Free Radic Biol Med. 1997;22(5):861-70.  Related Articles, Links  

 
Complexes of iron with phenolic compounds from soybean nodules and other legume
tissues: prooxidant and antioxidant properties.

Moran JF, Klucas RV, Grayer RJ, Abian J, Becana M.

Departamento de Nutricion Vegetal, Estacion Experimental de Aula Dei, CSIC,
Zaragoza, Spain.

The low-molecular-mass fraction of the soybean nodule cytosol contains Fe
capable of catalyzing free radical production through Fenton chemistry. A large
portion of the pool of catalytic Fe, measured as bleomycin-detectable Fe, was
characterized as complexes of Fe with phenolic compounds of three classes:
phenolic acids, cinnamic acids, and flavonoids. Many of these compounds, along
with other phenolics present in legume tissues, were used for a systematic
structure-activity relationship study. All phenolics tested were able to
chelate Fe, as judged from their inhibitory effect on site-specific deoxyribose
degradation (minus EDTA assay). However, only those having catechol,
pyrogallol, or 3-hydroxy-4-carbonyl groupings were potent chelators and
reductants of Fe3+ at pH 5.5. The same phenolics promoted oxidative damage to
DNA (bleomycin assay) and to deoxyribose (plus EDTA assay), but inhibited
linolenic acid peroxidation by chelating and reducing Fe3+ and by neutralizing
lipid radicals. Also, phenolics having a pyrogallol nucleus attenuated the free
radical-mediated inactivation of glutamine synthetase, which was used as a
model system, by chelating Fe2+. It is reasoned that under the microaerobic
(10-20 nM O2) and acidic (pH 5.5-6.4) conditions prevailing in nodules,
phenolics are likely to act primarily as antioxidants, decreasing oxidative
damage to biomolecules.

PMID: 9119255 [PubMed - indexed for MEDLINE]

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CINNAMIC ACID, or PHENYLACRYLIC Acm, C9H8O2 or C6HICH: CH~COOH, an
acid found in the form of its benzyl ester in Peru and Tolu balsams,
in storax and in some gumbenzoins. It can be prepared by the reduction
of phenyl propi-. olic acid with zinc and acetic acid, by heating
benzal malonic acid, by the condensation of ethyl acetate with
benzaldehyde in. the presence of sodium ethylate or by the so-called
Perkin reaction ; the latter being the method commonly employed. In
making the acid by this process benzaldehyde, acetic anhydride and
anhydrous sodium acetate are heated for some hours to about 180 C.,
the resulting product is made alkaline with sodium carbonate, and any
excess of benzaldehyde removed by a current of steam. The residual
liquor is filtered and acidified with hydrochloric acid, when cinnamic
acid is precipitated, C6H5CHO+ CHICOONa = CSHSCH :CH.COONa+HzO. It may
be purified by recrystallization from hot water. Considerable
controversy has taken place as to the course pursued by this reaction,
but the matter has been definitely settled by the work of R. Fittig
and his pupils (Annalen, 1883, 216, pp. 100, 115; 5885, 227, pp. 55,
119), in which it was shown that the aldehyde forms an addition
compound with the sodium salt of the fatty acid, and that the acetic
anhydride plays the part of a dehydrating agent. Cinnaniic acid
crystallizes in needles or prisms, melting at 33 C.; on reduction it
gives phenyl propionic acid, C6H5.CH2.CH2.COOH. Nitric acid oxidizes
it to benzoic acid and acetic acid. Potash fusion decomposes it into
benzoic and acetic acids. Being an unsaturated acid it combines
directly with hydrochloric acid, hydrobromic acid, bromine, &c. On
nitration it gives a mixture of ortho and para nitrocinnamic acids,
the former of which is of historical importance, as by converting it
into orthonitrophenyl propiolic acid A. Baeyer was enabled to carry
out the complete synthesis of indigo (q.v.). Reduction of
orthonitrocinnamic acid gives orthoaminocinnamic acid, C6H4(NH2)CH

quinoline derivative. An isomer of cinnamic acid known as
allo-cinnamic acid is also known.
For the oxy-cinnalnic acids see COUMARIN.