Proanthocyanidins in Cacao - Natural Antioxidants and Biocides from Wild Medicinal Plants - page 41

bitterness and astringency) in cacao and
chocolate products, they also seem to have
a host of health benefits in human diets.
The antioxidant activity of these com-
pounds seems to be important in many, but
not all, of these cases. For example, isolated
proanthocyanidins have inhibitory effects
on NADP-dependent lipid peroxidation in
microsomes and on the autoxidation of
linoleic acid. These effects were attributed
to radical-scavenging activity in peroxida-
tion chain reactions (Hatano et al. , 2002).
The NADPH-dependent lipid peroxidation
in rat liver microsomes was inhibited by
almost all of polyphenols tested, but, of the
compounds isolated, procyanidin B2 and
B5 had equal and the most powerful inhibi-
tory effect. Additionally, procyanidin B2
had the greatest radical-scavenging effect on
the DPPH radical, a common measure of
antioxidant activity.
Cocoa polyphenol was fractionated
from commercial cocoa powder that con-
tained 413 epicatechin-equivalent pheno-
lics. These phenols dose-dependently
inhibited xanthine oxidase activity, and
12- O -tetradecanoylphorbol-13-acetate
(TPA)-induced superoxide-anion genera-
tion in cultured human leukaemia HL-60
cells. The levels of cyclooxygenase
(COX)-2 expression induced in mouse skin
after 4-h treatment with topical TPA was
also diminished significantly by pre-treating
with cocoa polyphenol for 30 min. Cocoa
polyphenol at the same doses inhibited
TPA-induced nuclear translocation of
transcription factor p65 and subsequent
DNA binding of nuclear factor-kB (NF-kB)
by blocking the degradation of 1-kBa in
mouse skin. Moreover, phosphorylation of
p38 mitogen-activated protein kinase in ICR
mouse skin was suppressed by oral treat-
ment with cocoa proanthocyanidins. Because
cellular pro-inflammatory and pro-oxidant
states are closely linked to tumour promotion,
the antioxidant and anti-inflammatory prop-
erties of cocoa proanthocyanidins may consti-
tute the basis of possible antitumor-promoting
effects of this substance (Lee et al. , 2006).
A pentameric procyanidin from Theo-
broma cacao selectively inhibits growth of
human breast cancer cells (Ramijak et al. ,

2005). This compound causes G 0 /G 1 cell
cycle arrest in human breast cancer cells in
culture by an unknown mechanism. Further
studies revealed a specific dephosphoryla-
tion of several G 1 -modulatory proteins with-
out changes in gene expression (Ramijak
et al. , 2005). Synthetically derived penta-
meric oligomers based on the structure of
those from cacao that were formed from
(−)-epicatechin units also inhibited the growth
of several breast cancer cell lines. In this
case it was also established that the outcome
was based on the induction of cell cycle
arrest in the G 0 /G 1 phase. Subsequent cell
death is more likely necrotic rather than
apoptotic (Kozikowski et al. , 2003).
Chocolate products vary widely in fla-
vonoid content. On the basis of limited data,
approximately 150 mg of flavonoids in a sin-
gle dose is needed to trigger a rapid antioxi-
dant effect and changes in prostacyclin.
Various types of chocolate contain between
0.09 and 4 mg procyanidins per gram. Thus,
the amount of chocolate to exert acute and
chronic antioxidant effects and changes in
prostacyclin are between 38 and 125 g,
respectively (Kris-Etherton and Keen, 2002).
Habitual chocolate users performed
better in all cognitive tests and had sig-
nificantly reduced risk for poor test per-
formance in most tests. The mean intake
of chocolate among users was as little as
8 g/day (Nurk et al. , 2009). An effect of cocoa
flavonols on cerebral blood flow raises the
possibility that there may be a benefit to
increasing blood flow and enhancing brain
function in situations where individuals are
cognitively impaired (MacDonald, 2007).
In studies of the Kuna Indians of Panama,
who are heavy consumers of cocoa, the Indians
have a very low rate of hypertension and
cardiovascular diseases (Bayard et al. , 2007).
However, the same people living on mainland
Panama, who do not drink the flavanol-rich
chocolate had much higher rates of heart dis-
ease and of cancer (Hollenberg, 2007). These
workers observed that improvements in
blood vessel function following consump-
tion of flavanol-rich cocoa are paralleled by
an increase in the circulating pool of nitric
oxide, a molecule that helps dilate blood
vessels and keep them pliable.