They're Back.......

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RJB112 " <rjb112@y...>

Date: Sat Mar 13, 2004 2:30 pm

Subject: They're back........

Cranberries come out on top in a very interesting article on fruits.

Below is the abstract of the article. (I do not have the entire

article, but plan to get it, especially to take a look at the

Bioactivity Index for Dietary Cancer Prevention).

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I've got the article now, thanks very much to Al.

I've read the whole thing and extracted out the most important parts,

to give sort of a 'reader's digest' condensed version. Here it is....

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J Agric Food Chem. 2002 Dec 4;50(25):7449-54.

Antioxidant and antiproliferative activities of common fruits.

Sun J, Chu YF, Wu X, Liu RH.

Department of Food Science, Cornell University, Ithaca, New York

14853-7201, USA.

Consumption of fruits and vegetables has been associated with reduced

risk of chronic diseases such as cardiovascular disease and cancer.

Phytochemicals, especially phenolics, in fruits and vegetables are

suggested to be the major bioactive compounds for the health

benefits. However, the phenolic contents and their antioxidant

activities in fruits and vegetables were underestimated in the

literature…….. Overproduction of oxidants in certain conditions can

cause an imbalance, leading to oxidative damage to large

biomolecules such as lipids, DNA, and proteins... More and more

evidence suggest that this potentially cancer-inducing oxidative

damage might be prevented or limited by dietary antioxidants found in

fruits and vegetables. Phytochemicals in fruits and vegetables can

have complementary and overlapping mechanisms of oxidative agents,

stimulation of the immune system, regulation of gene expression in

cell proliferation and

apoptosis, hormone metabolism, and antibacterial and antiviral

effects...Recent studies showed that the phytochemicals, especially

phenolics, in fruits and vegetables are the major bioactive compounds

with human health benefits....There

was a direct relationship between the total phenolic contents and the

antioxidant activities in fruits and vegetables... Eberhardt et

al... demonstrated that the vitamin C in apples only contributed

less than 0.4% of total antioxidant activity, suggesting that the

complex mixture of phytochemicals in fruits and vegetables provided

protective health benefits mainly through a combination of additive

and/or synergistic effects.

Phenolics in fruits are in both soluble free and bound forms. Bound

phenolics, mainly

in the form of â-glycosides, may survive the human stomach and small

intestine digestion and reach the colon intact, where they are

released to exhibit their bioactivity with health benefits....

However, most of the previous research mainly determined the soluble

free phenolics on the basis of the solvent-soluble extraction.

Therefore, the total phenolic contents of fruits and their

antioxidant activities were underestimated in the literature……

Quantification of the Total Antioxidant Activity: A modified total

oxyradical scavenging capacity (TOSC) assay was used for determining

total antioxidant capacity of extracts....Total antioxidant activity

was expressed as

ímol of vitamin C equiv for 1 g of fresh weight of the edible part of

fruits. All TOSC values are presented as mean (SD) for at least three

replicates....

Phenolic Content of Common Fruits: Phenolic contents of

11 selected common fruits are expressed as mg of gallic acid

equiv/100 g of fresh weight of the edible part of fruits in Figure

2. Among all the fruits analyzed, cranberry had the highest

soluble free phenolic content (507.0 ( 21.1 mg/100 g, p < 0.01),

followed by apple (272.1 ( 6.2 mg/100 g), red grape (182.0 (

2.6 mg/100 g), strawberry (147.8 ( 1.1 mg/100 g), lemon (66.3

( 3.4 mg/100 g), peach (65.3 ( 0.4 mg/100 g), orange (56.8

( 0.9 mg/100 g), banana (56.1 ( 2.8 mg/100 g), pear (53.6

2.5 mg/100 g), and pineapple (40.4 ( 1.0 mg/100 g...Total Antioxidant

Activity and Antiproliferative Activity:

The total antioxidant activities of 11 selected common fruits

were expressed as ímol of vitamin C equiv/g of fresh weight

of the edible part of fruits and are summarized in Figure 3...

The phytochemical extract of cranberry had the highest total

antioxidant activity (177.0 ( 4.3 ímol/g, p < 0.01), followed

by apple (97.6 ( 4.6 ímol/g), red grape (64.7 ( 1.6 ímol/g),

strawberry (64.4 ( 1.1 ímol/g), peach (49.5 ( 2.8 ímol/g),

lemon (42.8 ( 1.0 ímol/g), pear (34.2 ( 0.3 ímol/g), banana

(32.8 ( 1.5 ímol/g), orange (31.5 ( 0.27 ímol/g), grapefruit

(24.7 ( 0.17 ímol/g), and pineapple (16.9 ( 0.3 ímol/g). There

was no significant difference (p > 0.05) in antioxidant activities

between red grape and strawberry, peach, and lemon and banana

and orange.

Antiproliferative activities of fruit soluble free extracts on

the growth of HepG2 human liver cancer cells in vitro are

summarized in Figure 4. Among the 11 selected common fruits,

cranberry, lemon, apple, strawberry, red grape, banana, and

grapefruit showed relatively potent antiproliferative activities

on HepG2 cell growth in a dose-dependent manner. The

antiproliferative activities of fruits were expressed as the median

effective dose (EC50), with a lower EC50 value indicating a

higher antiproliferative activity (Figure 5). The soluble free

extract of cranberry had the highest antiproliferative activity

with the lowest EC50 of 14.5 ( 0.5 mg/mL, followed by lemon

(30.6 ( 0.8 mg/mL), apple (49.4 ( 1.6 mg/mL), strawberry (56.3 ( 1.5

mg/mL), red grape (71.0 ( 2.2 mg/mL), banana (110.1 ( 2.5 mg/mL), and

grapefruit (130.1 ( 4.5 mg/mL)……

Relationship between Total Phenolic Content, Antioxidant

Activity, and Antiproliferative Activity. There was a direct

relationship between total phenolic content and total antioxidant

activity in phytochemical extracts of different fruits….. The higher

total phenolic content

in fruits resulted in higher total antioxidant activity . There is no

obvious linear relationship between total phenolic content and

inhibition of HepG2 cell proliferation…. . Also there is no

significant linear relationship between total antioxidant activity

and antiproliferative activity of the fruits

tested.....Overproduction of oxidants can cause oxidative stress,

which is associated with chronic diseases………..

Relationship between Total Phenolic Content, Antioxidant

Activity, and Antiproliferative Activity. There was a direct

relationship between total phenolic content and total antioxidant

activity in phytochemical extracts of different fruits….. The higher

total phenolic content

in fruits resulted in higher total antioxidant activity. There is no

obvious linear relationship between total phenolic content and

inhibition of HepG2 cell proliferation… The significance of bound phy-

tochemicals in fruits to human health is not clear. However, it is

highly possible that different fruits with different amounts of

bound phytochemicals can be digested and absorbed at different sites

of the gastrointestinal tract and play their unique health benefits.

Bound phytochemicals, mainly in â-glycosides, cannot be digested by

human enzymes and could survive stomach and

small intestine digestion to reach the colon, providing site specific

health benefits… For example, banana and pineapple, with a high

percentage of bound phytochemicals, may

be able to survive the stomach and small intestine digestion to reach

the colon and be digested by bacteria flora to release phytochemicals

locally to have health benefits….

The phytochemical extracts of fruits showed potent antioxidant

activities. The total antioxidant activity of 100 g of cranberry was

equivalent to that of 3120 mg of vitamin C, followed by apple (1740

mg of vitamin C equiv/100 g), red grape (1140 mg of vitamin C

equiv/100 g), strawberry (1130 mg of vitamin C equiv/100 g), peach

(871 mg of vitamin C equiv/100 g), lemon (753 mg of vitamin C

equiv/100 g), pear (603 mg of vitamin C equiv/100 g), banana (578 mg

of vitamin C equiv/100 g), orange (554 mg of vitamin C equiv/100 g),

grapefruit (434 mg of vitamin C equiv/100 g), and pineapple

(298 mg of vitamin C equiv/100 g). The combination of phytochemicals

and synergistic mechanisms in the fruit matrix may be responsible for

the potent antioxidant activities of fruits… Vitamin C has been

considered as the major antioxidant in fruits. Our group has shown

that vitamin C only contributed 0.4% of the total antioxidant

activity in apples…. Here we further showed that the contributions of

vitamin C to the total antioxidant activities in the 11 fruits tested

were low, suggesting that the majority of the total antioxidant

activity was from other phytochemicals in fruits….. Interestingly,

there is no vitamin C in cranberry though it had the highest total

antioxidant activity….

the estimated contribution of vitamin C to the total antioxidant

activity is relatively low….. Therefore, the major contribution to

the total antioxidant activity in fruits was from the combination of

phytochemicals, not from the vitamin C, as suggested in our previous

report (10)……. It was reported that the antioxidant activity of

raspberry was

directly related to the phenolic content... Here we showed that there

was a direct linear relationship between the phenolic contents and

total antioxidant activities in the 11 fruits tested …..indicating

phenolics may be the major contributor to the total antioxidant

activities of fruits. Among the 11 fruits tested, 8 of them showed

the ability to inhibit

human liver cancer cell growth in vitro… The antiproliferative

activities of fruit extracts did not correlate with their antioxidant

activities or total phenolic contents. This was consistent with the

finding in raspberries that the relationship between total phenolics

and

EC50 of HepG2 cell inhibition was not significant… The inhibition of

cancer cell proliferation by fruit extracts cannot be explained by

the total phenolic contents in the fruits tested. This suggested that

a specific phenolic compound or a class of phenolics in fruits was

responsible for their antiproliferative activities. Therefore,

further identification of specific phytochemicals for their

antiproliferative activities

is worthy of investigation…. The bioactivity index (BI) was proposed

here to provide a simple reference for consumers to choose fruits on

the basis of their beneficial activities…

Bioactivity Index (BI) of Selected Fruits for Dietary Cancer

Prevention

fruit rank

cranberry 1

apple 2

lemon 3

strawberry 4

red grape 5

peach 6

banana 7

grapefruit 8

pear 9

orange 10

pineapple 11

BI : 1/2(score of total antioxidant activity + score of

antiproliferative activity).

Our results showed that cranberry had the highest BI value (1.00),

followed by apple (0.42), lemon (0.36), strawberry (0.31), red grape

(0.28), peach (0.18), banana (0.16), grapefruit (0.13), pear (0.10),

orange (0.09), and pineapple (0.05). We believe that the bioactivity

index reported here could be a new alternative biomarker for

epidemiological studies in dietary cancer prevention. The BI could

affect the rankings of fruits. If only considering the antioxidant

activity of the fruit extracts, lemon was ranked as number 6 out of

the 11 fruits tested, but when both antioxidant activity and

anticancer cell proliferation activity were considered, such as BI,

the ranking of lemon was moved to the number 3 position. Therefore,

BI is a better biomarker than either total antioxidant activity or

antiproliferative activity alone. However, this was only a simple

model, and

further research is needed to unveil the real role of phytochemicals

of fruits in dietary cancer prevention….. Our work clearly showed

that phytochemicals in fruits have potent antioxidant and

antiproliferative activities. The bioactive index (BI) for dietary

cancer prevention was proposed to provide a new biomarker for future

epidemiological studies…..

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p.s. I found the very high antioxidant activity of the fruits to be

striking. " The total antioxidant activity of 100 g of cranberry was

equivalent to that of 3120 mg of vitamin C, followed by apple (1740

mg of vitamin C equiv/100 g), red grape (1140 mg of vitamin C

equiv/100 g), strawberry (1130 mg of vitamin C equiv/100 g). "

100g (3 1/2 ounces) is not very much fruit to eat. But that amount

can deliver a lot of polyphenol antioxidant activity.

rjb112@...

bob bessen