These compounds have not previously been reviewed by the Joint
    FAO/WHO Expert Committee on Food Additives.


         Anthocyanins represent a large group of water-soluble plant
    pigments of the 2-phenylbenzophyrylium (flavylium) structure
    (Kuhnau, 1976). The class, "Anthocyanins", consists of some 200 or
    more compounds (Parkinson & Brown, 1981) chemically combined to a
    sugar moiety (glucose < rhamnose < galactose < xylose
    < arabinose) of which the most common are:


                    Anthocyanin structure

                             Carbon ring B substitution
         Compound               3'              5'

         pelargonidin           -H              -H
         cyanidin               -OH             -H
         delphinidin            -OH             -OH
         peonidin               -OCH3           -H
         petunidin              -OCH3           -OH
         malvidin               -OCH3           -OCH3

         The blue to red colour imparted by the anthocyanins depends
    largely upon the pH of the medium (Francis, 1977). The anthocyanins
    normally exist as glycosides; the aglycone component alone is
    extremely unstable.

         The anthocyanin pigments present in grape-skin extract consist
    of diglucosides, monoglucosides, acylated monoglucosides, and
    acylated diglucosides of peonidin, malvidin, cyanidin, petunidin
    and delphinidin. The amount of each compound varies depending upon
    the variety of grape and climatic conditions.



    Absorption, distribution and excretion

         Anthocyanins are poorly absorbed from the gastrointestinal
    tract. Anthocyanins (notably delphinidin) extracted from concord
    grapes were administered to rats by either gavage (100 mg) or by
    percutaneous injection (50 mg) and the urine tested for unchanged
    anthocyanins by an HCl-acid red test (Horwitt, 1933). Anthocyanin
    was detected in the urine of rats administered anthocyanin by the
    percutaneous route but not by gavage. In studies in dogs (Horwitt,
    1933) administered anthocyanin (500 mg) by gastric fistula, no
    urinary coloration was demonstrated. However, in the rabbit, 1-2%
    of an oral dose of anthocyanin (500 mg) was present in the urine as
    the unchanged pigment. It should be noted that the HCl-acid red
    test used in this study would only detect unchanged anthocyanins
    (Scheline, 1978). If the anthocyanins were transformed into
    colourless pseudobases or pale anhydrolases prior to absorption and
    excretion, they would not be detected (Kuhnau, 1976).

         The absence of pigmented urine in normal individuals ingesting
    anthocyanin-containing foods in humans coupled with the apparent
    lack of metabolism of anthocyanins has been interpreted as showing
    that gastrointestinal absorption of these compounds does not occur
    (Clark & Mackay, 1950). Clinical studies have reported
    anthocyaninuria in patients with a beet allergy, following the
    ingestion of large amounts of beets (Zindler & Colovos, 1950).
    However, this has been identified as betaninuria, and is related to
    the excretion of betanin, rather than anthocyanins (Forrai et al,

         Tissue disposition of anthocyanosides derived from Vaccinium
    myrtillus (approximately 25% anthocyanins) was examined in
    Charles River rats following intraperitoneal (i.p.) or intravenous
    (i.v.) injection. Following acute administration by either route,
    anthocyanins were found to distribute rapidly into the tissues.

    Accumulation was primarily in the kidney, skin, liver, heart and
    lung (Lietti & Forni, 1976). There was also some indication of
    lymph node uptake of the anthocyanins. Elimination of the compound
    occurred primarily via the kidney (25-29%/24 hours) and bile
    (15-18%/24 hours). Because of the high urinary excretion rate in
    these studies, the anthocyanins are considered to be eliminated by
    both glomerular filtration and renal tubular excretion (Lietti &
    Forni, 1976).


         Studies in rats have shown that some anthocyanins (notably
    pelargonidin, delphinidin, malvidin) were subject to degradation by
    intestinal bacteria (Griffiths & Smith, 1972a, b). p-hydroxyphenyl-
    lactic acid was detected in the urine of rats following the
    oral administration of pelargonidin (a 3',3-diglycoside of
    pelargonidin). Decoloration of "anthocyanin" by rat caecal cell
    extracts has been reported (Haveland-Smith, 1981). Anthocyanin
    extracts incubated with human faecal suspensions for 2-3 days
    remained unchanged (as measured by a reduction in suspension

         The presence of 2 unidentified metabolites in the urine of
    rats after gavage with 100 mg of delphinidin has also been reported
    (Scheline, 1978). Rats gavaged with malvidin (a 3',5'-diglycoside
    of malvidin) had 3 unidentified metabolites present in the urine.
    These studies suggest that some of the metabolites of anthocyanins
    (aglycones) can be absorbed. Metabolism of anthocyanins may occur
    to a limited degree by ring fission and/or glycoside hydrolysis of
    the anthocyanins (Parkinson & Brown, 1981). Cyanidin, the most
    widespread anthocyanin, has not been shown to be attacked by
    intestinal bacteria (Scheline, 1968; Griffiths & Smith, 1972a).

    Effects on enzymes and other biochemical parameters

         Both pelargonidin and delphinidin have been shown to inhibit
    aldoreductase in the lens of rats (Varma & Kinoshita, 1976). In
    other studies, anthocyanin-3-monoglycosides (namely petunidin-,
    delphinidin- and malvidin-) extracted from grapes were found to
    increase the activity of alpha glucan phosphorylase and glutamic
    acid dicarboxylase but inhibit glycerol dehydrogenase, malate
    dehydrogenase and hexokinase (Carpenter et al., 1967).

         Other studies have shown that anthocyanins are capable of
    chelating ions such as copper (Somaatmadja et al., 1964) and iodide
    (Moudgal et al., 1958). The iodide ion was observed in vitro to
    form a stable complex with the anthocyanins (Moudgal et al., 1958).


    Special studies on mutagenicity

         Cyanidin chloride was not mutagenic when examined in the Ames
    assay using Salmonella typhimurium strain TA-98 with and without
    metabolic activation (arochlor 1254 induced rat liver S-9 fraction)
    (MacGregor & Jurd, 1978). Structure-activity testing of a large
    group of flavonols for mutagenic response in this assay system
    indicated that compounds of flavylium class were inactive.

         Cyanidin and delphinidin were inactive in the Ames assay
    system using 5 different strains of Salmonella typhimurium
    (TA-1535, TA-100, TA-1537, TA-1538 and TA-98) with and without
    activation (Brown & Dietrich, 1979).

         Anthocyanin was tested in both the Ames test using
    Salmonella typhimurium TA-1538 for mutagenicity and in another
    in vitro test employing E. coli Wf2 for induction of DNA
    damage. In both assay procedures with or without metabolic
    activation (using either rat caecal extracts or rat liver
    microsomes) anthocyanins were not found to induce any response
    (Haveland-Smith, 1981). Negative findings were also reported for
    the anthocyanins in a gene conversion assay using S. cerevisiae
    D4 (Haveland-Smith, 1981).

    Special studies on pharmacology

         In rabbits administered anthocyanin glycosides 6 g/kg (oral)
    or 500 mg/kg (i.p.) acutely, no adverse effect was noted on blood
    pressure. However, 100-200 mg/kg i.v. was shown to elicit a
    transcent hypotension accompanied by a decrease in respiratory
    amplitude. At 25 mg/kg i.v., diuretic effects were also reported.
    Anthocyanin also caused a vasodilation in the isolated rabbit heart
    (Pourrat et al., 1967).

         In mice, anthocyanins given in oral doses of 500 mg/kg
    produced a sedative effect on the animals (Pourrat et al., 1967).

         Improvements in visual acuity and darkness adaptation have
    been reported in humans for a short period of time, after receiving
    oral doses of up to 700 mg of the anthocyanins (Pourrat et al.,

    Special studies on reproduction

         A 2-generation reproduction study was performed in rats
    (Sprague-Dawley) ingesting a grape-skin extract preparation that
    was prepared by spray drying the liquid form of the extract after
    addition of a carrier material (malto-dextrose). The preparation

    contained approximately 3% anthocyanins. The test group received
    dietary levels of 7.5% or 15% of the grape-skin extract throughout
    the study. There were two concurrent control groups, one receiving
    the basal diet, the other receiving a diet containing 9% of the
    malto-dextrin used as a carrier to the grape-skin extract
    preparation. The F2a generation (10/litter culled at 4 days) were
    maintained for 21 days post-partum, then autopsied. No differences
    in reproduction performance or indices including pup viability were
    apparent between control and dosed groups. At the high-dose level,
    both the F1a and F2a rats exhibited lower body weights than the
    concurrent controls. Body weights of the F2 pups in the 7.5% group
    were marginally depressed. However, it should be noted that the
    decrease in body weights was accompanied by a concomitant decrease
    in food intake. At week 6 and at termination of the studies,
    haematological and blood serum chemistry and urinalyses were
    carried out in the F1a group. There were no compound-related
    effects. At week 18 of the study, rats in the F1a group were
    sacrificed and absolute and relative organ weights determined, and
    a complete histological study was carried out in the principal
    organs and tissues. Decrease in organ weights of the liver, adrenal
    and thyroid occurred in the 15% group. There were no compound-
    related histological effects (Cox & Babish, 1978a).

    Special studies on teratogenicity

         The anthocyanin glycosides (an extract from currants,
    blueberries and elderberries) were reported not to be teratogenic
    in rats, mice or rabbits when given at dose levels of 1.5, 3 or
    9 g/kg over 3 successive generations (Pourrat et al., 1967).

    Acute toxicity

                              LD50            Reference
    Animal      Route      (mg/kg bw)

    Mice        i.p.          4 110       Pourrat et al., 1967
                i.v.            840       Pourrat et al., 1967
                Oral         25 000       Pourrat et al., 1967

    Rats        i.p.          2 850       Pourrat et al., 1967
                i.v.            240       Pourrat et al., 1967
                Oral         20 000       Pourrat et al., 1967

         Test animals were administered the anthocyanins (cyanidin,
    petunidin and delphinidin mixture extracted from currants,
    blueberries and elderberries) in doses from 0 to 25 000 mg/kg bw
    for mice and from 0 to 20 000 mg/kg for rats. Following i.v. or
    i.p. administration, toxic doses of anthocyanins produced sedation,
    convulsions and finally death.

    Short-term studies

         Weanling male and female Wistar rats (20/group) were fed a
    diet containing anthocyanin extract at levels equivalent to
    3000 mg/day or 6000 mg/day for a period of 90 days. A group of
    concurrent controls were also used in the study. The doses of
    anthocyanin administered were estimated to be 5 and 10 times,
    respectively, the level that a human would ingest. No differences
    were observed between the test animals and controls in survival,
    growth or histopathology of the principal tissues at the
    termination of the study (Pourrat et al., 1967).

         In another study, guinea-pigs received 3000 mg/kg of
    anthocyanin in the diet for 15 days. No adverse effects were
    reported (Pourrat et al., 1967).

         Male and female beagle dogs (4/sex/dose) received either 0,
    7.5% or 15% of grape-skin extract (approximately 2.39% anthocyanin
    by weight) in the diet for 90 days. No differences were noted
    between control and treated animals in body weights, growth,
    survival, clinical chemistries (haematology, biochemistry or
    urinalysis), organ weights or pathological lesions (gross or
    microscopic) (Cox & Babish, 1978a).


         Man is naturally exposed to anthocyanins through the ingestion
    of fruits and vegetables. Levels of exposure under normal dietary
    conditions have not been established.

         Information on the metabolism and toxicity of the anthocyanins
    is limited. Its interpretation is complicated because the
    anthocyanins represent a large group of chemically-related
    substances and the effect observed with one defined anthocyanin may
    not be applicable to another. The available information suggests
    that anthocyanins are poorly absorbed from the gastrointestinal
    tract. Metabolism is limited and may be due to the activity of the
    intestinal bacterial flora. The metabolites of anthocyanins have
    not been identified. However, the insensitivity of the assay
    techniques used for measuring unmetabolized anthocyanins may result
    in a significant underestimate of the degree of absorption and
    metabolism of the anthocyanins (Kuhnau, 1976).


         Toxicological studies are limited, and have been carried out
    with mixtures extracted from a variety of fruits. The available
    data indicate that such extracts are of a very low order of
    toxicity. Diets containing 7.5% or 15% of a grape-skin extract
    preparation (approximately 3% anthocyanin) had no effect on the
    reproductive performance of rats in a 2-generation reproductive
    study. The lower body weights of offspring were related to a
    concomitant decrease in food intake. At the highest level tested,
    there was a decreased organ weight of the liver, adrenal and
    thyroid. There were no compound-related histological effects. No
    compound-related effects were observed in a short-term study in
    which dogs were fed diets containing 7.5% or 15% of the grape-skin
    extract preparation.


    Level causing no toxicological effect (Grape-skin extract

    Rat (young):   7.5% of the diet equivalent to 7500 mg/kg bw.

    Estimate of acceptable daily intake for man

    0-2.5 mg/kg bw.*


    *    Anthocyanins (present in the grape-skin preparation at level
         of approximately 3%).


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         flavonols in the Salmonella/mammalian microsome test,
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    Carpenter, J. A., Wang, Y.-P. & Powers, J. J. (1967) Effects of
         anthocyanin pigments on certain enzymes, Proc. Soc. Exptl.
         Biol. Med., 124, 702-706

    Clark, W. G. & Mackay, E. W. (1950) The absorption and excretion of
         rutin and related flavanoid substances, J. Amer. Med.
         Assoc., 143, 1411-1415

    Cox, G. E. & Babish, J. C. (1978a) Evaluation of the safety of
         dietary administration of special grape color powder (type
         BW-AT) on reproduction, lactation and maturation when fed to
         Sprague-Dawley rats. Unpublished report No. 5417 by Food and
         Drug Research Laboratories, Inc., submitted to the World
         Health Organization by FDA

    Cox, G. E. & Babish, J. C. (1978b) A 90-day feeding study of
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         Unpublished report No. 5417 by Food and Drug Research
         Laboratories, Inc., submitted to the World Health Organization
         by FDA

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    Griffiths, L. A. & Smith, G. E. (1972b) Metabolism of apigenin and
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    Varma, S. D. & Kinoshita, J. H. (1976) Inhibition of lens aldose
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    See Also:
       Toxicological Abbreviations
       ANTHOCYANINS (JECFA Evaluation)