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tocotrienols), and vitamin K (phylloquinone and menaquinones) (Rizzolo and
Polesello 1992).
Some vitamins have hormonelike functions as regulators of mineral metabolism
(e.g., vitamin D) or regulators of cell and tissue growth and differentiation (e.g.,
some forms of vitamin A). Others work as antioxidants (e.g., vitamin E and sometimes vitamins B and C). The largest numbers of vitamins (e.g., B complex vitamins) work as precursors of enzyme cofactors (Bernard et al. 2011). Vitamin C
(L-ascorbic acid or L-ascorbate) is an essential nutrient for humans and other animal species. Deficiency in this vitamin causes the disease known as scurvy in
humans. This compound is also widely used as a food additive because of its antioxidant activity. Vitamin E is a generic term for tocopherols and tocotrienols, and it
is a fat-soluble antioxidant that blocks the production of reactive oxygen species
formed when lipids undergo oxidation.
Carotenoids Several hundred compounds belonging to carotenoids are known
today, synthesized by plants, algae, yeast, fungi, and photosynthetic bacteria. They
are prominent for their distribution, structural diversity, and various functions.
Fruits and vegetables provide most of the carotenoids in the human diet (Bernard
et al. 2011). Carotenoids are soluble in oils and organic solvents, and their color
varies from yellow through orange to red. Two structural groups of carotenoids are
distinguished: carotenes (α-carotene, β-carotene, or lycopene) and xanthophylls
(β-cryptoxanthin, lutein, or zeaxanthin). The basic structure of carotenoids consists
of covalently linked isoprene units. At the end of each chain, there is either a ring or
an open chain, and the carotenoids differ from each other. These are polyunsaturated compounds. The most common carotenoid in the plant world is β-carotene,
and other carotenoids found in plants are α-carotene (carrots), capsanthin (red peppers, peppers), lutein, zeaxanthin, violaxanthin, neoxanthin, and β-cryptoxanthin.
These compounds show antioxidant and immunomodulation activities, and they can
prevent degenerative diseases, such as cardiovascular diseases, diabetes, and several
types of cancer especially prostate and digestive tract tumors.
Polyphenols Polyphenols are secondary metabolites of plants in which they have
multiple roles:
• Sensory properties such as color, aroma, or taste.
• Affect the plant’s resistance to diseases and microorganisms.
• Some polyphenols indirectly affect plant growth as well.
• Protect sensitive cellular parts from harmful radiation (UV absorption).
Polyphenols include more than 10,000 compounds of various chemical structures which have been isolated and identified. The word “polyphenol” is formed
from the ancient Greek word “poli-,” which means “much,” and the word “phenol”
which is a molecule formed from a phenyl (-C 6 H 5 ) group linked to a hydroxyl (-OH)
group. They are essential for the growth and reproduction of plants and are produced to defend injured plants against pathogens. They are secondary metabolites
of plants and are known as hormones, vitamins, and food antioxidants.
V. I. Petropulos and B. Balabanova
tocotrienols), and vitamin K (phylloquinone and menaquinones) (Rizzolo and
Polesello 1992).
Some vitamins have hormonelike functions as regulators of mineral metabolism
(e.g., vitamin D) or regulators of cell and tissue growth and differentiation (e.g.,
some forms of vitamin A). Others work as antioxidants (e.g., vitamin E and sometimes vitamins B and C). The largest numbers of vitamins (e.g., B complex vitamins) work as precursors of enzyme cofactors (Bernard et al. 2011). Vitamin C
(L-ascorbic acid or L-ascorbate) is an essential nutrient for humans and other animal species. Deficiency in this vitamin causes the disease known as scurvy in
humans. This compound is also widely used as a food additive because of its antioxidant activity. Vitamin E is a generic term for tocopherols and tocotrienols, and it
is a fat-soluble antioxidant that blocks the production of reactive oxygen species
formed when lipids undergo oxidation.
Carotenoids Several hundred compounds belonging to carotenoids are known
today, synthesized by plants, algae, yeast, fungi, and photosynthetic bacteria. They
are prominent for their distribution, structural diversity, and various functions.
Fruits and vegetables provide most of the carotenoids in the human diet (Bernard
et al. 2011). Carotenoids are soluble in oils and organic solvents, and their color
varies from yellow through orange to red. Two structural groups of carotenoids are
distinguished: carotenes (α-carotene, β-carotene, or lycopene) and xanthophylls
(β-cryptoxanthin, lutein, or zeaxanthin). The basic structure of carotenoids consists
of covalently linked isoprene units. At the end of each chain, there is either a ring or
an open chain, and the carotenoids differ from each other. These are polyunsaturated compounds. The most common carotenoid in the plant world is β-carotene,
and other carotenoids found in plants are α-carotene (carrots), capsanthin (red peppers, peppers), lutein, zeaxanthin, violaxanthin, neoxanthin, and β-cryptoxanthin.
These compounds show antioxidant and immunomodulation activities, and they can
prevent degenerative diseases, such as cardiovascular diseases, diabetes, and several
types of cancer especially prostate and digestive tract tumors.
Polyphenols Polyphenols are secondary metabolites of plants in which they have
multiple roles:
• Sensory properties such as color, aroma, or taste.
• Affect the plant’s resistance to diseases and microorganisms.
• Some polyphenols indirectly affect plant growth as well.
• Protect sensitive cellular parts from harmful radiation (UV absorption).
Polyphenols include more than 10,000 compounds of various chemical structures which have been isolated and identified. The word “polyphenol” is formed
from the ancient Greek word “poli-,” which means “much,” and the word “phenol”
which is a molecule formed from a phenyl (-C 6 H 5 ) group linked to a hydroxyl (-OH)
group. They are essential for the growth and reproduction of plants and are produced to defend injured plants against pathogens. They are secondary metabolites
of plants and are known as hormones, vitamins, and food antioxidants.
V. I. Petropulos and B. Balabanova