World of phytochemicals explained. Main groups of phytochemicals.
There is thousands of recognised phytochemicals. They are divided into many groups based on chemical structures. The general, systematic breakdown of phytochemicals is presented on a picture below (it doesn’t contain vitamins – these are presented in a separate article).
Let’s look where we can find representative phytochemicals for each group.
1. Terpenoids (isoprenoids) - include: carotenoids, triterpenoids, diterpenes, monoterpenes and steroids.
1.1. Carotenoids (tetraterpenoids, more than 600 compounds) - provide yellow, orange, and red colours in fruits and vegetables. They are divided into two groups: carotenes and xanthophyls.
1.1.1. Carotenes – are hydrocarbons (do not contain oxygen atoms), usually orange pigments.
- alpha-Carotene (provitamin A) – is present in carrots, pumpkins, maize, tangerine and orange.
- beta-Carotene (provitamin A) – is present in leafy greens, red, orange and yellow fruits and vegetables.
- γ-Carotene, δ-Carotene, ε-carotene – are present in smaller quantities in plants.
- Lycopene – is present in tomatoes, grapefruit, watermelon, guava, apricots, carrots and olives.
- Phytofluene – is present in star fruit, sweet potato, and orange.
- Phytoene – is present in sweet potato and orange.
1.1.2. Xanthophylls – are carotenoids with oxygen atoms in molecules. They are present in plants usually as yellow pigments.
- Lutein – is present in spinach, turnip greens, romaine lettuce, eggs, red pepper, pumpkin, mango, papaya, oranges, kiwi, peaches, squash, brassicas, prunes, sweet potatoes, honeydew melon, rhubarb, plum, avocado, pear and cilantro.
- Zeaxanthin – is present in wolfberry, spinach, kale, turnip greens, maize, eggs, red pepper, pumpkin and orange.
- Astaxanthin – is present in microalgae, yeast, krill, shrimp, salmon, lobsters and some crabs.
- Canthaxanthin – is present in paprika.
- Cryptoxanthin (provitamin A) – is present in mango, tangerine, orange, papaya, peaches, avocado, pea, grapefruit and kiwi.
- Rubixanthin – is present in a rose hip.
1.2. Triterpenoids – include saponins and many acids:
- Saponins – are present in soybeans, beans, other legumes, maize and alfalfa.
- Oleanolic acid – is present in an american pokeweed, honey mesquite, garlic, java apple, cloves and many other Syzygium species.
- Ursolic acid – is present in apples, basil, bilberries, cranberries, elder flower, peppermint, lavender, oregano, thyme, hawthorn and prunes.
- Betulinic acid – is found in persimmons and jujubes.
- Moronic acid – is present in Rhus javanica (a sumac) and mistletoe.
- Limonoids – occur in citrus fruits.
1.3. Diterpenes - compounds like cafestol, which is found in coffee grains.
1.4. Monoterpenoids - compounds, which have often antibacterial activity.
- Limonene – is found in oils of citrus fruits, cherries, spearmint, dill, garlic, celery, maize, rosemary, ginger and basil.
- Perillyl alcohol – is present in citrus oils, caraway, mints.
- Geraniol – is included in rose oil, palmarosa oil and citronella oil.
- Terpineol – is sourced from cajuput oil, pine oil, and petitgrain oil.
1.5. Steroids – are presented mostly by phytosterols and tocopherols.
- Phytosterols – are present in almonds, cashews, peanuts, sesame seeds, sunflower seeds, whole wheat, maize and soybeans.
- Tocopherols (vitamin E) –are widely present in vegetable oils.
- Sitosterols (mainly beta-Sitosterol) – are available from avocado, rice bran, wheat germ, corn oils, fennel, peanuts, soybeans, hawthorn, basil and buckwheat.
- Stigmasterol and Campesterol – are present in buckwheat.
2. Phenolic compounds - consist of phenol group and they can scavenge free radicals and protect against oxidative destruction.
2.1. Monophenols - compounds like apiole present in parsley and celery leaf; carnosol occurs in rosemary and sage; carvacrol found in oregano, thyme, pepperwort and wild bergamot; dillapiole present in dill and fennel root; rosemarinol found in rosemary)
2.2. Polyphenols – is a group of chemicals which include mainly flavonoids, isoflavonoids, lignans, stilbenoids, curcuminoids and tannins.
2.2.1. Flavonoids - are present as red, blue or purple pigments. In this group are flavonols, flavanones, flavones, flavanols, flavanonols and flavonols.
- Quercetin –is widely present in red and yellow onions, tea, wine, apples, cranberries, buckwheat, beans and lovage.
- Kaempferol – is present in tea, strawberries, gooseberries, cranberries, grapefruit, apples, peas, brassicates (broccoli, kale, brussels sprouts, cabbage), chives, spinach, endive, leek and tomatoes.
- Myricetin – is found in grapes, red wine, berries and walnuts.
- Fisetin – is present in strawberries and cucumbers.
- Rutin – appears in citrus fruits, oranges, lemons, limes, grapefruit, berries, peaches, apples, pagoda tree fruits, asparagus, buckwheat, parsley, tomatoes, apricots, rhubarb and tea.
- Isorhamnetin – is found in red turnip, goldenrod, mustard leaf and ginkgo biloba.
- Hesperidin – is found in citrus fruits.
- Hesperidin and naringenin – is present in citrus fruits.
- Silybin – is found in milk thistle.
- Naringin - occurs in grapefruit
- Apigenin – is present in chamomile, celery and parsley.
- Tangeritin (tangeretin) and nobiletin – are found in tangerine and other citrus peels.
- Luteolin –is present in beets, artichokes, celery, carrots, celeriac, rutabaga, parsley, mint, chamomile, lemongrass and chrysanthemum.
220.127.116.11. Flavan-3-ols (flavanols)
- Catechins –are widely present in white tea, green tea, black tea, grapes, wine, apple juice, cocoa, lentils and black-eyed peas.
- Epicatechin – is found in cocoa, tea and grapes.
- Theaflavins – is present in black tea.
- Proanthocyanidins – occur in apples, cinnamon, aronia fruit, cocoa beans, seed and skin of grapes.
18.104.22.168. Flavanonols - are flavanones with a hydroxyl group on position 3. The main compound in this group is taxifolin present in citrus fruits.
22.214.171.124. Anthocyanidins (flavonals) and anthocyanins - are present in many red, purple or blue fruits and vegetables.
- Pelargonidin – is found in bilberry, raspberry and strawberry.
- Peonidin – is present in bilberry, blueberry, cherry, cranberry and peach.
- Cyanidin –is widely present in red apples and pears, bilberry, blackberry, blueberry, cherry, cranberry, peach, plum, hawthorn, loganberry and cocoa.
- Delphinidin and malvidin – are present in bilberry, blueberry and eggplant.
2.2.2. Isoflavonoids - is a group of compounds consists of isoflavones, isoflavanes, isoflavandiols, isoflavenes, pterocarpans, coumestans and coumestrol.
126.96.36.199. Isoflavones – are active as phytoestrogens. In this group is, for example, daidzein (called also formononetin) and genistein (called also biochanin A), which both are present in soy, alfalfa sprouts, red clover, chickpeas, peanuts, and coumestrol found in red clover, alfalfa sprouts, soy, peas and brussels sprouts.
188.8.131.52. Pterocarpans - have phytoestrogen activities.
184.108.40.206. Coumestans - have phytoestrogen activities.
220.127.116.11. Coumestrol - is found in red clover, alfalfa sprouts, soy, peas and brussels sprouts.
2.2.2. Aurones - provide yellow colour to the flowers of some popular ornamental plants and can be found in the brown algae.
2.2.3. Chalconoids - are natural phenols related to chalcone, which show antibacterial, antifungal, antitumor and anti-inflammatory properties.
2.2.4. Flavonolignans - are represented by for example silymarin, which is found in artichokes and milk thistle.
2.2.5. Lignans – are active as phytoestrogens. That group represent matairesinol and secoisolariciresinol, which are found in flax seed, sesame seed, strawberries, blackcurrants, or pinoresinol and lariciresinol, which are present in sesame seeds.
2.2.6. Stilbenoids – are represented by resveratrol, pterostilbene or piceatannol – all are found in grapes.
2.2.7. Curcuminoids – are natural phenols, which produce a pronounced yellow colour. The main compound in this group is curcumin found in turmeric and mustard.
2.2.8. Tannins – are divided into four classes: hydrolysable tannins, condensed tannins, phlorotannins and flavono-ellagitannins. In first class is for example punicalagin found in tea and berries. In a second class, we can find proanthocyanidins, which are presented in cranberries and peanut skin. Last two groups are not widely present in plants.
2.2.9. Aromatic acids – create a group of acidic phytochemicals contains: phenolic acids, hydroxycinnamic acids, phenylethanoids and a few other specific compounds listed below.
18.104.22.168. Phenolic acids
- Salicylic acid – is present in peppermint, licorice, peanut and wheat.
- Vanillin and vanillic acid - occurr in acai palm oil, vanilla beans and cloves.
- Gallic acid - is present in tea, mango, strawberries, rhubarb and soy.
- Ellagic acid – is found in walnuts, strawberries, cranberries, blackberries, guava and grapes.
- Tannic acid - remains in nettles, tea and berries.
- Rosmarinic acid – is obtained from rosemary.
22.214.171.124 Hydroxycinnamic acids
- Caffeic acid - exists in burdock, hawthorn, artichoke, pear, basil, thyme, oregano, apple and olive oil.
- Chlorogenic acid - is present in echinacea, strawberries, pineapple, coffee, sunflower and blueberries.
- Cinnamic acid – is found in cinnamon and aloe.
- Ferulic acid - is present in oats, rice, artichoke, orange, pineapple, apple, peanut and acai berries oil.
- Chicoric acid – occurs in chicory.
- Coumarin and scopoletin – are found in citrus fruits and maize.
2.2.10. Phenylethanoids – are compounds represented by tyrosol, hydroxytyrosol, oleocanthal and oleuropein – all found in olive oil.
2.2.11. Capsaicin – is found in chilli peppers.
2.2.12. Gingerol - is present in ginger.
2.2.13. Alkylresorcinols - is present in wheat, rye and barley.
3. Glucosides and Glucosinolates
3.1. Isothiocyanates – are formed from glucosinolates. In this group are, for example: sinigrin, which is present in broccoli, brussels sprouts or black mustard, and glucoraphanin, which is found in broccoli, cauliflower, brussels sprouts and cabbages.
3.2. Aglycone parts of glucosides(or glucosinolates) – are represented by for example sulforaphane, which exists in broccoli, cauliflower, brussels sprouts and cabbages.
3.3. Organosulfides and thiosulfonates– are compounds containing sulphur atoms in molecules, like for example allyl methyl trisulfide or diallyl disulphide, which are present in garlic, onions, leeks and chives, or allicin, which can be obtained from garlic, or glutathione occurs in avocado, asparagus, broccoli, grapefruit, potato, strawberries, orange, tomato, peach and spinach.
3.4. Indoles - are represented by, the most abundant, indole-3-carbinol, which is found in cabbage, kale, brussels sprouts, rutabaga, mustard greens and broccoli, or allyl isothiocyanate, which exists in horseradish, mustard and wasabi, or piperine, which is specific for black pepper.
4. Betalains – are red and yellow pigments represented by betanins, betacyanins, indicaxanthin, vulgaxanthin found in beets.
5. Chlorophylls – are green pigments found in many green plants. This group of compounds contain chlorophyllin, which is present in green leafy vegetables.
6. Organic acids (not classified above) –are compounds with carboxylic group, like for example:
- Phytic acid (inositol hexaphosphate), which is found in cereals, nuts, sesame seeds, soybeans, wheat, pumpkin, beans and almonds,
- Oxalic acid, which exists in orange, spinach, rhubarb, tea, coffee, banana, ginger, almond, sweet potato and bell pepper,
- Tartaric acid, which is supplied by apricots, apples, sunflower, avocado, grapes and tamarind,
- Anacardic acid, which is present in cashews and mangoes,
- Malic acid, which is delivered by apples.
7. Amine derivatives (not classified above) – are compounds with amine or ammonium group, like for example betaine, which is present in beetroot, as well as,
8. Alkaloids –is a class of nitrogenous organic compounds represented by caffeine, theobromine and theophylline.
9. Anthraquinones – are compounds represented by:
- Senna (senna glycoside), which is delivered from senna,
- Barbaloin (aloin), which is present in aloe,
- Hypericin, which is isolated from St. John's wort,
- Damnacanthal, which is found in coffee.
10. Carbohydrates – represents in this case sugars delivered from plants. This group is divided into two subgroups: monosaccharides and polysaccharides.
10.1. Monosaccharides - are presented by simple hexoses, which are found in wheat and barley and pentoses, which are presented in rye and oat.
10.2. Polysaccharides - are polymeric carbohydrate molecules found in plants. This subgroup includes: beta-glucan, chitin (from mushrooms), lentinan (from shiitake), fructans, inulins (found in e.g. chicory), lignin (present in beans), pectins (delivered from e.g. apples).
Laboratories testing phytochemicals and providers of laboratory equipment.
- Jenny Egan (Agilent Technologies)
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- Linus Pauling Institute at Oregon State University (http://lpi.oregonstate.edu/mic/dietary-factors/phytochemicals)