Article by: Chukwuma Muanya
African researchers from Tanzania have released anticancer data on dietary ethnomedicinal species spanning from 24 botanical families reported from various articles and journals.
The study published Journal of Medicinal Plants Studies in 2014 is titled “The role of selected plant families with dietary Ethnomedicinal species used as anticancer.”
The researchers led by Ezekiel Amri of the Department of Science and Laboratory Technology, Dar es Salaam Institute of Technology, Tanzania, wrote: “ The investigations focused primarily on dietary ethnomedicinal species reported with anticancer bioactive compounds distributed from 24 plant families.” Plant families with anticancer ethnomedicinal species used as staple foods
According to the study, the family Poaceae contains many cereal grains plant species used as staple food in different parts of the world like Zea mays (maize),
Sorghum bicolor (sorghum), Oryza sativa (rice) and Triticum aestivum (wheat). These species contain flavonoids as the most abundant polyphenols in diets. The flavonoids and anthocyanins in these cereals particularly from the whole grain have been reported to have antioxidant and antimutagenic properties.
Oryza sativa (brown rice) and Oryza sativa indica (black rice) have also anticancer effects due to the presence of anthocyanins and certain phenols example, tricin which has been reported as potential for breast cancer treatment.
Although all types of rice (Oryza sativa) are a good source of energy, white rice (polished or milled rice) contains phenols at much lower levels than in brown rice. Thus, the consumption of brown rice instead of milled white rice may be beneficial with respect to cancer prevention.
The family Euphorbiaceae contains species Manihot esculenta (cassava) a known staple crop in Africa, Asia, and South America. M. esculenta manufacture cyanide by producing a chemical called linamarine which releases hydrogen cyanide when it is broken down by the linamarase enzyme. It has previously been reported that linamarin has an antitumoral action, this ability might be useful as a form of gene therapy where the gene for linamarase could be selectively put into cancer cells.
If linamarin were then introduced into the body, cancer cells would break it down and release cyanide only in the area around the cancer cells, killing them. Since normal cells would not have the linamarase gene and would not be able to convert linamarin into cyanide, they would not be affected.
Ipomoea batatas (Sweet potatoes) from Convolvulaceae family is also staple food in different parts of the world contain many anticancer properties, including beta-carotene, which may protect DNA in the cell nucleus from cancer-causing chemicals outside the nuclear membrane.
The family Fabaceae contains species such as Phaseolus vulgaris, Glycine max and Vigna unguiculata mostly used in meals, which have been reported as useful anticancer agents. Eating Phaseolus vulgaris (beans) has been reported that may significantly lower colon cancer incidence and multiplicity.
Cloves…Anti-cancer activities of S. aromaticum has been revealed on esophageal squamous cell carcinoma.
Glycine max (Soybean) contains isoflavones, which have been identified as dietary components having an important role in reducing the incidence of breast and prostate cancers. Genistein, the predominant isoflavones found in soy has been found to have antioxidant property, and shown to be the most potent inhibitor of growth transplantable human prostate carcinoma and spread of cancerous cells.
Epidemiological studies have revealed that Asians, who consume a traditional diet high in soy products, have relatively low incidences of breast and prostate cancers, while the incidences are much higher in the western world.
Vigna unguiculata (cowpea) also from the family Fabaceae contain anthocyanins, which belong to the flavonoid group of compounds widely distributed in plants consumed in the human diet such as beans. These anthocyanins are associated with a wide range of biological activities including antioxidant and anticancer.
Another biological active compound against cancer from Fabaceae family is Cajanol, an isoflavonoid isolated from roots of Cajanus cajan (pigeon pea). Cajonol has been reported to show the anticancer activity towards human breast cancer cells. Nuts from the family Fabaceae contain the antioxidants that may suppress the growth of cancers, for example Arachis hypogaea (Peanuts) are known as a source of Beta-sitosterol, a sterol with anticancer properties and have been reported to be effective against colon, prostate, and breast cancer.
Arachis hypogaea also has resveratrol compound, which possesses anticancer activity, and studies have indicated that it induces programmed cell death (PCD) in human leukemia.
Plant families with anticancer ethnomedicinal species used as vegetables
The family Brassicaceae contain many species known as cruciferous or brassica vegetables. Many commonly consumed anticancer cruciferous vegetables come from the Brassica genus, which includes species of different variety of cultivars of Brassica oleracea L. namely cabbage, broccoli, kale, collard greens, cauliflower, kohlrabi and brussels sprouts.
Other Brassica species reported to have anticancer activity are Brassica juncea (mustard greens), Brassica nigra (black mustard), Brassica rupestris (brown mustard), Brassica tournefortii (Asian mustard), (Brassica napus (rapeseed), Brassica var. perviridis (mustard spinach), Brassica rapa var. rapifera (turnips), Brassica rapa var. chinensis (bok choy) and Brassica rapa var.pekinensis (Chinese cabbage).
Vegetables are strongly associated with a lower risk of developing numerous cancers due to the presence of phytochemicals, which exhibit strong antioxidant activity. Thus, many types of vegetables, cruciferous vegetables are considered as the main anticancer foods because of their abundant antioxidants.
Plant species considered as cruciferous vegetables are also unique due to the presence of rich sources of antioxidants such as isothiocyanates, ascorbic acid, carotenoids and indole-3-carbinol that may act as anticancer.
High intake of cruciferous vegetables has been associated with lower risk of lung and colorectal cancer and in some epidemiological studies provides evidence that the consumption of cruciferous vegetables protects against cancer more effectively than the total intake of fruits and other vegetables.
Deep-coloured vegetables also are known to be good sources of phenolics, including flavonoid and anthocyanin, and carotenoids which are anticancer. Vegetables also contain salicylates, which play a bigger role in protecting against cancer.
Ginger…the rhizome of Zingiber officinale Roscoe (ginger), contain a plant-based nutrients curcumin which has powerful antioxidant properties. Curcumin is believed to have medicinal properties because it inhibits production of the inflammation-related enzyme cyclo-oxygenase 2 (COX-2), levels of which are abnormally high in certain inflammatory diseases and cancers, especially bowel, pancreatic and colon cancer.
The family Apiaceae contains the following reported anticancer species Daucus carota (carrots), Apium graveolens (celery), Coriandrum sativum (coriander), Foeniculum vulgare (fennel), Pastinaca sativa (parsnips),Heracleum rigens and Levisticum officinale (lovage).
The high content of phyto-constituent called as coumarins in these plants, have been reported to inhibit the growth of breast cancer, colon cancer, lung cancer and prostrate cancer, possess anti-inflammatory properties, the inhibiting of angiogenesis and the direct attack on cancer cells in the body.
D. carota contains bioactive compounds namely carotenoids (beta-carotene and lutein), polyacetylenes, falcarindiol and falcarindiol-3-acetate which could be effective in the treatment of leukemia and may help reduce a wide range of cancers including lung, mouth, throat, stomach, intestine, bladder, prostate and Breast.
The family Solanaceae has a genus Capsicum with species such as Capsicum frutescens (Chili pepper) and Capsicum spp. (hot pepper) widely used in traditional medicines. The leaves of Capsicum spp are very extensively used as a green vegetable and contain a chemical known as capsaicin, the principal pungent ingredient of hot red and chili peppers which has been linked with anti-inflammatory and anticancer activities by neutralizing certain cancer-causing substances.
Capsaicin also produces reactive oxygen species in cells with resultant induction of apoptosis and cell cycle arrest, which is beneficial for cancer chemoprevention and inhibitory effects on cancer development in multiple organs, such as, stomach, lung, and liver. Solanum aculeastrum (goat apple), another species in Solanaceae family is also reported for possessing anticancer activity.
Solanum lycopersicum (tomatoes) from the family Solanaceae contain lycopene, an antioxidant that attacks roaming oxygen molecules known as free radicals, which are suspected of triggering cancer. An increased intake of lycopene has previously been reported linked to a reduced risk of breast, pancreas and colorectal cancer.
Consumption of S. lycopersicum products is associated with a decreased risk of developing prostate cancer, and lycopene, the red carotenoid in the tomato is a potent antioxidant that might contribute to this chemoprevention activity. Also S. lycopersicum has vitamin C, an antioxidant, which can stop cellular damage that leads to cancer.
Findings from epidemiologic studies have indicated that consumption of tomatoes at a rate of approximately five to seven servings per week, were associated with a 30 per cent to 40 per cent reduction in prostate cancer risk.
Cucurbitaceae family contains species like Cucurbita maxima (pumpkin), and varieties of squash (Cucurbita pepo) and Cucurbita maxima known to be used as anticancer. Most parts of the C. maxima and C. pepo are edible, including the fleshy shell, the seeds, the leaves, and even the flowers. These species contain Cucurbitacin, a tetracyclic triterpenoid compound reported to have several biological activities and are predominantly isolated from Cucurbitaceae family.
Cucurbitacins are efficient anti-oxidant and this property lies in their ability to scavenge free-radicals such as hydroxyl radical, superoxide anions and singlet oxygen. Another important species of the family Cucurbitaceae with anticancer activity is Lagenaria siceraria (Bottle gourd), reported to have effective antioxidant and free radical scavenging activity.
The broad-spectrum radical-scavenging capacity of cucurbitacin in Cucurbitaceae family surpasses what had been reported for other natural antioxidants such as grape-seed extract, wheat and alfalfa extracts. Plant families with anticancer ethnomedicinal species used as fruits
The family Rutaceae contains citrus fruits plant species such Citrus sinensis (sweet orange), Citrus aurantium (bitter orange), Citrus limon (lemon) and Citrus aurantifolia (key lime), which have antioxidants and free radical scavengers reported to prevent oxidative cell damage, have strong anti-cancer activity and protects against all stage of carcinogens. Citrus fruits contain flavonoids and limonene which strongly inhibit the growth of leukemia cells, human gastric cancer and stimulates cancer-killing immune cells that may also break down cancer-causing substances. Citrus paradise (grapefruit) like other citrus fruits contain vitamin C, beta-carotene and citrus limonoids and essential oil, which can help prevent cancer by sweeping carcinogens out of the body. Rubus idaeus (raspberries), Fragaria ananassa (strawberry) and Rubus fruticosus (blackberry) fruits from Rosaceae family contain many plant compounds and abundant antioxidants known as anthocyanins that may protect against various cancers.
Garlic…Allium sativum contains oil-soluble sulphur compounds, which are responsible for anticancer effects exerted through multiple mechanisms such as inhibition of metabolic carcinogenic activation, arrest of cell cycle, antioxidant and pro-apoptotic action.
Rubus idaeus are rich in antioxidants, thought to have even more cancer-preventing properties than blueberries and strawberries. Malus domestica
(Apple) also from Rosaceae family is one of the most widely known fruit for its health effects as it is portrayed by the proverbial saying “An apple a day keeps the doctor away”.
Researches have advocated that apples are rich source of other antioxidant compounds that may reduce the risk of colon cancer, prostate cancer and lung cancer. Apple’s antioxidant property prevents the damage to cells and tissues. The fiber content, while less than in most other fruits, helps regulate bowel movements and may thus reduce the risk of colon cancer.
Vitis vinifera (grapes) from Vitaceae family contain bioflavonoids, powerful antioxidants that work as cancer preventives and it has previously been reported for anti-cancer effects against breast cancer.
Grapes are also a rich source of resveratrol, which inhibits the enzymes that can stimulate cancer-cell growth and suppress immune response. Persea americana (Avocados) of the family Lauraceae are rich in glutathione, a powerful antioxidant that attacks free radicals in the body by blocking intestinal absorption of certain fats. They also supply even more potassium than bananas and are a strong source of beta-carotene. A number of studies have indicated that extracts obtained from avocado meat contain phytochemicals that have the ability to selectively inhibit cancerous cell growth.
Psidium guajava (guava) a tropical fruit, widely consumed fresh and also processed. Curative properties of P. guajava as a medicinal plant have often been indicated by epidemiological studies on its anti-cancer potential.
The studies have indicated that P. guajava pulp, peel and seeds were the relevant component for causing cell cycle arrest and apoptosis due to the presence of antioxidants and hypoglycemic agents. Studies also have shown that P. guajava budding leaves possess anti-prostate cancer activity.
Syzygium cumini (Java plum) is another species from the family Myrtaceae with biological active compounds from its fruit in which studies have reported to reveal strong antioxidant, anti- leukemia activities and free radical-scavenging ability.
From Caricaceae family, various parts of Carica papaya (papaya) have been traditionally used as ethnomedicine for a number of disorders, including cancer. Papaya contains folacin (also known as folic acid), which has been shown to minimize cervical dysplasia and certain cancers. There have been anecdotes of patients with advanced cancers achieving remission following consumption of tea extract made from papaya leaves.
The leaves of papaya have been shown to contain many active components that can increase the total antioxidant power in blood and reduce lipid peroxidation level. In the leaves of Carica papaya, components previously reported to potentially have anti-tumor activity include flavonoid and benzylisothiocyanate.
Mangifera indica (mango) varieties of the family Anacardiaceae also have bee reported to show anticancer effects and chemopreventive activity due to the presence of polyphenolics compounds contained in mango fruits with anticancer activity.
Other fruits species like Garcinia mangostana (mangosteen) from Clusiaceae family contains a variety of secondary metabolites, such as oxygenated and prenylated xanthones which exhibit a variety of biological activities containing anti-inflammatory, anti-bacterial, and anti-cancer effect.
Plant families with spice and flavouring anticancer plant species
The family Myrtaceae possesses one of the most widely used species as spice and food flavouring agent, one of such typical example is Syzygium aromaticum (clove). The sun-dried unopened flower buds from the plant S. aromaticum is a commonly used spice and food flavor are rich in health-promoting phytochemicals such as essential oils (eugenol, caryophyllene, acetyl eugenol, naphthalene) which have received much attention for its apoptogenic and anti-proliferative properties and as a possible source of cancer chemopreventive compounds. Anti-cancer activities of S. aromaticum has been revealed on esophageal squamous cell carcinoma.
Allium sativum (garlic) from the Alliaceae family has been used throughout the centuries as an effective remedy for tumours. Heated and crushed garlic produce a one of the main compounds formed from garlic known as ajoene, which possesses a broad spectrum of biological activities that include anticancer.
Allium sativum and Tulbaghia violaceae (wild garlic) have other several compounds including allicin and its corresponding sulfide inhibit the proliferation and induce apoptosis of several human non-leukaemia malignant cells including breast, bladder, colorectal, hepatic, prostate cancer, lymphoma and skin tumour cell lines.
Allium sativum contains oil-soluble sulphur compounds, which are responsible for anticancer effects exerted through multiple mechanisms such as inhibition of metabolic carcinogenic activation, arrest of cell cycle, antioxidant and pro-apoptotic action.
People who consume raw or cooked garlic regularly face about half the risk of stomach cancer and two-thirds the risk of colorectal cancer as people who eat little or none.
Other allium vegetables species example Allium cepa (onions) are reported as the richest source of flavonoids and organosulphur compounds such as diallyl trisulfide which studies have shown that can offer protection against cancer through alteration in carcinogen-metabolizing enzymes, cell cycle arrest, induction of apoptotic cell death, suppression of oncogenic signal transduction pathways, and inhibition of neoangiogenesis.
Chilli pepper… Capsaicin also produces reactive oxygen species in cells with resultant induction of apoptosis and cell cycle arrest, which is beneficial for cancer chemoprevention and inhibitory effects on cancer development in multiple organs, such as, stomach, lung, and liver.
From the family Piperaceae, Piper nigrum (blackpepper) also used as spice is known to exert immune-modulatory roles and antitumor activities, consequently can be used as potential therapeutic tools to regulate inflammatory responses and prevent carcinogenesis.
The seeds of Nigella sativa L. of the family Ranunculaceae, commonly known as black seed or black cumin are another important spice used in folk (herbal) medicine all over the world for the treatment and prevention of a number of diseases and conditions that include cancer. Some studies have shown that the antioxidant role of crude oil and thymoquinone (TQ) extracted from Nigella sativa seeds and oil are effective against cancer in blood system, lung, kidney, liver, prostate, breast, cervix and skin cancer with much safety. Xylopia aethiopica (African pepper) is a species from the family Annonaceae also used as spice. The species has been reported to have antioxidant properties with cytotoxic effects on a wide range of cancer cell lines such as pancreatic and leukemia cells.
Rosmarinus officinalis (rosemary) of the family Lamiaceae contains carnosic acid and rosmarinic acid, compounds, which may shield the brain from free radicals, acting as anti-inflammatory and anti-cancer agent. The leaves of Rosmarinus officinalis are used as a flavouring in foods like stuffing and roast lamb, pork, chicken.
Others species from the family Lamiaceae commonly used in many kinds of food preparations with reported anticancer activity are Ocimum basilicum (sweet basil), Thymus vulgaris (thyme) and Mentha spicata (mint). The named species possess essential oil, luteolin, flavonoids and ursolic acid, which have been reported to have as antioxidant and anticancer activity towards human oral cavity squamous cell carcinoma. Plant families with anticancer ethnomedicinal species used in foods and beverages
Plants of the family Zingiberaceae have been frequently and widely used as spices and also, in traditional oriental medicine. The rhizome of Zingiber officinale Roscoe (ginger), contain a plant-based nutrients curcumin which has powerful antioxidant properties. Curcumin is believed to have medicinal properties because it inhibits production of the inflammation-related enzyme cyclo-oxygenase 2 (COX-2), levels of which are abnormally high in certain inflammatory diseases and cancers, especially bowel, pancreatic and colon cancer.
Studies have reported that curcumin acts as a free radical scavenger, thus could be the answer to stopping a fatal brain cancer known as glioblastoma. Curcumin has revealed its potential anticancer effects from its ability to induce apostosis in cancer cells without cytotoxic effects on healthy cells, suggesting curcumin selectively targets cancer cells.
Curcuma longa L. (turmeric) is another rhizomatous herbaceous perennial plant containing curcumin from the Zingiberaceae family. Curcumin a yellow natural polyphenol extracted from Curcuma longa has demonstrated effective anti-cancer properties in various human cancer cells.
The Rhizome of Alpinia galanga, Kaempferia galanga and Kaempferia rotunda also of the family Zingiberaceae contain biologically active compounds reported to show anticancer activity.
Camellia sinensis (green tea) from the family Theaceae is used in common beverages. C. sinensis contain certain antioxidants known as polyphenols which appear to prevent cancer cells from dividing and may protect against various types of cancer. This beneficial health effect has been in particularly attributed to the catechins (flavonoids) in tea.
Their biological benefits are due to their strong antioxidant and antiangiogenic activity as well as their potential to inhibit cell proliferation and modulate carcinogen metabolism. Green tea polyphenols have also shown the ability to lower risk of cardiovascular disease and many types of cancer including breast, ovarian, prostate, gastro-intestinal and lung cancer.
The researchers concluded: “From this review, it has been revealed that the families Apiaceae, Brassicaceae, Fabaceae and Rutaceae and Zingiberaceae had many ethnomedicinal species used as anticancer. Occurrence of other families also suggests the importance of all those families as source of useful chemical compounds in the management of cancer.
“Dietary ethnomedicinal plants possess plant derived natural products such as flavonoids, isoflavone genistein and curcumin as very promising anti-cancer agents because of their antioxidant, free radical scavenging properties and non-toxic and potent anti-cancer properties.
“Epidemiological and experimental studies reveal a negative correlation among the consumption abundant foods from plant-based dietary resources, fruits or vegetables and the risks for chronic diseases, including cancer.
“More research should continue on medicinal plants used traditionally as anticancer including dietary ethnomedicinal plants. In this review only some of the dietary ethnomedicinal plants have been explained here and there are many unexplored plants which need investigations for cancer fighting potentials.”