Scientists validate Nigerian food plants for cancer treatment

A very recent study on anti-cancer and free radical scavenging activity of some Nigerian food plants shows that regular intake of local spices and vegetables such as bitter leaf (Vernonia amygdalina), Gongronema latifolium (utazi in Ibo, arokeke in Yoruba), West African Black Pepper or Ashanti pepper (Piper guineense, uziza in Igbo and ata iyere in Yoruba), sesame (Sesamum indicum), and Cowhage also called Velvet bean (agbala or agbaloko in Ibo and werepe in Yoruba) could provide the elusive cure for cancers.

The study was published in February 25, 2015 edition of the International Journal of Cancer Research.

The researchers include: Emeka Eze Joshua Iweala, Fang-Fang Liu, Rong-Rong Cheng, Yan Li, Conrad Asotie Omonhinmin and Ying-Jun Zhang.

The authors wrote: “This study was designed to screen different extracts of 15 commonly consumed Nigerian food plants for anti-cancer and free radical scavenging activities. Leaves, seeds or fruits of the plants were each successively extracted with n-hexane, dichloromethane, ethanol and water.

“The cytotoxic activity of each of the extracts was tested against human myeloid leukemia (HL-60), human hepatocellular carcinoma (SMMC-7721), human lung carcinoma (A-549), human breast adenocarcinoma (MCF-7) and colon cancer (SW480) cell lines using Cisplatin as standard.

“The free radical scavenging activities of the extracts against 1,1-diphenyl-2-picrylhydrazyl (DPPH) were also determined. The dichloromethane extract of Vernonia amygdalina leaves (VA-D) showed the strongest cytotoxic activity against all the cancer cell lines with IC50 range of 5.85-8.84 μg mL-1. The dichloromethane extract of Gongronema latifolium leaves (GL-D) showed the highest activity against A-549 and MCF-7 with IC50 of 9.57 and 6.51 μg mL-1, respectively, while Piper guineense leaves (PG-D) exhibited the highest activity against HL-60 with IC50 of 3.62 μg mL-1.

“The other extracts were inactive against the cancer cell lines. The ethanolic extract of Sesamum indicum leaves (SI-E) and Mucuna pruriens seeds (MP-E) showed the highest free radical scavenging activity with SC50 of 6.8 and 7.3×10-2 mg mL-1, respectively.

“Other extracts of some of the food plant samples showed varying free radical scavenging activities. The results from this study suggest that some of the food plants screened may possess anti-cancer and antioxidant properties.”

The researchers concluded: “In conclusion, the dichloromethane extract of Vernonia amygdalina leaves (VA-D) showed the strongest cytotoxic activity against all the cancer cell lines while that of Gongronema latifolium leaves (GL-D) showed the highest activity against A-549 and MCF-7. Also the dichloromethane extract of Piper guineense leaves (PG-D) exhibited the highest activity against HL-60. The ethanolic extract of Sesamum indicum leaves (SI-E) and Mucuna pruriens seeds (MP-E) showed the highest free radical scavenging activity with SC50 against DPPH. This study reveals that several plant foods that are commonly consumed in Nigeria could have anti-cancer potential, which could provide a plausible explanation for the apparently and comparatively lower incidence of cancer.”

Another study on Nigerian foodstuffs with prostate cancer chemo-preventive polyphenols published in Infectious Agent Cancer by Sunday Eneojo Atawodi, found: “Dietary polyphenols are antioxidants that can scavenge biological free radicals, and chemo-prevent diseases with biological oxidation as their main etiological factor. In this paper, we review our laboratory data vis-ὰ-vis available literature on prostate cancer chemo-preventive substances in Nigerian foodstuffs.

“Dacryodes edulis fruit (local pear), Moringa oleifera and Syzygium aromaticum (Nutmeg) contained prostate active polyphenols like ellagic acid, gallate, methylgallate, catechol, kaempferol quercetin and their derivatives. Also Canarium schweinfurthii (Bush candle tree) oil contained ten phenolic compounds and lignans, namely; catechol, p-hydroxybenzaldehyde, dihydroxyphenylacetic acid, tyrosol, p-hydroxybenzoic acid, dihydroxybenzoic acid, vanillic acid, phloretic acid, pinoresinol, secoisolariciresinol.

“In addition, tomatoes (Lycopersicon esculentum Mill) which contains the powerful antioxidant and anti-prostate cancer agent, lycopene; cabbage (Brassica oleracea) containing indole-3-carbinol; citrus fruits containing pectin; Soursop (Annona muricata) containing annonaceous acetogenins; soya beans (Glycine max) containing isoflavones; chilli pepper (Capsicum annuum) containing capsaicin, and green tea (Camellia sinensis) containing (-) epigallocatechin gallate (EGCG), (-) epicatechin, (-) epicatechin-3-gallate and (-) epigallocatechin -3-gallate which are widely reported to posses prostate cancer chemo-preventive compounds are also grown in Nigeria and other African countries. Thus, the high incidence of prostate cancer among males of African extraction can be dramatically reduced, and the age of onset drastically increased, if the population at risk consumes the right kinds of foods in the right proportion, beginning early in life, especially as prostate cancer has a latency period of about 50 years.”

Credit: Chukwuma Muanya/the Guardian