African Natural Plant Products: New Discoveries ... - ACS Publications

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Chapter 7

The Diversity of Medicinal Plants in Nigeria: An Overview Albert Philip Ekanem1 and Francis Vincent Udoh2 1

Institute of Oceanography, University of Calabar, P.M.B. 1115, Calabar, Nigeria. 2 Department of Pharmacology, University of Calabar, P.M.B. 1115, Calabar, Nigeria.

Plants constitute a major economic resource of most countries of the world including Nigeria. They have taxonomic classes which enable their classification with respect to their role in economic development. In the health sector, plant parts are employed in pharmaceutical research and in the development of new drugs. In Nigeria and some other countries of the world, plant parts or herbal preparations are used as herbaldrugs for the treatment of various ailments. In Nigeria herbal practices, the practitioners claim that plant parts posses various phytochemicals which exhibits diverse pharmacological and biological responses and diversities. Nigeria is a country stepped in the use of and belief in traditional medicines in which plants play a major role. This paper provides a brief snapshot or overview to several indigenous medicinal Nigeria plants.

© 2009 American Chemical Society

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In African Natural Plant Products: New Discoveries and Challenges in Chemistry and Quality; Juliani, H., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2010.

136 The majority of the Nigerian populace depends on herbal preparations in the treatment of certain ailments and diseases. This can be attributed to the high cost of orthodox drugs as compared to herbal preparations, to the efficacies of some of the preparations to their health needs, and notably to the traditional and historical role that plants have played in Nigerian health care. Although some medicinal plants are found used for similar purposes in different places and countries, there are plants that exhibit different properties dependent upon the environment in which the grow.


Phytopharmacology The significant use of medicinal plants in the Nigerian traditional health care system prompted an increase in the number of scientific studies on medicinal plants including their chemistry, biology, and pharmacological activities. The results were sufficiently promising to suggest that Nigerian indigenous medicinal plants used in traditional medicine would be excellent candidates for further study and for pharmaceutical development for the treatment and eradication of some infectious diseases. Global research on the medicinal properties of plants is highly impressive and increasing and provides yet a further justification for an examination of Nigerian medicinal plants (1). A Medicinal plant has been defined as one which contains substances that can be used for therapeutic purposes or contains biological active substances that are precursors for development of new drugs (2). Research on medicinal plants has further proved that some plants have excellent ability to strengthen human resistance to diseases as well as the ability to support good health. The health potentials of medicinal plants have given rise to the development and production of food supplements from plants and other natural products for the improvement of health care delivery (3). The pandemic explosion of diseases such as malaria, diabetes, hepatitis and AIDS etc, in Nigeria has posed challenges even to traditional medical practitioners who do believe that cures to each and every of these diseases are within the herbal resources of their nation. These serious infectious diseases have prompted increased interest on the part of the Traditional herbal practitioners to work with those in science to configure ways to both study traditional medicines in a more integrated approach and in seeking avenues to screen and validate herbal formulas as was done with the Nigerian herbal formula NIPRISAN available now as a pharmaceutical drug Nicosan in Nigeria, shown to be effective in the treatment of sickle cell anema (4).The long term goal of such programs is to ensure the best health care can reach the most people in the most affordable way and strongly suggests the need to integrate traditional herbal practices into the network of modern health care delivery. As a result of the intense research on Nigerian medicinal plants, sources of new therapeutic agents have been identified. The National Institute for Pharmaceutical Research and Development (NIPRD), Abuja, Nigeria has developed a plant-based cure for sickle cell anaemia using extract from four plants (5, 6, 7). This and this product was later commercialized and is being manufacterured as Nicosan in Nigeria (4). Gongronema latifolium, another



137 indigenous herb found in the Niger Delta of Nigeria which is now being used for the treatment of diabetis (8). Studies on several Nigerian herbs have led to the identification of plant extracts with therapeutic efficacies against diabetes. Extracts from Garcinia kola commonly called bitter kola reduces gastrointestinal spasm in rats thereby showing promise in the treatment of diarrhea (4). Their findings also revealed that the plant extract has the potential for the treatment of respiratory infections. Phytochemical analysis shows that the seed has a high content of alkaloid and biflavonoids. Nauclea latifolia, a plant indigenous to Nigeria possesses a high activity against cardiovascular disorders and a depleting effect on the cholesterol LDL and VLDL (9,10). Earlier, Udoh et al (unpublished) had shown that extract from the leaf of N. latifolia possesses potent myotensive activity in rat. Using hypertensive human subjects, he further showed this extract to exhibit antihypertensive activity. The plant contains a high level of alkaloids. Locally, N.latifolia is called Mfang mbube in the Nigerian region to which it is indigenous. Other Nigerian medicinal plants have also been studied intensively. Ethanol extract of Piper guineense with high contents of alkaloidal amides was found efficacious against helminth parasites (Monogenean) of cultured fish (11,12). Petroleum ether extract of seeds of Carica. papaya and ethanol extract of leaves of Mucuna pruriens were effective against protozoan parasites (Ichthyophthirius multifilis) of fish (13). The research on these plants led to the pioneering discovery on the use of extracts from plants for the treatment of diseases in fish. Ethanol extracts of P. guineense have also shown efficacies in the control of conception in mice (14). The antiobesity properties of Aframomum melegutta by pancreatic lipase inhibition has also been demonstrated (15). There are so many edicinal plants indigenous to Nigeria, a selected few are highlighted by their medicinal uses and pharmacological active substances (Table I).


Table I. Selected Nigerian medicinal plants and their biological activities. Scientific and Plant Family Biological Activities common Name Piper guineense Piperaceae Neuromuscular activity, contraceptive, antiparasitic, Schumach et aphrodisiac Abdominal disorders, chest complaints, used as Thonn; an enema, Bronchitis, Headache, Anthelmintic,Caries, West African diarrhea, hemorrhoids, antibiotic, black pepper, Ashanti pepper Garcinia kola Clusiaceae Cough, nasal conjestion, control of diarrhaea, antidiabetic, Bitter kola Aphrodisiac, hypertension, stimulant, gastrointestinal problems, dysentery, headache, backpain, skin ailments, stimulates digestion, antiviral activity, , Nauclea latifolia Rubiaceae Antihypertensive, antimicrobial Fever, stomachache, diarrhea Aframomum Zingiberaceae Antiobesity, dysentery, antibacterial, Abortifacient, melegutta hemorrhoids (used with Garcinia kola), antifungal, colds, Grains of migraine, stimulant Paradise


Alkaloids. 10, 17, 19 Gingerols, shogaols and paradol. 15, 17

Alkaloids and biflavonoid. 4; 17, 18

Responsible Bioactive Compounds. References Alkaloidal amide, 12, 16, 17

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Asteraceae

Euphorbiaceae

Euphorbia heterophylla

Caparaceae

Fabaceae

Emilia coccinea

Mucuna pruriens Gongronema latifolium Cleome rutidesperma

Table I. Continued. Scientific and Plant Family common Name Carica papaya Caricaceae Melon tree

Fever, convulsion, ringworm, ulcer, dizziness, epilepsy, cardiac problems, eye inflammation, gonorrhea, ovarian problems, respiratory problems, snakebite, scabies, wound healing, stomachic Erysipelas, cough, bronchial paraxymal asthma, hayfever. Constipation, parasitosis, chest abscess.

Anti-inflammatory, antihelmintic, carminative, ear aches.

Antifertility, antiparasitic, antihelmitic, abortifacient, amnesia, insomnia, headache, arthritis, asthma, coughs, dysentery, hepatitis, gall bladder problems, diuretic, stomachic, AntiparasiticSnakebite Diabetes, Digestive disorders, colic, worms and as a purgative

Biological Activities


Alkaloids, tannin, saponin, flavonoids, cardiac glycosides. 17, 20, 21 Alkaloids, tannin, saponin, steroid, terpenes, flavonoids, cardiac glycosides. 17, 20, 22 Alkaloids, tannin, phlobatanin, flavonoid, trepenoid, cardiac glycosides. 17, 21, 23, 24

13, 17 17

Responsible Bioactive Compounds. References 13, 17

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Verbanaceae

Asteraceae

Stachytarpheta cayennensis

Tridax procumbeus

Stops bleeding. Treatment of diarrheca, malaria and stomachache. Hypertension, edema, jaundice, wound healing.

dysentery, syphilis, gonorrhea, measles

Worm expeller, antiparasitic, sore throat, chest complaints, .

Lonaniaceae

Spigelia anthelmia

Sida, acuta

Scrophulaiaceae Antiviral, antitumuor chest pains, sore throat, gonorrhoea, otitis, vomiting, cough, snake repellent, anthelmintic, conjunctivitis, rickets, dizziness, constipation, diabetes, diarrhea, antibiotic, fever, respiratory problems, ease childbirth. Malvaceae Stops bleeding, treatment of sores and wounds; antipyretic, catarrh, dysentery, gonorrhea, chest pains, fevers, aphrodisiac, dizziness, galactagogue

Eczema, Treatment of boils, avine malaria, cataract


Scoparia dulcis

Table I. Continued. Scientific and Plant Family common Name Richardia Rubiaceae bransilensis


Alkaloid, saponon, tannin, steroids, flavonoids, cardiac glycosides. 17, 21 Alkaloids, tannin, saponin, phlobatanin, flavonoid, cardiac glycosides. 17, 21 Alkaloids, tannin, saponin, flavonoid. 17, 20, 24

Alkaloid, flavonoid, cardiac glycosides. 17, 26

Alkaloids, tannin, saponin, phlobatanin, terpenes. 17, 21, 25

Responsible Bioactive Compounds. References Alkaloids, tannin, saponin, steroid, terpenes. 17, 20

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Lamiaceae

Euphorbiaceae

Ocimum gratissimum

Phyllanthus discoideas (P. diandrus) Acalypha, wilkesiana Antibacterial

Combretaceae

Anogeissus leiocarpus

Euphorbiaceae

Biological Activities Asthma, cough, hemoptysis, tuberculosis, sore throat, diarrhea, shigellocidal activity ascites, edema, conjunctivitis, ophthalmia, ulcers, wounds, burns, bruises, rheumatism, swollen joints, diarrhea, dysentery, toothache, epilepsy Asthma, cough, tuberculosis, anthelmintic, tapeworm, Gonorrhoea, tonic, enema, jaundice, body pain, chest pain, wounds, ulcers, skin rashes, itching, hemorrhoids, abscesses, hernia, diarrhea, ophthalmia, abdominal pain, rheumatism, fishing poison, stimulant, toothache, Antibacterial, gonorrhea, eye health, eye and ear diseases, emetic, fever, anthelmintic, constipation, abdominal pain, gastrointestinal disorders childrens colds, cough, bronchitis, headache, otitis, conjunctivitis, fever, rheumatism, colic, diarrhea, toothache, hemorrhoids, nosebleed, purgative, respiratory problems, nasal congestion, mosquito repellent, convulsions, epilepsy, Antibacterial, palpitations.

Table I. Continued. Scientific and Plant Family common Name Terminalia Combretaceae avicennioides


Alkaloids saponin and tannin. 30

Alkaloids saponin and tannin. 17, 30

Alkaloids saponin and tannins. 17, 29, 30

Anthraquinone, flavonoid, saponin, steroids, tannin, terpenoids. 17, 28

Responsible Bioactive Compounds. References Anthraquinones, saponin, steroids, Ttnnin, terpenoids. 17, 27, 28

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Capparidaceae Mimosaceae

Burseraceae

Connraceae

Capparis brassei Entada africana

Canarium(spp)

Cnestis ferruginea,

Table I. Continued. Scientific and Plant Family common Name Anogeissus Combretaceae leiocarpus Antimicrobial, tonic, body pain, chest pain, coughs, wounds, ulcers, skin rashes, itching, worms and tapeworms, coughs, gonorrhea, jaundice, hemorrhoids, amenorrhea, abscesses, hernia, diarrhea, ophthalmia, rheumatism, fishing poison, stimulant, aphrodisiac, toothache, fevers, wounds, sores, ulcers. Antimicrobial, tuberculosis, coughs Bronchitis, cough, whooping cough, dysentery, fever, wound healing, abdominal pain, dysentery, ulcers, sore eyes, constipation, stomachic, abortifacient, throat problems, colds, emetic, rickets, stimulant, gonnorrhea, diuretic, diarrhea, headache, internal bleeding, chest abscesses, dermatosis, snakebite, jaundice. Antioxidant activity, colic, hemoorrhoids, jaundice, enema, scabies, gland inflammation, liver disease, wound healing, skin dermatitis, coughs, stomachic, Several species reported to be used in premature birthing, to expel the placenta, leprosy Antioxidant activity, bronchitis, abortifacient, wound healing, purgative, coughs, dysmenorrhea, fever, body pain, dysentery, diarrhea, migraine, sinusitis, threatened abortion, ophthalmia, pneumonia, mouth and wound infections, coughs, tuberculosis, whooping cough, toothache, snakebite, hemorrhoids, abscesses, gum pain headache, appetite stimulant, stomachic.



17, 31

17, 31

Terpenes, saponin. 17, 28 Terpenes, triterpenoid saponins. 17, 21, 28

Responsible Bioactive Compounds. References Terpenes, triterpenoid saponins. 16, 17

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Menispermace ae Liliaceae

Sphenocentrum jollyanum,

Voacanga africana

Antioxidant activity, gonorrhea, burns, bronchitis, whooping cough, skin fungus and wound healing, diarrhea, diuretic, hemorrhoids, purgative, anthelmintic, respiratory problems, stomachic. Antioxidant activity, dental care, caries, toothache, diarrhea, anthelmintic, dizziness, epilepsy, rheumatism, edema, purgative, stomachic, stiffness. Antioxidant activity, stimulant, stomachic, constipation, poisoning, ulcers, coughs, wound healing, aphrodisiac, dysentery, epilepsy. Antioxidant activity, cardiac spasms, caries, disinfectant, fatigue, amebic dysentery, asthma, diarrhea, edema, leprosy, convulsions in children, to calm the insane, epilepsy.


17, 31

17, 31

17, 31

Responsible Bioactive Compounds. References 17, 31

NOTE: *The medical applications cited from Neuwinger (2000) (17) contain the original research and traditional reports.

Apocynaceae

Landolfia owariensis,

Table I. Continued. Scientific and Plant Family common Name Funtumia Apocynaceae elastica


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Plant-Drug Discovery The use of plants as sources of bioactive chemicals and as inspiration for new chemistry with medicinal applications has been a fruitful approach in search for new drug entities (32-34). The diversity of plant species is an invaluable repository of unusual chemical compounds, given that secondary metabolites are like chemical finger prints of individual’s species (35).. The pharmacological activity of these chemical substances can be identified with test procedures at various biological levels, ranging from sub-cellular elements to the normal or modified intact animal. Studies on the biological activity of some African medicinal plants are performed with in vitro and in vivo methods. Since such biological screens can reveal prototype drugs with unknown mechanisms of action, the inclusion of in vivo animal models to complement the in vitro approach can prove advantageous by “short-gun” or “target-directed”. The short-gun approach screens for active substances by means of tests that are irrelevant to the subsequent application of the drug. In contrast, the target-direct or mechanistic approach is employed when a specific and ultimately molecular biological mode of action is desired for a given therapeutic area (10, 36). One strategy towards reducing drug importations and making drugs available at a lower cost in Nigeria would be to cultivate and locally process native species that are known to contain therapeutically useful compounds. That would involve communities and growers in the collection and cultivation of medicinal plants (37), thus providing additional cash income opportunities to many. This would also involve the development of standardized botanical and herbal formulas, extracts and products, often now lacking in the manufacturing of herbals, again generating additional income opportunities and an improvement of available locally made herbal products now found in the Nigerian marketplace. The need to authenticate the botanical materials used in the commercial herbal remedies and the need to develop standardized products could strengthen this sector and not only provide again more income generating opportunities but ensure safer and higher quality traditional herbal products. Lastly, this approach would be both culturally acceptable as these same products are used today and if done in concert with the public heath care system help to alleviate the over pressured national health care system that some consider to be failing (2). This approach could help integrate our modern Nigerian health care and medical system with our traditional medicines which are largely based upon plants and for which the majority of our population already use and rely. Drug discovery has been primarily an industrial effort and true innovation has generally been achieved by intensive screening of many compounds for selected activities (37). Plant products have been employed in the identification of biological receptors in mammalian systems and their uses in investigation of the physiological and pathological functions of potential drug targets. Classical examples include nicotine, physostigmine, curare, muscarine, pilocarpine, and tropane alkaloids in the study of nicotinic and muscarinic receptors (38). Innovative discovery of drugs leans heavily on the basic physiological and



145 biochemical knowledge with much help from serendipitous pharmacological and clinical observations. It is the availability of drugs that permits new biochemical, physiological and especially, pharmacological knowledge to accrue (9). Therefore the importance of careful evaluation of really novel pharmacological effects has to be seriously considered, rather than limiting drug discovery and development to previously determined therapeutic goals. This is of particular relevance when discussing Nigerian and African medicinal plants. Many of our indigenous medicinals have not been subjected to these modern biological screens. By either conducting more of these screens in-country and/or in partnership with others that would support and champion the processing and value-addition in Nigeria, then greater economic benefit will filter down to the country. The validation of traditional applications could also lead to a significant economy developed that is soley geared to providing, local, regional or national standardize traditional medicinal products.

Concluding Remarks Nigeria is home to thousands of indigenous and naturalized plants, many that have been used for centuries as medicinal plants. Many of these plants have a diversity of biological activities and appplications. Many of these plants serve a dual function both as a food and medicine. In Nigeria over 60% of the population depends plants and plant products for their medicines. Common ailments traditionally treated with plants include: malaria fever, jaundice, diabetes, arthritis and typhoid fever. Each have been treated efficaciously with some herbs from plants indigenous to Nigeria. Recently, some Nigerian phytotherapists have claimed to successfully treat HIV infected patients with plant-extracts but this claim must be sufficiently investigated. Because of the dual nature of the plants, being consumed both as a food and used as a medicine, it is important to recognize that besides the direct medicinal benefits, plants are often rich sources of the macro- and micronutrients, vitamins and other chemicals we need to maintain and improve our health and repair damaged tissues. Improved quality, increased attention to the scientific study of these plants, and more favorable public policies are needed to strengthen this sector and provide economic opportunities to all those involved as well and provide more affordable medicines.


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African Natural Plant Products: New Discoveries ... - ACS Publications

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