The discovery of new drugs is vital to achieving the eradication of neglected tropical diseases (NTDs) in Africa and around the world. Now, researchers reporting in PLOS Neglected Tropical Diseases have identified traditional Ghanaian medicines which work in the lab against schistosomiasis, onchocerciasis and lymphatic filariasis, three diseases endemic to Ghana.
The major intervention for NTDs in Ghana is currently mass drug administration of a few repeatedly recycled drugs, which can lead to reduced efficacy and the emergence of drug resistance. Chronic infections of schistosomiasis, onchocerciasis and lymphatic filariasis can be fatal.
Schistosomiasis is caused by the blood flukes Schistosome haematobium and S. mansoni. Onchocerciasis, or river blindness, is caused by the parasitic worm Onchocerca volvulus. Lymphatic filariasis, also called elephantiasis, is caused by the parasitic filarial worm Wuchereria bancrofti.
In the new work, Dorcas Osei-Safo of the University of Ghana, and colleagues obtained – from the Ghana Federation of Traditional Medicines Practitioners Association – 15 traditional medicines used for treating NTDs in local communities.
The medicines were available in aqueous herbal preparations or dried powdered herbs. In all cases, crude extracts were prepared from the herbs and screened in the laboratory for their ability to treat various NTDs.
Two extracts, NTD-B4-DCM and NTD-B7-DCM, displayed high activity against S. mansoni adult worms, decreasing the movement of the worms by 78.4% and 84.3% respectively.
A different extract, NTD-B2-DCM, was the most active against adult Onchocera onchengi worms, killing 100% of males and more than 60% of females.
Eight of 26 crude extracts tested, including NTD-B4-DCM and NTD-B2-DCM, also exhibited good activity against trypanosomes—parasites that cause other human diseases but weren’t the original targets of the traditional medicines.
“By embracing indigenous knowledge systems which have evolved over centuries, we can potentially unlock a wealth of untapped research and shape it by conducting sound scientific investigations to produce safe, efficacious and good quality remedies,” the researchers say.
Neglected tropical diseases (NTDs)
NTDs are found in several countries in Africa, Asia, and Latin America. NTDs are especially common in tropical areas where people do not have access to clean water or safe ways to dispose of human waste.
Information on diseases included in the WHO portfolio of NTDs is available at https://www.who.int/neglected_diseases/diseases/en/external icon
See below for more information on selected neglected tropical diseases:
- Buruli Ulcer
- Chagas Disease
- Cysticercosis
- Dengue Fever
- Dracunculiasis (Guinea Worm Disease)
- Echinococcosis
- Fascioliasis
- Human African Trypanosomiasis (African Sleeping Sickness)
- Leishmaniasis
he following six NTDs can be controlled or even eliminated through mass administration of safe and effective medicines or other, effective interventions:
- Dracunculiasis (Guinea Worm Disease)
- Lymphatic Filariasis
- Onchocerciasis
- Schistosomiasis
- Soil-transmitted Helminths (STH) (i.e., Ascaris, Hookworm, and Whipworm)
- Trachoma
Controlling the vectors (e.g., mosquitoes, black flies) that transmit these diseases and improving basic water, sanitation, and hygiene are highly effective strategies against these NTDs.
According to the World Health Organization (WHO) about 80% of developing countries depend on traditional medicines for their primary health care needs [1]. In Ghana, traditional medicine, particularly herbal medicines, is an important component of the health care system of the people [2]. The utilization of herbal medicines and associated medicinal plants in Ghana has been documented by many authors [e.g., [3–5]] although there are still many indigenous cultures and communities in Ghana that possess a great store of traditional knowledge about herbal medicines for treatment of various human ailments, which are yet to be documented. The use of herbal medicine in Ghana is widespread but highly diverse due to floristic and cultural diversity, and traditional medicine has huge impacts on the local economy and biodiversity conservation. The rich history of use of herbal medicines and innovative utilization of plants as sources of medicines in Ghana, and broadly within Africa, has been passed down through generations largely as oral tradition [6] and as such it is important that this knowledge be documented. The WHO has a keen interest in documenting the use of medicinal plants by indigenous people from different parts of the world [7].
Documentation of indigenous knowledge about utilization of medicinal plants is important for a plethora of reasons. Firstly, it ensures that indigenous culture heritage is preserved from being lost for the use of both present and future generations [8]. Studies have indicated that indigenous knowledge about herbal medicines is continuously being lost through factors such as acculturation and biodiversity losses. For example, a comparative study of contemporary plant uses in Ghana shows that the materia medica of the Fanti, Ga, and Ashanti has changed considerably over time [6].
Secondly, through further research such as phytochemical, biochemical, pharmacological, and clinical studies information on indigenous herbal medicines can lead to discovery of new bioactive agents for treatment of ailments. Despite the recent interest in molecular modelling, combinatorial chemistry, and other synthetic chemistry techniques by pharmaceutical companies and funding organizations, natural products, and particularly medicinal plants, remain an important source of new drugs, new drug leads, and new chemical entities (NCEs) [9, 10].
Thirdly, biodiversity conservation can be enhanced when information about plants that are harvested and utilized in the management of ailments within particular areas are available [3]. For biodiversity conservation, it is also important to know what quantities of plant materials are harvested, not only for home consumption but also for trade. Commercial trade often stimulates extensive wild-collection, which often has negative effects on medicinal plant population sizes and recovery after harvesting. On the other hand, the trade and marketing of herbal medicine creates employment for thousands of people, for example, in Ghana [11]. For these reasons, the harvest should be documented and sustainable so this can continue to be a profitable resource for future generations [12].
The aim of this study was to investigate herbal medicines commonly used for the treatment and management of human diseases and ailments by some communities living in southern Ghana. To the best of our knowledge no specific previous ethnobotanical report on use of herbal medicines as yet exists for the studied communities. Here, we investigated aspects of the diversity and harvesting of medicinal plants as well as the modes of preparation and routes of administration of the herbal medicines.
It is hoped that this baseline data will, in addition to preservation of indigenous knowledge, generate interest for studies regarding the harvesting patterns, bioactivity, and safety of the medicinal plants being used. Specifically, our study addressed the following questions:
- (1) What are the most important species and families of plants being used?
- (2) Which plant parts are most frequently used?
- (3) Which diseases are commonly treated with the herbal medicines?
- (4) What is the percentage of plants that are used for treatment and management of a single disease versus multiple diseases?
- (5) Which factors of place and time are considered important during harvesting of plants for treatments?
- (6) What are the most common methods of preparation and routes of administration of the herbal medicines?
We hypothesize that healers are consulted for herbal medicines for the treatment and management of only specialized human diseases/ailments. We further hypothesize that factors of place and time are considered important during harvesting of individual plants for treatments and management of human diseases by traditional healers.
Composition of Herbal Medicines
In total, 52 species of plants belonging to 28 plant families were documented (Table 2). Of the 28 families of plants, members of the Fabaceae, Euphorbiaceae, Asteraceae, and Sapindaceae were the most commonly used ones (12% in each case) in the herbal medicines (Figure 2(a)).
The use of members of the above families in herbal medicines is widely known in Ghana [3]. It is widely known that members of the families contain secondary metabolites such as tannins, phenolics, and alkaloids that are responsible for their bioactivity.
| Families | Scientific names (voucher specimen #) | Local names (Akuapem/Krobo) | Frequency of citation (%) | Habit of plant | Diseases and/ailments | Plant parts | Methods of preparation | Route of administration |
| Acanthaceae | Ruellia brevifolia (Pohl) C. Ezcurra (A029) | Mokotso (Krobo) | 1.1 | Herb | Halitosis | Leaf | Infusion | Nasal |
| Aloaceae | Aloe vera L. (A001) | Aloe | 6.5 | Herb | Diabetes | Leaf | Decoction | Oral |
| Diabetes | Leaf | Decoction | Oral | |||||
| Typhoid fever | Leaf | Infusion | Oral | |||||
| Baldness | Leaf | Decoction | Topical | |||||
| Amaranthaceae | Alternanthera pungens Kunth. (A028) | Nkassenkasee (Akuapem) | 1.1 | Herb | Stomach ulcer | Whole plant | Infusion | Rectal |
| Annonaceae | Polyalthia longifolia (Sonn.) Thwaites (K001) | Tsogaga (Krobo) | 2.2 | Tree | Fever | Leaf | Decoction | Oral |
| Apocynaceae | Alstonia boonei De Wild. (A026) | Nyamedua (Akuapem) | 1.1 | Tree | Sexual disorders | Root and bark | Infusion | Topical |
| Rauvolfia vomitoria Wennberg (A025) | Unknown | 1.1 | Tree | Osteoarthritis | Leaf and bark | Infusion | Rectal | |
| Asclepiadaceae | Calotropis gigantea (L.) W. T. Aiton | Unknown | 1.1 | Shrub | Heart burns | Leaf | Decoction | Oral |
| Asteraceae | Chromolaena odorata (L.) R. M. King (K003) | Acheampong (Akuapem/Krobo) | 3.2 | Shrub | Typhoid fever | Leaf | Decoction | Oral |
| Stop bleeding | Leaf | Decoction | Oral | |||||
| Typhoid fever | Leaf | Infusion | Oral | |||||
| Launaea taraxacifolia. (Wild). Amin ex. C. Jeffrey (K002) | Unknown | 3.2 | Herb | Blood pressure | Leaf | Infusion | Oral | |
| Diuretic | Leaf | Decoction | Oral | |||||
| Blood pressure | Leaf | Infusion | Oral | |||||
| Vernonia amygdalina Delile (A023) | Awunyun (Akuapem) | 3.2 | Shrub | Malaria | Whole plant | Infusion | Oral | |
| Vernonia conferta Benth. (K010) | Owudifukete (Akuapem) | 2.2 | Shrub | Diabetes | Root and bark | Decoction | Oral | |
| Bignoniaceae | Kigelia africana (Lam.) Benth. (K004) | Nfuten (Akuapem) | 1.1 | Tree | Piles | Bark | Infusion | Oral |
| Spathodea campanulata P. Beauv. (K005) | Akuakua nisuo (Akuapem) | 1.1 | Tree | Stroke | Leaf | Decoction | Oral | |
| Bombacaceae | Bombax buonopozense P. Beauv. (A002) | Nyankuduro/Akonkodies (Akuapem) | Tree | Stroke | Leaf | Decoction | Oral | |
| Diabetes | Leaf | Infusion | Oral/Topical | |||||
| Boraginaceae | Heliotropium indicum L. (K007) | Akomfemtikoro (Akuapem) | 2.2 | Herb | Convulsion | Leaf | Infusion | Oral |
| Capparidaceae | Euadenia eminens L. (K008) | Dinsikuro (Akuapem) | 1.1 | Herb | Low sperm count | Root and bark | Decoction | Oral |
| Chrysobalanaceae | Maranthes robusta (Oliv.) Prance (K009) | Afambere (Akuapem) | 1.1 | Tree | Rheumatism | Leaf and seed | Decoction | Oral/Topical |
| Combretaceae | Terminalia superba Engl. & Diels (A021) | Ofram (Akuapem) | 1.1 | Tree | Convulsion | Root and bark | Decoction | Oral/Topical |
| Cucurbitaceae | Momordica charantia L. (K020) | Nyenye (Krobo) | 2.2 | Climber | Snake bite | Whole plant | Infusion | Oral |
| Diabetes | Whole plant | Decoction | Oral | |||||
| Cyperaceae | Cyperus esculentus L. (A020) | Winto/Wintino (Krobo) | 1.1 | Herb | Typhoid fever | Whole plant | Decoction | Oral |
| Dennstaedtiaceae | Pteridium aquilinum (L.) Kuhn (A012) | Unknown | 1.1 | Herb | Fever | Leaf | Decoction | Oral |
| Pteridium esculentum (Forst.) Nakai (A018) | Meyaabea (Akuapem) | 1.1 | Herb | Menstrual disorders | Leaf | Decoction | Oral | |
| Euphorbiaceae | Bridelia ferruginea Benth (K014) | Unknown | 1.1 | Tree | Diarrhoea | Root | Decoction | Oral |
| Discoglypremna caloneura (Pax) Prain (A017) | Unknown | 2.2. | Tree | Stroke | Leaf and root | Decoction | Oral | |
| Female infertility | Leaf and root | Decoction | Oral/Rectal | |||||
| Drypetes aubrevillei Leandri (K017) | Duameko (Akuapem) | 1.1 | Shrub | Stroke | Root | Decoction | Oral/Topical | |
| Drypetes floribunda Hutch. (K016) | Katirika (Akuapem) | 1.1 | Shrub | Miscarriage | Root and bark | Decoction | Oral | |
| Jatropha curcas L. (A014) | Unknown | 1.1 | Shrub | Hernia | Leaf | Infusion | Oral | |
| Jatropha gossypifolia L. (A015) | Unknown | 1.1 | Shrub | High fever | Leaf and fruit | Decoction | Oral | |
| Macaranga barteri Müll. Arg. (K015) | Opam (Akuapem) | 1.1 | Shrub | Foot rot | Bark | Decoction | Oral | |
| Uapaca guineensis Müll. Arg. (A016) | Agyahere (Akuapem) | 1.1 | Tree | Stroke | Root, bark and leaf | Decoction | Topical | |
| Fabaceae | Acacia senegalensis (Houtt.) Roberty (K022) | Unknown | 1.1 | Tree | High fever | Leaf | Decoction | Oral |
| Albizia ferruginea (Guill. & Perr.) B. (K021) | Awiemtosamina (Akuapem) | 1.1 | Tree | Diarrhoea | Root | Decoction | Oral | |
| Baphia nitida Lodd. (A005) | Odwaen | 1.1 | Shrub | Retarded growth | Leaf | Infusion | Topical | |
| Berlinia sp. (A013) | Unknown | 2.2 | Tree | Rheumatism | Root and bark | Infusion | Topical | |
| Fever | Bark | Decoction | Oral | |||||
| Cassia alata L. (K023) | Kobatso (Krobo) | 3.3 | Shrub | Purgative | Leaf | Decoction | Oral | |
| Menstrual disorders | Leaf | Decoction | Oral | |||||
| Fertility problems | Leaf | Decoction | Oral | |||||
| Copaifera salikounda Heckel (A030) | Otedua (Akuapem) | 2.2 | Tree | High fever | Bark | Decoction | Topical | |
| Piles | Root and bark | Decoction | Oral/Rectal | |||||
| Lamiaceae | Ocimum gratissimum Seem. (A011) | Nunnum (Akuapem) | 2.2 | Herb | Bloating | Leaf | Infusion | Oral/Topical |
| Malvaceae | Gossypium hirsutum L. (K024) | Asawadua (Akuapem) | 2.2 | Herb | Osteoarthritis | Leaf | Infusion | Oral |
| Infertility | Leaf | Infusion | Oral | |||||
| Meliaceae | Azadirachta indica A. Juss (A008) | Nimtso (Krobo) | 5.4 | Tree | Fever | Leaf | Decoction | Oral |
| Fever | Leaf | Decoction | Oral | |||||
| Malaria | Leaf | Decoction | Oral | |||||
| Khaya senegalensis A. Juss. (K008) | Mahogany (Akuapem/Krobo) | 3.3 | Tree | Infertility | Bark | Decoction | Oral | |
| Male infertility | Leaf | Decoction | Oral | |||||
| Menispermaceae | Sphenocentrium jollyanum Pierre (K026) | Kramaoti (Akuapem) | 1.1 | Herb | Diabetes | Whole plant | Decoction | Oral |
| Moringaceae | Moringa oleifera Lam. (A007) | Moringa | 3.3 | Tree | Blood tonic | Leaf | Decoction | Oral |
| Pruritus | Leaf | Decoction | Oral | |||||
| Jaundice | Leaf | Decoction | Oral | |||||
| Myrtaceae | Psidium guajava L. (K028) | Aguava (Akuapem/Krobo) | 2.2 | Shrub | Diarrhoea | Root | Decoction | Oral |
| Rutaceae | Citrus sinensis Pers. (K030) | Anka (Akuapem)/Kpeta (Krobo) | 1.1 | Tree | Constipation | Leaf and fruit | Infusion | Oral |
| Zanthoxylum leprieurii Guill. & Perr. (K029) | Okanto (Akuapem)/Oyaa (Krobo) | 2.2 | Shrub | Sexual weakness | Leaf | Decoction | Oral | |
| Stroke | Root | Decoction | Oral/Topical | |||||
| Sapindaceae | Lecaniodiscus cupanioides Planch. (K031) | Unknown | 1.1 | Shrub | Stomach ulcer | Leaf | Decoction | Oral |
| Paullinia pinnata L. (A002) | Tuatin (Twi) Detsemamu (Krobo) | 6.5 | Herb | Miscarriage | Leaf | Decoction | Oral | |
| Stomach ulcer | Leaf | Infusion | Oral | |||||
| Stroke | Leaf | Decoction | Oral | |||||
| HIV/AIDS | Leaf | Decoction | Oral | |||||
| Bone fracture | Leaf | Infusion | Oral/Rectal | |||||
| Sapotaceae | Aningeria altissima (A. Chev.) Aubrév. (K033) | Asanfena (Twi) | 2.2 | Shrub | Stops bleeding | Leaf and bark | Decoction | Oral |
| Malacantha alnifolia Pierre (K032) | Unknown | 2.2 | Shrub | Miscarriage | Leaf | Decoction | Oral | |
| Solanaceae | Physalis angulata L. (K034) | Totoa (Krobo) | 1.1 | Herb | Cancer | Whole plant | Infusion | Oral/Topical |
| Solanum melongena L. (A003) | Unknown | 3.3 | Shrub | Anaemia | Fruit | Infusion | Oral |
Species of plants reportedly being used by healers arranged according to their families with information on their habits, ailments treated, plant parts used, methods of preparation, and route of administration of the plants.
| (a) |
| (b) |
| (c) |
Trees formed the majority (37%) of the plants being used (Figure 2(b)). Two of the species of plants reported being used, namely, Pteridium aquilinum (L.) Kuhn and Pteridium esculentum (Forst.) Nakai, were ferns whereas the rest of the plants were vascular plants. There is very little information on the use of ferns in the Ghanaian traditional pharmacopeia [see, e.g., [3, 4]].
Species most commonly reported being used were Aloe vera L. and Paullinia pinnata L. with a percentage frequency of citation 7% each out of a total of 92 citations. About 54% of the species reported being used were cited only once by the healers during the period of the current study.
Leaves formed 57% of the herbal medicines documented. Other plant parts used were fruits, barks, and whole plants (Figure 2(c)). Leaves are commonly used in herbal medicines because they represent the site of most photosynthetic activity in plants and they also contain very high concentrations of secondary metabolites.
The benefit of a high proportion of leaves being used is also that the threat posed to the populations of the plant community is minimal compared to harvesting of roots and barks. The use of a combination of various plants parts formed 18% of the herbal medicines and this use is well documented in the literature. Since the composition of secondary metabolites differs in plant organs [18], the use of different organs of the same plant in the herbal medicines might be to ensure extraction of the different bioactive agents.
Common Human Diseases and Ailments
Herbal medicines were reportedly used for treatment and management of 42 diseases and ailments. Two or more herbal medicines were reportedly used for treatment and management of 17 the diseases and/ailments, and the herbals were most commonly used for treatment and management of stroke, fevers, and diabetes (Figure 3).
The herbal medicines were used for treatment and management of both common ailments (e.g., cuts, foot root) as well as the more specialized diseases such as stroke, diabetes, cancer, and stomach ulcer. Some of the diseases such as stroke, malaria, and HIV/AIDS are among the top 10 causes of deaths in Ghana (https://www.cdc.gov/globalhealth/countries/ghana/). Knowledge of frequently reported diseases and/ailments can be an indication of health care issues in a region and it should be of great importance to health care organizations and government.
Human diseases commonly treated and/managed with herbal medicines.
About 43% of the species of plants were reportedly used in treatment of a single disease whereas the rest of the plants (57%) were involved in treatment of more than one disease/ailment. Medicinal plants are commonly used in the management of different ailments because they contain a variety of bioactive agents such as alkaloids and terpenoids [18, 19].
It is possible to isolate the bioactive agents or compounds from extracts made from plants for detailed pharmacological and clinical investigations to be made. Nevertheless, in some cases isolation of bioactive agents has been unsuccessful even though the extracts are active.
In the latter case, characterization of the active extract could enable structure-related activity studies leading to possible synthesis of a more potent drug to be developed.
reference link: https://www.hindawi.com/journals/ecam/2017/3043061/
More information: Twumasi EB, Akazue PI, Kyeremeh K, Gwira TM, Keiser J, Cho-Ngwa F, et al. (2020) Antischistosomal, antionchocercal and antitrypanosomal potentials of some Ghanaian traditional medicines and their constituents. PLoS Negl Trop Dis 14(12): e0008919. DOI: 10.1371/journal.pntd.0008919
