Medicinal plants used by traditional healers to treat malignancies and other human ailments in Dalle District, Sidama Zone, Ethiopia

Ethiopia is known for its ancient civilization and is home to people of diverse ethnolinguistic backgrounds [1]. It stretches from about 120 m below sea level (the Kobat Sink in the Afar depression) to 4543 m above sea level (the highest peak of Ras Dashen mountain) [2, 3]. This feature had its share for the creation of varied ecosystems and a high diversity of vascular plants (about 6027 species) with 10% endemism [4‐7]. More than 1000 plant species have so far been reported for use in Ethiopia’s traditional herbal medicine, and about 33 of these species are endemic to the country [8, 9]. Ethiopia is one of the six plant-rich countries of Africa where about 60% of the plants are said to be indigenous and most of them with healing potential [10]. Jansen [11] had once stated that almost all plants of the Ethiopian flora are used medicinally in different parts of the country in one way or the other.

In Ethiopia, over 70% of the people depend on traditional medicines (TMs) for their healthcare, and more than 95% of the preparations are made from plant origin [12, 13]. According to various reports, local people in rural Ethiopia mostly rely on TMs for healthcare services and others revert to TM when modern health services fail due to various reasons [14]. Dissatisfaction with modern medicines and lack of their efficacy, especially in the cases of certain human ailments including cancer, liver diseases, herpes zoster, eczema, swelling, and hemorrhoids, were some of the reasons that traditional healing systems were preferred over conventional medicines [15]. There are case reports of TMs being the preferred treatment options for the early stages of some diseases, including malignancies [16].

In Ethiopia, environmental degradation, deforestation, intermittent drought, and various anthropogenic activities are threatening the natural resources in general, and MPs are most affected. A few ethnobotanical studies undertaken in Sidama Zone, where the present study was conducted, showed that TM is an integral part of the healthcare system of the Sidama people [17‐19]. This corroborates the national report on TM use in healthcare [12, 20].

The hypothesis for the present study emerged from observations on the long history of use of herbal medicine to treat human ailments by traditional healers (THs) among the Sidama people. It was deemed necessary to retrieve essential ethnobotanical information from the THs before the MP resources and the associated indigenous knowledge are lost. Therefore, we hypothesized that the THs that provide treatment for various human ailments have valuable knowledge about the traditional MPs used to treat various malignancies, jaundice, and helminthiases. Hence, the objective of the study was to record, compile, and document ethnobotanical knowledge held by THs of Megera subdistrict (kebele) and three other adjacent kebeles of Dalle District, Sidama Zone, southern Ethiopia. Emphasis was given to the MPs used to treat various malignancies, jaundice, and helminthiases.

TM is an important and often underestimated part of healthcare, and it is practiced in almost every country in the world, and demand for its services is currently increasing in the form of alternative medicine. It is the main source of healthcare, and sometimes the only source of care, due to its closeness to the ordinary rural communities and its accessibility and affordability in view of the rising healthcare costs [36]. Ethiopians, by and large, depend on TM for their primary healthcare due to limited access to functional modern healthcare facilities, affordability, cultural acceptability of healers, perceived efficacy against certain types of diseases, and the belief that TM has low side effects [15, 37‐39]. As a result of improved access to modern medicines and environmental degradation, both traditional knowledge and the plants that have been in use as medicines, for millennia, are highly threatened. However, in spite of this environmental degradation by anthropogenic activities and periodic droughts, there are still many MP species in different parts of Ethiopia [12, 38, 40‐42]. And the findings of the present study in a highly limited area in Sidama Zone, where 71 species of medicinally useful plants are in use for the treatment of various human ailments, are an indication of the potential for the conservation of MPs in the country.

Shrubs make a larger proportion of the MPs used in the study area, and this finding agrees with previous reports [13, 43‐46]. This could be attributed to the common pattern of growth forms in the study area [47]. However, reports elsewhere showed that herbs were the frequently used MPs, which have a higher relative abundance of herbs as compared to other life forms [48‐50]. This could further relate to the abundance of areas with bushy vegetation in the first case and less woody species in the second.

The present findings revealed that the families Lamiaceae (six species), Asteraceae, Euphorbiaceae, and Rubiaceae (four species each) encompass more numbers of MP species. These families are among the MP families topping the list in other reports from different parts of the country, and their higher proportion in the flora of Ethiopia substantiates this report, implying documentation of wide distribution and higher number of species of these families throughout the country [13, 38, 51, 52].

In the present study, it was determined that 19.7% of the MPs were used to treat various forms of malignancies. Reports from other parts of the country also substantiate the present finding [13, 20]. Plants have a reputable contribution to the discovery of anticancer bioactive compounds [53]. Polyphenols, brassinosteroids, and taxols, among others, have experimentally proven anticancer activities [53‐55].

It was also found that the most widely used part of the MPs was the leaf, and this finding agrees with previous reports [19, 42, 49, 52, 56‐62]. Naturally, the plants are surrounded by a series of potential threats, and evolutionarily, they have developed strategies of defense against the attacks of various pathogens (e.g., bacteria, viruses, fungi, nematodes, mites, insects), herbivores, and various kinds of abiotic stresses [63]. Therefore, plants produce ranges of organic compounds known as secondary metabolites, which a priori is not directly involved in their growth and development. Arguably, the leaves are exposed more to the enemies, and these chemicals, therefore, play a defensive role [64, 65]. Thus, an approach of using leaves as a major part of a plant for a remedy preparation could be taken as an indicator of scientific relevance. It also is noteworthy that zoopharmacognostic approach (observation of animal self-medication behavior) where animals consume mainly leaves of certain plants had led historically to the discovery of some aliphatic drugs, and this further establishes the preferential use of leaves as a source of TMs [66, 67]. Furthermore, harvesting aerial parts, such as leaves, poses less threat to the MPs when compared to exploiting the roots and barks, as also argued in other reports [42, 58, 68].

In the study area, all the TMs are said to be used preferably in their fresh forms, and this may compromise the sustainability of the MPs in the long run as it would be exploited extensively every time the remedy will have to be prepared. Other researchers [58, 69] have also expressed similar concerns.

Since the majority (64.7%) of the MPs collected from the study area were found in the wild habitats, the high risk of MP destruction by anthropogenic activities, on top of ensuing climate change, is a matter of serious concern. The anthropogenic activities driven by population growth are real and put pressure on natural resources. These include agricultural expansion, tree cutting for urbanization, house construction, firewood, fodder, drought, overgrazing, and charcoal making which serve as major threats to the MPs [46, 59, 70].

It was found that THs of the study area keep the MPs in strict secrecy and transfer their knowledge to their trustworthy elder sons only at an advanced age. This is a matter of concern because in the process, there might be misrepresentation, distortion, incompleteness, or omission of the original information as this is done orally [40, 52]. Though keeping the MPs away from the home gardens is believed to ensure the secrecy by the practitioners, it renders the MPs to grazing and unsustainable use [46]. Conversely, one report argues that keeping the MPs in strict secrecy contributed to sustaining the MPs [45], and it has an added advantage of safety against improper self-medication, which could be dangerous in the case of some plants.

The finding that 15.5% of the MP preparations were made by mixing two or more plants as a single remedy, could be explained by the assumption that a cocktail of plant material would be more effective in addition to maintaining the secrecy of the MPs. Furthermore, Megersa and co-workers [58] had reported that using such concoction is believed to increase the strength and efficacy of the remedy. Others have also argued that mixing two or more remedies helps to avoid or minimize possible side effect(s) [13].

The reports of the THs have also indicated the toxicity of some MPs, such as Hagenia abyssinica, a widely used anti-helminthic MP, which also was corroborated by other reports [35]. Reports from laboratory animal tests have shown that many reputable plants are medicinally used for centuries to have potential toxicity on blood parameters and histopathology of internal organs [71]. Therefore, it is recommendable that in vivo and in vitro toxicity investigations on the frequently used TMs must be conducted to avoid possible toxic effects of the MP reported in the present study.

Furthermore, one of the challenges identified by the present study was the inconsistency of the dosage from one preparation to the other even for the same kind of illness. However, in some cases, these variations are in relation to age, physical status, the course of illness, presence or absence of pregnancy, and other concomitant illness as also reported by earlier workers [42, 46, 50, 58]. Thus, the lack of precise dosage is one of the drawbacks of traditional medicine practices, as also emphasized by others [12, 72].

The community of the study area relies on mixed agricultural practices involving both crop farming and livestock rearing. Due to a shortage of farmland, farm expansion into the woodlands is affecting the vegetation cover and hence the MPs in the area. Furthermore, cattle, sheep, and goats compose main livestock reared in the area, and some of the MPs are collected as forage for the livestock, as also reported elsewhere, and goats are known to forage on open fields on various MPs [58]. Thus, the reality of existential threats to the sustainability of valuable MPs of the area is a serious one.

One of the greatest challenges in ethnomedicinal researches is the issue of access and benefit sharing (ABS). There have been attempts to implement ABS system of the Convention on Biological Diversity (CBD) in Ethiopia, taking into account the international obligations, including Nagoya Protocol, and other national considerations [73, 74]. The Nagoya Protocol, which came into effect on 12 October 2014, is an international legal tool that offers protection for traditional knowledge of medicines with the associated rights of indigenous communities [75]. Even though the country has acceded to the Nagoya Protocol and had developed a code of conduct to enforce the ABS provisions, there are several issues which demand thorough action [73]. These encompass, problems related to human resources and institutional capacity building, centralization system, lack of effective enforcement and follow up mechanisms, vagueness of the code of conduct, and lack of effective scheme for community participation in ABS [73, 74]. It would therefore be very appropriate to recommend enforcement of the Nagoya Protocol with all its international recommendations so that the TM knowledge and associated rights of the indigenous communities are fully protected. If this is addressed adequately, it will facilitate the proper documentation of valuable knowledge held by the TM practitioners and contribute to salvaging the loss of traditional herbal medicines.

The present study compiled the knowledge held by TM practitioners, in addition to assessing the ethnobotanical knowledge available in the public domain. Megera and adjacent kebeles have diverse MP species used to treat various human ailments. The present study has shown that the THs of the area have a rich knowledge of TM and that traditional herbal medicine is an integral part of the healthcare system. Due to very scarce modern healthcare facilities around Megera and the economic insufficiency of the community to meet the prices of available modern healthcare services, THs are the most reliable providers of healthcare services to the community.

The majority (64.7%) of the MPs are found in wild habitats where anthropogenic activities are advancing and hence are vulnerable for destruction. Therefore, sustainable integrated natural resource management system has to be put in place as soon as possible. Indigenous stewardship of the natural resource, including the TM plants, has to be documented and augmented with government and non-government environmental rehabilitation programs to conserve the vegetation of the area. Other plant use categories including foods and drinks, firewood, charcoal making, construction and tools, commercial, bee forage, fodder, shade, cultural rituals, ornamental, etc. must also be documented in order to enhance the conservation of these vital natural resources.

We recommend an in-depth experimental investigation of the frequently cited MPs believed by the THs to have high comparative advantages over others in treating various malignancies, jaundice, and helminthiases. This would possibly contribute to the current global drug development endeavors.