Ethnobotanical Survey of Medicinal Plants Used in the Management of Diabetes in Ibadan North-East and Ibadan South-East, Oyo State, Nigeria

Background: Diabetes mellitus, which is described to be a lifestyle disease, affects about 8.3% of the adult population of the world. Due to its alarming rate, it is one of the most common non-communicable diseases of current era. The burden of this disease is immense owing to transition in lifestyle and dietary habits, ageing of the population and urbanization in the setting of a genetically predisposed environment. Methodology: The study was aimed at documenting the knowledge of Traditional Medical Practitioners (TMPs) in Ibadan on ethnomedicinal plants used in the management of diabetes. A semi-structured questionnaire was used to obtain data from 100 TMPs and herb sellers within the study area. Data obtained was analysed using both descriptive statistics as well as quantitative ethnobotany including Use Mention Index, Use Value index and Fidelity level. Results:The total number of respondents from both study areas were 100, which were mainly females (94%) and most of them had no formal education. All respondents were Yoruba speaking. Results revealed 60 plants species belonging to 35 different families and 57 genera were cited by the respondents which they use in the management of diabetes. Hunteria umbellata is the most prominent plant species having the highest UMI reecting it popularity and ecacy in the management of diabetes in both areas. Fabaceae (23%) has the highest number of plants species followed by Apocynaceae (17%), Annonaceae (11%), Curcurbitaceae (11%) and Liliaceae (8%). The leaves (25%) were the most commonly used plant parts for the management of diabetes followed by fruits (22%) and Bark (13%).in that order. Conclusion: rich and these documented analysis of all the 60 antidiabetic medicinal plants of these plants have reported to have significant antidiabetic


Background
Ethno-botany has been de ned as the study as well as the investigation of traditional knowledge of indigenous communities about surrounding plant diversity and how various people make use of indigenous plants found in their localities [1]. Studies have demonstrated ethnobotany to be an effective tool in understanding the social cultural and economic factors that in uence decisions as regards health and illness within a community. It also aids in getting the right information on the types of diseases and health problems prevalent amongst the people of a particular locality.
. Ethnobotanical survey of plants traditionally used in the management of diabetes in different parts of Nigeria have been carried out by different authors [2,3,4,5,6,7]. These medicinal plants are used either alone as a primary therapeutic choice, or in conjunction with conventional medicines.
Since plants are rich sources of medication, information about them are obtained based on the rich experiences of innumerable healers over centuries inherited from ancestors, healer-to-healer transfer or developed through personal experience over time or apprenticeship under those versatile with this knowledge. This information is obtained using different techniques such as the use of questionnaires, interview, voice recording, etc.
In ancient times, the primitive man observed and appreciated the great diversity of plants available to him. Herbs had been used by all cultures for the treatment and management of diabetes mellitus [8;9] which was an integral part of the development of modern civilization. Hence, herbal medicines continue to play signi cant role in diabetic therapy as well as alternative to conventional therapy, most especially in the developing nations where most people are resource-poor and with little or no access to modern treatment [10].
Currently available therapy for diabetes includes insulin and various oral hypoglycaemic agents such as sulfonylureas, biguanides, thiazolinediones, glinides and α-glucosidase inhibitors [11]. These are known to produce serious adverse effects, are not easily affordable and are not readily available [12,13] There is no effective cure for diabetes mellitus; this has resulted in the dependency on medicinal plants by majority of the populace for their primary health care needs [14,15,16], since they pose less side effect, are effective, readily accessible and affordable. Hence, the search for traditional or alternative medicinal plants which are safe and effective is ongoing [17]. The WHO (World Health Organization) recommended the search for medicinal plants that are effective and bene cial for the treatment of Diabetes Mellitus as well as their use in the management of diabetes mellitus. This act encourages the expansion of the frontiers of scienti c evaluation of hypoglycaemic properties of diverse plant species [18]. Thus, there is the need to isolate, identify, characterize and screen these bioactive chemicals responsible for the therapeutic effects seen.  [20,21,24] Diabetes Mellitus (DM) is a group of metabolic disorders characterized by a chronic hyperglycemic condition resulting from absolute or relative de ciency in secretion, insulin action or both. It can also be said that diabetes is due to autoimmune antibody induced destruction of insulin secreting β-cells of pancreatic islets of Langerhans or from resistance to insulin release from β-cells as well as desensitization of peripheral tissue to insulin and down regulation of insulin receptors [25][26][27] It is accompanied by greater or lesser impairment in the metabolism of carbohydrates, lipids and proteins. It could result in abnormal high amounts of glucagon and other counter regulatory hormones such as growth hormone, sympathomimetic amines and corticosteroids [28] The World Health Organization projects, that diabetes will be the 7th leading cause of death by the year 2030 [29].
In USA, diabetes is now the leading cause of end stage renal disease (ESRD). Other complications such as cardiovascular disease including coronary heart disease (CHD), cerebrovascular disease (CVD) or stroke and peripheral vascular disease (PVD) are the common causes of morbidity and mortality among people with diabetes [30][31][32][33][34].
In Africa, 19.8 million dwellers suffered from diabetes in 2013 and this is expected to rise to 41.5 million by 2035 [35]. Reports have it that the disease is on the increasing trend with more than 80% cases of death coming from low and middle income countries.
In Nigeria, one third of all the cases of diabetes are known to occur in rural communities, while the rest are in the urban centres. Nigeria has the highest burden in Africa, followed by South Africa with 2.6 million cases, Ethiopia 1.9 million, and Tanzania 1.7 million in 2013. Another study, found that about 4.7 million Nigerians aged between 20 and 79 years had type 2 diabetes [36].
The emotional and social impact of Diabetes Mellitus and demand therapy may result in signi cant psychosocial dysfunction in patients and their families. Poorly controlled diabetes would aggravate the risk of diabetes complications, particularly cardiovascular diseases. The clinical coups and prognosis for diabetic patients are in uenced predominantly by the duration of the disease and degree of metabolic control exercised (37).
According to WHO, it was estimated that 3% of the world's population have diabetes and the prevalence is expected to double by the year 2025 to 6.3% [38,39].
The rise in prevalence rate is as a result of aging of the population, rapid urbanization, westernization and their associated lifestyle changes, nutritional status, high family aggregation, increase in life expectancy at birth, physical inactivity and obesity and possibly a genetic predisposition [40][41][42]. The prevalence of diabetes mellitus in Nigeria increased from 2.2% in 1997 to 5.0% in 2013 [43]. The incidence of type 2 Diabetes Mellitus varies substantially from one geographical region to the other as a result of environmental and lifestyle risk factors [44].

Study area
The study was carried out in Bode and Oje markets in Ibadan, Oyo state, Nigeria; which are located in Ibadan South-East and Ibadan North-East respectively ( Figure 1). Ibadan falls within latitude 7.40N and longitude 3.91E [45,46]. The city ranges in elevation from 160 m in the valley area, to 275 m above sea level on the major north-south ridge which crosses the central part of the city. The city covers a total area of 3,080 square kilometres (1,190 sq mi) in geographical size, the largest in Nigeria [47]. The Yoruba people are the main inhabitant of this popular city, as well as various communities from other parts of the country. There are eleven (11) Local Governments in Ibadan Metropolitan area consisting of ve urban local governments in the city [48] and six semi-urban local governments in the fewer cities.
The city of Ibadan is naturally drained by four rivers with many tributaries: Ona River in the North and West; Ogbere River towards the East; Ogunpa River owing through the city and Kudeti River in the Central part of the metropolis.
Ogunpa River, a third-order stream with a channel length of 12.76 km and a catchment area of 54.92 km. Lake Eleyele is located at the northwestern part of the city, while the Osun River and the Asejire Lake bounds the city to the east [49,50].

Data collection
The ethnobotanical survey was conducted between June and October, 2018 to document the knowledge of respondents on medicinal plants and the parts used in the management of diabetes in Ibadan North-east and Southeast, Oyo state, Nigeria. The data collection was based on oral interview with the aid of a semi-structured questionnaire. Ethical approval was obtained from the community leaders before the study and informed consent was also obtained orally from each of the respondent, before interview was made. Since most of the respondents were not educated, oral interview was adopted to obtain the relevant ethno-botanical data. The criteria proposed by Willcox for the conduct of a good ethnobotanical survey were observed [51].
The targeted population for this study comprises mainly Traditional Health practitioner, herb sellers, and few individuals with claims of medicinal plant knowledge. The interviews were done in their native language (Yoruba language) for clarity; while the information gathered was sorted, the data collected included the local names of plants and parts of the plants used. Plant specimens indicated in the recipe were photographed, collected, identi ed and authenticated using their local names by a botanist. Voucher specimens were prepared for all plants and deposited at the herbarium unit of the Department of Pharmacognosy, University of Ibadan, Nigeria.

Ethical Issues
In Nigeria, there are no existing regulations guiding the collection of data from informants on the use of plants in Traditional Medicine. However, all informants interviewed in this study gave oral informed consent following the description of the purpose of the research to them. In other words, informants showed voluntary willingness to participate in the study and they were allowed to discontinue the interviews at any time.

Ethnobotanical analysis
Data obtained were analyzed using both descriptive and quantitative statistics such as pie chart, tables, frequency of citation (FC), use mention index and expressed as a percentage based on taxonomic diversity, habitat and parts of the plant used to manage Diabetes. The frequency of citation, FC [52] was used to quantify indigenous antidiabetic plant species with the highest citation relative to other plant species cited. The FC is the value obtained from the number of times a particular species was mentioned (N s unit) divided by the total number of times that all species were mentioned (T s total) multiplied by 100.
Mathematically, FC = (N s unit)/(T s total) *100; where "N s unit" represents the number of times a particular species was mentioned and "T s total" is the total number of times that all species were mentioned The questionnaire data were also analyzed using the 'use-mention-index' (UMI) which has been de ned as the number of mentions for one plant (UM) for diabetes treatment, divided by the total number of informants interviewed for antidiabetes phytomedicine (nu) [6]. This was applied to compare the survey data for all documented antidiabetic plants.

Results And Discussion
The antidiabetic activity of Nauclea latifloria and Moringa oleifera have been validated scientifically [73][74][75][76]. There have been experimental evidences for the hypoglycemic activity of these medicinal plants, in experimental model of diabetes [58].
Quantitative analysis of survey data showed that the Fabaceae and Apocynaceae families have the highest Frequency of citation and Use mention indices which reflects the antidiabetic medicinal value of the 14-plant species mentioned under these two high scoring plant families. Their application in the traditional medicine of the study areas may be related to their availability, accessibility, their edibility and low carbohydrate content. For instance, legumes, a sub-family of Fabaceae are largely known to be very edible, high in protein, low in carbohydrate and interestingly have a low glycemic index [77]. In Map showing the areas of study; Bode, located in Ibadan South-East and Oje in Ibadan North-East Percentage distributionn of various plant part(s) used in preparation of anti-diabetic recipes.

Figure 3
Percentage distribution according to family of plants used in the management of diabetes